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SLS / Orion / Beyond-LEO HSF - Constellation => Heavy Lift Launch Vehicle (HLV/SLS) => Topic started by: Chris Bergin on 10/05/2011 04:19 am

Title: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 10/05/2011 04:19 am
http://www.nasaspaceflight.com/2011/10/sls-trades-opening-four-rs-25s-core-stage/

At least two more articles to come on SLS hardware. Starting to feel like the "good old days" of shuttle processing level of content to write up in L2.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: alexw on 10/05/2011 04:34 am
http://www.nasaspaceflight.com/2011/10/sls-trades-opening-four-rs-25s-core-stage/
At least two more articles to come on SLS hardware. Starting to feel like the "good old days" of shuttle processing level of content to write up in L2.

   Are they planning *two* complete new NASA-only upper stages?
    1) the "CPS", "NASA designed on-orbit stage... Enables Exploration missions", to be used for Block 1A+
    2) the "Upper Stage", with 3 * J-2X, "This Upper Stage burns out prior to orbit insertion (ala Saturn V)."

    plus, additionally,
    0) "iCPS", the DIVHUS with new avionics, "Requires Delta IV flight computer redesign."

                ?
              -Alex
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 10/05/2011 04:39 am
Noting they are trading (I feel like I have to keep saying that) the Block II shown on the presentation has a 3xJ-2X Upper Stage, with the CPS on orbit stage on top inside the fairing.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jason1701 on 10/05/2011 04:43 am
Quote
the automatic need for the core to be “stretched” – based on the five segment boosters on the configuration

Didn't DIRECT have some configurations that were Heavy (meaning 5-seg) but not Stretched?

How much clearance will there be between the top of the Block II and the ceiling of the VAB?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 10/05/2011 04:46 am
Direct had lots of configs, including four segs, if memory serves :)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: alexw on 10/05/2011 05:14 am
Quote
the automatic need for the core to be “stretched” – based on the five segment boosters on the configuration
Didn't DIRECT have some configurations that were Heavy (meaning 5-seg) but not Stretched?
      Yes, and the SRB would have attached at the second-segment from the top rather than the first, IIRC, as Shuttle had proposed had it gone to 5-segs. Chris, by use of the word "need" above, do your sources suggest that this config by DIRECT & SSP was judged technically infeasible?

Quote
How much clearance will there be between the top of the Block II and the ceiling of the VAB?
     Good question. And by how much will the stretched core stage clear the MAF doors?
          -Alex
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: aquanaut99 on 10/05/2011 05:42 am
Noting they are trading (I feel like I have to keep saying that) the Block II shown on the presentation has a 3xJ-2X Upper Stage, with the CPS on orbit stage on top inside the fairing.

So the full-up SLS-Block II is actually a 3 stage rocket plus boosters? Am I reading this right?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jamie Young on 10/05/2011 06:09 am
Core with boosters. Second Stage (Upper Stage) and EDS, right?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: FinalFrontier on 10/05/2011 06:58 am
Those liquids sure look like Atlas V CCBs ;)  ;)  ;)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: sdsds on 10/05/2011 07:30 am
Would it be OK to call it "LV 27"?

http://www.nasa.gov/pdf/140637main_ESAS_06.pdf
Page 420 (60 of 150 in the pdf).

Wait, that can't be right.  That was the plan back in November of 2005....
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Tez on 10/05/2011 07:47 am
Quote
     Good question. And by how much will the stretched core stage clear the MAF doors?
          -Alex

About 11ft, taking door height as 122m (400ft) and block 2 as 389ft.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MP99 on 10/05/2011 07:51 am
Noting they are trading (I feel like I have to keep saying that) the Block II shown on the presentation has a 3xJ-2X Upper Stage, with the CPS on orbit stage on top inside the fairing.

Broken record, but I still wonder how this really meets the requirements of PL 111-267:-

Quote
(1) IN GENERAL.—The Space Launch System developed pursuant to subsection (b) shall be designed to have, at a minimum, the following:

(A) The initial capability of the core elements, without an upper stage, of lifting payloads weighing between 70 tons and 100 tons into low-Earth orbit...

(B) The capability to carry an integrated upper Earth departure stage bringing the total lift capability of the Space Launch System to 130 tons or more.

...given that the upper & EDS functions are separated into two different stages rather than integrated.

cheers, Martin
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: uko on 10/05/2011 08:09 am
Great article Chris, thanks!

I wonder what will the crew configuration look like after Block 1?
What kind of upper stage will it have?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MP99 on 10/05/2011 08:17 am
Noting they are trading (I feel like I have to keep saying that) the Block II shown on the presentation has a 3xJ-2X Upper Stage, with the CPS on orbit stage on top inside the fairing.

So the full-up SLS-Block II is actually a 3 stage rocket plus boosters? Am I reading this right?

Given CPS doesn't burn during ascent, I don't believe it's a true third stage. That makes SLS a LEO-only vehicle, but CPS can be optimised for longer loiter. For instance, refer Mars DRA 5 for CPS's heritage as a modified AVUS (but using RL-10s instead of J-2X in order to provide the required Isp).

Given also that Block 2's upper stage is disposed of sub-orbitally, the upper stage won't require a restart. ISTM using 2x air-start RS-25 instead of 3x J-2X would be quite suitable in this application, and would increase commonality between core and upper stage (refer HEFT2.pdf).

cheers, Martin
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ben the Space Brit on 10/05/2011 08:56 am
Noting they are trading (I feel like I have to keep saying that) the Block II shown on the presentation has a 3xJ-2X Upper Stage, with the CPS on orbit stage on top inside the fairing.

That's what I call the SLS-SH configuration (the 3 x SSME being the SLS-M, the 4 x SSME being the SLS-H).  That's pretty much intended to be a one-launch lunar cargo version, much like how Ares-V was intended to be towards the end of the CxP era.

Given CPS doesn't burn during ascent, I don't believe it's a true third stage. That makes SLS a LEO-only vehicle, but CPS can be optimised for longer loiter. For instance, refer Mars DRA 5 for CPS's heritage as a modified AVUS (but using RL-10s instead of J-2X in order to provide the required Isp).

I've suspected for a while that talking about SLS's BEO performance was a red herring.  The type is an LEO cargo launcher - Only its' payload will perform escape burns, not any part of the launch vehicle itself.

That said, I wonder if it is possible for CPS to act as a third stage.  That might push up the payload throw if required.  I'm sure there is a 'sweet spot' balance that allows CPS to be used on ascent but still allows optimum escape burn performance.

Just out of interest, has there been even the slightest hypothetical discussion of using J-2XD instead of RL-10 on CPS? That would increase commonality across both SLS and BEO spacecraft applications.

I wonder what will the crew configuration look like after Block 1?
What kind of upper stage will it have?

It won't need one.  Indeed, the SLS-CLV will probably have a ballast drum in place of the DIVUS in the faux-Apollo PLF just so the crew won't be pulped by the g-loadings from launching a < 30t crew vehicle on a 100t IMLEO launcher.



[edit]
Added reply to Uko
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: mike robel on 10/05/2011 12:42 pm
Good article Chris.  Most imformative.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mark S on 10/05/2011 12:56 pm
Noting they are trading (I feel like I have to keep saying that) the Block II shown on the presentation has a 3xJ-2X Upper Stage, with the CPS on orbit stage on top inside the fairing.

Broken record, but I still wonder how this really meets the requirements of PL 111-267:-

Quote
(1) IN GENERAL.—The Space Launch System developed pursuant to subsection (b) shall be designed to have, at a minimum, the following:

(A) The initial capability of the core elements, without an upper stage, of lifting payloads weighing between 70 tons and 100 tons into low-Earth orbit...

(B) The capability to carry an integrated upper Earth departure stage bringing the total lift capability of the Space Launch System to 130 tons or more.

...given that the upper & EDS functions are separated into two different stages rather than integrated.

cheers, Martin

Yes, I have been asking the same question for a while now, and get nothing back but stony silence.

How does a separate CPS fit in the PL 111-267? It is nowhere to be found, and the SLS therein requires "an integrated upper Earth departure stage", not a dedicated second stage and a dedicated in-space stage. Especially when the funds for CPS are to be taken from the SLS budget, and when CPS is being set up as a completely separate project from SLS. Sounds like illegal diversion of funds to me.

Sorry, this just looks like the same old MSFC gigantism fetish all over again. And a lot of responsibility for that lies with the Senate and House, who both had plenty of opportunities to clarify that "tons" in the law's language refers to short tons (2000 lbs), not metric tonnes. And that "total lift capability" means IMLEO, not usable payload capacity. Those two ambiguities in the law gave the gigantists the wiggle room they needed to turn a reasonable J-130/J-241H back into Ares-V (ESAS LV-27).

Unless this approach is reversed, I don't see how SLS will be able to fit within the given budget. Sigh.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ben the Space Brit on 10/05/2011 01:05 pm
How does a separate CPS fit in the PL 111-267? It is nowhere to be found, and the SLS therein requires "an integrated upper Earth departure stage", not a dedicated second stage and a dedicated in-space stage. Especially when the funds for CPS are to be taken from the SLS budget, and when CPS is being set up as a completely separate project from SLS. Sounds like illegal diversion of funds to me.

I think that this is a case where "Practicable" rears its head.  Given that J-2X is ETO-optimised it may not be possible to abide by that clause of the Act.  As matters go, I don't think that this is a serious issue and it actually makes SLS more flexible as you optimise the upper stage for IMLEO performance and have an BLEO-optimised propulsion module if needed.

Just a thought: Delete the SLS upper stage, attach the CPS directly to the four-engine core and this should be sufficient for orbital missions to LLO or the EML points.  This isn't a capability that is currently required but so little of SLS utilisation is set in stone right now that it might emerge eventually.


[edit]
Corrected typos
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: aquanaut99 on 10/05/2011 01:08 pm
Unless this approach is reversed, I don't see how SLS will be able to fit within the given budget. Sigh.

Simple, by deferring Block II to never-never land. After all, the law only requires the rocket to be upgradable to 130 mT, not the 130 mT version actually flying, no? I thought only the 70 mT (Block I) has a law-mandated deadline?

We could already do plenty with Block I SLS alone. And Block IA with a good CPS could cover virtually all our HSF needs for the next 30 years at least, since I can't see any manned Mars mission (which would require Block II) before that time-frame anyway.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: demorcef on 10/05/2011 01:20 pm
Fantastic article Chris!  Another stellar piece of journalism from you.  It really makes me feel good to see real progress being made.  I hope the funding keeps up with the designs this time.  There might actually be light at the end of the sad tunnel we have been stuck in these past few years.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Rocket Science on 10/05/2011 03:02 pm
Great article Chris, loaded with information. I am curious if they will create a mock up of SLS as a design study. Although it is not needed with today’s computer aided design, it would go a long way if placed on display to the public for PR value and future funding. Gives the politicos some nice photo ops ;)

Regards
Robert
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/05/2011 03:20 pm
Great article Chris, loaded with information. I am curious if they will create a mock up of SLS as a design study. Although it is not needed with today’s computer aided design, it would go a long way if placed on display to the public for PR value and future funding. Gives the politicos some nice photo ops ;)

Regards
Robert

Not needed?  CAD does not give ground crews chance to practice, to test operations.  Only a pathfinder, a full sized mockup, allows for that.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 10/05/2011 03:25 pm
Thanks Uko, Mike, Demo and RS!

This is more technical than the next article - and needed to turn it around, but the next one will be via the wonderful industry presentation (which wasn't released for some reason, but we got it for L2), which includes what they want to do with SLS and lots of pretty pictures :)

That'll be another baseline level article for SLS. Might need to write that over a few days.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mr. Justice on 10/05/2011 03:53 pm
This is just a great disappointment. There are no missions of any substance in the planning: flying by and waving at the Moon is not a real mission. It is 51 years after the Apollo 8 mission proving that we cannot match that mission's abilities.

Seriously, there is no rational to spending the better part of the next two decades developing and redeveloping the SLS. Particularly when the principle reason for this is to reach the arbitrary 130 ton requirement. At this stage, keep the 5 segment boosters and make a decision if they should be recovered based solely on a cost benefit analysis. The core can be stretch from the start and fly with five RS-25 engines. The upper stage can be developed in parallel with the core. The only thing necessary to determine is the size and how many engines, perhaps the possibility of designing it to fly with one or three engines.

No need to spend time and money on multiple upper stages nor on multiple boosters and, well, we can actually accomplish something other than rocket building.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lurker Steve on 10/05/2011 03:57 pm
Did I read correctly that the current 5-Seg SRB design will only be used for the first 2 flights ?

After that, ATK has a more "advanced" design, or we switch to LRBs.

So that means we will have fired this design of the 5-Seg SRB more times on the ground than actually used as a booster.

Who pays for the development of this new ATK design ?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 10/05/2011 03:59 pm
This is just a great disappointment. There are no missions of any substance in the planning: flying by and waving at the Moon is not a real mission. It is 51 years after the Apollo 8 mission proving that we cannot match that mission's abilities.

It's been noted more times than I can remember that the mission planning is in work, via Mr Shannon :)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/05/2011 04:02 pm
Did I read correctly that the current 5-Seg SRB design will only be used for the first 2 flights ?

After that, ATK has a more "advanced" design, or we switch to LRBs.

So that means we will have fired this design of the 5-Seg SRB more times on the ground than actually used as a booster.

Who pays for the development of this new ATK design ?
No difference than the 2 and 3 segment SRB's, or the ASRM's, all of which have had ground testing, but none launched.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: marsavian on 10/05/2011 04:04 pm
Unless this approach is reversed, I don't see how SLS will be able to fit within the given budget. Sigh.

Simple, by deferring Block II to never-never land. After all, the law only requires the rocket to be upgradable to 130 mT, not the 130 mT version actually flying, no? I thought only the 70 mT (Block I) has a law-mandated deadline?

We could already do plenty with Block I SLS alone. And Block IA with a good CPS could cover virtually all our HSF needs for the next 30 years at least, since I can't see any manned Mars mission (which would require Block II) before that time-frame anyway.

That's probably how it will pan out. Lunar and NEO can be done with Block 1A/CPS but any Mars or Martian Moon missions will take Block 2 as the reference hardware and that will be developed along with mission modules in the $3+bn budget. I suppose it's all part of ensuring the use of all the CxP hardware in development, the J-2X will be developed and then parked until the upper stage can be developed in the fixed budget.

The 130mT Block 2 was obviously the line at which Congress, especially the House, drew the line at giving up CxP hardware i.e. we will sacrifice Ares I but we want at least an Ares V Classic class HLV. The politics of compromise ;). Maybe the Lunar drive-by missions will get political/public interest up and additional funds may follow to speed up mission module hardware, perhaps from the ending of ISS involvement. Considering how far apart the politicians and space community were originally this may not a bad compromise for everybody in achieving the final goal of manned Martian exploration but agreed compromises never please everybody entirely just upset them the least ;).
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 10/05/2011 04:07 pm
Did I read correctly that the current 5-Seg SRB design will only be used for the first 2 flights ?

After that, ATK has a more "advanced" design, or we switch to LRBs.

So that means we will have fired this design of the 5-Seg SRB more times on the ground than actually used as a booster.

Who pays for the development of this new ATK design ?

Yep, at this moment, the Ares Five Seg gets two flights. I know what you're getting at, not great value for a billion dollars of dev, but the alternative was absolutely nothing for a billion dollars of dev, so this is still a better situation. They may yet keep it flying through SLS-3 to 5 whatever, but those "Oh, we have to have a competition" funsters are the reason it may only see two flights.

It's worth noting to people who seem to point at ATK costs for a "new design" (note I've already reported, and it was linked in this article**, about the potential route to improve the ATK booster) that they also need to ask the same questions going to be asked about all that testing and dev of the Liquid boosters?

**
Quote
This example, provided to the RAC Team 1 at Marshall, proposes the change to a HTPB (Hydroxyl-terminated polybutadiene) fueled solid in “composite over wrapped steel cases” to allow higher MEOP (Maximum Expected Operating Pressure) – to as much as 1500 psi.

There are also proposals to use lighter weight nozzles with expansion ratios up to 12:1.....
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Rocket Science on 10/05/2011 04:10 pm
Great article Chris, loaded with information. I am curious if they will create a mock up of SLS as a design study. Although it is not needed with today’s computer aided design, it would go a long way if placed on display to the public for PR value and future funding. Gives the politicos some nice photo ops ;)

Regards
Robert

Not needed?  CAD does not give ground crews chance to practice, to test operations.  Only a pathfinder, a full sized mockup, allows for that.
I'm with you Nate ;) A low fidelity Pathfinder "Battleship" will be used for that. I'm saying a high fidelity mock-up for display. Even though CATIA software is powerful if that is what they may use…
Regards
Robert
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mr. Justice on 10/05/2011 04:29 pm
This is just a great disappointment. There are no missions of any substance in the planning: flying by and waving at the Moon is not a real mission. It is 51 years after the Apollo 8 mission proving that we cannot match that mission's abilities.

It's been noted more times than I can remember that the mission planning is in work, via Mr Shannon :)

Yes, the problem is it appears it is more of the old "don't call us, will call you line." It is an eternal wait. The real problem is if we keep spending money designing and redesigning the SLS that is money that cannot be spent on an LSAM or crew modules or the actual cost of a mission.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: aquanaut99 on 10/05/2011 04:33 pm
That's probably how it will pan out. Lunar and NEO can be done with Block 1A/CPS but any Mars or Martian Moon missions will take Block 2 as the reference hardware and that will be developed along with mission modules in the $3+bn budget. I suppose it's all part of ensuring the use of all the CxP hardware in development, the J-2X will be developed and then parked until the upper stage can be developed in the fixed budget.

Yes.

I predict the Block I will fly more than twice (maybe up to 4 times, since there are apparently about 16 RS-25Ds available, which would allow for 4 flights).

So that already puts us into the 2023 - 2025 timeframe before we get Block IA. Plenty of time for political / mission focus shifts.

As for the block IA, I predict we'll keep that at least until 2035.

Finally, I predict that after the first two Block I flights with the current 5-segs, we will get an evaluation between different "Advanced Booster Options" (as planned), but in the end, they'll most likely stick with the ATK 5 seg boosters, for cost reasons, (unless some very effective and cheap LRBs become available or unless the 5 segs fail completely), with a vague promise of some sort of "improved booster" somewhere down the road. Just like with Shuttle, which was supposed to replace the RSRBs with something new (ASRB, 5-segs, even LRBs) several times during its lifetime...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 10/05/2011 05:00 pm
This is just a great disappointment. There are no missions of any substance in the planning: flying by and waving at the Moon is not a real mission. It is 51 years after the Apollo 8 mission proving that we cannot match that mission's abilities.

It's been noted more times than I can remember that the mission planning is in work, via Mr Shannon :)
It shows where the real priorities are when the actual mission planning (and hardware, etc) is practically an afterthought compared to the launch vehicle.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Namechange User on 10/05/2011 05:06 pm
This is just a great disappointment. There are no missions of any substance in the planning: flying by and waving at the Moon is not a real mission. It is 51 years after the Apollo 8 mission proving that we cannot match that mission's abilities.

It's been noted more times than I can remember that the mission planning is in work, via Mr Shannon :)
It shows where the real priorities are when the actual mission planning (and hardware, etc) is practically an afterthought compared to the launch vehicle.

Where were your mission plans (and hardware, etc) for anything without SLS?  They had years.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 10/05/2011 05:19 pm
This is just a great disappointment. There are no missions of any substance in the planning: flying by and waving at the Moon is not a real mission. It is 51 years after the Apollo 8 mission proving that we cannot match that mission's abilities.

It's been noted more times than I can remember that the mission planning is in work, via Mr Shannon :)
It shows where the real priorities are when the actual mission planning (and hardware, etc) is practically an afterthought compared to the launch vehicle.

To be fair they had it, with the flexible path, which replaced the VSE, with a nice amount of flexibility on the LV (I think they mainly used an Ares V for that....and we're not a million miles off with SLS on that score).

I'm as frustrated with the next man on mission content, but I think the big problem is if they had designed the missions say two years ago, then they'd probably be redoing them now based on the latest budget cycles and such. Not sure, but I bet there would be some people saying "HA, you've created missions and you don't even have a LV yet".

We're not launching SLS any time soon, so Mr Shannon has everything he needs, the LV design, the crew capsule design, the latest budget projects and the time to - I'm sure - work his magic, as he's (Dr Evil voice) "a fricking genius" ;D
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/05/2011 05:24 pm

Maybe the Lunar drive-by missions will get political/public interest up and additional funds may follow to speed up mission module hardware, perhaps from the ending of ISS involvement. Considering how far apart the politicians and space community were originally this may not a bad compromise for everybody in achieving the final goal of manned Martian exploration but agreed compromises never please everybody entirely just upset them the least ;).

Especially if we could do the Apollo 8 redux on the 50th Anneversary of Apollo 8, Dec 2018.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: sewand on 10/05/2011 05:33 pm
The Block 1A upper stage is interesting - is this going to be ACES-like?  Any idea how much 1A can push through TLI?   
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: ChileVerde on 10/05/2011 06:08 pm
We're not launching SLS any time soon, so Mr Shannon has everything he needs, the LV design, the crew capsule design, the latest budget projects and the time to - I'm sure - work his magic, as he's (Dr Evil voice) "a fricking genius" ;D

Does Mr. Shannon's remit include defining in some detail what the crew is going to do once it gets wherever the DRMs say they're going? Or is that part to be supplied separately by the National Academies study?  Or (which would seem to make sense) is Mr Shannon going to coordinate with the National Academies in working all this out?

E.g., DRM 13.3 sends four people to Deimos and Phobos where they will stay for X weeks. NA says, "And while they're there, they will conduct studies S1 - S37."
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 10/05/2011 07:08 pm
Good question, Chile. We did ask Mr Shannon for an interview (main angle reflecting on Shuttle), but he refused....

....well PAO said he did, which is probably more to do with them than anything.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 10/05/2011 08:18 pm
It is an eternal wait.

It hasn't even been a month.  Give him some time.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 10/05/2011 10:22 pm
This is just a great disappointment. There are no missions of any substance in the planning: flying by and waving at the Moon is not a real mission. It is 51 years after the Apollo 8 mission proving that we cannot match that mission's abilities.

It's been noted more times than I can remember that the mission planning is in work, via Mr Shannon :)
It shows where the real priorities are when the actual mission planning (and hardware, etc) is practically an afterthought compared to the launch vehicle.

Where were your mission plans (and hardware, etc) for anything without SLS?  They had years.
Your question is off-topic, but one example:
http://www.nasaspaceflight.com/2009/09/ula-claim-gap-reducing-solution-via-eelv-exploration-master-plan/
Another:
http://ti.arc.nasa.gov/m/project/neo/pdf/neo_crewed_mission.pdf
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 10/05/2011 10:25 pm
Good question, Chile. We did ask Mr Shannon for an interview (main angle reflecting on Shuttle), but he refused....

....well PAO said he did, which is probably more to do with them than anything.
Well, I'd certainly be interested in an interview, especially if it focused on the mission studies!
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mr. Justice on 10/05/2011 10:31 pm
It is an eternal wait.

It hasn't even been a month.  Give him some time.

No, it has been 20 months since the cancellation of Constellation. Constellation had a mission. It's downfall was Ares. Had we simply modified Ares, in conjunction with commercial crew for LEO, into something more like Jupiter we would be set to return to the Moon. Jupiter could have supplied fuel to eventual depots for NEO missions and then Mars.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 10/05/2011 11:15 pm
I know all that.  The problem is that now that we're finally moving forward, and we've actually got people assigned to mission design, you almost instantly claim that it's taking forever.  You're ignoring actual facts and recent events in favour of averaging over the last couple of years.

It reminds me of the people who were complaining that ISS research hadn't changed the world, and that therefore the whole thing was a waste of money, about five minutes after we finished building the thing...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jason1701 on 10/05/2011 11:24 pm
Quote
the automatic need for the core to be “stretched” – based on the five segment boosters on the configuration
Didn't DIRECT have some configurations that were Heavy (meaning 5-seg) but not Stretched?
      Yes, and the SRB would have attached at the second-segment from the top rather than the first, IIRC, as Shuttle had proposed had it gone to 5-segs. Chris, by use of the word "need" above, do your sources suggest that this config by DIRECT & SSP was judged technically infeasible?

Can any DIRECT people clarify this?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Pheogh on 10/05/2011 11:40 pm
Quote
the automatic need for the core to be “stretched” – based on the five segment boosters on the configuration
Didn't DIRECT have some configurations that were Heavy (meaning 5-seg) but not Stretched?
      Yes, and the SRB would have attached at the second-segment from the top rather than the first, IIRC, as Shuttle had proposed had it gone to 5-segs. Chris, by use of the word "need" above, do your sources suggest that this config by DIRECT & SSP was judged technically infeasible?

Can any DIRECT people clarify this?

I don't believe it has anything to do with technical feasibility. Ultimately what we are seeing is the influence of ATK having a cascading affect. DIRECT ultimately arrived at a 4 engine max config meaning standard ET volumes were adequate, meaning a stretch was not necessary and neither was 5 seg. DIRECT was always optimized for cost, starting from the 5/5 baseline you have already canceled out this optimization. The tail is wagging the dog and that is never a good position to be trading from IMHO.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/06/2011 12:23 am
Quote
the automatic need for the core to be “stretched” – based on the five segment boosters on the configuration
Didn't DIRECT have some configurations that were Heavy (meaning 5-seg) but not Stretched?
      Yes, and the SRB would have attached at the second-segment from the top rather than the first, IIRC, as Shuttle had proposed had it gone to 5-segs. Chris, by use of the word "need" above, do your sources suggest that this config by DIRECT & SSP was judged technically infeasible?

Can any DIRECT people clarify this?

I don't believe it has anything to do with technical feasibility. Ultimately what we are seeing is the influence of ATK having a cascading affect. DIRECT ultimately arrived at a 4 engine max config meaning standard ET volumes were adequate, meaning a stretch was not necessary and neither was 5 seg. DIRECT was always optimized for cost, starting from the 5/5 baseline you have already canceled out this optimization. The tail is wagging the dog and that is never a good position to be trading from IMHO.
Even with the 5-segment, the core stretch is not necessary.  You can either lift from the bottom, or you can make the attachment point above the LOX dome at the top of the core.  Either option allows you to have a much lighter core structure.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: sdsds on 10/06/2011 12:40 am

Even with the 5-segment, the core stretch is not necessary.  You can either lift from the bottom, or you can make the attachment point above the LOX dome at the top of the core.  Either option allows you to have a much lighter core structure.

You're sure the thrust oscillations from the solids can be transferred down into (and thus dampened by) the mass of the LOX?  Is there some obvious structural mechanics proof of this?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/06/2011 12:49 am

Even with the 5-segment, the core stretch is not necessary.  You can either lift from the bottom, or you can make the attachment point above the LOX dome at the top of the core.  Either option allows you to have a much lighter core structure.

You're sure the thrust oscillations from the solids can be transferred down into (and thus dampened by) the mass of the LOX?  Is there some obvious structural mechanics proof of this?
It was a solution studied back in the late 80's, but I have no idea if they had worked on any solutions to the TO.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Herb Schaltegger on 10/06/2011 01:22 am
You're sure the thrust oscillations from the solids can be transferred down into (and thus dampened by) the mass of the LOX?  Is there some obvious structural mechanics proof of this?

To a first approximation, the whole thing is just a spring-mass system.  However, the ever-shrinking mass of the core stage complicates things.  Find yourself an engineering grad student and have them figure it out.  Shouldn't take them very long.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Namechange User on 10/06/2011 02:56 am
This is just a great disappointment. There are no missions of any substance in the planning: flying by and waving at the Moon is not a real mission. It is 51 years after the Apollo 8 mission proving that we cannot match that mission's abilities.

It's been noted more times than I can remember that the mission planning is in work, via Mr Shannon :)
It shows where the real priorities are when the actual mission planning (and hardware, etc) is practically an afterthought compared to the launch vehicle.

Where were your mission plans (and hardware, etc) for anything without SLS?  They had years.
Your question is off-topic, but one example:
http://www.nasaspaceflight.com/2009/09/ula-claim-gap-reducing-solution-via-eelv-exploration-master-plan/
Another:
http://ti.arc.nasa.gov/m/project/neo/pdf/neo_crewed_mission.pdf

Strange that it would be "off-topic" when it was a direct response to something you decided to bring up. 

But I'll address your examples rather easily.  Those are papers.  One of which is by a company and it is fairly common practice for companies to produce such white papers to show what capabilities they have or could provide for NASA.  They are marketing tactics mostly to help inform the agency. 

In other words those are a far cry from policy and a plan that NASA adopts formally.  That is what has been missing and that is the hole in your argument that is the size of SLS. 
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RyanC on 10/06/2011 05:27 am
The first escalations occur....soon my pretties, soon we will have ARES V again...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Khadgars on 10/06/2011 05:39 am
Quote
Designating the launch vehicle requirements (for a new launch vehicle) before having the mission scope/policy/plan/blah done is bass-ackwards. That I pointed that out is not off-topic; your asking for mission plans for anything without SLS was off-topic.

"Hey guys, I'm going to go order curtains from the store, then I'll measure my windows!"

EDIT:I mean, don't get me wrong, I'm glad we're finally measuring the windows, even if we ordered the curtains already.


The STS had no specific mission really until ISS and it flew for 30 years.  Are not all missions designed around the launch vehicles and not the other way around (Apollo era aside)?

Edit: Meant STS not SLS
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: aquanaut99 on 10/06/2011 05:53 am
Quote
Designating the launch vehicle requirements (for a new launch vehicle) before having the mission scope/policy/plan/blah done is bass-ackwards. That I pointed that out is not off-topic; your asking for mission plans for anything without SLS was off-topic.

"Hey guys, I'm going to go order curtains from the store, then I'll measure my windows!"

EDIT:I mean, don't get me wrong, I'm glad we're finally measuring the windows, even if we ordered the curtains already.


The SLS had no specific mission really until ISS and it flew for 30 years.  Are not all missions designed around the launch vehicles and not the other way around (Apollo era aside)?

You mean STS...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Khadgars on 10/06/2011 05:55 am
Quote
You mean STS...

Indeed I did, sorry about that ;p
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MP99 on 10/06/2011 08:14 am
How does a separate CPS fit in the PL 111-267? It is nowhere to be found, and the SLS therein requires "an integrated upper Earth departure stage", not a dedicated second stage and a dedicated in-space stage. Especially when the funds for CPS are to be taken from the SLS budget, and when CPS is being set up as a completely separate project from SLS. Sounds like illegal diversion of funds to me.

I think that this is a case where "Practicable" rears its head.  Given that J-2X is ETO-optimised it may not be possible to abide by that clause of the Act.  As matters go, I don't think that this is a serious issue and it actually makes SLS more flexible as you optimise the upper stage for IMLEO performance and have an BLEO-optimised propulsion module if needed.

Just a thought: Delete the SLS upper stage, attach the CPS directly to the four-engine core and this should be sufficient for orbital missions to LLO or the EML points.  This isn't a capability that is currently required but so little of SLS utilisation is set in stone right now that it might emerge eventually.



Look at it from the other direction - what non-LEO missions can you fly with block 2, and what does it need from the launcher?

1) Single three-stage launch with direct insertion to TLI. Think CxP cargo mission on Ares V launcher, etc. Used for:-

1a) LSR Lunar cargo delivery direct to surface (CxP cargo).

1a) LOR Lunar mission.

1b) EMLR assembly of Lunar or BEO mission.



2) Dual launch EOR TLI with monster CPS on one launch and payload on another. Think DIRECT phase 2.

2a) DIRECT-type Lunar mission.

2b) Delivery of huge mission element for EMLR assembly for BEO mission.



3) Multiple launch EOR.

3a) Mars DRA 5 style assembly of multiple payloads in LEO.




ISTM that SLS is designed for assembly of big missions in LEO (like Mars DRA 5) and/or injecting with SEP instead of chemical (implying HEO or EML rendezvous of crew with the mission stack). But look at the high boiloff & station-keeping requirements of DRM 5.

PL 111-267's "integrated" launcher is more optimised for Lunar and EML-assembled missions. It would make more sense to me if NASA optimised SLS as two-stage 60-ish-mT-through-TLI, since HEFT ended up assembling most of it's missions at EML. Then CPS can be truly "in-space optimised", ie hopefully it can avoid the high boiloff of DRM 5 without the high dry mass penalty of HEFT's CPS (http://forum.nasaspaceflight.com/index.php?topic=24585.0), which I suspect is driven by the LEO thermal environment.

cheers, Martin
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: woods170 on 10/06/2011 12:12 pm
The first escalations occur....soon my pretties, soon we will have ARES V again...

Interesting remark. What makes you think so?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: aquanaut99 on 10/06/2011 12:37 pm
The first escalations occur....soon my pretties, soon we will have ARES V again...

If anything, we will have Ares V classic again. Which wasn't such a bad design if taken as a stand-alone heavy lifter. What really did CxP in was insisting to design Ares I in parallel, a booster that merely duplicated EELV performance while being much more expensive. And that finally underperformed so much that Ares V had to be scaled up again and again to compensate.

Remember, monster Ares V rocketzilla was supposed to lift something like 180 tons. We're still a far cry from that.

Also, SLS might never make it to Phase II. In fact, I fully expect that Phase IA (maybe with some slight further upgrades down the line) will end up being the final production version of SLS (with Phase II being the eternal "future upgrade option for once we have the money", designed mainly to satisfy the letter of the law but never actually built).

Such a Phase IA SLS will be at around (standard) Energia-level performance with regards to LEO. Not bad at all, and proably sustainable for NASA (about as much as Shuttle was sustainable...), at least IMO. And it is fully BEO capable with an appropriate CPS.

PS: "Sustainable" for a NASA on current budget. Ofc, if the budget is axed 20% or more, then that's a different story...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Alexa431 on 10/06/2011 01:27 pm
With this approximate timeline and the blocks, is it safe to assume that NASA is planning to use the SLS for around 30 years or longer??
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ben the Space Brit on 10/06/2011 01:50 pm
With this approximate timeline and the blocks, is it safe to assume that NASA is planning to use the SLS for around 30 years or longer??

That's a big unknown.  After all, a breakthrough could come tomorrow that could render conventional rocketry as obsolete a technology as the horse-drawn carriage. ;)

Still, the invention of anti-gravity aside, the fact that President Obama talked about missions in the mid-2030s, then we're probably looking at a program with a 25-year timeline even if individual vehicles aren't used for the entire duration.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: gospacex on 10/06/2011 02:08 pm
Why Block 1 needs the second stage? It'd lift ~70 tons to LEO without it, and we have no payloads even in that class, not to mention heavier ones. Why do we spend $$$ developing something we don't need?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: aquanaut99 on 10/06/2011 02:14 pm
Why Block 1 needs the second stage? It'd lift ~70 tons to LEO without it, and we have no payloads even in that class, not to mention heavier ones. Why do we spend $$$ developing something we don't need?

Because the first Orion missions are circumlunar flights. The iCPS is actually an EDS, not a second stage.

You need an EDS for BEO operations, no matter how much your launcher can lift into LEO. Since NASA's HSF goal is BEO flights, we will need an EDS sooner or later. So we might as well develop it now (for Block I, the iCPS is probably not that hard to develop, since it is just a modified and man-rated existing upper-stage...)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ben the Space Brit on 10/06/2011 02:43 pm
Why Block 1 needs the second stage? It'd lift ~70 tons to LEO without it, and we have no payloads even in that class, not to mention heavier ones. Why do we spend $$$ developing something we don't need?

Because the first Orion missions are circumlunar flights. The iCPS is actually an EDS, not a second stage.

Purely speculative at this point but SLS Block-I can throw about 20-30t through escape velocity with the DIVHUS, depending on the target.  This might one day be useful for launching a heavy-weight Galilean Moon or Titan robotic survey mission.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 10/06/2011 04:20 pm
Thread purged of the sandpit fight from at least the mod report standpoint.

Carry on.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/06/2011 04:35 pm
Why Block 1 needs the second stage? It'd lift ~70 tons to LEO without it, and we have no payloads even in that class, not to mention heavier ones. Why do we spend $$$ developing something we don't need?

Because the first Orion missions are circumlunar flights. The iCPS is actually an EDS, not a second stage.

Purely speculative at this point but SLS Block-I can throw about 20-30t through escape velocity with the DIVHUS, depending on the target.  This might one day be useful for launching a heavy-weight Galilean Moon or Titan robotic survey mission.
Doing the math, it could push 40 metric tons to escape velocity, or 35 metric tons TLI (including the iCPS performing the final orbital insertion burn).  If you did not need it to perform the final orbital insertion burn, you can increase that to 45 metric tons.  45 Metric Tons, incidentally, would allow the inclusion of a Centaur dual-axis lunar lander along with Orion, using the Centaur for final orbital-insertion burn, and Orion handling the return burn to Earth by itself.

Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 10/06/2011 04:39 pm
Quote
Designating the launch vehicle requirements (for a new launch vehicle) before having the mission scope/policy/plan/blah done is bass-ackwards. That I pointed that out is not off-topic; your asking for mission plans for anything without SLS was off-topic.

"Hey guys, I'm going to go order curtains from the store, then I'll measure my windows!"

EDIT:I mean, don't get me wrong, I'm glad we're finally measuring the windows, even if we ordered the curtains already.


The STS had no specific mission really until ISS and it flew for 30 years.  Are not all missions designed around the launch vehicles and not the other way around (Apollo era aside)?

Edit: Meant STS not SLS

STS had a mission: it was sold as a general-purpose space truck that would eliminate the need for any other launch vehicles except perhaps for the very smallest.  By the time of the Challenger accident it had become obvious that STS could not fulfill that role.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: mrbliss on 10/06/2011 05:15 pm
The first escalations occur....soon my pretties, soon we will have ARES V again...

Actually, this is at least the 3rd escalation.

1) 5-seg solids
2) Stretch core to go with the 5-seggers
3) 4 RS-25s to use all that fuel in the stretched core
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jason1701 on 10/06/2011 05:24 pm
So it seems that SLS has its core stretched only because ATK wants it so, not because that's actually required to use 5-segs. Does NASA documentation have any evidence for or against this conclusion?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: AlexP on 10/06/2011 05:48 pm
I don't think it's fair to call any of those things "escalations". 5-seg with a core stretch was the originally released design, and the trade (as Chris called it multiple times in his much appreciated article) to the four-SSME configuration is because

Quote
...using four engines will allow the vehicle to fly fully fueled in all configurations saving the extra calculations/testing for an under-filled three engine core.

So not really an escalation, seems they're just trying to get it ready quicker/with less hassle, and using an extra SSME from the existing stock is deemed a worthwhile trade for it. There doesn't seem anything wrong with that from my perspective.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: BrightLight on 10/06/2011 06:26 pm
Why Block 1 needs the second stage? It'd lift ~70 tons to LEO without it, and we have no payloads even in that class, not to mention heavier ones. Why do we spend $$$ developing something we don't need?

Because the first Orion missions are circumlunar flights. The iCPS is actually an EDS, not a second stage.

Purely speculative at this point but SLS Block-I can throw about 20-30t through escape velocity with the DIVHUS, depending on the target.  This might one day be useful for launching a heavy-weight Galilean Moon or Titan robotic survey mission.
Doing the math, it could push 40 metric tons to escape velocity, or 35 metric tons TLI (including the iCPS performing the final orbital insertion burn).  If you did not need it to perform the final orbital insertion burn, you can increase that to 45 metric tons.  45 Metric Tons, incidentally, would allow the inclusion of a Centaur dual-axis lunar lander along with Orion, using the Centaur for final orbital-insertion burn, and Orion handling the return burn to Earth by itself.
Just as an aside, in the DTAL white paper
http://www.ulalaunch.com/site/docs/publications/DualThrustAxisLander%28DTAL%292009.pdf
I couldn't find the total mass of the lander plus fuel.  I take it from your post that it is less than 45t (including payload?).
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/06/2011 10:32 pm
Why Block 1 needs the second stage? It'd lift ~70 tons to LEO without it, and we have no payloads even in that class, not to mention heavier ones. Why do we spend $$$ developing something we don't need?

Because the first Orion missions are circumlunar flights. The iCPS is actually an EDS, not a second stage.

Purely speculative at this point but SLS Block-I can throw about 20-30t through escape velocity with the DIVHUS, depending on the target.  This might one day be useful for launching a heavy-weight Galilean Moon or Titan robotic survey mission.
Doing the math, it could push 40 metric tons to escape velocity, or 35 metric tons TLI (including the iCPS performing the final orbital insertion burn).  If you did not need it to perform the final orbital insertion burn, you can increase that to 45 metric tons.  45 Metric Tons, incidentally, would allow the inclusion of a Centaur dual-axis lunar lander along with Orion, using the Centaur for final orbital-insertion burn, and Orion handling the return burn to Earth by itself.
Just as an aside, in the DTAL white paper
http://www.ulalaunch.com/site/docs/publications/DualThrustAxisLander%28DTAL%292009.pdf
I couldn't find the total mass of the lander plus fuel.  I take it from your post that it is less than 45t (including payload?).

That's for the ACES lander, I'm speaking of the older Lockheed centaur lander, which is less than 45t.  The ACES upper stage is around 45 metric tons by my calcs, having twice the fuel load of Centaur, so a lander would be even heavier than that.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: ciscosdad on 10/06/2011 11:14 pm
I'm personally very heartened by progress so far.
I agree that an approach more akin to Direct (J130 and J240 eta al) would have been more desirable (cheaper), but we, and more specifically nasa have to work within the achievable political realities.
Once Mr Shannon works his magic with the missions, things should look even more positive.
I certainly prefer to be working on the rocket first then the missions. The other way around seems very pointless. It would be nice to have the funding and the political will to do an Apollo (missions and rocket), but that led to 6 moon landings then nothing, so that approach isn't perfect (unsustainable architecture).
Lets build the rocket within the budget,then put it to use within the budget, keep the industrial base alive and the agency and workforce in place and have a real manned spaceflight program. Even just Block 1 would do fine for a long list of interesting missions.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: muomega0 on 10/06/2011 11:46 pm
Why Block 1 needs the second stage? It'd lift ~70 tons to LEO without it, and we have no payloads even in that class, not to mention heavier ones. Why do we spend $$$ developing something we don't need?

Because the first Orion missions are circumlunar flights. The iCPS is actually an EDS, not a second stage.

Purely speculative at this point but SLS Block-I can throw about 20-30t through escape velocity with the DIVHUS, depending on the target.  This might one day be useful for launching a heavy-weight Galilean Moon or Titan robotic survey mission.
Doing the math, it could push 40 metric tons to escape velocity, or 35 metric tons TLI (including the iCPS performing the final orbital insertion burn).  If you did not need it to perform the final orbital insertion burn, you can increase that to 45 metric tons.  45 Metric Tons, incidentally, would allow the inclusion of a Centaur dual-axis lunar lander along with Orion, using the Centaur for final orbital-insertion burn, and Orion handling the return burn to Earth by itself.
Just as an aside, in the DTAL white paper
http://www.ulalaunch.com/site/docs/publications/DualThrustAxisLander%28DTAL%292009.pdf
I couldn't find the total mass of the lander plus fuel.  I take it from your post that it is less than 45t (including payload?).

That's for the ACES lander, I'm speaking of the older Lockheed centaur lander, which is less than 45t.  The ACES upper stage is around 45 metric tons by my calcs, having twice the fuel load of Centaur, so a lander would be even heavier than that.

The DTAL in Figure 9 (attached) has a mass fraction of ~ 0.87 and Propellant Mass of 42 mT, so the lander dry mass weights 6.2 mT and the total mass is ~48 mT. 

It is hard, if not impossible, to justify why the DTAL lander cannot be lofted on a small LV and filled up on orbit with a depot, along with all the other mission hardware for BEO exploration.  With the depot, many more missions will be flown for the same total price. 

It is time to move away from SLS, and the time is now.

Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/07/2011 12:07 am
That's for the ACES lander, I'm speaking of the older Lockheed centaur lander, which is less than 45t.  The ACES upper stage is around 45 metric tons by my calcs, having twice the fuel load of Centaur, so a lander would be even heavier than that.

Yea, the ACES DTAL was based on the ACES-41 stage, which is named that because it holds 41mt of propellant.  The dry weigh of the ACES-41 stage is about 5mt.  This article has some numbers on that.

http://www.ulalaunch.com/site/docs/publications/AffordableExplorationArchitecture2009.pdf

The DTAL ascender has about 4mt of propellant needed too for ascent.  So, the fully fueled ACES DTAL with ascender would be about 52mt.

I don't think I've ever seen the Centaur lander.  Downix, do you have any info on that?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Starlab90 on 10/07/2011 01:04 am
This is just a great disappointment. There are no missions of any substance in the planning: flying by and waving at the Moon is not a real mission. It is 51 years after the Apollo 8 mission proving that we cannot match that mission's abilities.


It's been noted more times than I can remember that the mission planning is in work, via Mr Shannon :)
It shows where the real priorities are when the actual mission planning (and hardware, etc) is practically an afterthought compared to the launch vehicle.

To be fair they had it, with the flexible path, which replaced the VSE, with a nice amount of flexibility on the LV (I think they mainly used an Ares V for that....and we're not a million miles off with SLS on that score).

I'm as frustrated with the next man on mission content, but I think the big problem is if they had designed the missions say two years ago, then they'd probably be redoing them now based on the latest budget cycles and such. Not sure, but I bet there would be some people saying "HA, you've created missions and you don't even have a LV yet".

We're not launching SLS any time soon, so Mr Shannon has everything he needs, the LV design, the crew capsule design, the latest budget projects and the time to - I'm sure - work his magic, as he's (Dr Evil voice) "a fricking genius" ;D

Also, people need to remember that there is a plan, of sorts, laid out in full-blown legalese in the 2010 NASA Authorization Bill. The plan is to:

1. Begin development of SLS, MPCV, and the supporting facilities at KSC and elsewhere in Fiscal Years 2011, 2012, and 2013.

2. In 2012, NASA is to ask the NRC to conduct a study on what the next steps in BEO system development should be.

3. Based on the results of the NRC study, Congress will develop the 2013 NASA Authorization Bill, covering FY 2014 through 2016. Hopefully, the study results will also influence a decision by the Administration as to what new start to request in the FY 2014 President's Budget Request, which will come out in early 2013.

It's not as fast a plan as I would like to see, but it's better than no plan at all. At least there is a political consensus that we should have a BEO program. We haven't always had that.

And don't forget, the lack of a manifest beyond the first 2 missions will have no effect on MPCV and SLS development for the next 2 years, except to make us all feel better.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: BrightLight on 10/07/2011 01:12 am
Why Block 1 needs the second stage? It'd lift ~70 tons to LEO without it, and we have no payloads even in that class, not to mention heavier ones. Why do we spend $$$ developing something we don't need?

Because the first Orion missions are circumlunar flights. The iCPS is actually an EDS, not a second stage.

Purely speculative at this point but SLS Block-I can throw about 20-30t through escape velocity with the DIVHUS, depending on the target.  This might one day be useful for launching a heavy-weight Galilean Moon or Titan robotic survey mission.
Doing the math, it could push 40 metric tons to escape velocity, or 35 metric tons TLI (including the iCPS performing the final orbital insertion burn).  If you did not need it to perform the final orbital insertion burn, you can increase that to 45 metric tons.  45 Metric Tons, incidentally, would allow the inclusion of a Centaur dual-axis lunar lander along with Orion, using the Centaur for final orbital-insertion burn, and Orion handling the return burn to Earth by itself.
Just as an aside, in the DTAL white paper
http://www.ulalaunch.com/site/docs/publications/DualThrustAxisLander%28DTAL%292009.pdf
I couldn't find the total mass of the lander plus fuel.  I take it from your post that it is less than 45t (including payload?).

That's for the ACES lander, I'm speaking of the older Lockheed centaur lander, which is less than 45t.  The ACES upper stage is around 45 metric tons by my calcs, having twice the fuel load of Centaur, so a lander would be even heavier than that.

The DTAL in Figure 9 (attached) has a mass fraction of ~ 0.87 and Propellant Mass of 42 mT, so the lander dry mass weights 6.2 mT and the total mass is ~48 mT. 

It is hard, if not impossible, to justify why the DTAL lander cannot be lofted on a small LV and filled up on orbit with a depot, along with all the other mission hardware for BEO exploration.  With the depot, many more missions will be flown for the same total price. 

It is time to move away from SLS, and the time is now.


That's for the ACES lander, I'm speaking of the older Lockheed centaur lander, which is less than 45t.  The ACES upper stage is around 45 metric tons by my calcs, having twice the fuel load of Centaur, so a lander would be even heavier than that.

Yea, the ACES DTAL was based on the ACES-41 stage, which is named that because it holds 41mt of propellant.  The dry weigh of the ACES-41 stage is about 5mt.  This article has some numbers on that.

http://www.ulalaunch.com/site/docs/publications/AffordableExplorationArchitecture2009.pdf

The DTAL ascender has about 4mt of propellant needed too for ascent.  So, the fully fueled ACES DTAL with ascender would be about 52mt.

I don't think I've ever seen the Centaur lander.  Downix, do you have any info on that?
Here is a white paper from ULA on lander options including the Centaur based system
http://www.ulalaunch.com/site/docs/publications/LunarLanderConfigurationsIncorporatingAccessibility20067284.pdf
It appears that the crew section was adapted from the Centaur lander to the DTAL.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/07/2011 02:57 am
Why Block 1 needs the second stage? It'd lift ~70 tons to LEO without it, and we have no payloads even in that class, not to mention heavier ones. Why do we spend $$$ developing something we don't need?

Because the first Orion missions are circumlunar flights. The iCPS is actually an EDS, not a second stage.

Purely speculative at this point but SLS Block-I can throw about 20-30t through escape velocity with the DIVHUS, depending on the target.  This might one day be useful for launching a heavy-weight Galilean Moon or Titan robotic survey mission.
Doing the math, it could push 40 metric tons to escape velocity, or 35 metric tons TLI (including the iCPS performing the final orbital insertion burn).  If you did not need it to perform the final orbital insertion burn, you can increase that to 45 metric tons.  45 Metric Tons, incidentally, would allow the inclusion of a Centaur dual-axis lunar lander along with Orion, using the Centaur for final orbital-insertion burn, and Orion handling the return burn to Earth by itself.
Just as an aside, in the DTAL white paper
http://www.ulalaunch.com/site/docs/publications/DualThrustAxisLander%28DTAL%292009.pdf
I couldn't find the total mass of the lander plus fuel.  I take it from your post that it is less than 45t (including payload?).

That's for the ACES lander, I'm speaking of the older Lockheed centaur lander, which is less than 45t.  The ACES upper stage is around 45 metric tons by my calcs, having twice the fuel load of Centaur, so a lander would be even heavier than that.

The DTAL in Figure 9 (attached) has a mass fraction of ~ 0.87 and Propellant Mass of 42 mT, so the lander dry mass weights 6.2 mT and the total mass is ~48 mT. 

It is hard, if not impossible, to justify why the DTAL lander cannot be lofted on a small LV and filled up on orbit with a depot, along with all the other mission hardware for BEO exploration.  With the depot, many more missions will be flown for the same total price. 

It is time to move away from SLS, and the time is now.


That's for the ACES lander, I'm speaking of the older Lockheed centaur lander, which is less than 45t.  The ACES upper stage is around 45 metric tons by my calcs, having twice the fuel load of Centaur, so a lander would be even heavier than that.

Yea, the ACES DTAL was based on the ACES-41 stage, which is named that because it holds 41mt of propellant.  The dry weigh of the ACES-41 stage is about 5mt.  This article has some numbers on that.

http://www.ulalaunch.com/site/docs/publications/AffordableExplorationArchitecture2009.pdf

The DTAL ascender has about 4mt of propellant needed too for ascent.  So, the fully fueled ACES DTAL with ascender would be about 52mt.

I don't think I've ever seen the Centaur lander.  Downix, do you have any info on that?
Here is a white paper from ULA on lander options including the Centaur based system
http://www.ulalaunch.com/site/docs/publications/LunarLanderConfigurationsIncorporatingAccessibility20067284.pdf
It appears that the crew section was adapted from the Centaur lander to the DTAL.
You can also use that paper to calculate out in reverse the dry weight of the lander, as it posts the total delta-v available with a 20 metric ton CEV.  Using those details, you reverse calculate that, to hit the 1911m/s total delta-v available with the 20.8 metric tons of fuel, of roughly 18.4 metric tons, or 39.2 metric tons fully loaded.  This with MPCV would bring the total payload to 60.5 metric tons, too much for Delta IV's upper stage.

*unless*

You use the Centaur for both the final piece of the outgoing *and* the TLI.  Having 1911 m/s, you find that it has ample delta-v for the need.  ACES would further improve this, with it's better fuel fraction and fuel load.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ben the Space Brit on 10/07/2011 08:30 am
Also, people need to remember that there is a plan, of sorts, laid out in full-blown legalese in the 2010 NASA Authorization Bill. The plan is to:

1. Begin development of SLS, MPCV, and the supporting facilities at KSC and elsewhere in Fiscal Years 2011, 2012, and 2013.

2. In 2012, NASA is to ask the NRC to conduct a study on what the next steps in BEO system development should be.

3. Based on the results of the NRC study, Congress will develop the 2013 NASA Authorization Bill, covering FY 2014 through 2016. Hopefully, the study results will also influence a decision by the Administration as to what new start to request in the FY 2014 President's Budget Request, which will come out in early 2013.

It's nice to know that there is a plan of sorts, even if lots of aspects, such as targets, is still TBD.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: JohnFornaro on 10/07/2011 02:31 pm
Sorry, this just looks like the same old MSFC gigantism fetish all over again. And a lot of responsibility for that lies with the Senate and House, who both had plenty of opportunities to clarify...

Dammit!  There, it would seem, they go again.

There are no missions of any substance in the planning: flying by and waving at the Moon is not a real mission. It is 51 years after the Apollo 8 mission proving that we cannot match that mission's abilities.

Yes, Apollo 8 redux is a mission, and it should be the second mission of SLS, well before December of 2018 if I had my way.  The first flight should be manned, and to the ISS with a boatload of supplies and experiments.  This launch system needs to get up and running ASAP.  The third mission probably should be a polar lunar landing and prospecting mission.  These programs are taking too long, and past work is seen as useless and is not used.  They are redesigning to no end purpose and much talent and effort is simply wasted.

It will be interesting to see what Mr. Shannon concludes.  Which means, I guess, that we're waiting for him to call, right?  The mission plan should be a return to the Moon for good, and we'll practice for Mars.  We don't need to make any plans for Mars other than robotic plans for the moment.  If the story line of "new technologies" has any truth to it, we will design the martian missions with that tech in hand.  The effort is wasted otherwise, or the story line is simply false.

The mission, return to stay, simply does not need to change at all.  Focus on designing the lander to fit on the rocket with no mass creep or function creep.

The wait for missions is not a month long.  It is more nearly four decades long.  You can have a mission without a rocket.  The rocket can support the mission.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/07/2011 03:58 pm
Quote
Designating the launch vehicle requirements (for a new launch vehicle) before having the mission scope/policy/plan/blah done is bass-ackwards. That I pointed that out is not off-topic; your asking for mission plans for anything without SLS was off-topic.

"Hey guys, I'm going to go order curtains from the store, then I'll measure my windows!"

EDIT:I mean, don't get me wrong, I'm glad we're finally measuring the windows, even if we ordered the curtains already.


The STS had no specific mission really until ISS and it flew for 30 years.  Are not all missions designed around the launch vehicles and not the other way around (Apollo era aside)?

Edit: Meant STS not SLS

STS had a mission: it was sold as a general-purpose space truck that would eliminate the need for any other launch vehicles except perhaps for the very smallest.  By the time of the Challenger accident it had become obvious that STS could not fulfill that role.

If that qualifies as a "mission", then SLS has a mission.  It's being sold as a general-purpose space heavly lifter that will be large enough to handle all possible BLEO manned missions that may come up in the next 3 decades, as well as any heavy loads that would go up to LEO during that time.

It's as much of a mission as STS had up front, and STS flew for 30 years.

As I've warned people on the forum before, be careful with this "we can't have a rocket without a defined mission" argument.  Saturn had a defined mission from it's inception, STS did not.  STS had multiple purposes, but not a definate mission it was developed for.  Saturn was developed for a single mission.  And once that mission was achieved, it went on the scrap heap (unfortunately) because it was [perceived] to expensive for any other mission. 
Since STS didn't have a singular "mission", but rather a "purpose", it continued to function in that purpose for 30 years.

I'm just saying given the history of rockets with missions and rockets without, then rocket without a mission had a much long lift than the rocket with a mission...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/07/2011 05:05 pm

You can also use that paper to calculate out in reverse the dry weight of the lander, as it posts the total delta-v available with a 20 metric ton CEV.  Using those details, you reverse calculate that, to hit the 1911m/s total delta-v available with the 20.8 metric tons of fuel, of roughly 18.4 metric tons, or 39.2 metric tons fully loaded.  This with MPCV would bring the total payload to 60.5 metric tons, too much for Delta IV's upper stage.

*unless*

You use the Centaur for both the final piece of the outgoing *and* the TLI.  Having 1911 m/s, you find that it has ample delta-v for the need.  ACES would further improve this, with it's better fuel fraction and fuel load.

Ahhh, I hadn't really seen this before, just the more evolved full cyro ACES design.   This DTAL concept looks like it uses a Centaur stage with hypergolics for the lateral thrusters.  With the ascender using hypergolics as well.  The ACES design uses cryo for the lateral thrusters, as well as the ascender.  So everything is just those two non toxic propellants, and fuel can be pumped back and forth between the ascender and ACES descent stage.  (ascender tanks filled prior to descent, upon a successful landing, ascender tanks are pumped into the ACES stage for passive cryo storage for minimal boiloff, then pumped back to the ascender prior to ascent.)

That concept probably came along after this.  But I also imagine you could do the ACES DTAL concept with a Centaur or DCSS with modifications.
However, I think ULA really wants an excuse to develop ACES, so they have a common upper stage accorss their whole line, and for future use with AVP2. 
So if we are looking at an upper stage based lander, that's probably the one to look at.  It also lends itself to a lunar orbit depot and propellant transfers for optimum mission capabilities.  As well as reusing the ascender.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Pheogh on 10/07/2011 05:24 pm
I have been meaning to ask this for some time now, but I am curious why images of SLS show a non tapered aft section? During DIRECT 2.0 we had looked at tapering the aft to increase airflow around the engines when it looked like the RS-68's were the political favorite, and probably would have trouble surviving the heat of the SRBs. When we went to SSME's the problem seemed to be mitigated by their regen system but I kept the taper in my imagery? airflow is good right?

So the question remains, what is the trade for tapering or not tapering? In short is it needless  structural complexity in the case of the SSME? Are there dynamics associated with airflow that could prove problematic? Can anyone on here share some of the calculus that goes into tapering or not?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: mike robel on 10/07/2011 07:17 pm
The most recent rendering do show a tapered aft end.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Pheogh on 10/07/2011 07:31 pm
The most recent rendering do show a tapered aft end.

Hey you are right! thank you. It almost looks like the taper matches the SRB skirt perfectly. It also looks like they are using the "squashed" 4/5 engine arrangement.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ben the Space Brit on 10/07/2011 08:01 pm
The most recent rendering do show a tapered aft end.

Hey you are right! thank you. It almost looks like the taper matches the SRB skirt perfectly. It also looks like they are using the "squashed" 4/5 engine arrangement.

From what I've seen, the main engines aren't arranged regularly around the circumferance but in two pairs at the 'top' and 'bottom' of the thrust structure, perpendicular to the axis through the boosters.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: luke strawwalker on 10/08/2011 05:56 am
Did I read correctly that the current 5-Seg SRB design will only be used for the first 2 flights ?

After that, ATK has a more "advanced" design, or we switch to LRBs.

So that means we will have fired this design of the 5-Seg SRB more times on the ground than actually used as a booster.

Who pays for the development of this new ATK design ?

Yes, I noticed that too...

Also note that they plan to allow the first sets of SRB's to sink the Atlantic-- not even recover for analysis... (so much for Jim's "manrated SRB's MUST be recovered and inspected for issues"). 

Pretty convenient way to ensure that you MUST get a fat development contract for NEW SRB's using new casings, if all the old reusable casings are in pieces on the bottom of the Atlantic...

And of course with the core being DESIGNED around SRB's, LRB's will never get a fair shot... they'll be found to be "too expensive" to redesign the core and the LRB's versus the costs of SRB's, even a NEW SRB DESIGN, that utilizes the core unchanged...

More thumbs on scales... SSDD...

later!  OL JR :)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: luke strawwalker on 10/08/2011 06:00 am
That's probably how it will pan out. Lunar and NEO can be done with Block 1A/CPS but any Mars or Martian Moon missions will take Block 2 as the reference hardware and that will be developed along with mission modules in the $3+bn budget. I suppose it's all part of ensuring the use of all the CxP hardware in development, the J-2X will be developed and then parked until the upper stage can be developed in the fixed budget.

Yes.

I predict the Block I will fly more than twice (maybe up to 4 times, since there are apparently about 16 RS-25Ds available, which would allow for 4 flights).

So that already puts us into the 2023 - 2025 timeframe before we get Block IA. Plenty of time for political / mission focus shifts.

As for the block IA, I predict we'll keep that at least until 2035.

Finally, I predict that after the first two Block I flights with the current 5-segs, we will get an evaluation between different "Advanced Booster Options" (as planned), but in the end, they'll most likely stick with the ATK 5 seg boosters, for cost reasons, (unless some very effective and cheap LRBs become available or unless the 5 segs fail completely), with a vague promise of some sort of "improved booster" somewhere down the road. Just like with Shuttle, which was supposed to replace the RSRBs with something new (ASRB, 5-segs, even LRBs) several times during its lifetime...

Exactly... I see that justification shooting down any chance of LRB's...

Later!  OL JR :)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 10/08/2011 06:58 am
I predict the Block I will fly more than twice (maybe up to 4 times, since there are apparently about 16 RS-25Ds available, which would allow for 4 flights).

So that already puts us into the 2023 - 2025 timeframe

I notice you've got a hidden assumption in there about the flight rate...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/08/2011 07:47 am
Did I read correctly that the current 5-Seg SRB design will only be used for the first 2 flights ?

After that, ATK has a more "advanced" design, or we switch to LRBs.

So that means we will have fired this design of the 5-Seg SRB more times on the ground than actually used as a booster.

Who pays for the development of this new ATK design ?

Yes, I noticed that too...

Also note that they plan to allow the first sets of SRB's to sink the Atlantic-- not even recover for analysis... (so much for Jim's "manrated SRB's MUST be recovered and inspected for issues"). 

Pretty convenient way to ensure that you MUST get a fat development contract for NEW SRB's using new casings, if all the old reusable casings are in pieces on the bottom of the Atlantic...

And of course with the core being DESIGNED around SRB's, LRB's will never get a fair shot... they'll be found to be "too expensive" to redesign the core and the LRB's versus the costs of SRB's, even a NEW SRB DESIGN, that utilizes the core unchanged...

More thumbs on scales... SSDD...

later!  OL JR :)
It may be thumbs on scales, but it can and will bite them in the butt badly.  They assume, incorrectly, that they are the only SRB company in the US, ignoring that there is another, and that other has built and fired SRB's which dwarf even the 5-segment of ATK.

And there is a way to build LRB's to beat SRB's even while sticking to the SRB design and load demands, in short, without redesigning the core.  8)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lurker Steve on 10/08/2011 04:12 pm
As a non-rocket scientist, let me ask some questions :
1) The current ATK 5-seg SRBs are designed with the same basic design of reusable casings that the Shuttle SRBs use. There is extra structural weight because the casings need to survive intact. There is a huge amount of labor to refurb the casings, but it is possible to reuse them.

2) If we aren't reusing the SRBs, then some of that extra structral weight can be removed. Since the SRB become lighter by several tons, that extra weight can be translated into extra cargo the SLS could lift.

3) Would these lighter SRBs have an increased thrust and/or ISP over the existing SRBs without reformulating the actual solid fuel ?

4) Without a re-formulation of the solid fuel, does this give ATK any additional advantage, other than being able to manufacture a less expensive SRB, due to the lighter structure / non-reusable design ?

5) If this comes down to purely a cost-based competition, with the vendor paying for all development of the improved booster, who wins: a pair of LRB boosters or a pair of ATK or Aerojet SRBs ?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mr. Justice on 10/08/2011 04:56 pm
As a non-rocket scientist, let me ask some questions :
1) The current ATK 5-seg SRBs are designed with the same basic design of reusable casings that the Shuttle SRBs use. There is extra structural weight because the casings need to survive intact. There is a huge amount of labor to refurb the casings, but it is possible to reuse them.

2) If we aren't reusing the SRBs, then some of that extra structral weight can be removed. Since the SRB become lighter by several tons, that extra weight can be translated into extra cargo the SLS could lift.

3) Would these lighter SRBs have an increased thrust and/or ISP over the existing SRBs without reformulating the actual solid fuel ?

4) Without a re-formulation of the solid fuel, does this give ATK any additional advantage, other than being able to manufacture a less expensive SRB, due to the lighter structure / non-reusable design ?

5) If this comes down to purely a cost-based competition, with the vendor paying for all development of the improved booster, who wins: a pair of LRB boosters or a pair of ATK or Aerojet SRBs ?

I was wondering about the same thing. Since STS never flew at a high rate, and SLS will not either how much of an increase in payload capacity can we get by making single use casings and what does that do to the cost of the SRBs?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mr. Justice on 10/08/2011 04:57 pm
Did I read correctly that the current 5-Seg SRB design will only be used for the first 2 flights ?

After that, ATK has a more "advanced" design, or we switch to LRBs.

So that means we will have fired this design of the 5-Seg SRB more times on the ground than actually used as a booster.

Who pays for the development of this new ATK design ?

Yes, I noticed that too...

Also note that they plan to allow the first sets of SRB's to sink the Atlantic-- not even recover for analysis... (so much for Jim's "manrated SRB's MUST be recovered and inspected for issues"). 

Pretty convenient way to ensure that you MUST get a fat development contract for NEW SRB's using new casings, if all the old reusable casings are in pieces on the bottom of the Atlantic...

And of course with the core being DESIGNED around SRB's, LRB's will never get a fair shot... they'll be found to be "too expensive" to redesign the core and the LRB's versus the costs of SRB's, even a NEW SRB DESIGN, that utilizes the core unchanged...

More thumbs on scales... SSDD...

later!  OL JR :)
It may be thumbs on scales, but it can and will bite them in the butt badly.  They assume, incorrectly, that they are the only SRB company in the US, ignoring that there is another, and that other has built and fired SRB's which dwarf even the 5-segment of ATK.

And there is a way to build LRB's to beat SRB's even while sticking to the SRB design and load demands, in short, without redesigning the core.  8)

I am not familiar with these other SRBs. Could you please provide some information or, at least the name, as I would like to do a little reading about them? Thanks.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/08/2011 06:53 pm
Did I read correctly that the current 5-Seg SRB design will only be used for the first 2 flights ?

After that, ATK has a more "advanced" design, or we switch to LRBs.

So that means we will have fired this design of the 5-Seg SRB more times on the ground than actually used as a booster.

Who pays for the development of this new ATK design ?

Yes, I noticed that too...

Also note that they plan to allow the first sets of SRB's to sink the Atlantic-- not even recover for analysis... (so much for Jim's "manrated SRB's MUST be recovered and inspected for issues"). 

Pretty convenient way to ensure that you MUST get a fat development contract for NEW SRB's using new casings, if all the old reusable casings are in pieces on the bottom of the Atlantic...

And of course with the core being DESIGNED around SRB's, LRB's will never get a fair shot... they'll be found to be "too expensive" to redesign the core and the LRB's versus the costs of SRB's, even a NEW SRB DESIGN, that utilizes the core unchanged...

More thumbs on scales... SSDD...

later!  OL JR :)
It may be thumbs on scales, but it can and will bite them in the butt badly.  They assume, incorrectly, that they are the only SRB company in the US, ignoring that there is another, and that other has built and fired SRB's which dwarf even the 5-segment of ATK.

And there is a way to build LRB's to beat SRB's even while sticking to the SRB design and load demands, in short, without redesigning the core.  8)

I am not familiar with these other SRBs. Could you please provide some information or, at least the name, as I would like to do a little reading about them? Thanks.
The Aerojet AJ-260 was designed during the 1960's to be the first stage replacement for the Saturn IB.  There's a thread on the demonstration motor, and its current abandoned state, here:

http://forum.nasaspaceflight.com/index.php?topic=23718.0

The basics however are simple.  It had ~3.9 million lbf peak, while the 5-segment peaks at 3.4 million lbf.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 10/10/2011 05:04 am
As a non-rocket scientist, let me ask some questions :
1) The current ATK 5-seg SRBs are designed with the same basic design of reusable casings that the Shuttle SRBs use. There is extra structural weight because the casings need to survive intact. There is a huge amount of labor to refurb the casings, but it is possible to reuse them.

SRB casings need to be heavy because of the large pressures the must withstand.  I doubt that dropping the re-usability requirement by itself would make them much lighter.  That's not to say, however, that SRBs can't be made lighter by building them of different materials.

My understanding is that for the low flight rate that the Shuttle achieved, there was little difference in cost between re-using SRBs and building new ones at the flight rates that were achieved.  Recovery of SRBs was desirable for safety (so they could be inspected after flight).  With the first part of the re-use process -- recovery -- justified on grounds of safety, re-use made sense.

Quote
2) If we aren't reusing the SRBs, then some of that extra structral weight can be removed. Since the SRB become lighter by several tons, that extra weight can be translated into extra cargo the SLS could lift.

Anyway, since the SRBs are attached only for the first couple of minutes anyway, changing their weight doesn't affect payload capability much.  A kilogram saved might add on the order of 100 grams to the payload.

Quote
<snip>

5) If this comes down to purely a cost-based competition, with the vendor paying for all development of the improved booster, who wins: a pair of LRB boosters or a pair of ATK or Aerojet SRBs ?

It strikes me that given the low flight rates foreseen for SLS, it will be hard to justify spending much money up front to reduce operating costs.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jorge on 10/10/2011 06:12 am
As a non-rocket scientist, let me ask some questions :
1) The current ATK 5-seg SRBs are designed with the same basic design of reusable casings that the Shuttle SRBs use. There is extra structural weight because the casings need to survive intact. There is a huge amount of labor to refurb the casings, but it is possible to reuse them.

SRB casings need to be heavy because of the large pressures the must withstand.  I doubt that dropping the re-usability requirement by itself would make them much lighter.

Right. The weight savings would come from deleting the recovery systems (parachutes, etc). The idea that there's extra structural weight is hogwash.

Quote
  That's not to say, however, that SRBs can't be made lighter by building them of different materials.

True (filament-wound casings, etc). But that's completely independent of the reuse/no-reuse decision.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ronsmytheiii on 10/10/2011 01:52 pm
Interesting:

Quote
“Our vision is we’ll have an interface that’s generic, and we’ll be able to carry potentially different boosters and change them out as needed,” Gerstenmaier told a session of the International Astronautical Congress here Thursday. “So we could go compete in the future, maybe downsize if something’s easier for a mission that requires less thrust. We have some variability there, so if we do our job right, we’ll have the ability to change the boosters that sit on the side. That’s our ultimate goal. We’re not going to pick one.”

http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/asd/2011/10/07/01.xml&headline=Booster%20Competition%20For%20New%20NASA%20Heavy%20Lifter
Quote
“It turns out that to get to the 130 metric tons, we’re going to have to redesign the five-segment booster as well,” Gerstenmaier says. “We have to go to potentially a composite case, away from our steel case to save some weight, and we might need to make a propellant change to use the more energetic propellant that sits in the solid rocket motor. So even if we go continuous solids, we’re going to have to make a pretty significant change to the solid-rocket booster segment.”
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: JohnFornaro on 10/10/2011 03:12 pm
Quote
Designating the launch vehicle requirements (for a new launch vehicle) before having the mission scope/policy/plan/blah done is bass-ackwards. ...

The STS had no specific mission really until ISS and it flew for 30 years.  Are not all missions designed around the launch vehicles and not the other way around (Apollo era aside)?

STS had a mission: it was sold as a general-purpose space truck ...

If that qualifies as a "mission", then SLS has a mission.  It's being sold as a general-purpose space heavly lifter that will be large enough to handle all possible BLEO manned missions that may come up in the next 3 decades, as well as any heavy loads that would go up to LEO during that time.

It's as much of a mission as STS had up front, and STS flew for 30 years.

As I've warned people on the forum before, be careful with this "we can't have a rocket without a defined mission" argument.  Saturn had a defined mission from it's inception, STS did not.  STS had multiple purposes, but not a definate mission it was developed for.  Saturn was developed for a single mission.  And once that mission was achieved, it went on the scrap heap ... Since STS didn't have a singular "mission", but rather a "purpose", it continued to function in that purpose for 30 years.

I'm just saying given the history of rockets with missions and rockets without, then rocket without a mission had a much longer life than the rocket with a mission...

That is an excellent rebuttal to the rocket without a mission argument.  SLS is a rocket with a general purpose.

SLS will still have to be built.  From VentureStar to Ares, the rockets were never built, so the missions could never evolve.  Furthermore, there already is a mission:  Go back to the Moon to stay.  To do that, a workhorse LV is needed to build the necessary infrastructure.  There's no physical reason that SLS could not be this workhorse LV, but there's plenty of political, porkical, and corporate insider reasons why that couldn't be.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MP99 on 10/10/2011 03:30 pm
Quote
“It turns out that to get to the 130 metric tons, we’re going to have to redesign the five-segment booster as well,” Gerstenmaier says. “We have to go to potentially a composite case, away from our steel case to save some weight, and we might need to make a propellant change to use the more energetic propellant that sits in the solid rocket motor. So even if we go continuous solids, we’re going to have to make a pretty significant change to the solid-rocket booster segment.”

This was pretty much as per Chris' "4x RS-25 on Block 1" article re performance of Block 1 / 1A / 2. Upgrade to HTPB can be traced all the way back to ESAS LV27.3, and way back on SLS too.

But the direct quote from Mr Gerstenmaier, and it's particular wording was fascinating to see.

cheers, Martin
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 10/10/2011 04:29 pm
Quote
Designating the launch vehicle requirements (for a new launch vehicle) before having the mission scope/policy/plan/blah done is bass-ackwards. That I pointed that out is not off-topic; your asking for mission plans for anything without SLS was off-topic.

"Hey guys, I'm going to go order curtains from the store, then I'll measure my windows!"

EDIT:I mean, don't get me wrong, I'm glad we're finally measuring the windows, even if we ordered the curtains already.


The STS had no specific mission really until ISS and it flew for 30 years.  Are not all missions designed around the launch vehicles and not the other way around (Apollo era aside)?

Edit: Meant STS not SLS

STS had a mission: it was sold as a general-purpose space truck that would eliminate the need for any other launch vehicles except perhaps for the very smallest.  By the time of the Challenger accident it had become obvious that STS could not fulfill that role.

If that qualifies as a "mission", then SLS has a mission.  It's being sold as a general-purpose space heavly lifter that will be large enough to handle all possible BLEO manned missions that may come up in the next 3 decades, as well as any heavy loads that would go up to LEO during that time.

The Shuttle was specifically designed to carry the payloads that were already being boosted by expendable rockets.  There was no doubt that the payloads existed, and no doubt that there would have been many payloads for the Shuttle had it performed as promised.  As we all know, the Shuttle did not perform as promised.  But it continued to fly, because it was the United States' only crew-carrying vehicle.  To stop flying the Shuttle would have meant abandonment of human spaceflight by the US.

As for "any heavy loads that might arise," well, SLS has much the same capabilities as the Saturn V:  60 tonnes to LEO for the INT-20 version (S-IC plus S-IVB; 72 tonnes with strengthening to withstand 6Gs), and and 116 tonnes for the INT-21 (S-IC plus S-II).  There was exactly one payload--Skylab--found for the Saturn V aside from the payload for which it was designed.  No one was willing to pay for payloads large enough to need the Saturn V.  Why would you think it's going to be any different for SLS?

SLS can be used for BEO exploration, but, as Robotbeat said above, it's bass-ackward to design the rocket before figuring out the payloads.

Quote
I'm just saying given the history of rockets with missions and rockets without, then rocket without a mission had a much long lift than the rocket with a mission...

From Vanguard onward, most rockets have been developed after the payloads they would initially carry were defined, and that's the way it should be.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RyanC on 10/10/2011 08:01 pm
“It turns out that to get to the 130 metric tons, we’re going to have to redesign the five-segment booster as well,” Gerstenmaier says. “We have to go to potentially a composite case, away from our steel case to save some weight, and we might need to make a propellant change to use the more energetic propellant that sits in the solid rocket motor. So even if we go continuous solids, we’re going to have to make a pretty significant change to the solid-rocket booster segment.”

This is really a very very good bait and switch.

They sold RAC-1 Shuttle Derived Heavy Lift as something that could be cheaply and affordably built using parts left over from Shuttle/Constellation, and now they say they need to do all new advanced new SRBs to meet the 130 ton evolved goal.

At this point, what reason is there to continue with SD-HLV if we keep having to redesign, redesign, redesign things; as opposed to the clean sheet RAC-2 architecture which used F-1A?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ben the Space Brit on 10/10/2011 08:46 pm
At this point, what reason is there to continue with SD-HLV if we keep having to redesign, redesign, redesign things; as opposed to the clean sheet RAC-2 architecture which used F-1A?

There is just one reason and it trumps every and all conceivable engineering and budget considerations short of "it can't fly": Political support.

RAC-2 and -3 would simply never get enough political support to ever be funded.  RAC-1 (SD-HLV) at least guarantees the support of the political sponsors of the Shuttle logistical chain and operations sites so they can protect their contributors' income streams.  Take that away and there would probably be very little or no enthusiasm whatsoever for the SLS.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/10/2011 11:10 pm
Quote
Designating the launch vehicle requirements (for a new launch vehicle) before having the mission scope/policy/plan/blah done is bass-ackwards. That I pointed that out is not off-topic; your asking for mission plans for anything without SLS was off-topic.

"Hey guys, I'm going to go order curtains from the store, then I'll measure my windows!"

EDIT:I mean, don't get me wrong, I'm glad we're finally measuring the windows, even if we ordered the curtains already.


The STS had no specific mission really until ISS and it flew for 30 years.  Are not all missions designed around the launch vehicles and not the other way around (Apollo era aside)?

Edit: Meant STS not SLS

STS had a mission: it was sold as a general-purpose space truck that would eliminate the need for any other launch vehicles except perhaps for the very smallest.  By the time of the Challenger accident it had become obvious that STS could not fulfill that role.

If that qualifies as a "mission", then SLS has a mission.  It's being sold as a general-purpose space heavly lifter that will be large enough to handle all possible BLEO manned missions that may come up in the next 3 decades, as well as any heavy loads that would go up to LEO during that time.

The Shuttle was specifically designed to carry the payloads that were already being boosted by expendable rockets.  There was no doubt that the payloads existed, and no doubt that there would have been many payloads for the Shuttle had it performed as promised.  As we all know, the Shuttle did not perform as promised.  But it continued to fly, because it was the United States' only crew-carrying vehicle.  To stop flying the Shuttle would have meant abandonment of human spaceflight by the US.

As for "any heavy loads that might arise," well, SLS has much the same capabilities as the Saturn V:  60 tonnes to LEO for the INT-20 version (S-IC plus S-IVB; 72 tonnes with strengthening to withstand 6Gs), and and 116 tonnes for the INT-21 (S-IC plus S-II).  There was exactly one payload--Skylab--found for the Saturn V aside from the payload for which it was designed.  No one was willing to pay for payloads large enough to need the Saturn V.  Why would you think it's going to be any different for SLS?

SLS can be used for BEO exploration, but, as Robotbeat said above, it's bass-ackward to design the rocket before figuring out the payloads.

Quote
I'm just saying given the history of rockets with missions and rockets without, then rocket without a mission had a much long lift than the rocket with a mission...

From Vanguard onward, most rockets have been developed after the payloads they would initially carry were defined, and that's the way it should be.

Well, I'll have to respectfully disagree with your points, although I see where you are coming from.  I suppose the whole issue is somewhat subjective, and open to interpretation.  So I guess that's to be expected.

But, as I understand, (and as always, please correct me when I understand incorrectly), STS did not actually have a -mission- is the same sense that Saturn V had.  It had a -purpose-, which was to be a cheap, reusable, space plane that could launch medium size payloads and crew quickly and cheaply.  DoD had some input into the Orbiter's size, because some of the original orbiter plans didn't have a large enough payload bay for some payloads they'd like to develop and launch at some point.  So NASA increase the size/capacity/power of STS to accomodate those potential payloads.  Reagan later mandated that STS would replace all EELV's for government payloads, but again, that was after the fact.  That wasn't necessarily the plan when it was developed. 

So, if you still disagree, we'll do a little test.

1)  What was the specific mission Saturn V was designed for?  When did it acheive that said goal?

2)  What was the specfic mission of STS?  When did it acheive that goal.

The answers to #1 are very simple and easy, the answers to #2 are much harder to state, if you can even state them difinitively at all, even after 30 years of operation!

That's what I mean when I say there is a difference between a rocket with or without a mission, and a rocket with or without a purpose. 
With Saturn, it's purpose was to fly one specific mission.  Once that was acheived, it becomes more difficult to keep justifying it.

With STS, it's purpose was to be flexible, and to handle various missions which -might- come about.  Nothing specific.  Her most notable missions over her lifetime weren't developed until years after she had been flying (ISS, Hubble, Galileo, etc).  Prior to that, we were just farting around in LEO looking for something to do to justify her, like launching small satilites that could have just as easily been launched with EELV's.  Other than Hubble, she almost never utilized her potential for retrieving and repairing old and malfunctioning satillites.
But what was her "mission"?
To build a Space station?  No...that didn't happen until decades later.

To launch satilites?  That job was already being done by EELV's, so it's hard to really say she was designed specifically for that mission.

To launch a crew into LEO?  Maybe, but we could already do that with Apollo + Saturn 1B.  Even by generous estimates of the day it would have been hard to really say she was expected to do that significantly cheaper than Apollo + SAturn 1B to just put a crew into LEO.  Certainly not enough savings to justify her huge development cost vs. hardware already developed, produced, and flying.

To repair satilites?  If so, she didn't succeed at her mission well, because she didn't do much of that out of 135 flights.

To retrieve satilites?  Ditto the repair argument.

To help humans explore?  Probably not, as she was stuck in LEO.  She gave us a platform to fart around a little with.  Do some experiments on boards and such in micro gravity.  Hard to justify her development  and expense (even with the optimistic early flight cost estimates) just for that.  Skylab could do that.

So what was her "mission" the way going to the Moon was Saturn's mission?

The answer is, she didn't have one specific mission or goal.  She was build to surve a "purpose".  To do many things Saturn + Apollo wasn't very good at, for much cheaper. 
And even with her cost being so much more than initially predicted, she served that purpose well enough to justify her operation for 30 years.

So I stand by my point that STS without a mission was a more successful system in terms of longevity than SAturn, a rocket -with- a mission.  And we need to be carful throwing around this misconception that you can't build a rocket without a single specific mission it's designed around.  STS didn't.

But will admit, that both of our views are subjective.

Finally, I want to take issue with your last point.

"There was exactly one payload--Skylab--found for the Saturn V aside from the payload for which it was designed.  No one was willing to pay for payloads large enough to need the Saturn V.  Why would you think it's going to be any different for SLS?"

Well, there are many differences.  It's not as simple as that. 
First of all, an SLS launch will probably cost about the same as an STS launch, and the yearly operating costs will likely be pretty similar.  Expendible boosters will be about the same as the reusable types from all I've heard.  The core will be similar in cost, as the core itself is very similar to the ET.  Engines will probably be a wash once you are using the RS25E's vs. the incredibly low production rate(with high cost) and refub costs of the SSME's.  You basically will then have the expensive orbiter refurb costs, vs. your other SLS expendible components such as your avionics, PLF, and Orion CSM.  Hard to say for sure, but I'll take a stab and call that a wash, or at least that the extra costs of those expendibles will be only a small amount more than than Orbiter refurb costs and infrastructure costs on a per flight basis.  (Yea, there will be Orion CSM and SLS development costs, but there wre STS and orbiter development costs too.  so I'm setting those aside and just going with per launch costs, and annual operation costs).
So, SLS should be about the same costs, or just a little more than STS per launch.  Around $1 billion per launch I think is considered what STS broke down to.  But we seemed to find the budget for an average of around 4-5 STS launches PER YEAR, did we not?  I was a HLV that could only launch an EELV class payload, but we still launched at that rate for 30 years, didn't we?
So when you say there's no paylaods that really need that much capacity right now.  IT doesn't matter, really.  We launched a HLV for 30 years with no heavy loads, there's no reason we can't keep doing that, is there?
It seems overkill or wasteful, but then so was STS for that perspective.
The Budget NASA's had for some time supported several flights a year.  (And it's pretty likely that once you had a HLV flying and proven, there will be payloads that can utilize it that will come along.  Maybe they won't need it's full capacity, but more than existing EELV's.) 

Saturn was a different time, and environment.
Part of the reason there was only one additional heavy load after the lunar missions, was that SAturn was cancelled long before then, and the plans for a "cheap", reusable space plane were in the works already.  Had NASA back then had the forsight to see that was a pipe dream, there was pleanty of money in NASA's budget to keep operation the Saturn system (more 1B than V launches for LEO missions, obviously, but manned flights into at least LEO could have continued) and Saturn would have evollved to become much cheaper and more flexible as manufacturing techniques and technology cought up with her.   That's why EELV's basically overtook the Shuttle in the 1980's in terms launch costs, but by then it was too late for Saturn.
Skylab was as much, "What can we do with this extra hardware that's not going to the moon now?"  How about we build a space station out of that Extra S-IVB stage, and launch it on those extra S-1C and S-II stages.  And then send some crews up to it on thos extra S-1B stages and those extra Apollo CSM's?   And that'll give us something to do while we're developing that new Shuttle....genius!"
Had that hardware not already been built, there probably wouldn't have even been -that- mission. 

However, had the Shuttle not been eating up all that extra money, NASA could have keep building and flying Apollo and Saturn 1B, maybe put up another Skylab with the lessons learned from the problems with the first.  As long as we had a Skylab, part of the purpose of the Shuttle would have been satisfied (a platform to do research in LEO).  With ELV's pretty much taking care of most everything else the Shuttle did.
With the occasional SV flying when there was need for that much lift.  History could have unfolded far differently than it did. 

That main point is, if there was money to fly STS 4-5 times a year with payloads, then there'll probably be money to fly SLS 4-5 times per year with similar payload (and a lot of reserve capacity to spare).  Or fly 1-2 times per year with bigger payloads when and if they manifest.
Like STS, she'll be a rocket with a "purpose" rather than  specific "mission".

(Although, it's unfortunate that SLS didn't take the AJAX approach.  Because then you'd have the equivalent of Saturn V, Saturn 1B (or INT-20), and INT-21 all with the AJAX and Atlas boosters.  AVH would be Saturn 1B, AJAX-440 (less upper stage) would be INT-21, and AJAX-441 (with upper stage) would be Saturn V.  Current SLS, once eveloved, will only be 100mt to LEO without upper stage, or 130mt to LEO with upper stage.  That's it.  No option to loft Orion CSM to LEO or the ISS with a common variant).


Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RyanC on 10/10/2011 11:11 pm
RAC-1 (SD-HLV) at least guarantees the support of the political sponsors of the Shuttle logistical chain and operations sites so they can protect their contributors' income streams.  Take that away and there would probably be very little or no enthusiasm whatsoever for the SLS.

The only real loser in RAC-1/RAC-2 trades was ATK in Utah; everything else would have been just as politically connected; Boeing would have been a strong competitor for RAC-2 stages, as would Rocketdyne for any F-1 restart.

Likewise, RAC-2 would have provided Stennis with even more work, since you can now test fire each stage as a qualification test before launch unlike Shuttle.

KSC would still use the VAB/LC-39 to stack and launch it; and MSFC would still be the main center for developing it.

Etc. Basically, only Utah loses out in a RAC-2 world.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mike D on 10/11/2011 04:00 am
"Well, there are many differences.  It's not as simple as that. 
First of all, an SLS launch will probably cost about the same as an STS launch, and the yearly operating costs will likely be pretty similar.  Expendible boosters will be about the same as the reusable types from all I've heard.  The core will be similar in cost, as the core itself is very similar to the ET.  Engines will probably be a wash once you are using the RS25E's vs. the incredibly low production rate(with high cost) and refub costs of the SSME's.  You basically will then have the expensive orbiter refurb costs, vs. your other SLS expendible components such as your avionics, PLF, and Orion CSM.  Hard to say for sure, but I'll take a stab and call that a wash, or at least that the extra costs of those expendibles will be only a small amount more than than Orbiter refurb costs and infrastructure costs on a per flight basis.  (Yea, there will be Orion CSM and SLS development costs, but there wre STS and orbiter development costs too.  so I'm setting those aside and just going with per launch costs, and annual operation costs).
So, SLS should be about the same costs, or just a little more than STS per launch.  Around $1 billion per launch I think is considered what STS broke down to.  But we seemed to find the budget for an average of around 4-5 STS launches PER YEAR, did we not?  I was a HLV that could only launch an EELV class payload, but we still launched at that rate for 30 years, didn't we?
So when you say there's no paylaods that really need that much capacity right now.  IT doesn't matter, really.  We launched a HLV for 30 years with no heavy loads, there's no reason we can't keep doing that, is there?"

Lobo, those are exactly my thoughts as well.

I've generally been lurking around here lately (mostly because I'd missplaced my password :)  ), but everytime someone states that there's no big payloads for the SLS, the same reasoning comes to my mind as well: The STS mission that launched any given ISS module (the Destiny lab, for example) launched the module, the crew, the Atlantis, the SRBs and ET.  That same mission in SLS form could have launched the module, the crew, an Orion (basically the equiv. of an orbiter crew module), an SSPDM (the equiv. of a lightweight shuttle cargo bay), the SRBs and ET  and the engines (the equiv. of the aft shuttle thrust structure) for the same or similar cost.  It's a waste of extra payload cappacity; but that's free anyway since you're basically using a Shuttle Stack without hauling the eatra weight of the shuttle's wings, tail, mid fusilage, etc, to orbit just to bring them back again.  And, with the extra cargo capacity, they could have fully outfitted the lab (all its racks, etc) in one launch.

Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 10/11/2011 04:15 am
But, as I understand, (and as always, please correct me when I understand incorrectly), STS did not actually have a -mission- is the same sense that Saturn V had.  It had a -purpose-, which was to be a cheap, reusable, space plane that could launch medium size payloads and crew quickly and cheaply.

We could go round and round on the semantics of "mission" and "purpose."  My point would be that NASA explicitly claimed STS would carry all payloads that would otherwise be carried by Titan, Atlas and Delta (such payloads included Hubble and Galileo, both of which had been under study for a long time).  There was no doubt that such payloads existed and would exist in the future.  As you point it out, STS was also tailored to satisfy specific Air Force requirements for anticipated future payloads.  Neither of these two design criteria falls under the category of "build it and they will come."  There was, however, also an element of the build-it-and-they-will-come philosophy, in that NASA claimed STS's low costs would create new payloads and allow retrieval and servicing.

[You mention that "Reagan later mandated that STS would replace all EELV's for government payloads, but again, that was after the fact."  I wonder if perhaps you meant to say that Reagan mandated that EELVs replace the Shuttle?  It's quite definite that when STS was approved, it was to take over the launching of just about all US payloads.]

That was the plan.  In reality, STS proved unable to fly nearly as frequently or cheaply as anticipated.  STS was thus unable to accomplish its major missions/purpose.  That, however, does not alter the fact that, like previous launch vehicles, it was designed for certain missions/purpose, and that there was no question there would be payloads for it to carry.

SLS is different.  It's stated purpose is human BEO in general, although the BEO architecture has not yet been defined.  In these forums, we also see speculation and some claims that LEO payloads will be developed for it.  (There is or was also the mission of back-up transport to ISS, though we haven't heard much about that lately.)  Let me take these two in turn.

No doubt SLS can be used for human BEO missions.  The trouble is, it's a bad idea to settle on the launch vehicle before defining the architecture and assessing whether the architecture is affordable.  Even leaving aside the question of affordability, consider what might have happened had Congress jumped in and defined an Apollo-era Saturn-like vehicle before NASA had chosen the best architecture.  In 1960, Congress might have talked to Milton Rosen at NASA HQ and decided that the right launch vehicle was what was then known as Nova, more or less equivalent to the later Saturn C-4 concept.  Choosing Nova in 1960 would have been an expensive mistake, for it would have proved inadequate for a robust direct mission, or even for LOR.  A little later, Congress might have spoken to John Houboldt at NASA Langley and ordered NASA to build a Saturn C-3, which Houboldt thought would suffice for LOR.  Again, that would have been an expensive mistake.  Or Congress might have consulted the Manned Spacecraft Center which was pushing a direct mission using a much larger Nova (Saturn C-8).  Once again, that would have been a hugely expensive mistake.  Define the architecture, make sure it's affordable, and then spec the rocket.  Do it the other way round, and you risk getting a rocket requiring either expensive re-design or a seriously sub-optimal architecture.

As for future LEO payloads that might be devised for SLS, again I refer to the Saturn V, which had LEO capabilities similar to those of both the interim and final versions of SLS.  You and others dismiss the comparison by saying that few non-Apollo payloads were developed for the Saturn V because it was cancelled.  But if the capability to put 60-116 tonnes into LEO in one shot was so useful and if the development costs had already been paid, why didn't DoD or NASA or industry fund LEO payloads for it while it was in or not long out of production?  DoD seems to have no need.  NASA could use SLS to build a huge LEO station, but it won't have the money if it's pursuing BEO exploration.  Maybe NASA could afford to launch SLS four times a year, but 70-plus-tonnes' worth of payload are going to be expensive, more expensive than the launch.  There's no money for that.  (Consider that NASA didn't even bother to fly the last to Saturn Vs, even though payloads for them had already been built and paid for; there were still a lot of costs and other factors besides launch vehicle.)

However, had the Shuttle not been eating up all that extra money, NASA could have keep building and flying Apollo and Saturn 1B, maybe put up another Skylab with the lessons learned from the problems with the first.  As long as we had a Skylab, part of the purpose of the Shuttle would have been satisfied (a platform to do research in LEO).  With ELV's pretty much taking care of most everything else the Shuttle did.
With the occasional SV flying when there was need for that much lift.  History could have unfolded far differently than it did.

I'm inclined to agree with you that, given the way the Shuttle turned out, a manned program based on Apollo hardware would probably have been a better choice than the Shuttle (though I'm quite certain that had I been a decision maker at the time, I would have been all-out in favor of the Shuttle).  Applying that lesson to today's situation, it seems to me the way to go is to use existing launch vehicles and to get on with developing the non-existent deep-space elements.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 10/11/2011 04:55 am
I've generally been lurking around here lately (mostly because I'd missplaced my password :)  ), but everytime someone states that there's no big payloads for the SLS, the same reasoning comes to my mind as well: The STS mission that launched any given ISS module (the Destiny lab, for example) launched the module, the crew, the Atlantis, the SRBs and ET.  That same mission in SLS form could have launched the module, the crew, an Orion (basically the equiv. of an orbiter crew module), an SSPDM (the equiv. of a lightweight shuttle cargo bay), the SRBs and ET  and the engines (the equiv. of the aft shuttle thrust structure) for the same or similar cost.  It's a waste of extra payload cappacity; but that's free anyway since you're basically using a Shuttle Stack without hauling the eatra weight of the shuttle's wings, tail, mid fusilage, etc, to orbit just to bring them back again.  And, with the extra cargo capacity, they could have fully outfitted the lab (all its racks, etc) in one launch.

ISS certainly could have been lofted with a small number of heavy-lift launches.  About three 130-tonners would have done it.  However, ISS's designers notably obeyed Aken's law (http://spacecraft.ssl.umd.edu/akins_laws.html) of launch-vehicle development:

"The three keys to keeping a new manned space program affordable and on schedule:
          1)  No new launch vehicles.
          2)  No new launch vehicles.
          3)  Whatever you do, don't decide to develop any new launch vehicles."

But suppose they had said: "We've got a big payload, so let's begin by building a big rocket" and started on an SLS-style launch-vehicle development program.  If so, NASA would spent have billions of dollars and several years at the beginning of the space-station program building the rocket.  Once that was done, it would have spent several years paying the fixed-costs of that rocket without flying it while developing ISS itself.  Then it would have flown the rocket three times to get ISS into orbit.  Once ISS was complete, NASA would either terminate the rocket, as it did the Saturn V, or go back to paying its fixed costs while having no missions for it.  With fixed costs running a billion or two a year, this is not a pretty picture.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 10/11/2011 05:13 am
The only real loser in RAC-1/RAC-2 trades was ATK in Utah; everything else would have been just as politically connected....

What about SRB-related employment in Florida?  Might that be large enough to appear on Sen. Nelson's radar?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/11/2011 02:59 pm
The only real loser in RAC-1/RAC-2 trades was ATK in Utah; everything else would have been just as politically connected....

What about SRB-related employment in Florida?  Might that be large enough to appear on Sen. Nelson's radar?
Those workers would be working regardless, unless the SLS was migrated to another state for launch which is highly unlikely.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 10/11/2011 03:06 pm
Why would the same people working on SRBs for a RAC-1 vehicle necessarily have jobs on an SRB-less RAC-2 vehicle?  No doubt most or all SRB workers are capable of doing RAC-2-vehicle-related jobs, but what guarantee is there that they would be hired rather than others?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/11/2011 07:35 pm

We could go round and round on the semantics of "mission" and "purpose."  My point would be that NASA explicitly claimed STS would carry all payloads that would otherwise be carried by Titan, Atlas and Delta (such payloads included Hubble and Galileo, both of which had been under study for a long time).  There was no doubt that such payloads existed and would exist in the future.  As you point it out, STS was also tailored to satisfy specific Air Force requirements for anticipated future payloads.  Neither of these two design criteria falls under the category of "build it and they will come."  There was, however, also an element of the build-it-and-they-will-come philosophy, in that NASA claimed STS's low costs would create new payloads and allow retrieval and servicing.

[You mention that "Reagan later mandated that STS would replace all EELV's for government payloads, but again, that was after the fact."  I wonder if perhaps you meant to say that Reagan mandated that EELVs replace the Shuttle?  It's quite definite that when STS was approved, it was to take over the launching of just about all US payloads.]


Propronent.  First thanks for all the interesting input.  I’ll never claim that my view or conclusions are the only ones, or even the best ones.  :-)

As to this point specifically, perhaps one of the big brain history buffs here can chime in with some input.  I’m sure when STS was under development, they hoped it could serve all of their future launch needs over the next couple of decades.  DoD’s input indicates that they had interest in using her for their payloads [assuming her cheap costs and high launch rates materialized].  However, I don’t know that DoD had plans to retire all of their ELV’s and be dependent completely on STS.  And I’m pretty sure it was Reagan who mandated that all US government payloads, both NASA and DoD, would use the shuttle and ELV’s would be retired completely.  (Reagan wasn’t inaugurated until January 1981, after Columbia was build and about ready to fly.  Development was already done by that point).  Part of the reason for this was to justify the Shuttle and ensure it’d have money and missions to keep flying.  (it’s high costs and incredible complexity would have been pretty much known then, and it would have been understood it’d never be the cheap space truck in was conceived to be.  So DoD depending on it would ensure it’s future)   This is why Discovery was assigned to VAFB and a Shuttle Launch Facility and 3-mile runway were constructed there.   For polar orbit launches that DoD had a need for from VAFB.  Unfortunately, shortly thereafter Challenger was lost, and DoD saw what could happen if their only LV was grounded for “crew safety” issues.  Which didn’t concern their unmanned payloads.  So that Reagan mandate was reversed, and ELV’s were reinstated for DoD payloads. 




http://www.aero.org/publications/crosslink/winter2003/05.html

“That first launch never happened. On January 28, 1986, the Challenger accident resulted in the death of seven astronauts and the demise of the Air Force's space shuttle plans. The White House rescinded its 1982 mandate requiring all government payloads to fly on the space shuttle and instructed the Air Force to restart the expendable launch vehicle production lines. The space shuttle facilities at Vandenberg were once again abandoned, partly because the investigation into the Challenger failure resulted in design changes that rendered the shuttle incapable of lifting the satellites planned for polar flights out of Vandenberg. The Aerospace space shuttle program office was disbanded, and its personnel were reassigned to the new expendable launch vehicle programs and advanced launch studies. The primary payload flew on a later space shuttle mission out of Cape Canaveral; however, the second payload, Teal Ruby, never flew in space. The remaining DOD shuttle payloads planned for Vandenberg were placed on the manifest for the older Titan 34D and the new Titan IV launch systems. No human spaceflight has yet taken place in polar orbit. “
So that would indicate that the mandate that all government payloads wasn’t until Reagan was in office.  It might have played a part in the hope of NASA and DoD, but it doesn’t sound like it was the PoR to retire ELV’s and use only STS until 1982.  So no, I didn’t mean that Reagan mandated ELV’s replace the shuttle.  That wasn’t until after Challenger, when the problem of the single LV for everything became apparent.  :-)


That was the plan.  In reality, STS proved unable to fly nearly as frequently or cheaply as anticipated.  STS was thus unable to accomplish its major missions/purpose.  That, however, does not alter the fact that, like previous launch vehicles, it was designed for certain missions/purpose, and that there was no question there would be payloads for it to carry.

SLS is different.  It's stated purpose is human BEO in general, although the BEO architecture has not yet been defined.  In these forums, we also see speculation and some claims that LEO payloads will be developed for it.  (There is or was also the mission of back-up transport to ISS, though we haven't heard much about that lately.)  Let me take these two in turn.

No doubt SLS can be used for human BEO missions.  The trouble is, it's a bad idea to settle on the launch vehicle before defining the architecture and assessing whether the architecture is affordable.  Even leaving aside the question of affordability, consider what might have happened had Congress jumped in and defined an Apollo-era Saturn-like vehicle before NASA had chosen the best architecture.  In 1960, Congress might have talked to Milton Rosen at NASA HQ and decided that the right launch vehicle was what was then known as Nova, more or less equivalent to the later Saturn C-4 concept.  Choosing Nova in 1960 would have been an expensive mistake, for it would have proved inadequate for a robust direct mission, or even for LOR.  A little later, Congress might have spoken to John Houboldt at NASA Langley and ordered NASA to build a Saturn C-3, which Houboldt thought would suffice for LOR.  Again, that would have been an expensive mistake.  Or Congress might have consulted the Manned Spacecraft Center which was pushing a direct mission using a much larger Nova (Saturn C-8).  Once again, that would have been a hugely expensive mistake.  Define the architecture, make sure it's affordable, and then spec the rocket.  Do it the other way round, and you risk getting a rocket requiring either expensive re-design or a seriously sub-optimal architecture.

As for future LEO payloads that might be devised for SLS, again I refer to the Saturn V, which had LEO capabilities similar to those of both the interim and final versions of SLS.  You and others dismiss the comparison by saying that few non-Apollo payloads were developed for the Saturn V because it was cancelled.  But if the capability to put 60-116 tonnes into LEO in one shot was so useful and if the development costs had already been paid, why didn't DoD or NASA or industry fund LEO payloads for it while it was in or not long out of production?  DoD seems to have no need.  NASA could use SLS to build a huge LEO station, but it won't have the money if it's pursuing BEO exploration.  Maybe NASA could afford to launch SLS four times a year, but 70-plus-tonnes' worth of payload are going to be expensive, more expensive than the launch.  There's no money for that.  (Consider that NASA didn't even bother to fly the last to Saturn Vs, even though payloads for them had already been built and paid for; there were still a lot of costs and other factors besides launch vehicle.)


Again, I think the comparisons are a little more complex than that.  Yes, SLS is different.  But it’s different because it is supposed to use existing hardware, technologies, and contracts from the Shuttle and CxP.   Saturn and STS were “clean sheet” designs.  You could make them as big or small as you wanted, and there were not existing political mouths to feed, or hardware that you are directed to reuse.  So of course you need a little more defined plan for them.  If SLS were completely clean sheet, with every scrap of CxP and STS deleted from consideration.  Then yes, it would need some better defined potential missions/purposes so engineers have an idea if they need to make a 30mt lifter, a 70mt lifter, a 100mt lifter, a 130mt lifter, or a 200mt super lifter. 
However, the “design” work of SLS was already defined.  It would use an 8.4m ET-based core with hydrolox fuel, it would use RS25 engines, it would initially use 5-seg ATK SRB’s developed for CxP, it would need to carry Orion that was developed for CxP, and it would need an upper stage powered by the J2X developed for CxP. 
So, right from the jump, you are looking at a Saturn V class HLV, because that’s what STS was (in terms of pure power.  Not delivered payload obviously) and those were mostly the hardware you were recycling.  The very best concept for this would have been Direct, as it used STS hardware in it’s most “sweet spot” configuration.  CxP was like trying to fit 8 gallons of water into a 5 gallon bucket by trying to recycle STS hardware….which is why it grew out of control as you were trying to get hardware optimized for 100mt to LEO to get 130mt+ to LEO. 
So that is why you really don’t need  “mission” for SLS.  It’s mission is “What’s the best/cheapest LV we can build from the STS and CxP leftovers?”  And it’s not actually even that question, because Direct would have been the cheapest, and AJAX would have been the best.  So SLS’s real mission is, “What’s the most politically viable LV we can build from the STS and CxP leftovers, while conforming with the 2010 NASA Authorization Act?”  the 130mt requirement kind of stretches SLS a bit out of the optimization zone.  Like trying to put 6 gallons of water in to a 5 gallon bucket.   Not nearly as bad as CxP, but not “5 gallons of water into a 5 gallon bucket” that AJAX or Direct would have been. 

And yes, I’m backtracking on my original claim that SLS is just like STS in a rocket without a mission, now that you’ve brought up a few points.  STS’s uses were probably better defined up front than SLS’s, because they had to be, because STS was clean-sheet.  Many of SLS’ parameters of size and dimensions were already defined by the requirement to used STS and CxP hardware.   A little like remodeling a house vs. building a new house.  If you are building a new house, then you need to know up front where you want to build it, how large you want it, how big of a foot print it will have, how many car garage you want, etc.  If you are remodeling and existing house, then you don’t need to know those things up front, because you are constrained by the existing foundation, location, size, and structure.  You can only do so much with what you start with, so there’s a lot fewer things you need to know up front.  It doesn’t really matter if you plan to have a family of 3 or 8, you only have as many bedrooms and bathrooms as your house starts out with.  Doesn’t matter if you have 4 cars if your garage can only hold 2.  (For the sake of argument, we’ll say we aren’t actually adding on to our house.  That’s more like CxP.  And sometimes if you add on too much to your house, it would have just been better to build a new house.  Again like CxP)
If you want 5 kids, and your house is 4 bedroom, 3 bath, we’ll, you just have to plan for some kids to share bedrooms.  Same with SLS if we want to go to a NEO, the Moon, or Mars.  We’ll make a plan that uses SLS as it exists, instead making the plan first, then building a new rocket to suit it.    Again, the difference between remodeling an existing house, and building a new house.

So, as another example, let’s say STS had never been planned to replace Saturn, and Saturn was going to stay NASA’s LV for the foreseeable future.  There’s enough money to continue LEO operations, and loft up the occasional Skylab or some other large payload (big Mars rover using 70’s and 80’s tech, etc.).  NASA decides to upgrade to F1A engines, J2S engines, new Al-Li tanks, replace Saturn 1B with INT-20, etc.   So, are these “Rockets without Mission”?, or are they just utilizing existing hardware, tech, and politics as best they can?  If we’re not going to the moon anymore, then technically it’s a rocket without a mission.  But politics demands we don’t just dump all of that hardware in the garbage.  If a new capitol mission comes along, then they have to work within the Saturn hardware.  They can’t design a new clean sheet rocket for it.   That is SLS.   
Saturn wouldn’t have necessarily been the best LV for going to Mars, if that’s what we had as our HLV, then a Mars mission would have had to be developed around it. 
SLS is a blend of STS, CxP, and politics, and it’s probably the most viable outcome of those three tangents. 

Does that make more sense?



I'm inclined to agree with you that, given the way the Shuttle turned out, a manned program based on Apollo hardware would probably have been a better choice than the Shuttle (though I'm quite certain that had I been a decision maker at the time, I would have been all-out in favor of the Shuttle).  Applying that lesson to today's situation, it seems to me the way to go is to use existing launch vehicles and to get on with developing the non-existent deep-space elements.

Yes, hindsight’s 20/20.  Back at that time, Saturn was pretty spendy, and it’s “mission” had been achieved.  Public and political support was waning.  Saturn V also –seemed- incredibly wasteful.  Out of that huge rocket, only the tiny capsule at the top came back.  Everything else was thrown away.  On it’s surface, that seems incredibly wasteful.   A reusable spaceplane, with reusable rocket engines, and reusable boosters, with only just a dumb fuel tank being expeneded, seems far more efficient!   Just that the economics of production and engineering show otherwise.  Also, we didn’t really know at that time how much high tech automation could change the way tanks and rocket engines would be made in the not-so distant future.  They didn’t know at the time that in just another 10 years or so, ELV’s would become much cheaper and easier to build.  You really can’t fault them for what they didn’t know at that time.  Although the thought of a continued, evolved, Saturn/Apollo program, and how differently history could have turned out in the last 40 years, almost makes me sad.   
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/11/2011 07:58 pm
I've generally been lurking around here lately (mostly because I'd missplaced my password :)  ), but everytime someone states that there's no big payloads for the SLS, the same reasoning comes to my mind as well: The STS mission that launched any given ISS module (the Destiny lab, for example) launched the module, the crew, the Atlantis, the SRBs and ET.  That same mission in SLS form could have launched the module, the crew, an Orion (basically the equiv. of an orbiter crew module), an SSPDM (the equiv. of a lightweight shuttle cargo bay), the SRBs and ET  and the engines (the equiv. of the aft shuttle thrust structure) for the same or similar cost.  It's a waste of extra payload cappacity; but that's free anyway since you're basically using a Shuttle Stack without hauling the eatra weight of the shuttle's wings, tail, mid fusilage, etc, to orbit just to bring them back again.  And, with the extra cargo capacity, they could have fully outfitted the lab (all its racks, etc) in one launch.

ISS certainly could have been lofted with a small number of heavy-lift launches.  About three 130-tonners would have done it.  However, ISS's designers notably obeyed Aken's law (http://spacecraft.ssl.umd.edu/akins_laws.html) of launch-vehicle development:

"The three keys to keeping a new manned space program affordable and on schedule:
          1)  No new launch vehicles.
          2)  No new launch vehicles.
          3)  Whatever you do, don't decide to develop any new launch vehicles."

But suppose they had said: "We've got a big payload, so let's begin by building a big rocket" and started on an SLS-style launch-vehicle development program.  If so, NASA would spent have billions of dollars and several years at the beginning of the space-station program building the rocket.  Once that was done, it would have spent several years paying the fixed-costs of that rocket without flying it while developing ISS itself.  Then it would have flown the rocket three times to get ISS into orbit.  Once ISS was complete, NASA would either terminate the rocket, as it did the Saturn V, or go back to paying its fixed costs while having no missions for it.  With fixed costs running a billion or two a year, this is not a pretty picture.

Yes, and no.  YOu do make a very good point about no new LV's.  Shuttle was what we had just then.  Had we kept Saturn V, we could have lofted ISS in just a few launches, using an existing LV, and saving all of that expensive Shuttle Development.  So that's a way it could have been done WAY cheaper that we did it.

The 2nd way, were to have actually pulled the trigger sometime before to develop the SDHLV to operate in tandem with the Shuttle.  Which was a concept starting during STS development in the 70's, and kept popping up throughout the STS program.  Had they developed that prior to starting ISS development, there's actually a pretty good argument you'd have come out money ahead because launch costs for the ISS were like $30 billion plus (35 some odd Shuttle launches for it)  If you could launch 4-6 SDHLV's, with a couple of Shuttle construction missions, for say less than $10 billion in launch costs, that leaves $20-$25 billion savings.  Even if SDHLV had taken $10 billion to develop (being conservative), we're still $10-$15 billion dollars ahead, and we now have an operating HLV that shares many system with STS, like the exact boosters, almost exact ET (as the core) and the same engines (although they would be expended on HLV launches).  Like a J-130 basically)

So yea, building a BRAND NEW HLV for the ISS would have probably cost more than the way we did it.  But building a companion HLV to Shuttle probably would have cost less in the end, and then we'd have had a tandem system that'd be pretty flexible.  Later a BLEO capsule like ORion could be slowly developed, along with an upper stage.   Then we'd have BLEO capability, then the Shuttle could have been phased out, and landers and things developed.

Or, better yet, if the Shuttle had been designed more like Energia/Buran, so that the core could basically cary unmanned payloads, or an orbiter.   (except carry paylaods inline rather than sidemount like Energia).  Then RS25E's could have been developed right from the jump, with a consistant production run on them keeping costs down.  SO you have a HLV right from day one.  With the Shuttle just being one payload it can carry, rather than an integral part of it.    And your development cost would have likely been no more than our STS as we did it.  The Soviets really were on to something with Energia. 

With such a system, we'd have been able to shave off around $25-$30 billion from the ISS (probably much more in savings from being able to design 70-100mt station modules, rather than 20mt ones.  The more you can do on the ground before you have to launch, means fewer pieces to have to string together in orbit, which reduces complexity and increases safety.  I have no idea what dollar figure to put on this for safings, but I'd be surpised if it wasn't at least another $10 billion). without having to develop a new HLV.

But hindsight's always 20/20.  And The Shuttle, any shuttle, as your crew lifter, has inherrent flaws.  Such as it's refurb costs, it's TPS vulnerability, and the risk of having your crew right next to your fuel tank, rather than far above it where you can have a reliable LAS system. 
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RyanC on 10/11/2011 11:05 pm
What about SRB-related employment in Florida?  Might that be large enough to appear on Sen. Nelson's radar?

Granted, you lose out on the people who stack together the SRBs in the VAB (fun fact, in all the Saturn V Strap on SRB studies, they explictly said that they'd be strapped on in a special SRB building on the way to the pad; for safety reasons...)

As well as the guys who run the railroad that ships SRB casings in and out of KSC; plus the two ships that recover the SRBs...

But against KSC's total employment level, those losses are small.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/12/2011 01:29 am
What about SRB-related employment in Florida?  Might that be large enough to appear on Sen. Nelson's radar?

Granted, you lose out on the people who stack together the SRBs in the VAB (fun fact, in all the Saturn V Strap on SRB studies, they explictly said that they'd be strapped on in a special SRB building on the way to the pad; for safety reasons...)

As well as the guys who run the railroad that ships SRB casings in and out of KSC; plus the two ships that recover the SRBs...

But against KSC's total employment level, those losses are small.
Those ships are used to transport the ET as well mind you, towing the Pegasus barge.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 10/12/2011 08:39 am
Propronent.  First thanks for all the interesting input.  I’ll never claim that my view or conclusions are the only ones, or even the best ones.  :-)

Thanks; it's always more interesting and productive to discuss things with someone who's willing to re-examine views on the basis of new information.  I try to do the same, though I don't always succeed.... :)

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As to this point specifically, perhaps one of the big brain history buffs here can chime in with some input.  I’m sure when STS was under development, they hoped it could serve all of their future launch needs over the next couple of decades.  DoD’s input indicates that they had interest in using her for their payloads [assuming her cheap costs and high launch rates materialized].  However, I don’t know that DoD had plans to retire all of their ELV’s and be dependent completely on STS.

T. A. Heppenheimer's book The Space Shuttle Decision (http://history.nasa.gov/SP-4221/sp4221.htm) is a good source for a lot of this stuff.  On 30 March 1971, Air Force secretary Robert Seamans testified to the Senate that
 
"When the operational system is achieved, we would expect to use it to orbit essentially all DOD payloads, 'phasing out' our expendable booster inventory with the possible exception of very small boosters such as the Scout."

Space Shuttle Decision makes clear that NASA worked hard to get Seamans to say that, because it needed as many payloads for the Shuttle  as it could get in order to make the economics appear attractive.  You  can bet NASA trumpeted Seamans' statement in Congress and the White  House in the following months as it secured approval for the Shuttle.   Though NASA claimed the Shuttle would have all sorts of transformative powers, it was also clearly selling the Shuttle as a replacement for almost all  other launch vehicles needed through the 1980s.  There were plenty of payloads intended to fly on it from the beginning.
 
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And I’m pretty sure it was Reagan who mandated that all US government payloads, both NASA and DoD, would use the shuttle and ELV’s would be retired completely....

I suspect Reagan directive you refer to was effectively an announcement  that the Shuttle had become operational and there was no longer any basis for using expendables beyond those already in the pipeline.  Such a statement would have been necessary because, as documented in Decision, some within the Air Force were resisting total reliance on the Shuttle (with good reason, as it turned out).  As you point out, DoD had invested quite a bit in the Shuttle (like the VAFB facilities).  That investment began well before Reagan arrived and would not have taken place if DoD had not intended to use the Shuttle heavily.  (All that said, if you turn up a copy of the specific Reagan  directive mentioned here, I'd be interested in seeing it.)
 
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Again, I think the comparisons are a little more complex than that.  Yes, SLS is different.  But it’s different because it is supposed to use existing hardware, technologies, and contracts from the Shuttle and CxP.   Saturn and STS were “clean sheet” designs.  You could make them as big or small as you wanted, and there were not existing political mouths to feed, or hardware that you are directed to reuse.  So of course you need a little more defined plan for them.  If SLS were completely clean sheet, with every scrap of CxP and STS deleted from consideration.  Then yes, it would need some better defined potential missions/purposes so engineers have an idea if they need to make a 30mt lifter, a 70mt lifter, a 100mt lifter, a 130mt lifter, or a 200mt super lifter....

I think it's a moot point, since DIRECT has shown that it's possible to produce a wide range of payload capabilities with SLS-like Shuttle-derived launch vehicles.

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Even if that weren't the case, doesn't it make sense to decide whe 
However, the “design” work of SLS was already defined.  It would use an 8.4m ET-based core with hydrolox fuel, it would use RS25 engines, it would initially use 5-seg ATK SRB’s developed for CxP, it would need to carry Orion that was developed for CxP, and it would need an upper stage powered by the J2X developed for CxP. 
So, right from the jump, you are looking at a Saturn V class HLV, because that’s what STS was (in terms of pure power.  Not delivered payload obviously) and those were mostly the hardware you were recycling.  The very best concept for this would have been Direct, as it used STS hardware in it’s most “sweet spot” configuration.  CxP was like trying to fit 8 gallons of water into a 5 gallon bucket by trying to recycle STS hardware….which is why it grew out of control as you were trying to get hardware optimized for 100mt to LEO to get 130mt+ to LEO. 
So that is why you really don’t need  “mission” for SLS.  It’s mission is “What’s the best/cheapest LV we can build from the STS and CxP leftovers?”

The fundamental problem is that you can't decide which, if any, of those vehicles is best without first figuring out what you want to do with them and how much you're willing to spend to do it.  So far, Congress isn't willing even to discuss that.
 
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And it’s not actually even that question, because Direct would have been the cheapest, and AJAX would have been the best.  So SLS’s real mission is, “What’s the most politically viable LV we can build from the STS and CxP leftovers, while conforming with the 2010 NASA Authorization Act?”  the 130mt requirement kind of stretches SLS a bit out of the optimization zone.  Like trying to put 6 gallons of water in to a 5 gallon bucket.   Not nearly as bad as CxP, but not “5 gallons of water into a 5 gallon bucket” that AJAX or Direct would have been.

OK, if the starting point is the Authorization Act, then it's likely that an SRB-based vehicle like the current SLS is the answer.  My problem is that I don't think the Authorization Act makes much sense if one's priority is exploring space rather than starting launch-vehicle programs.

To tie this all back to where we started, if you're going to spend many billions on a big rocket, you really ought to figure out just what you want to do with it beforehand.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 10/12/2011 09:03 am
Yes, and no.  YOu do make a very good point about no new LV's.  Shuttle was what we had just then.  Had we kept Saturn V, we could have lofted ISS in just a few launches, using an existing LV, and saving all of that expensive Shuttle Development.  So that's a way it could have been done WAY cheaper that we did it.

I agree, if we're imagining a scenario in which some other program had required Saturn Vs between 1970, when the last one actually rolled off the assembly line, and the late 1990s when ISS started going up.  Without that, the cost of keeping the Saturn alive for 25-plus years without any missions would have been huge.  We're also assuming here that the Shuttle goes away, otherwise in all of those years when the actual Shuttle was delivering pieces of ISS, you're stuck paying it's fixed costs without getting any useful missions out of it.

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The 2nd way, were to have actually pulled the trigger sometime before to develop the SDHLV to operate in tandem with the Shuttle.  Which was a concept starting during STS development in the 70's, and kept popping up throughout the STS program.  Had they developed that prior to starting ISS development, there's actually a pretty good argument you'd have come out money ahead because launch costs for the ISS were like $30 billion plus (35 some odd Shuttle launches for it)  If you could launch 4-6 SDHLV's, with a couple of Shuttle construction missions, for say less than $10 billion in launch costs, that leaves $20-$25 billion savings.  Even if SDHLV had taken $10 billion to develop (being conservative), we're still $10-$15 billion dollars ahead, and we now have an operating HLV that shares many system with STS, like the exact boosters, almost exact ET (as the core) and the same engines (although they would be expended on HLV launches).  Like a J-130 basically)

So yea, building a BRAND NEW HLV for the ISS would have probably cost more than the way we did it.  But building a companion HLV to Shuttle probably would have cost less in the end, and then we'd have had a tandem system that'd be pretty flexible.  Later a BLEO capsule like ORion could be slowly developed, along with an upper stage.   Then we'd have BLEO capability, then the Shuttle could have been phased out, and landers and things developed.

Yeah, I agree: if you wanted to assemble ISS with some kind of HLV, then, given the fact that the Saturn V was long gone, a Shuttle-derived HLV would have made sense.  But notice that ISS's designers chose not to do that either.  This makes the case against HLV even stronger.
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Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/12/2011 03:17 pm
Yes, and no.  YOu do make a very good point about no new LV's.  Shuttle was what we had just then.  Had we kept Saturn V, we could have lofted ISS in just a few launches, using an existing LV, and saving all of that expensive Shuttle Development.  So that's a way it could have been done WAY cheaper that we did it.

I agree, if we're imagining a scenario in which some other program had required Saturn Vs between 1970, when the last one actually rolled off the assembly line, and the late 1990s when ISS started going up.  Without that, the cost of keeping the Saturn alive for 25-plus years without any missions would have been huge.  We're also assuming here that the Shuttle goes away, otherwise in all of those years when the actual Shuttle was delivering pieces of ISS, you're stuck paying it's fixed costs without getting any useful missions out of it.
Other than Skylab you mean?  If Saturn had continued, Skylab also would have continued very likely.
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The 2nd way, were to have actually pulled the trigger sometime before to develop the SDHLV to operate in tandem with the Shuttle.  Which was a concept starting during STS development in the 70's, and kept popping up throughout the STS program.  Had they developed that prior to starting ISS development, there's actually a pretty good argument you'd have come out money ahead because launch costs for the ISS were like $30 billion plus (35 some odd Shuttle launches for it)  If you could launch 4-6 SDHLV's, with a couple of Shuttle construction missions, for say less than $10 billion in launch costs, that leaves $20-$25 billion savings.  Even if SDHLV had taken $10 billion to develop (being conservative), we're still $10-$15 billion dollars ahead, and we now have an operating HLV that shares many system with STS, like the exact boosters, almost exact ET (as the core) and the same engines (although they would be expended on HLV launches).  Like a J-130 basically)

So yea, building a BRAND NEW HLV for the ISS would have probably cost more than the way we did it.  But building a companion HLV to Shuttle probably would have cost less in the end, and then we'd have had a tandem system that'd be pretty flexible.  Later a BLEO capsule like ORion could be slowly developed, along with an upper stage.   Then we'd have BLEO capability, then the Shuttle could have been phased out, and landers and things developed.

Yeah, I agree: if you wanted to assemble ISS with some kind of HLV, then, given the fact that the Saturn V was long gone, a Shuttle-derived HLV would have made sense.  But notice that ISS's designers chose not to do that either.  This makes the case against HLV even stronger.
Not the case at all.  The ISS was built around the largest modules they could, delivered by Proton and Shuttle.  Had your own logic been used, the ISS would have been more likely built by Delta II and Soyuz with smaller modules. But no, they built it using the largest modules they could.  Had Saturn continued, likely Skylab would have as well.  The Shuttle could even have entered the picture, launched by Saturn.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/12/2011 05:32 pm
WEll, I suppose we're getting off topic here, but this is just such a facinating topic!

Real quick.

Proponent:
1)  It's better if there's a mission, sure.  But the "mission" of is building an LV out of STS and CxP leftovers.  NAA 2010 mandated that.  Unfortunately the NAA 2010 eliminated Direct from the running it's it's most efficient form.  So an LV that was a little over it's most efficient point had to be designed.  SLS, or Direct's J251SH.  Hopefully a new lunar program becomes SLS's first "mission".  :-)

2)  If STS had been designed like Energia/Buran, then we'd have a HLV for ISS with no additional money or development. 

3)  If Saturn/Apollo had remained the PoR, we'd have had a HLV for ISS.  But there probably wouldn't have been an ISS in it's current form, because like Downix said, we'd have probably maintained a Skylab program, and maybe linked a couple Skylabs to a central hub, Mir-like, and had an ISS sized space station in the 80's.  INT-20 probably would have replaced Saturn 1B, so the whole Saturn family could be supported without having to lauch the full up Saturn V much.  INT-20 would use F1 and J2 engines, with the S-IC and S-IVB stages.  INT-21 would use F1 and J2 engines, with S-IC and S-II stages for medium-heavy lift missions like lifting a space telescope to LEO, or lofting a new Skylab station module.  So the program could have been supported with intermediate config operations.  Same for Apollo, as that would have been the LEO taxi on the INT-20.  Remember, during the 80's and 90's, we were launching STS at a clip of about 5 per year.  So money was there to do things.  Even after DoD went back to ELV's after Challenger, once STS returned to flight, they were still launching at a 4-5 launch/year clip.  So there was money to do some building and launching, even if they didn't have the generous space race budget.

4)  Like I said, NASA probably could have still developed the directly SDHLV prior to developing and building the ISS, and been money ahead.  My guess is the reasons they didn't are:  a)  Didn't realize then they would be money ahead to do it, figured saving that development money would make the project cheaper overall.  By the time they figured out otherise, it was too late to possibly change course.  b)  NASA was looking for a Presidential back program like the ISS (Backed by Clinton) to justify flying the Shuttle itself.  Development of a SDHLV would have very likely reduced the launch rate of the shuttle in the future during ISS construction, and after, and NASA was always pushing for more Shuttle missions in an attempt to make it look like the cheap space truck it was originally touted as.  SDHLV might have just tarnished that image further.  Building and maintaining a large space station was a concept planners probably had for the Shuttle during development.  Certianly it was something they wanted to do with Space STation Freedom shortly after STS was flying in the 80's.  ISS probably seemed like a good way to try to recapture a little bit of credibility after the Shuttle already turned out not to be cheap or simple, and not to be the one LV that would handle all government paylaods. 


5)  Downix,  Interesting concept launching the Shuttle on Saturn.  Never thought of that!  No reason you couldn't, if it was built like Buran, and designed to specifically use the Saturn booster.  Modify an INT-21 to have side attachment points, and sling an orbiter from it's side.  Or perhaps design the Orbiter to be launched on top and boosted from behind by a 10m wide INT-21 stack.  Like a larger version of Dreamchaser.

Although if we'd kept Saturn/Apollo, I think there'd be better concepts (given today's 20/20 hindsight anyway) to have something like the shuttle, without the huge costs of both the Shuttles and Buran.
Develop a LEO version of the Apollo CSM.  The CM would be larger with more room, but designed for LEO missions only.  Maybe like CST-100 or Orion Lite.  The SM would be far smaller, as it won't need to perform LOI for a stack.  More like current 606 Orion SM plans.  And build something more like Direct's SSPDM which has an airlock and manipulator arm on it.  perhaps a small hab unit to approximate the extra cabin room the Shuttle had for a 14 day mission in LEO.  With this you could do just about everything the Shuttle could do (except the downmass), just much cheaper, safer, and more simple. 

But I digress...  ;-)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Rocket Science on 10/12/2011 05:49 pm
Shuttle on Saturn is an old idea...
http://www.pmview.com/spaceodysseytwo/spacelvs/sld036.htm
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/12/2011 06:38 pm
Shuttle on Saturn is an old idea...
http://www.pmview.com/spaceodysseytwo/spacelvs/sld036.htm


Damn you egg heads and your infinite knowledge of history!!

Making me look bad.

;-)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Rocket Science on 10/12/2011 08:55 pm
Shuttle on Saturn is an old idea...
http://www.pmview.com/spaceodysseytwo/spacelvs/sld036.htm


Damn you egg heads and your infinite knowledge of history!!

Making me look bad.

;-)
Yea, that and a "buck" won't get me a cup of coffee ;D
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 10/12/2011 09:15 pm
Shuttle on Saturn is an old idea...
http://www.pmview.com/spaceodysseytwo/spacelvs/sld036.htm

Weird feeling.  Those paintings were more or less science fiction when they were first done (they certainly have the style), and now they are again...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Namechange User on 10/12/2011 09:17 pm
The "picture" of the SRBs separating is a photoshop fake. 
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 10/12/2011 09:19 pm
It looks it.  The lighting and motor plumes are wonky.  But that's beside the point, isn't it?  It's composited from actual shots, I assume, and that configuration and sequence of events did actually happen numerous times.

If you can point me to a better one, I'll use it...  but as far as I know there has never been a camera close enough to get a decent shot at anything like a similar angle.

EDIT:  I have switched out the booster separation photo.  The angle and resolution are suboptimal, but at least it's real.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 10/15/2011 03:11 pm
Yeah, I agree: if you wanted to assemble ISS with some kind of HLV, then, given the fact that the Saturn V was long gone, a Shuttle-derived HLV would have made sense.  But notice that ISS's designers chose not to do that either.  This makes the case against HLV even stronger.
Not the case at all.  The ISS was built around the largest modules they could, delivered by Proton and Shuttle.  Had your own logic been used, the ISS would have been more likely built by Delta II and Soyuz with smaller modules. But no, they built it using the largest modules they could.  Had Saturn continued, likely Skylab would have as well.  The Shuttle could even have entered the picture, launched by Saturn.

I don't see how what I've said leads to using Delta II to build ISS.  My point is that the designers of ISS decided -- quite sensibly -- to use the largest launch vehicles already available.  Despite having a large payload to loft, they chose not to develop an HLV.  I think that too was sensible.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 10/15/2011 07:37 pm
Yeah, I agree: if you wanted to assemble ISS with some kind of HLV, then, given the fact that the Saturn V was long gone, a Shuttle-derived HLV would have made sense.  But notice that ISS's designers chose not to do that either.  This makes the case against HLV even stronger.
Not the case at all.  The ISS was built around the largest modules they could, delivered by Proton and Shuttle.  Had your own logic been used, the ISS would have been more likely built by Delta II and Soyuz with smaller modules. But no, they built it using the largest modules they could.  Had Saturn continued, likely Skylab would have as well.  The Shuttle could even have entered the picture, launched by Saturn.

I don't see how what I've said leads to using Delta II to build ISS.  My point is that the designers of ISS decided -- quite sensibly -- to use the largest launch vehicles already available.  Despite having a large payload to loft, they chose not to develop an HLV.  I think that too was sensible.
This is off-topic, you guys. And just FYI, I should point out that none of the USOS modules are greater than ~15 metric tons (not saying this helps anyone's argument, but it is interesting to me). The most massive modules are the Russian Zarya and Zvezda at  a little under 20 metric tons (part of that was a little extra mass for the automatic docking capability... but since our modules don't have that, we have to rely on Russian modules for attitude control and gyro desaturation when gravity gradient isn't sufficient and for debris avoidance maneuvers, etc). But it's off-topic.

Where's Jim's ISS-with-ELV thread, again?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Prober on 10/16/2011 05:21 pm
http://www.nasaspaceflight.com/2011/10/sls-trades-opening-four-rs-25s-core-stage/
At least two more articles to come on SLS hardware. Starting to feel like the "good old days" of shuttle processing level of content to write up in L2.

   Are they planning *two* complete new NASA-only upper stages?
    1) the "CPS", "NASA designed on-orbit stage... Enables Exploration missions", to be used for Block 1A+
    2) the "Upper Stage", with 3 * J-2X, "This Upper Stage burns out prior to orbit insertion (ala Saturn V)."

    plus, additionally,
    0) "iCPS", the DIVHUS with new avionics, "Requires Delta IV flight computer redesign."

                ?
              -Alex

sad to say .....don't even wish to waste my time reading the "future plans".  The direction tells me they couldn't kill the SLS the first round, so now they try again in the next phase.
sad, sad
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 10/16/2011 10:40 pm
http://www.nasaspaceflight.com/2011/10/sls-trades-opening-four-rs-25s-core-stage/
At least two more articles to come on SLS hardware. Starting to feel like the "good old days" of shuttle processing level of content to write up in L2.

   Are they planning *two* complete new NASA-only upper stages?
    1) the "CPS", "NASA designed on-orbit stage... Enables Exploration missions", to be used for Block 1A+
    2) the "Upper Stage", with 3 * J-2X, "This Upper Stage burns out prior to orbit insertion (ala Saturn V)."

    plus, additionally,
    0) "iCPS", the DIVHUS with new avionics, "Requires Delta IV flight computer redesign."

                ?
              -Alex

sad to say .....don't even wish to waste my time reading the "future plans".  The direction tells me they couldn't kill the SLS the first round, so now they try again in the next phase.
sad, sad
Don't attribute to malice...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 10/18/2011 04:36 pm
Bumping some of the previous leading threads back to the top after the Space Policy HLV threads were moved into here.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Herb Schaltegger on 10/19/2011 02:38 pm
And just FYI, I should point out that none of the USOS modules are greater than ~15 metric tons (not saying this helps anyone's argument, but it is interesting to me).

The USOS modules are "shrunken" in length compared to the original Space Station Freedom baseline (which was 10 racks x 4), due to orbiter CG constraints.  Further, with the cancellation of the ASRM program, they were all seriously mass-constrained even with the shorter length.  That's why so many of the modules and truss segments were launched essentially underpopulated and required substantial on-orbit outfitting, assembly and checkout. 
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: oldAtlas_Eguy on 10/19/2011 06:19 pm
So for SLS to be used to put up a >26MT and >5m diameter module funding for the new module design if started in 2013 would result in the module being added to the ISS in 2023. Funding would be at an annual budget of ~$1B per year for 8 to 10 years. The item here is that an expenditure of $10B for a single payload and SLS flight is not a reason for SLS to exist when other LV’s are capable of delivery far cheaper.

Large payloads other than MPCV for SLS will take at least 10 years to develop after the payload program is funded. Such funding cannot currently occur until the earliest of 2013, more likely in 2014 or 2015 if the US economy recovers. That leaves SLS without any missions other than MPCV flights with simplistic cis-lunar orbit destinations until after 2023. Until such time as there are payload programs/missions needing the larger 130MT SLS Block II funded, the SLS Block II introduction would be delayed leaving only the SLS Block I 100MT capable configuration under used and at a very low flight rate, at best 1 a year for 5 to 8 years, more likely only 3 flights scattered across those 5 to 8 years while waiting on other payloads/mission hardware.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 10/19/2011 08:04 pm
(Just a nit-pick... EELVs have 7+meter fairing sizes available optionally if a payload requires it... it'd require a little non-recurring costs, but not very much.... Also, >29mT Atlas V Heavy is also available in a shorter time than it'd cost to build a payload for ~$400 million non-recurring one-time cost...)

EDIT:Sorry, I acknowledge this post is off-topic.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 10/19/2011 08:46 pm
You guys are totally off topic. Discussions of payloads and missions have nothing to do with trade studies leaning toward 4xRS-25's on the core stage (thread topic). Take it to the appropriate thread please, which is not this one.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 10/19/2011 08:54 pm
You guys are totally off topic. Discussions of payloads and missions have nothing to do with trade studies leaning toward 4xRS-25's on the core stage (thread topic). Take it to the appropriate thread please, which is not this one.
I was initially inclined to agree, but... Doesn't it matter what the payloads/missions we're going to use for the SLS are? Or are we just building SLS for the heck of it?

(Yes, I acknowledge my previous post was off-topic. Sorry about that! But I disagree that talking about the payload/mission that SLS would be used--and designed--for is off-topic! I mean, what the heck are they trading for if not for payload/mission capability, schedule, and affordability? <-That question is not supposed to be a jab.)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: oldAtlas_Eguy on 10/19/2011 09:41 pm
You guys are totally off topic. Discussions of payloads and missions have nothing to do with trade studies leaning toward 4xRS-25's on the core stage (thread topic). Take it to the appropriate thread please, which is not this one.
I was initially inclined to agree, but... Doesn't it matter what the payloads/missions we're going to use for the SLS are? Or are we just building SLS for the heck of it?

(Yes, I acknowledge my previous post was off-topic. Sorry about that! But I disagree that talking about the payload/mission that SLS would be used for is off-topic! I mean, what the heck are they trading for if not for payload/mission capability, schedule, and affordability?)

Currently we seem to be building SLS just for the heck of it, since other than a few simplistic MPCV flights to cis-lunar orbits is all that can be acomplished without some specific currently un-funded mission hardware needed for a Lunar surface or NEA mission.

(sorry off topic again)

The 4 and 5 engine only core models will save some development money because of the thrust structures and engine cluster testing now only has two configurations not three.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Namechange User on 10/19/2011 09:52 pm
Ah, yes another attempt at hijacking the thread.  Can someone point me to the list of payloads NASA said it would build for HSF exploration, and of course the RFP's and contracts to unleash the "free market", before Congress forced NASA at gunpoint to build the SLS, robbing that money and canceling those payloads and contracts?

Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/20/2011 04:35 pm

Currently we seem to be building SLS just for the heck of it, since other than a few simplistic MPCV flights to cis-lunar orbits is all that can be acomplished without some specific currently un-funded mission hardware needed for a Lunar surface or NEA mission.


Hmmm...sounds almost like the reason we built the Saturn V and went to the Moon..."for the heck of it".

Or to quote JFK:
"But why, some say, the moon? Why choose this as our goal? And they may well ask why climb the highest mountain? Why, 35 years ago, fly the Atlantic? Why does Rice play Texas?

We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win, and the others, too."

1)  Note how radically different that mindset was then to what our government and for the most part, our citizen's mindset is today, unforutnately (OT, sorry).
2)  Sounds like JFK was saying we need to go to the Moon for the same reason someone climbs a mountain...because it's there and it's challenging.  "For the heck of it".

;-)


Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: kch on 10/20/2011 04:40 pm

Currently we seem to be building SLS just for the heck of it, since other than a few simplistic MPCV flights to cis-lunar orbits is all that can be acomplished without some specific currently un-funded mission hardware needed for a Lunar surface or NEA mission.


Hmmm...sounds almost like the reason we built the Saturn V and went to the Moon..."for the heck of it".

Or to quote JFK:
"But why, some say, the moon? Why choose this as our goal? And they may well ask why climb the highest mountain? Why, 35 years ago, fly the Atlantic? Why does Rice play Texas?

We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win, and the others, too."

1)  Note how radically different that mindset was then to what our government and for the most part, our citizen's mindset is today, unforutnately (OT, sorry).
2)  Sounds like JFK was saying we need to go to the Moon for the same reason someone climbs a mountain...because it's there and it's challenging.  "For the heck of it".

;-)




Good grief -- hope the rest of your understanding of history isn't as sadly flawed as *that*!  Yeesh ... :(
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/20/2011 07:59 pm
My understanding of history is just fine thank you.  However, here I wasn't trying to make a factual historical point about why we went to the moon.  Rather, I was just making a point about something being subjective to point of view.  If your point of view is that we are just building SLS "for the heck of it", then something similar could be said about going to the moon.  And JFK's own words could be interpreted to support that.

Obviously, (reading my statement), I'm not making the point that we went to the Moon just for the "heck of it".  But I also do not think that building SLS is just for the heck of it.

An analogy being used as a rhetorical device.  Perhaps if your understanding of language wasn't so fatally flawed...
Yeesh...  :-(

Note:  The last added mainly to illustrate the acrimonious nature of your comment.  Those comments can really be left off these posts.

;-)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 10/20/2011 08:18 pm
The world in the day of JFK's speech was filled with people with adventurous spirits, brave and dedicated to a cause. They were not fools, willing to take unnecessary risk that would likely get them killed, but they did have a different metric to determine what the level of risk actually was.

Today’s world is very, *very* different. The people are just as intelligent but are *far* more fearful! Today we live in a risk-averse world. Everything has a backup system and the backups all have backups so that if something didn’t go right you can do something else. People today are not willing to accept the possibility that failure can cause loss of life. If it is even possible that could result, people today won’t do it – they are too scared. People today completely loose sight of the fact that nobody gets out of life alive. Back in the day, they made it the best way they could and then just took their best shot – risk of death or not. Most of the time it worked but sometimes it did not. People today are too chicken to do that.

And that's my understanding of the history I lived. Mods, if you want to delete this it won't hurt my feelings but I really wanted to express my feelings, because it was brought up and they were talking about "back in the (my) day".
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/20/2011 09:55 pm
The world in the day of JFK's speech was filled with people with adventurous spirits, brave and dedicated to a cause. They were not fools, willing to take unnecessary risk that would likely get them killed, but they did have a different metric to determine what the level of risk actually was.

Today’s world is very, *very* different. The people are just as intelligent but are *far* more fearful! Today we live in a risk-averse world. Everything has a backup system and the backups all have backups so that if something didn’t go right you can do something else. People today are not willing to accept the possibility that failure can cause loss of life. If it is even possible that could result, people today won’t do it – they are too scared. People today completely loose sight of the fact that nobody gets out of life alive. Back in the day, they made it the best way they could and then just took their best shot – risk of death or not. Most of the time it worked but sometimes it did not. People today are too chicken to do that.

And that's my understanding of the history I lived. Mods, if you want to delete this it won't hurt my feelings but I really wanted to express my feelings, because it was brought up and they were talking about "back in the (my) day".

X2 !
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 10/21/2011 01:54 am
Moved from the Cheaper Alternatives thread:

If Direct with 4 seg solids had been developed several years ago, it would have been less expensive to operate.  SLS will be more expensive, 5 segs, stretched tanks, 4 engines.

I never understood this argument, really.  An extra two segments is about $25M, possibly less, unless ATK starts being a jerk again.  An extra RS-25E is maybe $25-50M depending on flight rate (and since it's an extra engine, the true incremental cost is lower than the unit price).  A tank stretch should be down in the noise, component-cost-wise.  How does this make the system unaffordable?

For an extra ~$50M per flight, you get something like 20 tonnes of extra payload IIRC.  That's ~$2500/kg incremental.  Now, if you don't use it that doesn't do you any good, but as I said I don't see where this idea breaks the bank operations-wise.  Development is a little murkier, but we already know what it's supposed to cost to develop and that doesn't break the bank either...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/21/2011 03:23 am
Moved from the Cheaper Alternatives thread:

If Direct with 4 seg solids had been developed several years ago, it would have been less expensive to operate.  SLS will be more expensive, 5 segs, stretched tanks, 4 engines.

I never understood this argument, really.  An extra two segments is about $25M, possibly less, unless ATK starts being a jerk again.  An extra RS-25E is maybe $25-50M depending on flight rate (and since it's an extra engine, the true incremental cost is lower than the unit price).  A tank stretch should be down in the noise, component-cost-wise.  How does this make the system unaffordable?

For an extra ~$50M per flight, you get something like 20 tonnes of extra payload IIRC.  That's ~$2500/kg incremental.  Now, if you don't use it that doesn't do you any good, but as I said I don't see where this idea breaks the bank operations-wise.  Development is a little murkier, but we already know what it's supposed to cost to develop and that doesn't break the bank either...
You need as well a longer main tank, which then requires an additional motor or two to get the job done due to the added fuel weight.  It is those extra two SSME's which are the cost increase.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 10/21/2011 03:45 am
Read it again.  I accounted for that.

It's not two extra, it's one.  Jupiter in the recommended configuration was 3 and 4, SLS is 4 and 5.  What's the incremental cost of an RS-25E?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mark S on 10/21/2011 12:12 pm
Read it again.  I accounted for that.

It's not two extra, it's one.  Jupiter in the recommended configuration was 3 and 4, SLS is 4 and 5.  What's the incremental cost of an RS-25E?

I think DIRECT's thrust was that the time and expense to develop the stretched version of the core (and the 5-seg motors) would outweigh the benefits of the incremental increase in payload capacity that would be gained. That was probably true three or four years ago, but at this point: (1) it's a few years later; (2) the 5-seg is nearly completed; (3) a full development plan is in place for the stretched tank; and (4) there is political consensus behind SLS; we might as well go for the whole enchilada.

So basically you're right, the incremental operational cost should not be a showstopper.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 10/21/2011 12:26 pm
Read it again.  I accounted for that.

It's not two extra, it's one.  Jupiter in the recommended configuration was 3 and 4, SLS is 4 and 5.  What's the incremental cost of an RS-25E?

I think DIRECT's thrust was that the time and expense to develop the stretched version of the core (and the 5-seg motors) would outweigh the benefits of the incremental increase in payload capacity that would be gained. That was probably true three or four years ago, but at this point: (1) it's a few years later; (2) the 5-seg is nearly completed; (3) a full development plan is in place for the stretched tank; and (4) there is political consensus behind SLS; we might as well go for the whole enchilada.

So basically you're right, the incremental operational cost should not be a showstopper.

That's correct Mark.
As one of the DIRECT co-founders, I will say that given the facts on the ground, I support the SLS configuration.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: beb on 10/21/2011 12:36 pm

Currently we seem to be building SLS just for the heck of it, since other than a few simplistic MPCV flights to cis-lunar orbits is all that can be acomplished without some specific currently un-funded mission hardware needed for a Lunar surface or NEA mission.


Hmmm...sounds almost like the reason we built the Saturn V and went to the Moon..."for the heck of it".

Or to quote JFK:
"But why, some say, the moon? Why choose this as our goal? And they may well ask why climb the highest mountain? Why, 35 years ago, fly the Atlantic? Why does Rice play Texas?

We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win, and the others, too."

1)  Note how radically different that mindset was then to what our government and for the most part, our citizen's mindset is today, unforutnately (OT, sorry).
2)  Sounds like JFK was saying we need to go to the Moon for the same reason someone climbs a mountain...because it's there and it's challenging.  "For the heck of it".

;-)




Missing from the analysis of Kennedy's speech is that we were in the middle of (and losing) a Space Race with the "Commies." Kennedy made his announcement after being assured that we were so much farther along in development of a large rocket that we were a shoe-in to beat the Red to the Moon. Thus the goal was to show up the Russians but he sold it to America as a glorious thing to do in and of itself.

Kennedy's speech is a wondering piece of writing from a time, before we got bogged down in a land war in Asia, when America thought it could do anything and everything just because we were Americans. It was a wonderful time to be alive.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 10/21/2011 06:09 pm
Moved from the Cheaper Alternatives thread:

If Direct with 4 seg solids had been developed several years ago, it would have been less expensive to operate.  SLS will be more expensive, 5 segs, stretched tanks, 4 engines.

I never understood this argument, really.  An extra two segments is about $25M, possibly less, unless ATK starts being a jerk again.  An extra RS-25E is maybe $25-50M depending on flight rate (and since it's an extra engine, the true incremental cost is lower than the unit price).  A tank stretch should be down in the noise, component-cost-wise.  How does this make the system unaffordable?

For an extra ~$50M per flight, you get something like 20 tonnes of extra payload IIRC.  That's ~$2500/kg incremental.  Now, if you don't use it that doesn't do you any good, but as I said I don't see where this idea breaks the bank operations-wise.  Development is a little murkier, but we already know what it's supposed to cost to develop and that doesn't break the bank either...

I think when talking about Direct, the context needs to be assumed as if it had been adopted as the PoR prior to ATK shutting down the 4-seg production and before they had gotten any development money for the 5-seg booster.  So, Direct would have just used completely the existing SRB infrastructure.  Everything in that area would be identical to STS.  There would have been zero development costs.

For the core, there would have been, but it would have been less.  As all they are really doing is redesigning the LOX tank, and then putting a new MPS on the bottom.  Granted, SLS's stretched core won't be a whole lot more to develop or produce than the Direct core would be, but Direct should have been a little cheaper, and faster as it's closer to the STS ET than the SLS core.  Also, there's a couple of existing ET's that could have been modified into the first couple of J-130's for testing and inital flights.  I don't think they can be used for the stretched SLS core.

The Upper stage would have been cheaper too if it used existing RL-10's, rather than developing the new J2X.

The CT's would probably not need to be upgraded either. 

So that's I think the argument for Direct is really tied in to.  Had it been adopted and applied at the right time, it could have slid right in along side the final few years of STS, and been ready to fly with Orion pretty much right when STS was done, eliminating the gap we now have.
Development costs would have been lower, and it would have been faster (allowing for development while STS was winding down). 

Once Direct was fully up and running vs. SLS fully up and running, once all of the development costs are in the books and history, my guess is the annual fixed costs of the programs, as well as hardware costs per launch, will actually not be too far apart.  Probably SLS will only be linerally more expensive than Jupiter with reference to it's increased performance. 
The big difference, is we'd probably have Jupiter flying today, rather than waiting for SLS flying at the end of the decade.

However, the longer we waited, the closer to SLS's costs and timeline Direct would become.  Once all of the money was spent on the 5-seg SRB, and the 4-seg line was retired, then the core had to be stretched to accomodate the 5-seg SRK, then money was spent on J2X, then probably another RS-25 was needed to be added due to the increased fuel load of the stretched core, etc. etc, then the advantages of Direct started to go away.  NAA2010 was the final nail in the coffin for the faster, cheaper, more efficient Direct plan.

In all honesty, SLS is really the Direct Jupiter that you get when you mandate a 5-seg SRB, J2X upper stage engine, and 130mt to LEO.
SLS -is- a J-251SH pretty much.
Direct's whole appeal was it was the easiest, fastest, and most efficient reuse of the STS hardware and infrastructure.  But that train left the station a few years ago.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Khadgars on 10/21/2011 07:00 pm
The world in the day of JFK's speech was filled with people with adventurous spirits, brave and dedicated to a cause. They were not fools, willing to take unnecessary risk that would likely get them killed, but they did have a different metric to determine what the level of risk actually was.

Today’s world is very, *very* different. The people are just as intelligent but are *far* more fearful! Today we live in a risk-averse world. Everything has a backup system and the backups all have backups so that if something didn’t go right you can do something else. People today are not willing to accept the possibility that failure can cause loss of life. If it is even possible that could result, people today won’t do it – they are too scared. People today completely loose sight of the fact that nobody gets out of life alive. Back in the day, they made it the best way they could and then just took their best shot – risk of death or not. Most of the time it worked but sometimes it did not. People today are too chicken to do that.

And that's my understanding of the history I lived. Mods, if you want to delete this it won't hurt my feelings but I really wanted to express my feelings, because it was brought up and they were talking about "back in the (my) day".

I enjoyed your post very much, thank you for sharing it.  Hopefully around this time next decade things will be quite different
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: TrueBlueWitt on 10/21/2011 07:14 pm
snip...

The Upper stage would have been cheaper too if it used existing RL-10's, rather than developing the new J2X.

snip.....

In all honesty, SLS is really the Direct Jupiter that you get when you mandate a 5-seg SRB, J2X upper stage engine, and 130mt to LEO.
SLS -is- a J-251SH pretty much.
Direct's whole appeal was it was the easiest, fastest, and most efficient reuse of the STS hardware and infrastructure.  But that train left the station a few years ago.

Lobo,

I have asked this several times in several threads.. with no response or answers. Seems like this may be the right place. 

Does anyone else believe that CPS could end up RL-10 powered and look a lot like DIRECT's US/EDS?  You still keep the J-2X as mandated(for 2nd stage down the road).. and in reality get something very close to a J-246SH for SLS Block-IA?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 10/21/2011 07:24 pm
It'd make a lot more sense to do it that way... Also, J-2X is pretty powerful for small payloads. For a small mission stack going to, say, a NEA, it'd be a design constraint... A modular mission stack would be difficult with such a high-thrust engine (even throttled down to ~50%). RL-10 is much better for that role, IMHO (and apparently those of the DIRECT team, etc).

Using a few RL-10s would mean higher Isp and lower dry mass and ability for lower throttle at the end of the burn, which would make designing an exploration stack easier.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 10/21/2011 07:42 pm
snip...

The Upper stage would have been cheaper too if it used existing RL-10's, rather than developing the new J2X.

snip.....

In all honesty, SLS is really the Direct Jupiter that you get when you mandate a 5-seg SRB, J2X upper stage engine, and 130mt to LEO.
SLS -is- a J-251SH pretty much.
Direct's whole appeal was it was the easiest, fastest, and most efficient reuse of the STS hardware and infrastructure.  But that train left the station a few years ago.

Lobo,

I have asked this several times in several threads.. with no response or answers. Seems like this may be the right place

Does anyone else believe that CPS could end up RL-10 powered and look a lot like DIRECT's US/EDS?  You still keep the J-2X as mandated(for 2nd stage down the road).. and in reality get something very close to a J-246SH for SLS Block-IA?

Just to address your question, I'll echo Chris's statement just above but this really isn't the thread for that. It actually belongs in a SLS general development thread. This one specificaly revolves around a core MPS design change to use 4xSSME's vs. the initial 3xSSME's.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: aquanaut99 on 10/21/2011 07:59 pm
The J-2X was never a good EDS stage motor. Where the J-2X really shines is as a second stage engine.

I think it is entirely possible, maybe even likely, that the CPS will end up being powered by RL-10s. The J-2X will have its main role in the Block II config as a second stage engine.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 10/21/2011 08:01 pm
I thought I should point out that the current plan is for the first upper/earth-departure stage for SLS to use the RL-10. The Delta IV upper stage.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 10/21/2011 08:08 pm
If Direct with 4 seg solids had been developed several years ago, it would have been less expensive to operate.  SLS will be more expensive, 5 segs, stretched tanks, 4 engines.
I never understood this argument, really.  ...
[good summary of why DIRECT was a good idea]

So IOW, no, the operational costs aren't much different.  The key was development, which by this point is a wash.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ben the Space Brit on 10/21/2011 08:12 pm
Given the likely performance of the four-engine SLS core, how much ballast, realistically, will 'back-up' LEO crewed missions need to keep the g-loadings during ascent within sensible limits?


@ Robotbeat,

As I understand it, the 'iCPS', the D-IVH-heritage EDS that will be used on SLS-01 and SLS-02, is not an upper stage in the strictest sense of the word.  It is being described as a 'kick stage'.  It's only purpose is to launch the MPCV through TLI; it will not have any significant role in the ascent to orbit, so it isn't an upper stage.  The SLS 4-engine core is powerful enough to carry the MPCV/iCPS stack to stable orbit without an upper stage.

So, no, RL-10 is not being planned as an SLS upper stage engine , only an EDS engine.  There is a difference in this context.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 10/21/2011 08:31 pm
Given the likely performance of the four-engine SLS core, how much ballast, realistically, will 'back-up' LEO crewed missions need to keep the g-loadings during ascent within sensible limits?


@ Robotbeat,

As I understand it, the 'iCPS', the D-IVH-heritage EDS that will be used on SLS-01 and SLS-02, is not an upper stage in the strictest sense of the word.  It is being described as a 'kick stage'.  It's only purpose is to launch the MPCV through TLI; it will not have any significant role in the ascent to orbit, so it isn't an upper stage.  The SLS 4-engine core is powerful enough to carry the MPCV/iCPS stack to stable orbit without an upper stage.

So, no, RL-10 is not being planned as an SLS upper stage engine , only an EDS engine.  There is a difference in this context.
*sigh* I said:
"..the current plan is for the first upper/earth-departure stage for SLS to use the RL-10. The Delta IV upper stage."

And besides, I'd be quite surprised if it didn't do at least a small orbital insertion burn to allow for core disposal.

I know it's fun to nit-pick, but come on.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mark S on 10/21/2011 09:07 pm
@ Robotbeat,

As I understand it, the 'iCPS', the D-IVH-heritage EDS that will be used on SLS-01 and SLS-02, is not an upper stage in the strictest sense of the word.  It is being described as a 'kick stage'.  It's only purpose is to launch the MPCV through TLI; it will not have any significant role in the ascent to orbit, so it isn't an upper stage.  The SLS 4-engine core is powerful enough to carry the MPCV/iCPS stack to stable orbit without an upper stage.

So, no, RL-10 is not being planned as an SLS upper stage engine , only an EDS engine.  There is a difference in this context.

*sigh* I said:
"..the current plan is for the first upper/earth-departure stage for SLS to use the RL-10. The Delta IV upper stage."

And besides, I'd be quite surprised if it didn't do at least a small orbital insertion burn to allow for core disposal.

I know it's fun to nit-pick, but come on.

Well, iCPS is not an upper stage, it's payload. There is a difference. And performing a circularization burn does not make it an upper stage, because that burn takes place long after core stage burnout and orbital insertion.

The "integrated upper Earth departure stage" nomenclature is enshrined in PL# 111-267 (Sec 302(c)(1)(B)), but it will not be put into actual practice. NASA wants the EDS to be separate from the upper stage, so we get three development items instead of just one: the interim iCPS; the ascent-only SLS upper stage with 1, 2, or maybe 3 J2X engines; and the dedicated in-space "CPS" stage for BLEO missions, which may or may not use RL10 engine(s).

The beefiness of the SLS upper stage is required to meet the Congressional target of 130 tonnes of payload to LEO (Sec 302(c)(1)(B) again). Which also makes it unsuitable as an EDS.

Cheers!
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 10/21/2011 10:00 pm
Again, how are they going to do core disposal without a small burn by the Delta IV upper?

And as I said originally, it is an EDS. Just because you can POSSIBLY interpret what someone said as incorrect, doesn't mean you should do so for the sake of nit-picking. I am well aware the Delta IV upper wouldn't be used as a real upper stage.

EDIT:Let me clarify, you're right, of course, that the Delta IV upper stage will not be 'the' or even 'a' upper stage for SLS in the strict sense.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 10/22/2011 12:02 am
As army commitments are low this weekend, I'm going to try and write a monster SLS article updating where things stand. Get it on Sunday. Bim-bam-bosh ;D
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: cro-magnon gramps on 10/22/2011 12:26 am
As army commitments are low this weekend, I'm going to try and write a monster SLS article updating where things stand. Get it on Sunday. Bim-bam-bosh ;D

the army's loss is our gain

Go For Broke, Chris!!!!  ;D

We're all ears  ???
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: luke strawwalker on 10/22/2011 06:27 am

  Applying that lesson to today's situation, it seems to me the way to go is to use existing launch vehicles and to get on with developing the non-existent deep-space elements.

EXACTLY!  Unfortunately this ignores political reality which bears little resemblence to everyone else's reality, let alone sanity or logic. 

Build a new HLV when you need it... not build an HLV first and then figure out what you can do with it... if anything... 

Nobody has even TRIED to do exploration with existing vehicles.  Rockets can be done by any of the contractors/commercial space companies.  Deep space EXPLORATION hardware, on the other hand, isn't going to be done by anybody but NASA (or contractors directly in their employ).  Maybe it'll turn out that 70-130 tons IS needed for sustained long-term exploration.  But maybe it won't, either... fact is, we don't know, because we haven't TRIED.  It's the same assumptions that sold shuttle as "we have to have this-- it's gonna do A, B, and C for XYZ" based on cherry-picked fundamental assumptions which may not be borne out by reality...

Later!  OL JR :)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: luke strawwalker on 10/22/2011 06:34 am
ISS certainly could have been lofted with a small number of heavy-lift launches.  About three 130-tonners would have done it.  However, ISS's designers notably obeyed Aken's law (http://spacecraft.ssl.umd.edu/akins_laws.html) of launch-vehicle development:

"The three keys to keeping a new manned space program affordable and on schedule:

ISS was affordable and on schedule???? (shocking!) I'd HATE to see what unaffordable and delayed looked like!!!!


          1)  No new launch vehicles.
          2)  No new launch vehicles.
          3)  Whatever you do, don't decide to develop any new launch vehicles."

But suppose they had said: "We've got a big payload, so let's begin by building a big rocket" and started on an SLS-style launch-vehicle development program.  If so, NASA would spent have billions of dollars and several years at the beginning of the space-station program building the rocket.  Once that was done, it would have spent several years paying the fixed-costs of that rocket without flying it while developing ISS itself.  Then it would have flown the rocket three times to get ISS into orbit.  Once ISS was complete, NASA would either terminate the rocket, as it did the Saturn V, or go back to paying its fixed costs while having no missions for it.  With fixed costs running a billion or two a year, this is not a pretty picture.

Depends on the launch vehicle.  Had it been something like NLS or even a souped up version of Shuttle C, something that shared costs and infrastructure, it might not have been too bad, and certainly would have opened up a lot of possibilities that remained closed with shuttle alone. 

Politically/budgetarily survivable??  That's another story...

That was the fundamental problem with Shuttle C all along and why it would never happen-- it would put shuttle out of a job, because shuttle was just too expensive to launch crew alone and put all the cargo on Shuttle C...

Later! OL JR :)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: luke strawwalker on 10/22/2011 06:52 am

Yeah, I agree: if you wanted to assemble ISS with some kind of HLV, then, given the fact that the Saturn V was long gone, a Shuttle-derived HLV would have made sense.  But notice that ISS's designers chose not to do that either.  This makes the case against HLV even stronger.

I wouldn't say that... ISS existed largely to give shuttle "something to do", a reason for its continued existence.  So, ISS was designed with the shuttle in mind and required to launch and service it. 

Had shuttle been retired after Challenger, and something "shuttle derived" like NLS or even "clean sheet" like Jarvis, those design criteria (using shuttle for construction/service) would not have existed and the design would have been very different. 

The statements that ISS could not be launched without shuttle are disingenuous... ISS "as we know it" could not be launched without shuttle (even that's a stretch as proposals like the payload bay fairing prove the point it was possible to do it with another vehicle beside shuttle).  In all likelihood the design would have been a lot more practical-- larger ground-integrated fully equipped modules launched by HLV and simply docked together in orbit and the plumbing/wiring connections made, not assembled in orbit from 20 ton building blocks and equipped/supplied later.  In other words, FAR more like MIR...

IMHO ISS's main contribution is to teach us how NOT to build a massive space station...

Later!  OL JR :)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: luke strawwalker on 10/22/2011 07:02 am
So for SLS to be used to put up a >26MT and >5m diameter module funding for the new module design if started in 2013 would result in the module being added to the ISS in 2023. Funding would be at an annual budget of ~$1B per year for 8 to 10 years. The item here is that an expenditure of $10B for a single payload and SLS flight is not a reason for SLS to exist when other LV’s are capable of delivery far cheaper.

Large payloads other than MPCV for SLS will take at least 10 years to develop after the payload program is funded. Such funding cannot currently occur until the earliest of 2013, more likely in 2014 or 2015 if the US economy recovers. That leaves SLS without any missions other than MPCV flights with simplistic cis-lunar orbit destinations until after 2023. Until such time as there are payload programs/missions needing the larger 130MT SLS Block II funded, the SLS Block II introduction would be delayed leaving only the SLS Block I 100MT capable configuration under used and at a very low flight rate, at best 1 a year for 5 to 8 years, more likely only 3 flights scattered across those 5 to 8 years while waiting on other payloads/mission hardware.


Doesn't sound particularly sustainable or interesting to me...

More like cancellation bait...

OL JR :)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: TrueBlueWitt on 10/22/2011 04:33 pm
snip...

The Upper stage would have been cheaper too if it used existing RL-10's, rather than developing the new J2X.

snip.....

In all honesty, SLS is really the Direct Jupiter that you get when you mandate a 5-seg SRB, J2X upper stage engine, and 130mt to LEO.
SLS -is- a J-251SH pretty much.
Direct's whole appeal was it was the easiest, fastest, and most efficient reuse of the STS hardware and infrastructure.  But that train left the station a few years ago.

Lobo,

I have asked this several times in several threads.. with no response or answers. Seems like this may be the right place

Does anyone else believe that CPS could end up RL-10 powered and look a lot like DIRECT's US/EDS?  You still keep the J-2X as mandated(for 2nd stage down the road).. and in reality get something very close to a J-246SH for SLS Block-IA?

Just to address your question, I'll echo Chris's statement just above but this really isn't the thread for that. It actually belongs in a SLS general development thread. This one specificaly revolves around a core MPS design change to use 4xSSME's vs. the initial 3xSSME's.

CPS now has it's own thread.
http://forum.nasaspaceflight.com/index.php?topic=27139.0

Very interesting Trade studies(J-2 class vs RL-10/NGE/Vinces/MB-60..) How many engines and also answers questions about SLS core including the Planned insertion orbit for SLS. 

CPS does provide circularization burn from 30x130nm insertion. 

Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MP99 on 10/23/2011 09:49 am
@ Robotbeat,

As I understand it, the 'iCPS', the D-IVH-heritage EDS that will be used on SLS-01 and SLS-02, is not an upper stage in the strictest sense of the word.  It is being described as a 'kick stage'.  It's only purpose is to launch the MPCV through TLI; it will not have any significant role in the ascent to orbit, so it isn't an upper stage.  The SLS 4-engine core is powerful enough to carry the MPCV/iCPS stack to stable orbit without an upper stage.

So, no, RL-10 is not being planned as an SLS upper stage engine , only an EDS engine.  There is a difference in this context.

*sigh* I said:
"..the current plan is for the first upper/earth-departure stage for SLS to use the RL-10. The Delta IV upper stage."

And besides, I'd be quite surprised if it didn't do at least a small orbital insertion burn to allow for core disposal.

I know it's fun to nit-pick, but come on.

Well, iCPS is not an upper stage, it's payload. There is a difference. And performing a circularization burn does not make it an upper stage, because that burn takes place long after core stage burnout and orbital insertion.

The "integrated upper Earth departure stage" nomenclature is enshrined in PL# 111-267 (Sec 302(c)(1)(B)), but it will not be put into actual practice. NASA wants the EDS to be separate from the upper stage, so we get three development items instead of just one: the interim iCPS; the ascent-only SLS upper stage with 1, 2, or maybe 3 J2X engines; and the dedicated in-space "CPS" stage for BLEO missions, which may or may not use RL10 engine(s).

The beefiness of the SLS upper stage is required to meet the Congressional target of 130 tonnes of payload to LEO (Sec 302(c)(1)(B) again). Which also makes it unsuitable as an EDS.

Agreed, upper stage will be J-2X as a result of PL 111-267, but CPS won't be an "integrated upper Earth departure stage" despite PL 111-267.

cheers, Martin
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RocketmanUS on 10/27/2011 10:21 pm
SLS Block 1a
Will they be using the composite SRB's or could they stay with the 5 segment SRB's now being designed?

Can they still make the 4 segment SRB's if they wanted to?

What is the sea level thrust needed for a SRB for SLS block II and burn time?

SLS block I
What is it's net payload mass in pounds to a 100x100nim, 29.0 degree orbit?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jason1701 on 10/28/2011 03:43 am
Can they still make the 4 segment SRB's if they wanted to?

No, all the production lines are geared to the 5-segment.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Namechange User on 10/28/2011 03:48 am
Can they still make the 4 segment SRB's if they wanted to?

No, all the production lines are geared to the 5-segment.

Well, it's not quite as bad as you make it sound.  It's not like we lost the instructions on how to do it.  At worse, t's essentially manufacturing new mandrills (but I think they actually kept those and didn't scrap them) and maybe re-qualifying some suppliers. 
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/28/2011 03:55 am
Can they still make the 4 segment SRB's if they wanted to?

No, all the production lines are geared to the 5-segment.

Well, it's not quite as bad as you make it sound.  It's not like we lost the instructions on how to do it.  At worse, t's essentially manufacturing new mandrills (but I think they actually kept those and didn't scrap them) and maybe re-qualifying some suppliers. 
It still is time and money to recreate.  While not dire, it needs to be considered regardless.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RocketmanUS on 10/28/2011 04:44 am
Can they still make the 4 segment SRB's if they wanted to?

No, all the production lines are geared to the 5-segment.

Well, it's not quite as bad as you make it sound.  It's not like we lost the instructions on how to do it.  At worse, t's essentially manufacturing new mandrills (but I think they actually kept those and didn't scrap them) and maybe re-qualifying some suppliers. 
It still is time and money to recreate.  While not dire, it needs to be considered regardless.

So if given the option , 4seg with proven flights , or 5seg with greater mass to orbit? How soon can the 5 segs be ready for flight if the other parts of SLS were ready today?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: sdsds on 10/28/2011 06:21 am
So if given the option , 4seg with proven flights , or 5seg with greater mass to orbit?

Having looked at ATK's situation for awhile, I think NASA's two realistic options for solid boosters from ATK are:

- 5 segment motors made with the technologies developed for the Ares-I first stage, or

- 4 segment motors made with the technologies developed for the Ares-I first stage

ATK would only charge NASA a little more (half a billion dollars, maybe?) to qualify the new 4 segment motors, and would undoubtedly price them no higher than 5 segment motors.

Now which do you want NASA to buy?

Quote
How soon can the 5 segs be ready for flight if the other parts of SLS were ready today?

Right now ATK is essentially sitting out there in the Utah desert twiddling their thumbs.  How soon did you want them to have motors ready?  And what were you willing to pay to have them yesterday?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 10/28/2011 09:59 am
Can they still make the 4 segment SRB's if they wanted to?

No, all the production lines are geared to the 5-segment.

A 4-segment SRB made entirely with the new 5-segment facilities and hardware is available.
All that is required is to leave the center segment out when assembling the motor.
The only loss is to ATK - they get to charge NASA a little less.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RocketmanUS on 10/29/2011 01:59 am
Will the Ares RSRMV ( for block 1 ) still be available if the advanced boosters are not ready for block 1A or if the a new administration just wants to go with block 1 for the time being?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RocketmanUS on 10/29/2011 03:55 am
So if given the option , 4seg with proven flights , or 5seg with greater mass to orbit?

Having looked at ATK's situation for awhile, I think NASA's two realistic options for solid boosters from ATK are:

- 5 segment motors made with the technologies developed for the Ares-I first stage, or

- 4 segment motors made with the technologies developed for the Ares-I first stage

ATK would only charge NASA a little more (half a billion dollars, maybe?) to qualify the new 4 segment motors, and would undoubtedly price them no higher than 5 segment motors.

Now which do you want NASA to buy?

Quote
How soon can the 5 segs be ready for flight if the other parts of SLS were ready today?

Right now ATK is essentially sitting out there in the Utah desert twiddling their thumbs.  How soon did you want them to have motors ready?  And what were you willing to pay to have them yesterday?

So you are saying go with the 5 seg then and get more payload into orbit per launch and not have to pay to qualify the 4 seg then?

What I was asking was how soon would the 5 seg be ready for a HLV?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jason1701 on 10/29/2011 04:43 am
Can they still make the 4 segment SRB's if they wanted to?

No, all the production lines are geared to the 5-segment.

A 4-segment SRB made entirely with the new 5-segment facilities and hardware is available.
All that is required is to leave the center segment out when assembling the motor.
The only loss is to ATK - they get to charge NASA a little less.

You're certain there would be no extra testing, requalification, or integration changes?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 10/29/2011 04:57 am
Will the Ares RSRMV ( for block 1 ) still be available if the advanced boosters are not ready for block 1A or if the a new administration just wants to go with block 1 for the time being?
No.  The equipment would have been used up in the Block 1 flights.  Only a limited number of TVC units so I understand.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: sdsds on 10/29/2011 05:35 am
So you are saying go with the 5 seg then and get more payload into orbit per launch and not have to pay to qualify the 4 seg then?

I'm truly sorry:  I was feeling cocky and my answer was inappropriately glib.  Now that I'm in a more humble mood let me say:  "I don't really know."  That's because there might be implicit costs to 5 seg boosters beyond what ATK charges for them.  Here are two examples:  (1) the crawler-way and the crawler-transporters might require substantial and costly upgrades to carry an HLV with 5 seg boosters to the pad; (2) making SLS cores appropriately sized for 5 seg boosters might have costs markedly above the costs associated with making (Shuttle-sized) cores sized for 4 seg boosters.  (There's a third aspect; judge for yourself if it's a cost or a benefit.  If ATK has a flight-proven 5 seg motor, that increases the likelihood of reanimating the "rocket that will not die," i.e. Ares-I.)

Really on-topic for this thread: there are lots of folks who know about this stuff -- people at Boeing for example -- who like the 5 seg booster, stretched core, and 4x RS-25 vehicle.  And really, Boeing ought to know about this stuff!

Quote
What I was asking was how soon would the 5 seg be ready for a HLV?

ATK could be ready with 5 seg boosters, maybe even recoverable ones, before Boeing will be ready with an SLS core.  Quoting from page 29 of the recent SLS Industry Day presentation, "Core Stage Is on the Program’s Critical Path to First Flight in 2017."
http://www.nasa.gov/pdf/594163main_2011-SLS_Industry_Day_Final_Public1-1_rev2.pdf
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 10/29/2011 02:03 pm
Can they still make the 4 segment SRB's if they wanted to?

No, all the production lines are geared to the 5-segment.

A 4-segment SRB made entirely with the new 5-segment facilities and hardware is available.
All that is required is to leave the center segment out when assembling the motor.
The only loss is to ATK - they get to charge NASA a little less.

You're certain there would be no extra testing, requalification, or integration changes?

My statement was for flight-qualified boosters on a per-unit basis. Of course they will have to flight qualify it but that only takes one test flight.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RocketmanUS on 10/30/2011 02:48 am
Will the Ares RSRMV ( for block 1 ) still be available if the advanced boosters are not ready for block 1A or if the a new administration just wants to go with block 1 for the time being?
No.  The equipment would have been used up in the Block 1 flights.  Only a limited number of TVC units so I understand.

Can we not make more RSRMV's? If not why?

Not to be off topic, but what is Liberty block I's SRB ( is it not the RSRMV )? What about block II? To get a better picture of what might be going on and know what might be available.

Senate bill 3729 says 130t HLV payload to low Earth orbit but does not say what part of LEO ( 160km-2,000km ). Can we not assume a
160kmx160km orbit then?

Should we just go with block I SLS so we can start BEO missions and not just keep upgrading the launcher?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mr. Justice on 10/30/2011 03:36 am
It is my understanding that the J-2x upper stage/EDS is going to use the same avionics as the first stage. The J-2x is already being test fired. So, is there really any reason the J-2x upper stage/EDS could not fly on the 2017 launch?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: TrueBlueWitt on 10/30/2011 03:45 am
It is my understanding that the J-2x upper stage/EDS is going to use the same avionics as the first stage. The J-2x is already being test fired. So, is there really any reason the J-2x upper stage/EDS could not fly on the 2017 launch?

Money.. Money.. and.. you guessed it.. Money! On the budget they have now NO CHANCE.. and if they did.. they'd have no money for any payloads for another 10 years.. so what would be the point?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mark S on 10/30/2011 12:42 pm
It is my understanding that the J-2x upper stage/EDS is going to use the same avionics as the first stage. The J-2x is already being test fired. So, is there really any reason the J-2x upper stage/EDS could not fly on the 2017 launch?

First, SLS was mandated to be usable both with and without an upper stage, with the upper stage designed in from the start. However, it will not actually deployed until later in the program. So the budget has not been allocated to have the SLS upper stage ready in time for the initial missions.

Also, I think that the SLS upper stage will not be used as an Earth departure stage. It will use all of its propellant during the launch, and will be disposed of before the payload's orbital circularization burn. It will strictly be used to increase the SLS payload from the initial 70-100t range to ultimate 130t or more range.

From what I understand, the CPS (Cryogenic Propulsion Stage) will be a dedicated in-space stage for BLEO missions. It will be optimized for this role by using much lighter and more efficient engines (RL-10 variant in all probability).

Mark S.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mr. Justice on 10/30/2011 01:52 pm
So, if I am understanding correctly the Block-1 CPS will proceed the SLS upper stage into service. The CPS is only going to be able to send about 27 tons through TLI, which comes up short of the Saturn V's TLI performance. In fact, it could not even send a fully loaded Orion through TLI. Of course, since there will not be a required to perform a TEI, it will not need to be fully load. Still, it seems like it would only barely get Orion through TLI.

If we can undertake real missions without the upper stage, I am perfectly fine with that. However, it would seem, the only way the Block-1 CPS would allow for a real mission is with a fuel depot, and I am a fan of fuel depots. But, do we have the money to get a fuel depot up by later this decade?

Then, of course, the Block-1A SLS will not even be able to lift the Block-1 CPS. And, of course, to get from the Block-1A to the Block-1 SLS we will need to spend more money on developing new boosters of some kind.

Is there really any hope of a real mission being undertaken anytime in the foreseeable future?

Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ben the Space Brit on 10/30/2011 02:25 pm
However, it would seem, the only way the Block-1 CPS would allow for a real mission is with a fuel depot

And that would require considerable modification to the iCPS.  At present, it's just a block DIVHUS with a few software tweaks.

As I understand the plan, iCPS is only for BEO test flights through (to?) cis-Lunar space.  Operational missions will require the SLSUS and full operational CPS.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 10/30/2011 05:03 pm
Should we just go with block I SLS so we can start BEO missions and not just keep upgrading the launcher?

That would be, in my opinion, the right thing to do.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: TrueBlueWitt on 10/30/2011 05:15 pm
So, if I am understanding correctly the Block-1 CPS will proceed the SLS upper stage into service. The CPS is only going to be able to send about 27 tons through TLI, which comes up short of the Saturn V's TLI performance. In fact, it could not even send a fully loaded Orion through TLI. Of course, since there will not be a required to perform a TEI, it will not need to be fully load. Still, it seems like it would only barely get Orion through TLI.

If we can undertake real missions without the upper stage, I am perfectly fine with that. However, it would seem, the only way the Block-1 CPS would allow for a real mission is with a fuel depot, and I am a fan of fuel depots. But, do we have the money to get a fuel depot up by later this decade?

Then, of course, the Block-1A SLS will not even be able to lift the Block-1 CPS. And, of course, to get from the Block-1A to the Block-1 SLS we will need to spend more money on developing new boosters of some kind.

Is there really any hope of a real mission being undertaken anytime in the foreseeable future?



If NASA can't do a Lunar Orion and Service module in less than 27t.. NASA shouldn't be in the spacecraft business.  I though Lunar was closer to 24t.. with ISS around 21t.. although part of that fuel mass for Constellation at least was due to Ares I needing the SM to provide a significant "3rd-stage" burn to get to orbit.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 10/30/2011 05:18 pm
So, if I am understanding correctly the Block-1 CPS will proceed the SLS upper stage into service. The CPS is only going to be able to send about 27 tons through TLI, which comes up short of the Saturn V's TLI performance. In fact, it could not even send a fully loaded Orion through TLI. Of course, since there will not be a required to perform a TEI, it will not need to be fully load. Still, it seems like it would only barely get Orion through TLI.

That's why we didn't make the Jupiter any bigger. A properly outfitted 2-launch Jupiter lunar mission could push more than 40-45 (+) tons thru TLI without a fuel depot. Put a fuel depot in the mix and the same mission could be done with 1 launch. The reason I didn't want to support SLS in the beginning is because it's too big. Jupiter was optimal and anything bigger results in diminishing returns. The bigger it gets the less efficient it is. We optimized the Jupiter design for TLI. But we digress. So SLS Block-1 will fly and will resemble the Jupiter, but it is still too big. Still, it is what has been approved and it's not a bad launch vehicle. It's just not as good as it could have been. It's what has been authorized, approved and funded and I am supporting it.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mr. Justice on 10/30/2011 05:37 pm
So, if I am understanding correctly the Block-1 CPS will proceed the SLS upper stage into service. The CPS is only going to be able to send about 27 tons through TLI, which comes up short of the Saturn V's TLI performance. In fact, it could not even send a fully loaded Orion through TLI. Of course, since there will not be a required to perform a TEI, it will not need to be fully load. Still, it seems like it would only barely get Orion through TLI.

If we can undertake real missions without the upper stage, I am perfectly fine with that. However, it would seem, the only way the Block-1 CPS would allow for a real mission is with a fuel depot, and I am a fan of fuel depots. But, do we have the money to get a fuel depot up by later this decade?

Then, of course, the Block-1A SLS will not even be able to lift the Block-1 CPS. And, of course, to get from the Block-1A to the Block-1 SLS we will need to spend more money on developing new boosters of some kind.

Is there really any hope of a real mission being undertaken anytime in the foreseeable future?



If NASA can't do a Lunar Orion and Service module in less than 27t.. NASA shouldn't be in the spacecraft business.  I though Lunar was closer to 24t.. with ISS around 21t.. although part of that fuel mass for Constellation at least was due to Ares I needing the SM to provide a significant "3rd-stage" burn to get to orbit.

My goof! It is actually a little over 23 tons. I was counting what the total weight, as being just that of the SM, as opposed to the combined total weight of the CM and SM when looking at it on Wikipedia. I thought it seemed awfully heavy. 

So, we were to launch a depot to L-1 and develop a LSAM, preferably reusable, and launch it dry to the depot we could undertake real missions sooner.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RocketmanUS on 10/31/2011 05:20 am
Should we just go with block I SLS so we can start BEO missions and not just keep upgrading the launcher?

That would be, in my opinion, the right thing to do.

So should we ask congress then to have a production of SRB's and SSME's ready for flights after the first one or two test flights?

Should we ask that a 2018 congress after the test flight make a decision on any type of upgrade if any be made for block II for future mission ( SRB, LRB, US )? Would this not give a better assessment of what we would need, based on what missions are planned for SLS at that time and any new technologies ( fuel depot, BEO craft, Mars base items, ect. )? Six years down the road a new budget and economy!

Can we use a JUS style stage with the 5SSME on block I SLS? If so what LEO payload mass might we see for 130x130nm 29 degree?

Large On-Orbit Stage
new Cryo Prop Stage (CPS)
What are the specs?
Dry mass?
Fuel capacity?
Type of engines and how many?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ben the Space Brit on 10/31/2011 12:07 pm
Large On-Orbit Stage
new Cryo Prop Stage (CPS)
What are the specs?
Dry mass?
Fuel capacity?
Type of engines and how many?

All still very much TBD.  As I understand it, the front-runners for the enginer at the moment are the EADS Astrum's daVinci and PWR's RL-10C.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: BrightLight on 10/31/2011 09:24 pm
Is the cost for a single SLS LV Block 1 at one billion - just to clarify.
I assume stretched ET core, 4 SSME, 2 five-segment SRM (or even 2 five-segement SRM minus center segment).
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jason1701 on 10/31/2011 10:55 pm
Is the cost for a single SLS LV Block 1 at one billion - just to clarify.
I assume stretched ET core, 4 SSME, 2 five-segment SRM (or even 2 five-segement SRM minus center segment).

What kind of cost? The marginal cost would probably be less, but if you add the several billion dollars of fixed costs per year, the average cost with a reasonable flight rate would probably be more than $1B. (Was $1.45B for Shuttle.)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/01/2011 01:47 am
Not wasting the money of sending an entire shuttle into orbit though.

So you get much better value $ per mt delivered to LEO.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/01/2011 02:45 am
Is the cost for a single SLS LV Block 1 at one billion - just to clarify.
I assume stretched ET core, 4 SSME, 2 five-segment SRM (or even 2 five-segement SRM minus center segment).

What kind of cost? The marginal cost would probably be less, but if you add the several billion dollars of fixed costs per year, the average cost with a reasonable flight rate would probably be more than $1B. (Was $1.45B for Shuttle.)

The marginal cost for an SLS launch would be a few hundred million or so, as far as I can tell, or probably less if you count SRB and RS-25 minimum sustainment as fixed costs.

The fixed costs should be somewhere between one and two billion per year, perhaps about halfway in between.

At two flights per year, it might be about a billion per launch.  At five, it would be roughly similar to Shuttle, probably less IMO.

Shuttle at five flights per year, near the end of the program, was about $560-640M per flight.  The higher figure of $1.45B sounds like it includes development costs and RTF for both accidents, averaging over the whole program in modern dollars.  Also, if that's what it is, it's inflated since I last heard it, when it was $1.3B.

Please note that for about 100 tonnes to orbit in one shot (the J-140SH is not a 70-ton LV), even $1B per launch is better per kg than the EELVs at the prices they were going for the last time I checked...  so it isn't a preposterous amount of money like it sounds like.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Namechange User on 11/01/2011 02:55 am
Is the cost for a single SLS LV Block 1 at one billion - just to clarify.
I assume stretched ET core, 4 SSME, 2 five-segment SRM (or even 2 five-segement SRM minus center segment).

What kind of cost? The marginal cost would probably be less, but if you add the several billion dollars of fixed costs per year, the average cost with a reasonable flight rate would probably be more than $1B. (Was $1.45B for Shuttle.)

Where do you get that number???

When a programs budget is approximately 3 billion a year and we can fly 6, 7 or 8 times in a calendar year, how do you arrive at that?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RocketmanUS on 11/01/2011 03:11 am
For SLS
Block I
Block IA
Block II

What if any upgrades might be needed for the Crawler-way for each block?

Can the crawler handle Block II or do we need a new one?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Namechange User on 11/01/2011 03:36 am
For SLS
Block I
Block IA
Block II

What if any upgrades might be needed for the Crawler-way for each block?

Can the crawler handle Block II or do we need a new one?


To the best of my knowledge, the currently planned minor mods to the crawlers can handle pretty much anything.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jason1701 on 11/01/2011 04:15 am
Is the cost for a single SLS LV Block 1 at one billion - just to clarify.
I assume stretched ET core, 4 SSME, 2 five-segment SRM (or even 2 five-segement SRM minus center segment).

What kind of cost? The marginal cost would probably be less, but if you add the several billion dollars of fixed costs per year, the average cost with a reasonable flight rate would probably be more than $1B. (Was $1.45B for Shuttle.)

Where do you get that number???

When a programs budget is approximately 3 billion a year and we can fly 6, 7 or 8 times in a calendar year, how do you arrive at that?

Program cost divided by number of launches.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 11/01/2011 04:44 am
Is the cost for a single SLS LV Block 1 at one billion - just to clarify.
I assume stretched ET core, 4 SSME, 2 five-segment SRM (or even 2 five-segement SRM minus center segment).

What kind of cost? The marginal cost would probably be less, but if you add the several billion dollars of fixed costs per year, the average cost with a reasonable flight rate would probably be more than $1B. (Was $1.45B for Shuttle.)

Where do you get that number???

When a programs budget is approximately 3 billion a year and we can fly 6, 7 or 8 times in a calendar year, how do you arrive at that?

Program cost divided by number of launches.
The often quoted program cost includes the payload costs such as ISS and Hubble however. Need to revise to account for those.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/01/2011 06:13 am
Besides which, the comparison was with the cost to launch SLS, which by any reasonable measure does not include the amortized development costs since we have no idea how long it will operate or how many times it will launch in total.

The question can be safely interpreted as meaning operational costs only, and Shuttle did a hell of a lot better in that respect than $1.45B per mission.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: BrightLight on 11/01/2011 03:49 pm
When I asked the question about the cost of a SLS launch, I assumed that the answers would vary.  I find it curious and telling that in another thread about a cheaper alternative to SLS, the cost of SLS is fixed and known.  I suspect a good economics post-doc at one of the NASA centers could spend some time developing a model for government based purchasing or financing large projects such as SLS.  This forum might be one of the few places where we can debate the true cost of these programs.  I am now convinced that the factions in our government have there own agendas which make technical decisions very difficult. Clearly the cost of a Block 1 SLS is not the sum of its parts and incremental costs such as a J2-X stage or CPS have some clear impact on cost and should be designed as the most cost effective  approach. The true cost to the tax payer includes national capability and infrastructure - how do you put a price on that?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/01/2011 04:33 pm
Is the cost for a single SLS LV Block 1 at one billion - just to clarify.
I assume stretched ET core, 4 SSME, 2 five-segment SRM (or even 2 five-segement SRM minus center segment).

What kind of cost? The marginal cost would probably be less, but if you add the several billion dollars of fixed costs per year, the average cost with a reasonable flight rate would probably be more than $1B. (Was $1.45B for Shuttle.)

Well, no one really knows until NASA comes out with some cost analysis I think.  I think it's all pretty much speculation at this point.
I've been assuming when you take SLS's fixed and annuals costs (including Orion), that you'll probably be about a push with STS.
SLS doesn't have the expensive Orbiter refurb cost, but it does have the cost of an Orion CSM, and 3 or 4 or 5 expended RS25E's.  The E's are cheaper than the D's, but they are expended. 
You also have a MPS syste that's expended rather than saved on the Orbiter. 
You SRB's are probably about a push with STS.  Yea, they are 5-seg and expedible, but apparently ATK was in there with some tasty pricing to get in there for the first 2-4 launches, and have a shot at the long term contract.  So we'll say rounghly about the same.
AFter your development costs, the core itself (less the engines and MPS) will probably be about the same as the Shuttle ET.
Your overall costs of running KSC might actually be a little less, as I think they are planning on doing some overall staff/facility downsizing/streamlining.  At least from some of the proposals for the new 21st Century KSC that I've seen.
If the Orion capsules get reused, that might drop the cost a bit more, as I imagine a capsule refurb will be cheaper than a brand new capsule.  And a capsule refurb should be a -lot- cheaper than a shuttle refurb.

(For now, I'm not comparing SLS block 2, just block 1 with STS.  Block 2 is really meant for BLEO operations, and STS never was, so that becomes more of a apples-to-oranges comparison.  So I'm going STS vs. SLS-block 1 as that's a more apples-to-apples comparison I think)

So, I think, overall, we're at a push with SLS and STS in the overall calculus.  At least sitting from afar and speculating as we are doing.

This is why I really don't understand those who say there's no money to launch SLS more than once every year or couple of years, and not money for payloads.  The budget for NASA s about the same (roughly) as it's been for the past several years (correct me if that's wrong), and we had enough money to launch 4-5 STS's and have money for payloads for them.  Many were expensive ISS components.  Granted, those playloads were EELV-Heavy class, rather than HLV class, but the point is, you could lauch 20+ mt NASA payloads on SLS if you have them, and you wouldn't be any more money than a Shuttle mission.
A nice, big, fat 70mt payload might only come along occasionally, But you can operate SLS with Shuttle class payloads, and launch 4-5 of them -per year- on the same budget you did for the shuttle, worst case scenario.  Or launch maybe 1-2 SLS's per year, with larger payloads. 

Look, I think the most ideal way to go in a perfect work, would be to go with EELV's, with a plan to grow them to Medium (30-50mt) and heavy (50-70mt) lift configs as we go forward.  AVP2-heavy or AVP3a, or FX/FXH.  I think it would be more flexible and can grow as needed.
But, the EELV path has been looked at ad nauseum and has beeen shown to be politically non-viable.  It is what it is.
But that said, I don't see where people think SLS will be too expensive to ever fly, and if it ever does, it will never have a payload.  The Shuttle would never have had a payload if that were true because it cost probably about what a block 1 SLS will (block 1a should only be a little more expensive per launch)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/01/2011 07:36 pm
Lobo’s points are well taken and I roughly concur. Where I would differ is that I would not include the cost of KSC facility maintenance in the SLS per-launch cost, nor would I include the cost of the payload – that’s a completely unrelated cost. Even payload integration costs imo should fall into payload costs, not launch vehicle costs. That’s how it’s done in the commercial transportation world of trucks, planes, ships and trains (P.S. Orion is a payload). Those are not related to the question. The question had to do with the cost of launching “A” SLS vehicle. To my mind that breaks down to:

How much does it cost NASA to buy 1 SLS rocket? (determined by the # of units in the group buy contract)
How much does NASA pay for the propellant for that one rocket? (how many gallons of LH2/LH2)
How much does the workforce cost to support that one single launch? (limited time window)

Anything else really doesn’t belong in the equation unless you want to change the question and say how much does it cost to maintain and use the SLS system per year. That’s a completely different question, a very open ended question that can suck in any number of things and one that has been misused very successfully by opponents of almost any project you can think of to prove that project’s too expensive, whether it’s a rocket, a bridge, a building or a dam or anything else that the cheap people don’t want to do or build. I have a brother-in-law like that. He can’t justify spending anything that doesn’t directly contribute to keeping him alive. I feel sorry for the poor sod! He needs to get a life.

So if you want to know how much it costs to launch one SLS, that’s just about it.

So Lobo’s belief that it shouldn’t cost any more per unit than Shuttle, and will probably be less, is in my mind pretty much correct. If NASA could afford to fly 4 to 5 Shuttles per year with payloads then there is no reason they couldn’t fly 4 to 5 SLS’s per year. The only question is will Mr Shannon’s task force provide a mission architecture that will use that number of launches? Maybe for the same money we fly 1 or 2 less flights and buy more expensive payloads. We know that we can afford them because we’ve been paying that amount for years now, naysayers and doomsayers not withstanding.

Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Rocket Science on 11/01/2011 07:58 pm
Well that really gets down to the crux of the matter… It’s not the rocket science but the accounting method applied to SLS. KSC was bought and paid for years ago and the maintenance costs for the facility are known and the Orbiter refurbishment is now out of the equation. So what really is the big deal?

Regards
Robert
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: ChileVerde on 11/01/2011 08:32 pm

So Lobo’s belief that it shouldn’t cost any more per unit than Shuttle, and will probably be less, is in my mind pretty much correct. If NASA could afford to fly 4 to 5 Shuttles per year with payloads then there is no reason they couldn’t fly 4 to 5 SLS’s per year. The only question is will Mr Shannon’s task force provide a mission architecture that will use that number of launches? Maybe for the same money we fly 1 or 2 less flights and buy more expensive payloads. We know that we can afford them because we’ve been paying that amount for years now, naysayers and doomsayers not withstanding.


Leaving aside the question of getting to the point of having a proven SLS rocket, a production and other infrastructure facilities, I'd be inclined to agree or, more precisely, not disagree.

But after that it does indeed come down to the missions, their payloads, and the costs of the missions and payloads. (Payload costs are, of course, just one component of mission costs.)

I suppose we'll just have to wait and see what Mr. Shannon and the parallel National Academies' study come up with.  Hopefully those will be available by this time next year.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/01/2011 08:58 pm
It should also be remembered that we aren't talking about 70-100 ton bleeding-edge one-off payloads like JWST or MSL, or Hubble.  There will be a fair degree of standardization in a manned exploration architecture; for instance, once you have Orion in your repertoire, a new one is only $150M or so.

Having the systems at all is more expensive than flying them at a decent clip.  Flight rate doesn't need to be low.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/01/2011 10:18 pm
It should also be remembered that we aren't talking about 70-100 ton bleeding-edge one-off payloads like JWST or MSL, or Hubble.  There will be a fair degree of standardization in a manned exploration architecture; for instance, once you have Orion in your repertoire, a new one is only $150M or so.

Having the systems at all is more expensive than flying them at a decent clip.  Flight rate doesn't need to be low.
It doesn't need to be a low flightrate, but it certainly will be unless the HSF effort is given a significant funding increase, which I strongly support and urge.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/02/2011 02:49 am
SLS will launch more times than Saturn V.

Developing the rocket that enabes Mars exploration is a big step.

The sooner the better.

There's no way this rocket would be built if Mars weren't the goal so many launches will be required. This means getting cost per launch down and rates up.

I really wish those building the SLS the best of luck.

Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jason1701 on 11/02/2011 03:32 am
SLS will launch more times than Saturn V.

You're on! I hope so though.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: aquanaut99 on 11/02/2011 04:27 am
So what really is the big deal?

The big deal is that Lobo's calculations (which I mostly agree with) are based on the premise that NASA's HSF budget will remain roughly the same.

That is far from certain.

How does it look if the total NASA budget get a 20 or 25% cut across the board?

Sure, if we switched to any other architecture (EELV based for example) a huge cut would be sure to be incoming due to political anger...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/02/2011 09:04 am
So what really is the big deal?

The big deal is that Lobo's calculations (which I mostly agree with) are based on the premise that NASA's HSF budget will remain roughly the same.

That is far from certain.

How does it look if the total NASA budget get a 20 or 25% cut across the board?

Sure, if we switched to any other architecture (EELV based for example) a huge cut would be sure to be incoming due to political anger...

*Nothing* is certain - ever.

Look at it this way: The Congress went to a great deal of trouble to make sure that the SLS was authorized, appropriated and passed. All budget forecasts are assumptions but because of the nasty fight Congress engaged in with the Administration to make the SLS happen, it is a reasonable assumption that the budget for it will continue at the levels that have been previously authorized. Under those circumstances to assume otherwise is the unreasonable option. Having come away from that fight bloodied but victorious, they are not going to abandon it now.

I believe that Lobo's assumption is therefore reasonable.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mike D on 11/03/2011 03:03 am
So what really is the big deal?

The big deal is that Lobo's calculations (which I mostly agree with) are based on the premise that NASA's HSF budget will remain roughly the same.

That is far from certain.

How does it look if the total NASA budget get a 20 or 25% cut across the board?

Sure, if we switched to any other architecture (EELV based for example) a huge cut would be sure to be incoming due to political anger...

*Nothing* is certain - ever.

Look at it this way: The Congress went to a great deal of trouble to make sure that the SLS was authorized, appropriated and passed. All budget forecasts are assumptions but because of the nasty fight Congress engaged in with the Administration to make the SLS happen, it is a reasonable assumption that the budget for it will continue at the levels that have been previously authorized. Under those circumstances to assume otherwise is the unreasonable option. Having come away from that fight bloodied but victorious, they are not going to abandon it now.

I believe that Lobo's assumption is therefore reasonable.

Lobo is always reasonable . . .

It seems to me that, once the SLS Block 1 is in place, using it to launch a 30 ton payload to LEO is a wash, financially, with launching a 30 ton payload by shuttle.  Launching a 70 ton payload is better; but 30 tons is the break-even point as SLS compares to STS.  Same SRM's, same ET, same SSME's; an Orion as opposed to an Orbiter, etc.  That's kind of why I think NASA should embrace the SLS/Orion architecture for LEO/ISS duty as a natural extension of STS.  More trips to orbit = cheaper system costs per flight . . .

Use it for everything; BEO exploritory missions and shuttle-like ISS flights (with Orion and SSPDM, etc.).
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jason1701 on 11/03/2011 05:01 am
It seems to me that, once the SLS Block 1 is in place, using it to launch a 30 ton payload to LEO is a wash, financially, with launching a 30 ton payload by shuttle.  Launching a 70 ton payload is better; but 30 tons is the break-even point as SLS compares to STS.  Same SRM's, same ET, same SSME's; an Orion as opposed to an Orbiter, etc.  That's kind of why I think NASA should embrace the SLS/Orion architecture for LEO/ISS duty as a natural extension of STS.  More trips to orbit = cheaper system costs per flight . . .

Use it for everything; BEO exploritory missions and shuttle-like ISS flights (with Orion and SSPDM, etc.).

That would be more expensive than purchasing crew and cargo resupply services from commercial providers. The hardware to allow Orion to carry large amounts of cargo is a substantial cost and not in the budget.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: aquanaut99 on 11/03/2011 06:14 am
It seems to me that, once the SLS Block 1 is in place, using it to launch a 30 ton payload to LEO is a wash, financially, with launching a 30 ton payload by shuttle.  Launching a 70 ton payload is better; but 30 tons is the break-even point as SLS compares to STS.  Same SRM's, same ET, same SSME's; an Orion as opposed to an Orbiter, etc.  That's kind of why I think NASA should embrace the SLS/Orion architecture for LEO/ISS duty as a natural extension of STS.  More trips to orbit = cheaper system costs per flight . . .

Use it for everything; BEO exploritory missions and shuttle-like ISS flights (with Orion and SSPDM, etc.).

That would be more expensive than purchasing crew and cargo resupply services from commercial providers. The hardware to allow Orion to carry large amounts of cargo is a substantial cost and not in the budget.

Also, if we only launch 30 mT payloads with a 70 mT launcher, we would need to add 40 tons of ballast to every launch. Sure, ballast is cheap, but this also adds up.

Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/03/2011 09:01 am
It seems to me that, once the SLS Block 1 is in place, using it to launch a 30 ton payload to LEO is a wash, financially, with launching a 30 ton payload by shuttle.  Launching a 70 ton payload is better; but 30 tons is the break-even point as SLS compares to STS.  Same SRM's, same ET, same SSME's; an Orion as opposed to an Orbiter, etc.  That's kind of why I think NASA should embrace the SLS/Orion architecture for LEO/ISS duty as a natural extension of STS.  More trips to orbit = cheaper system costs per flight . . .

Use it for everything; BEO exploritory missions and shuttle-like ISS flights (with Orion and SSPDM, etc.).

That would be more expensive than purchasing crew and cargo resupply services from commercial providers. The hardware to allow Orion to carry large amounts of cargo is a substantial cost and not in the budget.

Also, if we only launch 30 mT payloads with a 70 mT launcher, we would need to add 40 tons of ballast to every launch. Sure, ballast is cheap, but this also adds up.

DIRECT had planned on putting a water tank under the plf whenever ballast was needed. They can fill it with sea water right from the ocean next to the launch pad. The only cost would be the electricity to run the water pumps. Ballast does not have to be expensive. The beauty of this is that the amount of sea water ballast is variable, easily adaptable to whatever the actual payload is; 70 tonnes minus the mass of the actual payload equals the amount of sea water to pump into the tank. Simple - cheap. In the past NASA has flown sand for the same reason.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: A_M_Swallow on 11/03/2011 10:32 am
DIRECT had planned on putting a water tank under the plf whenever ballast was needed. They can fill it with sea water right from the ocean next to the launch pad. The only cost would be the electricity to run the water pumps. Ballast does not have to be expensive. The beauty of this is that the amount of sea water ballast is variable, easily adaptable to whatever the actual payload is; 70 tonnes minus the mass of the actual payload equals the amount of sea water to pump into the tank. Simple - cheap. In the past NASA has flown sand for the same reason.

If it could be half empty they had better put slosh baffles in the sea water tank.

Fresh water in space can be drunk or converted into propellant (H2 + O2).
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Herb Schaltegger on 11/03/2011 01:41 pm

Fresh water in space can be drunk or converted into propellant (H2 + O2).

If you're flying crew, water is a metabolic byproduct, produced in quantities large enough to require water and/or urine dumps.  There's no need to fly excess fresh water as ballast.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Bill White on 11/03/2011 02:14 pm
RP-1 or NOFBX could be useful ballast to incorporate into an SLS ISS mission, if NASA goes ahead with plans for an EML depot.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/03/2011 02:23 pm
RP-1 or NOFBX could be useful ballast to incorporate into an SLS ISS mission, if NASA goes ahead with plans for an EML depot.
Pretty sure NOFBX isn't what you'd call inert ballast.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/03/2011 03:45 pm
Lobo’s points are well taken and I roughly concur. Where I would differ is that I would not include the cost of KSC facility maintenance in the SLS per-launch cost, nor would I include the cost of the payload – that’s a completely unrelated cost. Even payload integration costs imo should fall into payload costs, not launch vehicle costs. That’s how it’s done in the commercial transportation world of trucks, planes, ships and trains (P.S. Orion is a payload). Those are not related to the question. The question had to do with the cost of launching “A” SLS vehicle. To my mind that breaks down to:

How much does it cost NASA to buy 1 SLS rocket? (determined by the # of units in the group buy contract)
How much does NASA pay for the propellant for that one rocket? (how many gallons of LH2/LH2)
How much does the workforce cost to support that one single launch? (limited time window)

Anything else really doesn’t belong in the equation unless you want to change the question and say how much does it cost to maintain and use the SLS system per year. That’s a completely different question, a very open ended question that can suck in any number of things and one that has been misused very successfully by opponents of almost any project you can think of to prove that project’s too expensive, whether it’s a rocket, a bridge, a building or a dam or anything else that the cheap people don’t want to do or build. I have a brother-in-law like that. He can’t justify spending anything that doesn’t directly contribute to keeping him alive. I feel sorry for the poor sod! He needs to get a life.

So if you want to know how much it costs to launch one SLS, that’s just about it.

So Lobo’s belief that it shouldn’t cost any more per unit than Shuttle, and will probably be less, is in my mind pretty much correct. If NASA could afford to fly 4 to 5 Shuttles per year with payloads then there is no reason they couldn’t fly 4 to 5 SLS’s per year. The only question is will Mr Shannon’s task force provide a mission architecture that will use that number of launches? Maybe for the same money we fly 1 or 2 less flights and buy more expensive payloads. We know that we can afford them because we’ve been paying that amount for years now, naysayers and doomsayers not withstanding.



Chuck,

Yea, good points.  I guess it depends on what you are comparing SLS with.  Seems like most of the numbers I heard for STS were basically total cost of launches per year, plus the operation of KSC and whatever other various annual operational costs.  Which seem to usually come out to around $1 billion per launch when STS launches as is [sort of] normal rate of 4-5 per year.  Sometimes I hear STS numbers for more like $600-$700 million per launch, but I assume that's just the cost of the launch, and doesn't include the other annual overheads costs.

So, I was just kinda using the totals costs that I've seen for STS with SLS.  To make the case that unless NASA's budget were to get appreciably cut, if we afforded it before with STS, I don't really see a reason we can't afford it going forward with SLS.

However, I think if you are comparing SLS to EELV, then I think Chuck's got a good point.  If you want to compare apples to apples, you need to just consider SLS's actual cost of each launch, whatever that is (I don't really know, $600-$700 million maybe? Like STS?  Probably a fair bit less if you aren't counting Orion costs), because that's the number the pro-EELV folks are using when making the case for EELV's.  They aren't adding in the costs of KSC, Orion, payloads, etc, into those per-launch numbers.
If you don't, then SLS's costs are over-estimated compared to EELV's. 

So, anyone have some reasonable estimated numbers for SLS, which don't include the additional costs like KSC overhead, and Orion capsules and overhead?  $500 million per LV maybe?
Wasn't Direct estimating that a J130, which would be a little cheaper than SLS block 1(1-2 less RS25's, and two less SRB segs), at around $350-$400 million per LV?
 
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/03/2011 03:57 pm
It should also be remembered that we aren't talking about 70-100 ton bleeding-edge one-off payloads like JWST or MSL, or Hubble.  There will be a fair degree of standardization in a manned exploration architecture; for instance, once you have Orion in your repertoire, a new one is only $150M or so.

Having the systems at all is more expensive than flying them at a decent clip.  Flight rate doesn't need to be low.

An interesting future payload stream, once Orion is in production and flying, is that Orion can be used as a LEO "tug" to take payloads and placing them in LEO, without the need for the payload itself to have an OMS.  So it could place telescopes and satilites into LEO that might have a cost benefit of doing it that way, as well as perhaps a large MPLM to the ISS now and again, or any replacement modules, if such things are deemed desirable. 
For example, if say JWST were to be launched on SLS with Orion, the astronauts could stay on station while the oragami mirror unfolded, and could perform an emergency EVA (depressurizing the Cabin like Apollo 9) to try to free up the mechanisms so JWST didn't end up being a multi-billion dollar boat anchor out there.

Again, not sure how often that would be desirable, but I would figure there would be some missions that would be desirable.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/03/2011 04:12 pm
Remember that Orion is no longer reusable. So, it costs hundreds of millions, maybe even a billion, per Orion.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/03/2011 04:20 pm
So what really is the big deal?

The big deal is that Lobo's calculations (which I mostly agree with) are based on the premise that NASA's HSF budget will remain roughly the same.

That is far from certain.

How does it look if the total NASA budget get a 20 or 25% cut across the board?

Sure, if we switched to any other architecture (EELV based for example) a huge cut would be sure to be incoming due to political anger...

Well, that is a big assumption of mine, certainly.  I don't think NASA will get a budget cut however, because they really haven't (to my knowledge) given NASA a real, actual, major cut since after Apollo.
AFter that, we've had Republican Presidents with Democrat House and Senates (1981-1992), we've had Democrat Presidents with Democrat House and Senate (late 70's, 1993-1994, 2009-2010), We've had Democrat Presidents with Republican House and Senate (1995-2000), and we've had Republican Presidents with Republican House and Sentate (2003-2007), and we've had Republican and Democrat Presidents with split Congresses (2001-2002, 2011-now).

So, since the big post-Apollo cuts, we're had just about every combination of White House, House, and Senate that you can have, and in all of that time, have there been any big actual cuts to NASA's budget?  And I don't mean the way politicians classify a "cut", which is a reduction in the rate of growth (like most of the "cuts" that are being batted about now are just reduction in growth rates, not actual budget cuts).  I mean a real budget cut to NASA.  AS in this year our Budget is $18 billion, and next year it will be $16 billion?

Now, I certainly might just be ignorant, and maybe there were some real, large budget cust to NASA after the post-Apollo cuts, and I certainly would like to be corrected if I am in errror.  I'm just am not aware of any.

Going forward, there -must- be some -real- budget custs to the Federal budget, or we'll end up like Greece, and sooner, not later.
But there's far bigger budget fish to fry than NASA.  And for those worried about more Tea Party Concervatives getting into Congress, who actually might be inclined to cut more than just the rate of growth in some areas, most of what I've heard form them hasn't been hostile to NASA. 
We currently take in about $2.2 trillion dollars, and spend about $3.8 trillion, and thus a $1.5 trillion-ish dollar deficit.
If you go back to the Clinton years, that Democrats like to tout as the ideal tax rate era when we had a balanced budget, they leave out one big thing from that.
in FY1999, the Federal government with those little bit higher tax rates than after the Bush tax cust, took in about $1.8 trillion dollars.  (So actually less money than we take in today, with higher tax rates), but our federal budget was only $1.7 trillion.  Thus a "surplus".
So, the point being, in 1999, although the population was a little less, we literally spent over $2 trillion dollars LESS than we do today.  And, correct me if I'm wrong, when adjusted for inflation, NASA's 1999 budget was probably roughly the same as it is today?
If so, while the overal federal budget bloated to twice what it was in 1999 (under both Republican and Democrats...so trusting either to actually "cut" any budgets is dubious), NASA's budget didn't double. 
And to be honest, there's probably a lot of politicians and officials that would say that if it's cut anything from where it's at, it probably won't be able to do much of anything.  Certainly not launch big, impressive rockets with US Astronauts on them.   

So...while I am just guessing that NASA's budget won't be cut (but probably won't be significantly increased either in the near future, obviously), a guess that it will be cut, is just a guess too.  ANd I think history is an indicator to make me lean the way I do.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/03/2011 04:24 pm

Lobo is always reasonable . . .


"So let it be written...so let it be done..."

Heheheh....thanks man!
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Bill White on 11/03/2011 04:51 pm
RP-1 or NOFBX could be useful ballast to incorporate into an SLS ISS mission, if NASA goes ahead with plans for an EML depot.
Pretty sure NOFBX isn't what you'd call inert ballast.

True . . .
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/03/2011 07:56 pm
Sometimes I hear STS numbers for more like $600-$700 million per launch, but I assume that's just the cost of the launch, and doesn't include the other annual overheads costs.

Nope.  That's the SSP cost, including fixed costs, divided by number of launches.  Incremental cost of a Shuttle launch is hard to figure exactly, since it depends on what you consider a unit cost and what gets rolled into fixed costs (the price of boosters and engines, for instance, includes a large fixed-cost component), but it wasn't above $300M, and might have been a lot less - my low-S/N math says maybe half that.

Quote
Wasn't Direct estimating that a J130, which would be a little cheaper than SLS block 1(1-2 less RS25's, and two less SRB segs), at around $350-$400 million per LV?

Purely incremental?  It was about $185M IIRC.  Or was that the old J-120?

Remember that Orion is no longer reusable. So, it costs hundreds of millions, maybe even a billion, per Orion.

Orion hasn't been reusable for quite a while.  Incremental cost is in the vicinity of $150M for a brand new one (EDIT:  based on a number from Ross as well as my own attempts at backing it out of total-cost data).
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/03/2011 09:29 pm
How much does it cost to produce an SSME? There's no way SLS will be less than $200 million. SSMEs cost, what, about $30-$80 million a piece, there's to be at least 4 of them, plus 10 SRB segments (estimated by DIRECT at, what, $15-$25 million per segment)... Minimum cost of $~270-500 million. This is the cost JUST for the engines and boosters WITHOUT the Delta IV upper, not counting the tank (another $50 million at least for the longer version?), thrust structure, avionics, integration costs of both the rocket and the payload onto the rocket, pad refurb after flight, payload fairing, etc! Rockets are far more than the sum of their parts. $185 million is a pure pipe-dream.

How much does it cost to produce a Space Shuttle Orbiter? Remove the tiles and wings and thrusters (except for core disposal) and landing gear, remove the cabin, and add the cost of the bigger (likely expendable) boosters and the external tank and another SSME, and you've approximated the marginal cost of an SLS (without an upper stage or EDS) from another angle. It cost about $3 billion to build Endeavor (adjusted for inflation), and thus I doubt the marginal cost to build SLS will be much less than $1 billion.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/03/2011 10:15 pm
Incremental costs, please.  Quoting $80M for an SSME is just disingenuous.

Also, I believe it was $15-25M per pair of segments.  IIRC, $100M per booster pair was the number from an actual buy a while back.

What you want is the asymptote (well, there's still a bit of a curve involved, but you know what I mean).  I can't find the engine cost chart any more, but I wouldn't be surprised if the true incremental cost for an RS-25E were less than $25M.  And we all know the boosters carry large fixed costs...

DIRECT sidestepped this issue by not calculating incremental costs directly.  They calculated program costs at various flight rates.  According to Ross' charts (http://forum.nasaspaceflight.com/index.php?topic=18752.msg622582#msg622582), an extra J-246 is about $260M if you're already launching two or three a year.

Sure, a rocket is more than the sum of its parts.  But the "more" is mostly fixed costs.

Summing the parts for J-130, using reasonable best-known-cases, I get 3x$25M+4x$15M+$10M for the propulsion elements and IU, leaving $40M for the core stage, payload adapter, and fairing, as well as anyone you might have to hire due to the increased launch tempo (labour costs are very far from linear with launch rate; hence the "standing army" complaints).  Doesn't sound too implausible...

I wonder what ATK's prices will look like in light of the looming booster competition?

I never said SLS would be less than $200M.  SLS is not J-130.

...

Your orbiter angle is ridiculous, I'm afraid.  The gap between an STS orbiter (especially as a one-off) and an SLS core stage is far too large to bridge with handwaving.

Let's put it this way - the ET is supposed to be around $29M, and I think that includes some fixed costs.  IIRC, It's been said to be less than $1M incremental.  The IU is supposed to be around $10M.  What's left?  The MPS and thrust structure.  You go ahead and tell me that the MPS and thrust structure, less engines, is a several hundred million dollar job, disregarding all fixed costs.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/03/2011 10:34 pm
Remember that Orion is no longer reusable. So, it costs hundreds of millions, maybe even a billion, per Orion.

Orion hasn't been reusable for quite a while.  Incremental cost is in the vicinity of $150M for a brand new one.

Yea, I was wondering about that.  If we are looking at upwards of a billion dollars per Orion, then I think we have bigger problems, and won't get going anywhere anyway, not matter the LV.

$150M sounds better, but I just had no clue what it even might be to hazard a guess.

Is that $150M for the capsule alone, or for the whole CSM?

As far as reusibility goes, if it hasn't been reusable for awhile, I assume that's because it'd be cheaper and/or safer to build a new one each time and let the economics of "mass production" help bring the costs down, so they don't run into a SSME situation, where new ones are built so infrequently, there's no incentive to streamline or optimize the manufacturing, and cost per new unit is super inflated?

Maybe they could recycle some parts of used capsules into new ones?  Like computer, avionics, heat shield, or other parts that would likely survive the reentry and spashdown in tact (I thought the heat shield was supposed to be good for like 10 reentries or something?).

Then they could just build new frames and shells for each and run them down a production line that could be streamlined and updated as time went on. 
Or not...just thinking out loud.  ;-)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/03/2011 10:46 pm
It would be for the whole CSM.

I tried to back out the incremental cost per unit from DIRECT's estimate of $800M/year at 4/year juxtaposed with HEFT's estimate of $840M/unit at 1/three years, and got ~$140M incremental.  Ross then quoted $150M incremental.

He also said it would be close to $1B fixed cost per year, which doesn't seem to jive with either of the total cost estimates, but that may include non-LM support costs at NASA, like part of SFS (just guessing here)...  the total cost estimate accompanying the $1B figure was ~$400M/unit at 4/year, so there's perhaps a bit of apples-to-oranges going on here...

So yeah, I neglected to add the usual caveats about 'as far as I can tell from what I've heard'...  I considered adding something like that, but I was annoyed enough that I didn't bother.  Bad form...

Reusability was lost with land landing, IIRC.  Ares I, as usual, was the culprit.

Though you may have a point - if they go to reusability later, as I hope they do, it could be with a considerably refined design...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: baldusi on 11/04/2011 12:51 am
I clearly remember a NASA FAQ stating that the marginal cost of a Shuttle launch was around 450M. I seriously doubt an SLS would be less. That means the additional launch. And they were launching four times per year, so that's with a very good launch rate.
In any case, what are you going to launch six times a year? You seriously think it would be cheaper than CST-100/Atlas V 402 or Dragon/F9? Really?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ronsmytheiii on 11/04/2011 01:01 am
Remember that Orion is no longer reusable. So, it costs hundreds of millions, maybe even a billion, per Orion.

Orion hasn't been reusable for quite a while.  Incremental cost is in the vicinity of $150M for a brand new one.

However, the true question is how much inside can be salvaged, as I recall hearing that there was talk of doing so (ie avionics ect) So perhaps $150 million for all new, however possible lowering costs through system reuse.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/04/2011 01:51 am
I clearly remember a NASA FAQ stating that the marginal cost of a Shuttle launch was around 450M.

That's a really high number.  Consider that the SSP burned about $3.2B launching five or six times per year, and was said to have a ~$2.4B floor without any launches at all.

As I said, it depends on what you consider a unit price and what you assign to the fixed costs.  AIUI there's no clear standard; the marginal cost of a Shuttle launch varies quite a bit depending on who's quoting it.

How old was that FAQ?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 11/04/2011 02:28 am
How much does it cost to produce an SSME? There's no way SLS will be less than $200 million. SSMEs cost, what, about $30-$80 million a piece, there's to be at least 4 of them....

It occurs to me that an expendable core-plus-boosters design has a built-in economic weakness compared to an classic expendable two-stage design.  Since the core flies all the way to orbit, its engines must function efficiently both at sea level and in vacuo, and the entire core stage is weight-critical, since each additional kilogram of weight costs a kilogram of payload.  Hence, the engines are structure are going to be more expensive than those of the classic two-stager.

For a re-usable vehicle it might not matter much, but for an expendable its going to be a bigger deal.  This doesn't mean that an expendable core-plus-boosters design is a non-starter, but it's a bit of a handicap.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/04/2011 02:43 am
MPCV gets billions before SLS will ever launch.

Can anybody tell me why?

Isn't it already built?

Do they just need to stack them up in a pile?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/04/2011 04:22 am
MPCV gets billions before SLS will ever launch.

Can anybody tell me why?

Isn't it already built?

Do they just need to stack them up in a pile?
1) Hasn't been built. They are building the first one that will actually go into space right now.
2) OFT/EFT-1 will launch on a Delta IV Heavy in 2013ish. This will be the first flight of Orion in space.
3) The service module hasn't been finished, maybe not even the design completely finalized (just a guess, I don't know on that point). I don't even remember seeing a test article, though one might be out there. More progress is needed for that.
4) OFT/EFT-1 may not be the only test on Delta IV Heavy.
5) There are still a few abort tests that need to be done.
6) Payloads need to be built before the launch vehicle is ready to fly, obviously, or your launch vehicle will be sitting around waiting for the payload. So, after OFT-1 gives its results, the insights the test provided should probably influence the design of later Orions, so funding is needed for those tweaks as well.
7) The real cost of producing an Orion isn't going to be just $150 million.

These are just some points that I as an outsider can think of why it needs significant funding before SLS is ready. Others who are actually working with Orion can tell you more. It's helpful not to have a launcher-centric mindset, since the payloads are almost always more expensive than the launch.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/04/2011 05:01 am
Thanks very much Robo.

That helps me understand the MPCV a bit better.

Obviously didn't get as far along as Orion as I thought it might've.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MikeAtkinson on 11/04/2011 07:15 am
I'm always concerned when incremental costs are being bandied about. It usually means that there is something to hide, and it almost always leads to unfair comparisons. These often take the form of <insert favoured LV> has an incremental cost of X, while <insert commercial LV> costs X.

I'm even more suspicious when component costs are being compared. It is irrelevant what a segment costs or what a SSME costs, what matters is their cost when integrated into the vehicle over the full lifetime of the launcher.

I think the only fair way to compare costs is at a program level, where development costs are amortized over the expected length of the program.

When comparing programs, it should be for similar missions. Comparing the Shuttle supporting ISS to SLS + Orion is not apples to apples and just confuses the debate. For what it is worth, it looks like for the SSP supporting ISS, each shuttle flight cost a little under $1B, while SLS + Orion + logistics module would be a bit less for similar capability. That is just about irrelevant as SLS won't be supporting ISS with logistics flights.

What is relevant is the program cost of SLS at different flight rates supporting exploration missions, and how that that compares with different launch vehicles. Problem is we don't know what the exploration missions will be or the requirements they put on the launcher.

Without knowing the mission(s) plan(s), it is impossible to compare options.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 11/04/2011 07:32 am
Without knowing the mission(s) plan(s), it is impossible to compare options.

Amen.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/04/2011 09:09 am
Without knowing the mission(s) plan(s), it is impossible to compare options.

Amen.

Which is exactly why, in answering the questions about the cost of each SLS launch, I explicitly excluded the payload, which is for mission support. The launcher costs are not the same as the mission costs and it is also disingenuous to be including the costs of the maintenance of KSC in the launcher costs. What is appropriate is to include the personnel costs *directly* associated with the launch, but only for the length of time they are actually working the launch.

The question was what it costs to launch a single SLS vehicle. The answer is (1) the purchase price of that single vehicle plus (2) the propellant cost for that single vehicle plus (3) the labor associated directly with that single launch *while* they are actually working that single launch. That's what it costs to launch a single SLS, or for that matter, any other rocket one cares to name. And that cost equation will remain constant, adjusted for inflation, for the entire lifetime of that vehicle.

Maintenance of the launch facilities and infrastructure is not a launch cost. These facilities would exist regardless of the launch vehicle being used and belong under the heading of infrastructure costs. In the commercial world all those kinds of things are rolled up under the heading of the cost of doing business and are never included in the specific wholesale cost of the product produced. Now the retail cost is a different matter and, like *mission* costs, literally everything gets rolled in and amortized. So again, the actual cost to launch a single SLS consists of those 3 things I itemized, and nothing more. But if you want to start talking about "mission costs", well that is an entirely different matter and the SLS cost I described above is only part of that equation.

Launch cost and mission cost are completely different with launch cost being only a single component of the mission cost. Mission cost can never be determined until the mission itself is defined and its cost analysis completed. Right now we do not have the mission definition so its cost analysis is not possible yet. But the SLS launch costs themselves can be estimated with a high degree of fidelity right now. We have all the data we need for that and all that is really required to have a reasonably clear picture of *that* cost is for folks to stop muddying the water by mixing launch and mission costs as if they were the same thing because they are not.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MikeAtkinson on 11/04/2011 12:57 pm
Maintenance of the launch facilities and infrastructure is not a launch cost. These facilities would exist regardless of the launch vehicle being used and belong under the heading of infrastructure costs. In the commercial world all those kinds of things are rolled up under the heading of the cost of doing business and are never included in the specific wholesale cost of the product produced.

What you are calling the "wholesale cost" is important within an organisation, but is not visible outside that organisation. In some way it is purely notional, as you cannot buy anything at that "wholesale cost" as by definition it does not include selling costs.

Even within an organisation it has limited utility, consider two companies providing launch services. The first buys in stages and integrates them at the launch site. The second is vertically integrated and builds everything inhouse. The second has much lower "wholesale cost" by your definition as all the factories, machinery, etc. needed to make the stages is not included as "these facilities would exist regardless of the launch vehicle being used".

Where the launch facilities are owned and operated by a separate organisation, then there is some utility in keeping those costs separate. Even then you cannot get at the wholesale cost as it always costs something for the user to actually use a facility above any usage payments, even if they are supposedly fully managed.

Even if a company knows what its "wholesale costs" are (and that is by no means assured, no company I've worked for have required me to fill in timesheets in such a way that full costs of doing business could be determined), they are some of the most confidential information the company has, it is unlikely that it would be disclosed to anyone.

Now the retail cost is a different matter and, like *mission* costs, literally everything gets rolled in and amortized.

But you still cannot buy anything at "retail cost", you buy it at retail price.

The retail price includes profit (or occasionally loss). When NASA buys launch services off ULA or SpaceX they are paying the retail price.


So again, the actual cost to launch a single SLS consists of those 3 things I itemized, and nothing more. But if you want to start talking about "mission costs", well that is an entirely different matter and the SLS cost I described above is only part of that equation.

The SLS cost you described is almost meaningless for any comparison, it can't even be used to choose between Phase 1A only, Phase 2 only and mixed Phase 1A and Phase 2 SLS launchers because all the development and infrastructure cost differences are excluded.

For SLS NASA have insight and oversight of the various components, the considerable cost to NASA in performing this insight and oversight does not seem to be included in any of your three costs. I would not be surprised if there were other things not included too. This whole artificial distinction between infrastructure and directly associated costs strikes me as a great way of hiding things and producing really low numbers
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: madscientist197 on 11/04/2011 12:58 pm
I think the only fair way to compare costs is at a program level, where development costs are amortized over the expected length of the program.

Sounds great for comparing the true cost of programmes after-the-fact.

The problem is that no-one will be able to agree on the assumed cost-of-capital, length of programme etc in advance. All this method does is incorporate even more, probably erroneous, assumptions into the calculation. When Nasa can't even reliably plan five years in the future due to unreliable appropriations, making presumptions about how many decades a programme will last and what aerospace inflation will be in twenty years time is absurd.

Even if we restrict ourselves to quoting the development, yearly fixed costs and marginal costs in constant-year dollars (and making naive assumptions about aerospace inflation) there is so much room for the massaging of figures that it seems near impossible to get to the truth. When Nasa still gets large cost overruns on relatively short programmes, how can we possibly cost a multi-decade programme accurately? (Not that all of these overruns are Nasa's fault, of course.)

I feel like throwing my hands in the air and giving up ;)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: ChileVerde on 11/04/2011 01:17 pm

2) OFT/EFT-1 will launch on a Delta IV Heavy in 2013ish. This will be the first flight of Orion in space.

What is the status of procuring the DIVH for that flight? 
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/04/2011 02:05 pm
I'm always concerned when incremental costs are being bandied about. It usually means that there is something to hide, and it almost always leads to unfair comparisons. These often take the form of <insert favoured LV> has an incremental cost of X, while <insert commercial LV> costs X.

First off, that was the question being answered.  (Whether or not that was the question being asked may be debatable...)  If you want to know how easily flight rate can be increased, incremental costs are how you find that out.  No one's trying to hide anything.

Second, I suspect that what you are complaining about includes my ISS mission comparisons from a while back.  Your objection is invalid, because the scenario assumes SLS exists anyway for an unrelated reason (BEO exploration), so what you want is the additional cost of doing the mission on SLS versus the additional cost of doing the missions on a commercial vehicle.  Unless NASA is the sole user of the "commercial" vehicle, the second cost will include some fixed costs, and it seems that for certain commercial providers at least, the ratio of fixed costs to incremental costs may be lower than it is likely to be for SLS, resulting in a smaller difference between incremental and full launch costs.  The actual cost to NASA of the commercial service is somewhere between the incremental cost and the sticker price, assuming NASA already uses it.  If NASA does not use it, and the choice is between using it at all and launching another SLS, comparing incremental SLS mission cost with commercial sticker price (adjusted for the bump in flight rate) is completely fair.

It's essentially a sunk cost argument, and not the fallacious kind.  You can't recover any of the fixed costs of an existing system by not using it.

Not that I think SLS should be used for ISS unless there's no other choice...

The real cost of producing an Orion isn't going to be just $150 million.

Support this.  Or are you including fixed costs and development costs?  That would be fair, but you'd have to specify that your comparison with my number is apples-to-oranges.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/04/2011 02:34 pm
A couple of points: fixed costs can vary quite a bit depending on the flight rate. For instance, if you need two SLS launches close to each other, you're likely to need a decked out MLP, possibly even another launch pad. Also, you may have to upgrade propellant storage capability, etc, if the launch rate is higher. These are fixed costs that aren't accounted for in incremental costs, but they DO depend on launch rate.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/04/2011 02:41 pm
No, those are incremental costs.  You don't calculate incremental costs like I did; that's just an a posteriori exercise to demonstrate plausibility.  You do it like DIRECT did - calculate program costs at various flight rates and then subtract.

Your fixed costs set you up for a certain capability, and if you bump up against a hard limit and need to increase the capability, the incremental cost for that one extra mission is very high.  You can see this effect on DIRECT's charts for the EELVs, where there's a jag in prices above 40 cores per year due to the need for more factory capacity.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/04/2011 04:39 pm

Reusability was lost with land landing, IIRC.  Ares I, as usual, was the culprit.

Though you may have a point - if they go to reusability later, as I hope they do, it could be with a considerably refined design...

Well, I'd think SLS will have enough capacity to add land-landings and reusability back in, if that's still desirable.  But the real question is, is Orion too far along now in design/fabrication to add that back.
However, if each ORion is new, then the design could always be changed and things added later...since they'd be building it new.  It's not like the shuttle, where you would be modifying exising metal to try to incorporate new features.  Depends if they think in the long run they'd save more money by having Orion reusable, vs. the costs to design and qualify an upgraded Orion model once the single-use splashdown model was rolling off the assembly line.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Pheogh on 11/04/2011 04:46 pm

Reusability was lost with land landing, IIRC.  Ares I, as usual, was the culprit.

Though you may have a point - if they go to reusability later, as I hope they do, it could be with a considerably refined design...

Well, I'd think SLS will have enough capacity to add land-landings and reusability back in, if that's still desirable.  But the real question is, is Orion too far along now in design/fabrication to add that back.
However, if each ORion is new, then the design could always be changed and things added later...since they'd be building it new.  It's not like the shuttle, where you would be modifying exising metal to try to incorporate new features.  Depends if they think in the long run they'd save more money by having Orion reusable, vs. the costs to design and qualify an upgraded Orion model once the single-use splashdown model was rolling off the assembly line.

I used to be really adamant about the re-usability and land landing as well until someone made what I thought was  very significant point regarding Orion's ultimate future. The argument is if you had to trade airbags and land landing for a roughly equivalent amount of say Mars samples which would you rather. In reality an Orion carrying "priceless" samples from a BEO destination kind renders the weight, cost, and re-usablity issue moot. IMHO
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/04/2011 05:07 pm

Reusability was lost with land landing, IIRC.  Ares I, as usual, was the culprit.

Though you may have a point - if they go to reusability later, as I hope they do, it could be with a considerably refined design...

Well, I'd think SLS will have enough capacity to add land-landings and reusability back in, if that's still desirable.  But the real question is, is Orion too far along now in design/fabrication to add that back.
However, if each ORion is new, then the design could always be changed and things added later...since they'd be building it new.  It's not like the shuttle, where you would be modifying exising metal to try to incorporate new features.  Depends if they think in the long run they'd save more money by having Orion reusable, vs. the costs to design and qualify an upgraded Orion model once the single-use splashdown model was rolling off the assembly line.

I used to be really adamant about the re-usability and land landing as well until someone made what I thought was  very significant point regarding Orion's ultimate future. The argument is if you had to trade airbags and land landing for a roughly equivalent amount of say Mars samples which would you rather. In reality an Orion carrying "priceless" samples from a BEO destination kind renders the weight, cost, and re-usablity issue moot. IMHO
Agreed. And by the way, the Mars Orion would likely be considerably lighter than the other flavors, due to a much smaller service module (only <400m/s is needed once the Mars Orion separates from the MTV when it gets close to Earth on the return trip). Because of mass considerations, it probably also wouldn't be the same Orion which transports the crew to the MTV at the beginning, either.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: dks13827 on 11/04/2011 06:38 pm
Mike Griffin said recently, in the House meeting, that a shuttle launch cost a little over 300 M.     And owning the shuttles costs about   3.4 B, even with no flights.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/04/2011 06:48 pm
You'd have to include all of SFS to get the numbers anywhere near that high.  SSP sure didn't spend that much.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/04/2011 09:32 pm
Mike Griffin said recently, in the House meeting, that a shuttle launch cost a little over 300 M.     And owning the shuttles costs about   3.4 B, even with no flights.

I would assume, if that is correct (no reason to think Griffin would lie to congress, regardless of what people think of his decision making), that would entail:
1) Hydrolox fuel
2) Solid fuel.
3) SRB retreival, transport, and refurb costs (if he's saying it costs 3.4B even with no flights, then you wouldn't be retrieving, transporting, and refubishing the SRB's)
4)  The cost of the ET.
5)  Orbiter refurb costs including SSME's. (again, you won't be refubing the SSME's or other orbiter systems if it ain't flying).

So, if we could do all of that for a little over 300M, then I really can't see where SLS less Orion would be much more than that.  You have two more SRB segs to pay for.  As I understand, over the life of the shuttle, the SRB refurb costs were about a wash vs. the cost of a new SRB, or so I've heard.  You are expending 3-5 RS25E's, rather than refurbing 3 RS25D's, so that would probably cost some more.  And your core is more expensive than the ET, mainly because it has an expendible MPS, vs. the reused one on the Orbiter.  But even with the stretched core, that rest of the core less the MPS should be pretty close in price to the ET.
However, you aren't refurbing a whole orbiter, so that may cancel out those extra expenses, and thus an SLS Block 1 would probably be around that 300M.

I think SLS BLock 2 will have the SS expese for BLEO or super heavy lift mission on top of that 300M.
And I would imagine if SLS was carrying Orion, it's cost per CSM would be on top of that. So, an SLS block 1 carrying Orion CSM to LEO would probably be around $450M?  (assuming $150M for Orion CSM).
That would be a similar LV to STS, less the payloads.  Both are launching a crew of up to 7 to LEO.  But you can put almost 50mt of payload on SLS block along with Orion, vs. something less than 25mt with STS and crew. 

So, that's not really too bad compared to SLS, and we seemed to have money for 4-5 STS launches per year, plus <25mt payloads for each.  Doesn't sound like a bad first step. 

Question:  Would the yearly cost of "ownership" for SLS and Orion be more or less than 3.4B per year?  (I'm including Orion in that to get a little more apples to apples comparison, as every STS launch had up to 7 astronauts on it by default).
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/04/2011 09:54 pm
Again, something like a third of an orbiter needs to be built and thrown away every time for SLS, plus the SRBs are supposed to be expendable now. It's not going to be cheap.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 11/04/2011 11:39 pm
Again, something like a third of an orbiter needs to be built and thrown away every time for SLS, plus the SRBs are supposed to be expendable now. It's not going to be cheap.
By being expendable, the SRB cost is going from ~$1 billion/year to ~$150 million per flight.  Pretty good tradeoff in my book.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Proponent on 11/05/2011 01:51 am
I think the only fair way to compare costs is at a program level, where development costs are amortized over the expected length of the program.

Sounds great for comparing the true cost of programmes after-the-fact.

The problem is that no-one will be able to agree on the assumed cost-of-capital, length of programme etc in advance. All this method does is incorporate even more, probably erroneous, assumptions into the calculation. When Nasa can't even reliably plan five years in the future due to unreliable appropriations, making presumptions about how many decades a programme will last and what aerospace inflation will be in twenty years time is absurd.

It's quite true that estimates of just about anything decades into the future are going to be highly uncertain in an absolute sense.  Relative estimates, however, are usually less uncertain.  Given, say, a program of lunar exploration to be carried out, we can compare costs of an SLS-based version against those of a depot-based version.  To a first approximation, uncertainties about things like inflation rates will affect the two approaches similarly.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/05/2011 03:37 am
Again, something like a third of an orbiter needs to be built and thrown away every time for SLS

Not enough "like" it for this argument to have any meaning.

It's just a rocket stage.  Rocket stages do not cost a billion dollars a pop.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/05/2011 10:08 am
Again, something like a third of an orbiter needs to be built and thrown away every time for SLS

Not enough "like" it for this argument to have any meaning.

It's just a rocket stage.  Rocket stages do not cost a billion dollars a pop.
It uses the same propulsion system, except bigger. It's going to be the largest hydrolox stage ever. Using some of the highest performing and most expensive hydrolox engines (originally optimized for all-the-way-to-orbit and reusability... thus operating at higher pressures, etc, than would be cost-optimal for an engine designed from scratch to be primarily for a first-stage and for expendability like RS-68). And legacy infrastructure and hardware. Most rockets are not so expensive, but this one will be expensive.

If you reuse legacy hardware, you don't get to escape legacy costs.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/05/2011 05:04 pm
I already broke this down for you.  $29M for an ET, maybe $10M for the IU, plus the MPS.  The big-ticket item in the MPS is the engines, which should be in the general vicinity of $30-35M in reasonably high volume, or less if you take into account the price reduction with flight rate (incremental cost of an engine is less than the sticker price).

I don't see how a 5-engine SLS core could possibly be more than about $300M incremental, and I'd expect it to be closer to half that.

You sound like you're engaging in an attempt at FUD.  You really do.  I've tried to address this with numbers, and you haul in an analogy so distant as to be almost totally invalid and start handwaving wildly.

...What legacy hardware?  Aside from the bought and paid for stuff (existing SSMEs and MPS equipment), the core is all new build with new techniques.  So is the RS-25E.  As for legacy, what's wrong with legacy?  The RL-10 is legacy hardware by your apparent definition.

What do you mean by "legacy costs"?  Do you have a breakdown of the "legacy costs" SLS won't be able to escape?  Remember, we're not talking about KSC maintenance here; we're talking about building a core stage...

Anyone who has better numbers than me, feel free to step in...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/05/2011 05:51 pm
This is a whole new rocket.  8)

Some presentations make it look like you can just strap engines on the shuttle ET and launch it.

Will SLS-1 have 3 or 4 engines?

Does it need 4?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: oldAtlas_Eguy on 11/05/2011 06:05 pm
This is a whole new rocket.  8)

Some presentations make it look like you can just strap engines on the shuttle ET and launch it.

Will SLS-1 have 3 or 4 engines?

Does it need 4?

It needs 4 to launch with the non-short "ET" fully fueled. So the now minimum number of engines is 4.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: lkm on 11/05/2011 06:07 pm
Can I ask, why in all this argument over the SLS incremental cost has nobody brought
up the Budget integration document where the 2nd SLS launch per year has an incremental cost of $400m, is this not applicable for some reason? Or has it already been raised and I've missed the thread?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/05/2011 06:20 pm
I'm not sure I trust those numbers; the document was, after all, about availability scenarios rather than cost estimation, and may have had significant margins built in on top of low-fidelity numbers.  (I'm not going to cast further aspersions because I can't remember the specifics of the back-and-forth over that report.)  Also, the flights in question happen more than ten years in the future, and significant inflation has already taken place by then.

But even if the number isn't adjusted for those factors, it's a lot lower than Robotbeat has been suggesting.  With inflation adjustment, it looks like my ~$300M was pretty close.

It needs 4 to launch with the non-short "ET" fully fueled. So the now minimum number of engines is 4.

Read the articles (http://www.nasaspaceflight.com/2011/11/sls-nasa-dac-1-configuration-candidates-wind-tunnel-tests/).  It can still launch with three engines; that's the 70-tonne version.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: joek on 11/05/2011 07:10 pm
Backing up from $400M ten years out, and assuming 3% inflation rate and 20% margin yields current-year incremental  cost of ~$240M.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: baldusi on 11/06/2011 03:22 pm
I already broke this down for you.  $29M for an ET, maybe $10M for the IU, plus the MPS.  The big-ticket item in the MPS is the engines, which should be in the general vicinity of $30-35M in reasonably high volume, or less if you take into account the price reduction with flight rate (incremental cost of an engine is less than the sticker price).
You mean 30M to 35M each engine, right? We are talking always at current prices, right? Because the inflation rate is completely unknown. Again, all the prices I quote are 2011.
Since we are talking about the SLS Block 1A version, that would be five engines, at 25M (the RS-25E are supposed to be cheap), that's 125M in engines. So, let's say the whole MPS is 136M. That's 175M for the cores parts.
You need to add two boosters. If you can keep it down to SRB, and assume 10M per segment, that's another 100M in boosters. Let's remember that those are going to be graphite epoxy disposable boosters. You'd need the equivalent thrust of a Falcon Heavy as each boosters. That is, two cost-plus acquired, fully custom, over powerful boosters would be less cost than a single FH, even for a price and performance that haven't been demonstrated. So I seriously doubt that you can get them for 100M total, in fact, I consider this to be a cheap price. So, core plus boosters 275M in parts.
Now, you have to add the CPS (remember that core uses a ballistic trajectory, the CPS does the final circularization burn). It seems it will use two NGE engines. Might start with two Vinci engines, until the NGE are ready. But let's say that each engine costs 10M (cheaper than an RL10). Plus the avionics, and tanks and that, let's say that the CPS is 40M? So we are at 315M.
You need a fairing, I assume. It's going to be an exclusive 10m piece. So let's say 10M. We are at 325M in parts.
Now you have to add integration. And testing. Let's say 25M? That's 350M fully integrated.
Now you have to add launch operation, fuel, range configuration, TDRS time and such and such. And all this was considered in today's dollars. And without a single payload nor Second Stage (that's going to cost a lot with a few J-2X).
So, I can't see them launching for less than 400M marginal cost the Block 1A. And that's assuming 100M for boosters, and 25M per RS-25E and 40M for the CPS. I think I'm more than generous with those numbers.
But we have to amortize the RS-25E, the Advanced Boosters, the CPS and Second Stage DDT&E.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/06/2011 10:20 pm
You've moved the goalposts.  We were talking about Block 1 with no upper stage.  Robotbeat said it would be near a billion dollars incremental.  I called incorrect.

[In fact, the part you quoted was referring specifically to the core, excluding the boosters...]

That said, Block 1A is a valid subject for discussion...

It sounds like you're talking all-in costs for the engines and boosters.  This fails to take into account price reductions due to flight rate increases, which apply across all flights and thus take quite a large chunk out of the cost of the added flight.  On the other hand, you are using pretty generous numbers...

Launch operations should be largely fixed costs; you wouldn't fire half your launch control team if the flight rate was halved...  right?  Same with integration and testing; you need those facilities and personnel regardless.

As I pointed out earlier, Ross (do you trust him?  Jim doesn't (http://forum.nasaspaceflight.com/index.php?topic=26394.msg813786#msg813786), but he clammed up when I asked him why not) showed a chart (http://forum.nasaspaceflight.com/index.php?topic=18752.msg622582#msg622582) a while back that indicated a Jupiter 246 would be about $260M incremental at a couple flights per year.  It didn't actually show incremental costs directly; it just gave program cost as a function of flight rate.  The incremental cost of a flight actually decreased a bit as the flight rate went up...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lars_J on 11/06/2011 10:46 pm
But we all know that the flight rate will be VERY low (1 per year for the first decade IF we are lucky), so it is intellectually dishonest IMO to argue SLS costs at high (STS-like) flight rates.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/06/2011 11:11 pm
You've stated that far too strongly.  Decades are long; look what's happened to NASA (and the United States in general) in just the last one.  Also, groupthink among a certain collection of detractors does not warrant an accusation of intellectual dishonesty against anyone who disagrees.

Also, who said anything (pivotal) about flight rate?  This is a low-fidelity incremental cost estimating exercise.  At this level of analysis, flight rate is irrelevant.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Patchouli on 11/06/2011 11:13 pm
SLS will launch more times than Saturn V.

You're on! I hope so though.

Hopefully it will as low flight rate is one of the issues that killed the Saturn V.

The real problem for SLS is finding payloads that can benefit from such as large LV.


Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/07/2011 12:57 am
I believe the plan to land big things on Mars involves a 10m diameter triconic aero shell that launches as the payload fairing.

These will add weight and plenty of it.

The biggest cargo SLS is a vital part of NASA being capable of sending men to Mars.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jason1701 on 11/07/2011 01:37 am
I believe the plan to land big things on Mars involves a 10m diameter triconic aero shell that launches as the payload fairing.

These will add weight and plenty of it.

As well as cost and plenty of it. As of now, there is no plan to fund giant payloads like this.

Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/07/2011 01:48 am
As well as cost and plenty of it. As of now, there is no plan to fund giant payloads like this.

Don't be silly.  It's part of a Mars architecture.  As of now, there is no plan, period.  It's in work.  And near-term, it will probably involve the moon and asteroids.  The Mars architecture will have to wait.

I repeat:  large payloads are only preposterously expensive as one-offs.  If you launch ten missions you don't pay anywhere near ten times as much as you do for one.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/07/2011 02:40 am
The plan is to be Mars forward not to go straight to Mars.

Right now without any heavy lift humans will never go.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/07/2011 03:09 am
...
Right now without any heavy lift humans will never go [to Mars].
False. This is taken as axiomatic for many on this forum, but there's really no reason why it is necessarily true. What is true and cannot be denied is that if we never develop the payloads, we're certainly never going to Mars.

We're launching a rover the size (and roughly mass) of a Mini Couper in less than a month, and it's not even using the largest (or second largest) launch vehicle we have and isn't using any of the orbital rendezvous (or assembly or refueling) techniques we've used over a hundred times on ISS or advanced propulsion techniques from Dawn and its entry technology is mostly the same from Viking (though we are using entry guidance derived from Apollo for MSL). There are so many things we can do right now to enable human exploration (yes, even of Mars) with normal, current launch vehicles which already are used for commercial and military and scientific payloads regularly, most of which will be needed no matter the size of the launch vehicle we plan on using.

Now maybe SLS is a sure thing, fine. Maybe you even think we should all get behind it because it satisfies the right stakeholders. But don't think that changes the fact that it isn't the only way to do it.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/07/2011 03:34 am
Ok fair enough I retract that line.

I can see some posters will not like you saying SLS is the only way to Mars.

Go EELV and all that  ::)

I don't think that's the right way to go but indeed SLS isn't the only option.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/07/2011 03:47 am
Ok fair enough I retract that line.

I can see some posters will not like you saying SLS is the only way to Mars.

Go EELV and all that  ::)

I don't think that's the right way to go but indeed SLS isn't the only option.
Fair enough. ;) I just think it's important to think outside the box a little. We also aren't stuck with just the EELVs. By the time any sort of hardware is ready for Mars, the partially reusable replacements for EELVs will have entered service. And I'm not talking about SpaceX's vehicles, which we can say for certain will be part of the equation (even if they somehow fail utterly, parts of them will be bought and used by someone, now that they're proven to work).

If we're talking about very unlikely high, STS-like SLS flight rates, I think its comparisons shouldn't be our current EELVs only, but at least a partially reusable EELV or partially/fully reusable Falcon 9 or an evolved EELV with ACES upper stage or expendable Falcon Heavy plus Raptor, etc, should be the comparison. If you compare the most highly optimistic flight rates for SLS, they should compare with the most optimistic scenario for EELVs, Falcon 9, etc.

For the record, I would welcome the scenario required to have a high flight rate for SLS.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: baldusi on 11/07/2011 06:08 am
You've moved the goalposts.  We were talking about Block 1 with no upper stage.  Robotbeat said it would be near a billion dollars incremental.  I called incorrect.

[In fact, the part you quoted was referring specifically to the core, excluding the boosters...]

That said, Block 1A is a valid subject for discussion...

It sounds like you're talking all-in costs for the engines and boosters.  This fails to take into account price reductions due to flight rate increases, which apply across all flights and thus take quite a large chunk out of the cost of the added flight.  On the other hand, you are using pretty generous numbers...

Launch operations should be largely fixed costs; you wouldn't fire half your launch control team if the flight rate was halved...  right?  Same with integration and testing; you need those facilities and personnel regardless.

As I pointed out earlier, Ross (do you trust him?  Jim doesn't (http://forum.nasaspaceflight.com/index.php?topic=26394.msg813786#msg813786), but he clammed up when I asked him why not) showed a chart (http://forum.nasaspaceflight.com/index.php?topic=18752.msg622582#msg622582) a while back that indicated a Jupiter 246 would be about $260M incremental at a couple flights per year.  It didn't actually show incremental costs directly; it just gave program cost as a function of flight rate.  The incremental cost of a flight actually decreased a bit as the flight rate went up...
I assumed we can only talk about Block 1A on an ongoing basis, since that's the only one that NASA plans to actually use on an ongoing basis. The rest are in prototype mode. So, the only reasonable discussion here, would be the marginal cost (which has a very specific definition) of an SLS Block 1A or Block 2 launch. Comparing core costs and such is completely meaningless. Only the launch cost is a valid comparison to other LV (even to Jupiter).
As I stated, I did used the marginal costs of the engines. Marginal Cost is defined as the extra cost of the last added unit. On all the RS-25 cost estimations, I never seen it get anywhere near 25M. In fact, I think it was a sort of asymptote to 35M, at 2005 or 2006 prices. So, a marginal cost of 25M at 2011/12 prices seems like a lower bound. The 100M for both boosters follows a similar analysis. As I said, the CPS and fairing are integral parts of the SLS. You can't have a launch without either of those. It might be argued that that is a fundamental difference to AJAX and Jupiter. Even a regrettable difference. Yet, that's how it seems to be panning out.
So, in parts alone 325M as marginal cost seems like a lower bound. I still think, that even if you have all the people on the factory, you would spend at least a 10% in integration and testing. A lot of work would be done by contractors, and a lot of workers would have found other useful things to do if they didn't had to do this last launch. Else, you do have excessive workers. And you do need parts, electricity, fuel, food for the people, administrative overhead of just assigning working hours and such.
Ditto for the launch operations. You have fuel, you have to pay the range, the Coast Guard has to clear the launch path, you need to check the airspace and have a couple of jets on patrol and at least one on follow duty. Just taking a big boat out of the moors might cost 50k. And I don't know how much for the follow plane.
We can discuss that the marginal cost of a launch is a bit less of 400 (of which I'm very doubtful) or closer to 800M (which is what I expect it to cost to the government). Don't forget that the government can't go and pay a dollar. It's got to be authorized, it's got to be accounted for, and if it's not purely commercial, its cost has to be certified, and even the origin has to be demonstrated (like in US production requirements, small business, etc.) So, what you would not even spend time thinking, the government has to spend a small army's time just doing follow up. The GTO is a very competitive business, nobody gives any advantage, and it might be argued that the LV receive some subsidies. Yet, an Ariane 5 launch is around 200M. A Proton-M is what? 80M, I think, right? So, for a 20% extra over an Ariane 5, you think you could get a 95tn to LEO launcher? You could launch five GTO payloads/launch and corner the GTO market! Nope, I simply don't see that cheap.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/07/2011 08:54 am
As I stated, I did used the marginal costs of the engines.

You didn't state that, but okay.  Your numbers are actually lower than mine (same for RS-25E, less for RSRBV), so that doesn't really surprise me too much...  not sure why I bothered objecting.

Except...  you talk as though you have a good idea of what the incremental cost of a set of boosters might be.  Do you have a source?  IIRC there was an actual Shuttle SRB purchase in which the segments were $12.5M each ($100M for the set), and we know the SRBs are heavy on the fixed costs...

Oh, and the RS-25 chart you're probably talking about (http://forum.nasaspaceflight.com/index.php?topic=19548.msg535586#msg535586) was in 2010 dollars.

Quote
As I said, the CPS and fairing are integral parts of the SLS. You can't have a launch without either of those.

You're wrong.  You do need a fairing, but fairings are cheap.  You do not need a CPS; I don't know where you got that idea.  There are at least two known SLS configurations that have no upper stage whatsoever, and one of them is a cargo launcher.

Quote
800M

You've more than doubled the cost with nothing but handwaving.  A sanity check is in order.  Your mess of extra costs and government inefficiency are not new to SLS; they applied to Shuttle too - what was the marginal cost of a Shuttle launch?

The program would have cost about $2.4B to keep the ability to launch Shuttles without actually doing so.  At a flight rate of around 5-6 per year, it was around $3.2B IIRC.  Sounds like less than $200M incremental to me - possibly around $160M?

There were two proposals for commercial operation of the Shuttle fleet - the first was for five flights per year at $1.8B, and the second was for two flights per year at $1.5B.  That's ~$100M per launch incremental.  I can't remember how far apart the two proposals were, but let's say two years (it can't have been more than that), and assume aerospace inflation of 4.5%.  The upper-bound incremental launch cost is now $155M.

Preparation and handling for SLS should be similar to STS or better, since except for the orbiter they're very similar systems.  What are the hardware costs that SLS will bear but Shuttle didn't?  The MPS, IU, and two extra booster segments.  By your math, $166M.

Sounds like about $326M for the SLS w/o upper stage, not taking into account anything Shuttle needed but SLS won't.

If you take the ~$400M from the Budget Integration document and depreciate it ten years at 2%, you get $330M.  And that was with the upper stage operational and probably being used...

Quote
Yet, an Ariane 5 launch is around 200M. A Proton-M is what? 80M, I think, right? So, for a 20% extra over an Ariane 5, you think you could get a 95tn to LEO launcher? You could launch five GTO payloads/launch and corner the GTO market! Nope, I simply don't see that cheap.

Apples to oranges.  We're discussing incremental costs.  A company that charged incremental costs to its customers would go out of business very quickly, especially if its fixed costs were a large chunk of its total costs (it looks like SLS with upper stage is expected to be around $1.5B or so in modern dollars, judging by the Budget Integration document).

Also, since when is the Ariane 5 that expensive?

Also, gut feeling is no reason to dismiss math.  By all appearances, if NASA could somehow get away with selling SLS launches at marginal cost (charging fixed costs to the government to maintain the "national capability"), it would be extremely competitive.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/07/2011 10:21 am
Ok fair enough I retract that line.

I can see some posters will not like you saying SLS is the only way to Mars.

Go EELV and all that  ::)

I don't think that's the right way to go but indeed SLS isn't the only option.
Fair enough. ;) I just think it's important to think outside the box a little. We also aren't stuck with just the EELVs. By the time any sort of hardware is ready for Mars, the partially reusable replacements for EELVs will have entered service. And I'm not talking about SpaceX's vehicles, which we can say for certain will be part of the equation (even if they somehow fail utterly, parts of them will be bought and used by someone, now that they're proven to work).

If we're talking about very unlikely high, STS-like SLS flight rates, I think its comparisons shouldn't be our current EELVs only, but at least a partially reusable EELV or partially/fully reusable Falcon 9 or an evolved EELV with ACES upper stage or expendable Falcon Heavy plus Raptor, etc, should be the comparison. If you compare the most highly optimistic flight rates for SLS, they should compare with the most optimistic scenario for EELVs, Falcon 9, etc.

For the record, I would welcome the scenario required to have a high flight rate for SLS.

If NASA wanted to go to Mars with all payloads designed for Falcon Heavy I would support that.

I'd support any rocket/mission that will send humans to Mars.

For now I believe that SLS is the best option.

I think bigger rockets are better, you get more done per launch.

I would change this opinion if rockets started launching on time.  ::)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/08/2011 01:15 am
The real problem for SLS is finding payloads that can benefit from such as large LV.

Which is why I said it is too big, even though I'm supporting it. It's too big to be useful except as a HLV. What is really needed is a MLV that can be configured on demand to cover HLV needs. That was what DIRECT's Jupiter was and what AJAX actually is. We could have made it bigger but chose not to because any bigger, like the current SLS, and it becomes a one-trick pony - HLV *only*, which won't fly all that often. SLS will not see any economies of scale because of that.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/09/2011 08:54 pm
This is a whole new rocket.  8)

Some presentations make it look like you can just strap engines on the shuttle ET and launch it.

Will SLS-1 have 3 or 4 engines?

Does it need 4?

It needs 4 to launch with the non-short "ET" fully fueled. So the now minimum number of engines is 4.

http://www.youtube.com/watch?v=4e-bqzaZh-o
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mark S on 11/09/2011 11:20 pm
http://www.youtube.com/watch?v=4e-bqzaZh-o

Wow, that's very exciting!  If only the hardware came together as quickly as the CG animation....

Pretty nice CG work, actually, except maybe for the Lego(TM)-brand people. Or maybe it's Little Tykes(TM)?.  :)

Mark S.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Pheogh on 11/09/2011 11:41 pm
http://www.youtube.com/watch?v=4e-bqzaZh-o

Wow, that's very exciting!  If only the hardware came together as quickly as the CG animation....

Pretty nice CG work, actually, except maybe for the Lego(TM)-brand people. Or maybe it's Little Tykes(TM)?.  :)

Mark S.

You know I hate to admit it but after all the water that has gone under the bridge I can't help but get a little emotional at seeing that.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RocketmanUS on 11/10/2011 05:02 am
New Cryo Prop Stage (CPS)
Any idea of what the dry mass might be?
The type and how many engines it will have?
Fuel load capacity?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 11/10/2011 05:18 am
http://www.youtube.com/watch?v=4e-bqzaZh-o

Wow, that's very exciting!  If only the hardware came together as quickly as the CG animation....

Pretty nice CG work, actually, except maybe for the Lego(TM)-brand people. Or maybe it's Little Tykes(TM)?.  :)

Mark S.
Actually they are Roblox people
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MikeAtkinson on 11/10/2011 07:45 am
Yet, an Ariane 5 launch is around 200M. A Proton-M is what? 80M, I think, right? So, for a 20% extra over an Ariane 5, you think you could get a 95tn to LEO launcher? You could launch five GTO payloads/launch and corner the GTO market! Nope, I simply don't see that cheap.

Apples to oranges.  We're discussing incremental costs.  A company that charged incremental costs to its customers would go out of business very quickly, especially if its fixed costs were a large chunk of its total costs (it looks like SLS with upper stage is expected to be around $1.5B or so in modern dollars, judging by the Budget Integration document).

This whole exchange (not just the part quoted) shows the reason I don't like incremental costs. It makes it impossible to do comparisons between systems, architectures or missions.

The only situation where incremental costs are valid is where the cost of doing X missions is compared to doing X+1 missions, and that is where the incremental cost is for the mission.

Even then that ignores budget realities. It seems that Congress decides overall budgets then fits programs within those budgets. So if Congress has decided that $5.5B is available for non-ISS HSF and two lunar sortie missions a year cost $5B and three cost $6.2B, then it does not matter that the incremental cost of the third mission is only $1.2B, it breaks the budget. If three missions had fitted within the budget, again the incremental cost of the fourth would have been irrelevant because it would have broken the budget.

Incremental costs can be used to argue that the overall budget should be increases, "just give us a bit more money and we can do so much more", but we have seen the lack of results from that strategy over the last few years.

Incremental launch costs are only a small proportion of incremental mission costs. Changing from incremental mission costs to adding new mission types and still using incremental launch costs as the metric is even worse. Going from a NEO mission every other year to a NEO mission plus a Lunar sortie mission every over year doubles the launch rate from 1 to 2 per year (incremental launch cost of $400M) and might have an incremental mission cost of $1B/year, but both numbers pale into insignificance to the increased program costs which would include $20-50B for development.

When comparing SLS against commercial launchers, things get complicated. A graph of tonnage to LEO against cost for the different launchers is often used.

1. the commercial launchers, already have many flights already booked, these should be discounted, so the graph for the commercial launchers is moved to the left.

2. the effect of lower costs for all their customers needs to be included, they are likely to win more commercial business and potentially more NASA and DOD business as well.

3. it is comparing SLS costs after a large number of development dolars have been spent against commercial costs with a much smaller number of dolars spent

4. flight rates for the commercial are now in the range where reusability starts to make sense, this is a joker because it causes a discontinuity in their price graphs, the magnitude of which is difficult to access.


As a side note in general the incremental cost is not the same as the decremental cost. So if going from X units to X+1 units has an incremental cost of Y, going from X+1 units down to X units does not save Y, but usually a smaller amount.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: JohnFornaro on 11/10/2011 03:10 pm
Quote from: Mike Atkinson
It seems that Congress decides overall budgets then fits programs within those budgets. So if Congress has decided that $5.5B is available for non-ISS HSF and two lunar sortie missions a year cost $5B and three cost $6.2B, then it does not matter that the incremental cost of the third mission is only $1.2B, it breaks the budget. If three missions had fitted within the budget, again the incremental cost of the fourth would have been irrelevant because it would have broken the budget.

The way I look at it Congress can only allocate a budget.  True, there is a risk, as you point out that "incremental costs", loosely defined, might result in the scenario you mention.  But has that ever happened in the past?  Budget overruns reliably preclude this possible eventuality.  Obviously, you've given this some thought as well; "...we have seen the lack of results from that strategy over the last few years".

Nevertheless, I agree that, in principle, Congress should consider incremental costs, and that the term itself should be better defined.  The only possible way that incremental costs could be used in establishing budgets is if there is a trust factor regarding the costs themselves.  Since this is not the case, and is unlikely to be the case without a better oversight process, I don't see how Congress could proceed otherwise.

As to your points 1,2,3,4, I more or less agree, but note that the demonstrated proficiency of the commercial providers is still in the "to be determined" stage, awaiting sufficient successful missions to really establish op costs and reliability.  The policymakers continue to use too few data points to establish policy.  This could probably be accomodated were they to revise policy going forward, but they hang onto, for one thing, "sunk costs", long past the time that they would be justified.

Quote from: RoboBeat
What is true and cannot be denied is that if we never develop the payloads, we're certainly never going to Mars.

Which is another way of saying that if we don't build it, then surely they will not come.  Mars will not be forgotten.  Ever.  If the idea of permanence has any meaning, the proximate arena needs to be developed first, with demonstrable proficiency and predictable costs.  Then we attempt Mars, even if it should mean tours of duty only, should the medical problem prove insurmountable.

Point is, focus nearby, and forget about manned missions to Mars using the already obsolete SLS launch system.

I'm still confused about the number of engines being currently considered.  And, BTW, I cannot abide the discussions already, about a 140ton vehicle.  This is prima facie evidence, I'd say, that they're already planning to fail.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MikeAtkinson on 11/10/2011 04:00 pm
I'm still confused about the number of engines being currently considered. 

So am I.

And, BTW, I cannot abide the discussions already, about a 140ton vehicle.  This is prima facie evidence, I'd say, that they're already planning to fail.

A good example is the booster competition.

As oldAtlas_Eguy said on another thread:
If Spacex had a FX size booster they would do a FXH version and then sue NASA to make them use it because it would be cheaper than SLS. SLS is not protected by any clause of the Space Act.

If SpaceX or some other company win the booster competition with a liquid booster, then in three core configuration it could compete directly with SLS in terms of payload. They would have a powerful incentive to do so as they could capture most of the SLS revenues instead of only 20% or so for just the boosters. NASA would have paid for the replacement for SLS out of the SLS budget.

Another example is the growth from 130 tonne to 140+ tonne LEO performance for the block II version. I would not be surprised if we do not see 150 tonnes mentioned before long. The knock on effect of this is that missions will probably get larger and larger missions cost more. More mission cost leads to less missions. So, what seems like a good idea, increasing payload while not increasing costs ( => lower cost/kg), might end up with less launches ( => much higher cost/kg).
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: RocketmanUS on 11/10/2011 04:36 pm
As oldAtlas_Eguy said on another thread:
If Spacex had a FX size booster they would do a FXH version and then sue NASA to make them use it because it would be cheaper than SLS. SLS is not protected by any clause of the Space Act.

If SpaceX or some other company win the booster competition with a liquid booster, then in three core configuration it could compete directly with SLS in terms of payload. They would have a powerful incentive to do so as they could capture most of the SLS revenues instead of only 20% or so for just the boosters. NASA would have paid for the replacement for SLS out of the SLS budget.

Another example is the growth from 130 tonne to 140+ tonne LEO performance for the block II version. I would not be surprised if we do not see 150 tonnes mentioned before long. The knock on effect of this is that missions will probably get larger and larger missions cost more. More mission cost leads to less missions. So, what seems like a good idea, increasing payload while not increasing costs ( => lower cost/kg), might end up with less launches ( => much higher cost/kg).

Over 130t is just to big a rocket, that is just asking to be canceled.
Why not just put a JUS on top of SLS block I? (moon , MArs , NEO)

I like the other part of statement , win booster competition.
So that could end up funding the FXH, at least the engines if SpaceX won the contract.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Downix on 11/10/2011 05:45 pm
As oldAtlas_Eguy said on another thread:
If Spacex had a FX size booster they would do a FXH version and then sue NASA to make them use it because it would be cheaper than SLS. SLS is not protected by any clause of the Space Act.

If SpaceX or some other company win the booster competition with a liquid booster, then in three core configuration it could compete directly with SLS in terms of payload. They would have a powerful incentive to do so as they could capture most of the SLS revenues instead of only 20% or so for just the boosters. NASA would have paid for the replacement for SLS out of the SLS budget.

Another example is the growth from 130 tonne to 140+ tonne LEO performance for the block II version. I would not be surprised if we do not see 150 tonnes mentioned before long. The knock on effect of this is that missions will probably get larger and larger missions cost more. More mission cost leads to less missions. So, what seems like a good idea, increasing payload while not increasing costs ( => lower cost/kg), might end up with less launches ( => much higher cost/kg).

Over 130t is just to big a rocket, that is just asking to be canceled.
Why not just put a JUS on top of SLS block I? (moon , MArs , NEO)

I like the other part of statement , win booster competition.
So that could end up funding the FXH, at least the engines if SpaceX won the contract.
Or Atlas Phase II, or a Taurus III, or what have you.  FX is not a shoe in regardless.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ronsmytheiii on 11/10/2011 06:15 pm
SSMS GSE was loaded on the Pegasus barge, which has left to deliver it to Stennis Space Center:

http://mediaarchive.ksc.nasa.gov/search.cfm?cat=4
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mark S on 11/10/2011 07:00 pm
SSMS GSE was loaded on the Pegasus barge, which has left to deliver it to Stennis Space Center:

http://mediaarchive.ksc.nasa.gov/search.cfm?cat=4

OMG! NASA is competing with commercial freight shipping companies! Quick, someone convene a Congressional investigation. And where's that darned NASA OIG when you need them?

:)

Mark S.

Edit: Actually, I'm more interested in 39A there in the background. Is it already starting to look a bit shabby and run-down, or is it just me?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: oldAtlas_Eguy on 11/10/2011 07:51 pm
The barge would be specialized equipment which is used for ET transport and would be later used for SLS core transport. The tug that push it arround NASA actually owns as well. This was a schedule risk concern by NASA over the lease of tugs. Actually NASA still leassed tugs when they had to use deep water routes (not the inter-coastal shalows) because the NASA barge tug is only a shallow water tug. I wonder what will happen to NASA's tug? Do they cost share it with ULA for transport of the Atlas/Delta barge?


Edit: Or do I have that backward in that NASA's tug is a deep water tug, one they use for SRB retrieval, and they had to lease a shallow water tug during the oil-slick mess in the gulf?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ronsmytheiii on 11/10/2011 08:13 pm
HEre is a view of the GSE inside Pegasus
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: JayP on 11/10/2011 10:19 pm
The barge would be specialized equipment which is used for ET transport and would be later used for SLS core transport. The tug that push it arround NASA actually owns as well. This was a schedule risk concern by NASA over the lease of tugs. Actually NASA still leassed tugs when they had to use deep water routes (not the inter-coastal shalows) because the NASA barge tug is only a shallow water tug. I wonder what will happen to NASA's tug? Do they cost share it with ULA for transport of the Atlas/Delta barge?


Edit: Or do I have that backward in that NASA's tug is a deep water tug, one they use for SRB retrieval, and they had to lease a shallow water tug during the oil-slick mess in the gulf?
No,

 NASA uses the SRB retrieval ships to tow the barge in open water. They used to hire comercial towing services to do it, but switched years ago as a cost saving measure.

 Once inside of the locks at port canaveral, they contract with a comercial tow boat company to move the barge up the banana river to the turning basin. Nasa does have a pair of small push boats used to help mooring the barge to the quay, but they're not the ones in the photos above.

The Mecondo spill had no effect on NASA opperations.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: oldAtlas_Eguy on 11/11/2011 12:07 am
The barge would be specialized equipment which is used for ET transport and would be later used for SLS core transport. The tug that push it arround NASA actually owns as well. This was a schedule risk concern by NASA over the lease of tugs. Actually NASA still leassed tugs when they had to use deep water routes (not the inter-coastal shalows) because the NASA barge tug is only a shallow water tug. I wonder what will happen to NASA's tug? Do they cost share it with ULA for transport of the Atlas/Delta barge?


Edit: Or do I have that backward in that NASA's tug is a deep water tug, one they use for SRB retrieval, and they had to lease a shallow water tug during the oil-slick mess in the gulf?
No,

 NASA uses the SRB retrieval ships to tow the barge in open water. They used to hire comercial towing services to do it, but switched years ago as a cost saving measure.

 Once inside of the locks at port canaveral, they contract with a comercial tow boat company to move the barge up the banana river to the turning basin. Nasa does have a pair of small push boats used to help mooring the barge to the quay, but they're not the ones in the photos above.

The Mecondo spill had no effect on NASA opperations.

Thanks I think that answered most of the questions about the barge and tugs.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/11/2011 03:53 pm
[a bunch of stuff everyone should already know]

I wasn't trying to make a point.  I was trying to answer a question.  If you don't want the question asked for some reason, say so.

No one uses incremental costs in isolation.  That would be like trying to determine how easy a room is to move around in by measuring just the bookshelf and sofa (taking care not to annoy the elephant while doing so).

But I see far too many people on here that simply state as a fact that SLS will be $1B per launch (or sometimes $1.5B per launch), without any mention of flight rate, which is also a misrepresentation.  I also see claims that because of this high cost, it will be too expensive to launch often, which without the context of incremental cost gives a very pessimistic impression.  You need to understand how the costs break down - development, fixed, incremental - otherwise you end up with a skewed idea (or no idea at all) of how the "mission costs" are affected by flight rate and program lifetime.  Just quoting a single number is never an adequate explanation.

A good example is Robotbeat, who was apparently under the impression that SLS and Orion would be close to $1B incremental, each.  No wonder he's been opposing them...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/11/2011 04:31 pm
The SLS is Ares V lite.

I've heard 700mt IMLEO is the minimum for a manned Mars mission.

chemical/aerocapture DRM5 included in screenshot.

This chart calls for 12 Ares V launches.

SLS might be able to do it in 10? Can NASA launch that many of these in a short timeframe?

More weight savings might have to be made.


Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/11/2011 05:03 pm
I don't think 700 mT is the minimum for a manned Mars mission stack (I saw more than one DRM with I think ~450mT IMLEO, and of course Mars Direct does it for far less than that, though probably not terribly realistically) , though it may if you include pre-placed equipment, etc.

It depends heavily on number of crew, pre-placement of equipment, mission mode (short-stay, etc), propulsion technology (NTR, solar-electric, aerocapture/braking, all-chemical), extent of ISRU, ECLSS, etc. How many launches you need in a short time-frame also depends a lot on if you have depot technology available. With depot technology available, NASA may not need to have 2 SLS launch pads.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jason1701 on 11/11/2011 05:04 pm
The SLS is Ares V lite.

I've heard 700mt IMLEO is the minimum for a manned Mars mission.

chemical/aerocapture DRM5 included in screenshot.

This chart calls for 12 Ares V launches.

SLS might be able to do it in 10? Can NASA launch that many of these in a short timeframe?

More weight savings might have to be made.

Weight savings from DRM5 are easy. It's incredibly bloated. A realistic first Mars mission would be somewhere between DRM and Zubrin's Dragon proposal.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: edkyle99 on 11/13/2011 03:18 pm
But I see far too many people on here that simply state as a fact that SLS will be $1B per launch (or sometimes $1.5B per launch), without any mention of flight rate, which is also a misrepresentation.  I also see claims that because of this high cost, it will be too expensive to launch often, which without the context of incremental cost gives a very pessimistic impression.  You need to understand how the costs break down - development, fixed, incremental - otherwise you end up with a skewed idea (or no idea at all) of how the "mission costs" are affected by flight rate and program lifetime.  Just quoting a single number is never an adequate explanation.

I agree.  Consider the leaked budget studies, which had an option or two with only one SLS/MPCV launch every two years.  At the projected $2.8 billion per year program budget we would be looking at $5.6 billion per launch ($3.6 billion for SLS, $2 billion for MPCV).  But even the most optimistic (unrealistic) scenarios showing two SLS launches per year (not going to happen) had each SLS launch costing $1.3 billion.  This rocket is a money sink.

 - Ed Kyle
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/13/2011 06:25 pm
But I see far too many people on here that simply state as a fact that SLS will be $1B per launch (or sometimes $1.5B per launch), without any mention of flight rate, which is also a misrepresentation.  I also see claims that because of this high cost, it will be too expensive to launch often, which without the context of incremental cost gives a very pessimistic impression.  You need to understand how the costs break down - development, fixed, incremental - otherwise you end up with a skewed idea (or no idea at all) of how the "mission costs" are affected by flight rate and program lifetime.  Just quoting a single number is never an adequate explanation.

I agree.  Consider the leaked budget studies, which had an option or two with only one SLS/MPCV launch every two years.  At the projected $2.8 billion per year program budget we would be looking at $5.6 billion per launch ($3.6 billion for SLS, $2 billion for MPCV).  But even the most optimistic (unrealistic) scenarios showing two SLS launches per year (not going to happen) had each SLS launch costing $1.3 billion.  This rocket is a money sink.

 - Ed Kyle

At two (2) Shuttle launches per year, what was the cost per Shuttle mission?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: edkyle99 on 11/13/2011 08:41 pm
But I see far too many people on here that simply state as a fact that SLS will be $1B per launch (or sometimes $1.5B per launch), without any mention of flight rate, which is also a misrepresentation.  I also see claims that because of this high cost, it will be too expensive to launch often, which without the context of incremental cost gives a very pessimistic impression.  You need to understand how the costs break down - development, fixed, incremental - otherwise you end up with a skewed idea (or no idea at all) of how the "mission costs" are affected by flight rate and program lifetime.  Just quoting a single number is never an adequate explanation.

I agree.  Consider the leaked budget studies, which had an option or two with only one SLS/MPCV launch every two years.  At the projected $2.8 billion per year program budget we would be looking at $5.6 billion per launch ($3.6 billion for SLS, $2 billion for MPCV).  But even the most optimistic (unrealistic) scenarios showing two SLS launches per year (not going to happen) had each SLS launch costing $1.3 billion.  This rocket is a money sink.

 - Ed Kyle

At two (2) Shuttle launches per year, what was the cost per Shuttle mission?

Pretty much in line with the total program cost divided by the 135 launches, which works out to about $1.5 billion per launch.

But SLS is not going to fly twice per year, and the SLS rocket cost is only a part of the total mission cost.  For a side-by-side comparison with STS, you have to add the cost of SLS and its payload.  When all is said and done, $1.5 billion per launch would look cheap compared to SLS + MPCV + Upper Stage, etc..

 - Ed Kyle
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/13/2011 10:02 pm
But I see far too many people on here that simply state as a fact that SLS will be $1B per launch (or sometimes $1.5B per launch), without any mention of flight rate, which is also a misrepresentation.  I also see claims that because of this high cost, it will be too expensive to launch often, which without the context of incremental cost gives a very pessimistic impression.  You need to understand how the costs break down - development, fixed, incremental - otherwise you end up with a skewed idea (or no idea at all) of how the "mission costs" are affected by flight rate and program lifetime.  Just quoting a single number is never an adequate explanation.

I agree.  Consider the leaked budget studies, which had an option or two with only one SLS/MPCV launch every two years.  At the projected $2.8 billion per year program budget we would be looking at $5.6 billion per launch ($3.6 billion for SLS, $2 billion for MPCV).  But even the most optimistic (unrealistic) scenarios showing two SLS launches per year (not going to happen) had each SLS launch costing $1.3 billion.  This rocket is a money sink.

 - Ed Kyle

At two (2) Shuttle launches per year, what was the cost per Shuttle mission?

Pretty much in line with the total program cost divided by the 135 launches, which works out to about $1.5 billion per launch.

But SLS is not going to fly twice per year, and the SLS rocket cost is only a part of the total mission cost.  For a side-by-side comparison with STS, you have to add the cost of SLS and its payload.  When all is said and done, $1.5 billion per launch would look cheap compared to SLS + MPCV + Upper Stage, etc..

 - Ed Kyle

Agreed. Which is why I was *VERY* careful earlier in the discussion to draw a very clear and distinct difference between what it costs to launch a single SLS rocket (sans payload) and what mission costs are, which has to include a lot more stuff in the equation.

And while you may ultimately prove to be correct, I would be cautious at this point about stating categorically that SLS will not fly twice per year, or any other flight rate for that matter. It really depends on what the mission(s) going forward actually are, the schedule to execute that mission, and the willingness of the Congress, which WANTED the SLS very badly, to fund it. None of those things are known at this point so the future flight rate is nothing more than opinion-based speculation, to which you are certainly entitled.But one simply cannot state with *any* certainty that "SLS is not going to fly twice per year".

If we are all very lucky, we won't have very many more uber super cheap, cheap, cheap Congresses like we currently are being forced to painfully endure. Like the rest of the country, there are too many legislators with Champagne  tastes but want to satisfy that on a beer budget. Sooner or later they will wake up, smell the coffee, and write the checks. For the sake of the United States HSF program I hope it is sooner rather than later.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Xplor on 11/13/2011 10:14 pm
Discussing that if only Congress would fund SLS another X hundred million we could add an additional launch at marginal pricing is very miss leading.  The payload/mission costs could easily be measured at over a billion per launch. Thus Congress would likely have to increase Explorations budget by $2B or more per each additional SLS launch.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/13/2011 11:54 pm
Discussing that if only Congress would fund SLS another X hundred million we could add an additional launch at marginal pricing is very miss leading.  The payload/mission costs could easily be measured at over a billion per launch. Thus Congress would likely have to increase Explorations budget by $2B or more per each additional SLS launch.

You've conjured the better part of a billion dollars out of thin air with no explanation at all, adding it on top of "over a billion per launch", which was handwaving to start with.

Besides, as I said, you need to break down the costs to understand them.  I don't see you having done that.

What's the marginal cost for an Orion?  What's the marginal cost for a lander?  What's the extra operations cost that wouldn't have to be paid if the mission weren't flown?  (You can't just hire MOD personnel off the streets to fly a mission; the payroll and ancillary infrastructure costs should look fairly flat over a relatively wide range of flight rates.)

The ISS budget is mostly center maintenance costs, so I hear.  If the ISS went away, most of that would just be shifted around into different budget lines.  Ops aren't all that expensive in and of themselves.

Yes, getting started (development) is expensive.  Having these sorts of capabilities is expensive.  But these costs do not all belong in an amorphous handwavy lump.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: kkattula on 11/14/2011 02:45 am
Billion dollar payloads?  A few maybe, but most will be just the marginal cost of a CPS plus propellant.

At 10 SLS for a Mars mission, 8 of those would just be propellant launches.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/14/2011 04:07 am
Billion dollar payloads?  A few maybe, but most will be just the marginal cost of a CPS plus propellant.

At 10 SLS for a Mars mission, 8 of those would just be propellant launches.
And the rest would be far more than a billion dollars each.

Really, it's not even the cost of the payload that matters. It's the cost of the whole program that matters. I mean, we're not going to start talking about the price of aluminum, are we (which is roughly $1/pound)? The whole is much greater than the parts.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/14/2011 05:42 am
You people keep trying to drag the argument back to total integrated program cost.  That's an important thing to keep in mind, but it's not what we're talking about.

We're talking about the extra cost to add a mission (or a launch, if someone else's budget pays for the spacecraft and ops), given that the program already exists.  Incremental costs, as distinct from amortized mean costs.

You know, that annoying little feature of the cost structure that people like to ignore when they say stuff like "at $1.5B per flight, SLS will be too expensive to launch often"?

Don't try to fudge the issue.  You are the one misleading people here, not me.

...

Mods, warn me first if I've crossed a line.  I'm not in a good mood right now, so it's hard to tell...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/14/2011 06:08 am
Obviously this rocket needs a mission.

Asteroid
Moon
Mars

The way Charlie talks about Mars you would think it's a sure thing.

If he's not giving up hope that SLS will take men to Mars I'm with him all the way  ;D
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MATTBLAK on 11/14/2011 07:04 am
You people keep trying to drag the argument back to total integrated program cost.  That's an important thing to keep in mind, but it's not what we're talking about.

We're talking about the extra cost to add a mission (or a launch, if someone else's budget pays for the spacecraft and ops), given that the program already exists.  Incremental costs, as distinct from amortized mean costs.

You know, that annoying little feature of the cost structure that people like to ignore when they say stuff like "at $1.5B per flight, SLS will be too expensive to launch often"?

Don't try to fudge the issue.  You are the one misleading people here, not me.

...

Mods, warn me first if I've crossed a line.  I'm not in a good mood right now, so it's hard to tell...

I for one don't blame you... However; the cost per mission would need to be broken down in terms of first, the launcher and then the payload. I know during the Shuttle era few bothered to be that specific, but critics (right or wrong) need to have their concerns rebutted (rightly or wrongly) from time to time.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MikeAtkinson on 11/14/2011 08:28 am
There are three costs we need to be concerned with:

total program
per year program
incremental program

within those the costs of the various launchers, CEV, landers, habs, etc. can be broken out, particularly if they are shared between several programs.

Lets analyse them (in handwavy terms and with made up numbers) for various missions

mission(mission) launch ratelimited byprogramyearlyincremental
SLS1congressv. high1.5B0.5B
SLS8-14missionsv. high4-6B0.4B
NEO(.5) 1suitable NEOmoderate1B1B
Lunar sorties(1-2) 2-4BTDThigh2B1.5B
Lunar base(1-4) 2-8budgetv. high3-5B1B
Phobos(0.5) 2-3BTDTmoderate2B3B
Mars(0.5) 5-8budgetv. high5B7B

where BTDT is Been There Done That

For the SLS I'm pretty sure that if there was 1 or less launch per year then congress would cancel it. At the high end there does not seem to be enough missions (affordable within the budget) to have more than 8 launches per year, or perhaps 14 with both a Lunar base and Mars missions.

So for example a Lunar base needs 1-4 missions a year depending on whether it is constantly manned or not and 2-8 SLS launches a year, its launch rate is likely to be limited by the available overall NASA budget.

There does not seem to be enough money to maintain a peramently manned Lunar base and do Mars missions within the current budget, even excluding development costs.

It looks like incremental costs for SLS are not appropriate for NEO missons, because of lack of suitable targets. Neither are they appropriate for Lunar sorties, as in my opinion BTDT will limit the total number of missions.

The same applies for Phobos missions, I doubt that congress would approve of more than a couple.

Mars missions are limited by launch opportunities, the step from 1 mission per opportunity to 2 missions is very high. SLS incremental costs are important in planning the mission architecture as adding extra tanker flights for Kerolox can be traded with the increased development cost of NTR, for example.

Incremental costs also seem appropriate for a Lunar base as extra missions can increase the manning level without changing the other program costs too much.

Quote
You know, that annoying little feature of the cost structure that people like to ignore when they say stuff like "at $1.5B per flight, SLS will be too expensive to launch often"?

I too am anoyed by such sloppy thinking. High per flight costs at low launch rates are an argument to increase the launch rate, or to cancel the program, not to limit the launch rate even further.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/14/2011 10:05 am
Obviously this rocket needs a mission.

Asteroid
Moon
Mars

The way Charlie talks about Mars you would think it's a sure thing.

If he's not giving up hope that SLS will take men to Mars I'm with him all the way  ;D

It does have a mission; it just hasn't been made public yet.
John Shannon's group is putting the finishing touches on it as we speak.
Be patient just a little while longer. You won't be disappointed.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MATTBLAK on 11/14/2011 10:11 am
Well, if it's not the Moon (I hope it is) then I would hope its Phobos - with a decent-sized NEA being the 'warmup'.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: JohnFornaro on 11/14/2011 01:34 pm
If we are all very lucky, we won't have very many more uber super cheap, cheap, cheap Congresses like we currently are being forced to painfully endure. Like the rest of the country, there are too many legislators with Champagne  tastes but want to satisfy that on a beer budget. Sooner or later they will wake up, smell the coffee, and write the checks. For the sake of the United States HSF program I hope it is sooner rather than later.

I'm not quite sure where you're going with this line of reasoning.  First, your analogy here is way off, I'd say.  Congress indeed does have champagne tastes, but they prefer to drink it in paper cups, with tattered clothes, poor health, and worst of all, with borrowed money.  While it is certainly true that

Quote
one simply cannot state with *any* certainty that "SLS is not going to fly twice per year"

right now, it certainly appears that that option is more likely than the option where SLS flies at all within the next five years or even in any of the years after that.  It most certainly is not that it "depends on what the mission(s) going forward actually are", it depends solely upon whether they build it on time and on budget.  And here they are, talking about 140 ton versions already, in direct written, willful, contradiction of the clear language of the Act.  And everybody's fine with that?  What we're seeing is the stage scenery being painted for future program failure.

93143's continued discussion of "incremental costs" is very much to the point.  There is no rocket and no mission and no hardware.  There's no such thing as incremental costs as of the moment.  And if Mr. Shannon says anything but the Moon first, it will be a great disappointment.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/14/2011 03:56 pm
My point is that everybody wants to read the tea leaves and call their stock broker before the leaves are even harvested, let alone boiled. Maybe it will be Moon First and Congress will shell out $500 billion. Maybe it will be ISS-2 and Congress will shell out $500 million. Or maybe it will be an international station at EML-1 and Congress will shell out $50 billion. Or maybe it will be Hubble-2 and a colony at ESL-5 and Congress will write a blank check. Or maybe it will be a fleet of tugs for ISS so personnel can go grab probes like Russia’s Phobos-Grunt and fix them and Congress will ask the Russians for the money.

Speculation - everything is speculation ad nauseam, which by itself is fine. But we tire of indignant pronouncements of what it most certainly "will" be and what it most certainly "won't" be. Please people; lend me your crystal ball and your broker's phone number.

This has gotten WAY far off topic (and I'm just as guilty as the rest). Please tell me what any of this has to do with whether the SLS will have 4xSSME’s on the core or not (topic of discussion). Let’s either get back on topic or shut down the thread.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/14/2011 05:33 pm

If we are all very lucky, we won't have very many more uber super cheap, cheap, cheap Congresses like we currently are being forced to painfully endure. Like the rest of the country, there are too many legislators with Champagne  tastes but want to satisfy that on a beer budget. Sooner or later they will wake up, smell the coffee, and write the checks. For the sake of the United States HSF program I hope it is sooner rather than later.

Hmmm...
No offense Chuck, but I find this statement stunning.  We currently have a Congress and a White House that spends $1.5 trillion dollars more than it takes in.  Any attempts to lessen that has been met with attacks and demagoguery.  If this is what you consider an uber cheap Congress, I shutter to think at what you consider a "normal" congress, much less a "spend thrift" Congress.

How much over budget do they have to be before you wouldn't consider them "cheap".  ;-)

Good grief...

PS:  I agree their priorities are all out of whack.  Note that we take in about $2.2 trillion now, and spend about $3.8 trillion.
If NASA's budget is $18 billion, then that's about 0.8% of what they take in, or about 0.47% of what we spend. 
In FY1999, we managed about that same budget for NASA, and took in only $1.8 trillion, and spent only $1.7 trillion.  So there's absolutely no reason we can't live well within $2.2 trillion in revenue, and have money for NASA at least at their exisitng budgets, if not a little more.

Also note, that we are taking in $2.2 trillion despite being in one of the worst recessions in history.  FY1999 took in $1.8 trillion, and that was at the height of one of the best economic growth periods in history. 
During FY2007, we were taking in about $2.7 trillion, during that good economy. 
So we are actually flush with money despite what many partisons tell you, but we'd doubled our spending over the past decade on apparently non-essential things, because in 1999, the Federal Government seemed to run just fine on $1.7 trillion, and people weren't starving in the streets and old people weren't eating dog food, or whatever else they say will happen if we don't keep up this insane level of spending.

No, we could cut $1.6 trillion from -next year's- budget, and fund NASA and the world woudn't come to an end. 
That wouldn't be "uber cheap" that'd be "responsible".

:-)


Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: MATTBLAK on 11/14/2011 06:01 pm
4x RS-25E versus 5x in the corestage. Just a recap - is the extra thrust of another engine worth it versus the extra fuel consumption the fifth engine would cause? And how much corestage stretch difference does 4 versus 5x engines require?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Mark S on 11/14/2011 06:21 pm
.........
  And here they are, talking about 140 ton versions already, in direct written, willful, contradiction of the clear language of the Act.  And everybody's fine with that? 
.........

Actually they are well within the language of the authorization act in regards to total lift capacity for phase two, which was specified as "130 tons or more" to LEO. 140 tons is authorized within the "or more" part. :)

Where NASA is deviating significantly from the law is in the design of the SLS upper stage and the separate dedicated CPS stage. The law's language does not authorize the development of the CPS, nor of a dedicated second stage that is discarded before reaching orbit. NASA was directed to design an "integrated upper Earth departure stage", with no mention of a second stage at all, nor of a dedicated in-space CPS. But that's what we're getting apparently. And everyone's fine with that?

Mark S.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/14/2011 06:35 pm
.........
  And here they are, talking about 140 ton versions already, in direct written, willful, contradiction of the clear language of the Act.  And everybody's fine with that? 
.........

Actually they are well within the language of the authorization act in regards to total lift capacity for phase two, which was specified as "130 tons or more" to LEO. 140 tons is authorized within the "or more" part. :)

Where NASA is deviating significantly from the law is in the design of the SLS upper stage and the separate dedicated CPS stage. The law's language does not authorize the development of the CPS, nor of a dedicated second stage that is discarded before reaching orbit. NASA was directed to design an "integrated upper Earth departure stage", with no mention of a second stage at all, nor of a dedicated in-space CPS. But that's what we're getting apparently. And everyone's fine with that?

Mark S.

If you don't mind my asking, how exactly is an "integrated upper Earth Departure stage" different from the currently planned CPS?

Any upper stage really has to be separate if SLS is to fly in LEO configs without it.  If your upper stage was truely "integrated", then that would mean it would fly on all SLS configs, regardless of if the payload was going just to LEO or BLEO.  Integrated would mean it's an integral part of SLS, and SLS cannot fly without it.  Just as the orbiter was an integral part of STS, but not an integral part of Energia. 

So you'd either need a 2nd stage that's married to every SLS launch, or you'd have to find a way for the core to do the EDS burn...which I don't think would be possible?

Seems a separate CPS that SLS can fly with or without, would be the more flexible design, doesn't it?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/14/2011 06:41 pm
NASA was directed to design an "integrated upper Earth departure stage", with no mention of a second stage at all, nor of a dedicated in-space CPS. But that's what we're getting apparently. And everyone's fine with that?

Mark S.

No, I'm not fine with that. It's too much. We do not need and cannot use that capability for many, many years to come - if ever. You are right Mark. They are ignoring the Congressional mandate to design and build a "upper earth departure stage". But perhaps - just perhaps - they could still obey the law if they field a depot in LEO. Then they could expend the upper stage propellant getting to orbit, refuel at the depot and use that same stage as an earth departure stage. If they planned it that way then there would not be any need for the in-space CPS, which NASA is currently targeting as the EDS.

And to Matt's question about why the 5th SSME, it is all related. SLS needs the upper stage *and* a CPS EDS because that 5th SSME needs to consume more propellant, which causes the barrel stretch, which increases the core propellant load which increases the lift-off mass and decreases the IMLEO which consumes all the propellant in that upper stage – none left for the TLI burn without a depot. If they stayed with a 4xSSME design only and forgot about a 5th SSME then they wouldn't need the barrel stretch and additional propellant and they certainly wouldn't need a CPS because there would still be sufficient propellant remaining in the upper/EDS stage after orbital insertion for the TLI burn without a depot.

So no, I am not fine with that. NASA is once again thumbing their nose at what is practical and pulling out all the stops to go for the BFR because everybody likes shiney new monster rockets, right? They are addicted. They have totally lost the mental capacity to think straight, just like an addict. Look at their eyes when they talk about the SLS. They are all glazed over. Tell me they're not high! :)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: sdsds on 11/14/2011 07:00 pm
Where NASA is deviating significantly from the law is in the design of the SLS upper stage and the separate dedicated CPS stage. The law's language does not authorize the development of the CPS, nor of a dedicated second stage that is discarded before reaching orbit. NASA was directed to design an "integrated upper Earth departure stage", with no mention of a second stage at all, nor of a dedicated in-space CPS. But that's what we're getting apparently. And everyone's fine with that?

Apparently not everyone.  ;)  Aside from the engineering considerations it seems one major intent of the IU-EDS language was to force continued development of J-2X.  With funding for that work now looking secure, Congress has minimal interest in the actual stage!  Also, this might indicate some designers within NASA don't want to put an EDS on an SLS CLV.  They (still) want to develop a stage that launches separately and loiters in LEO waiting for crew to arrive.  That is, they want each crewed departure from LEO to require two launches.  IMHO that still leaves open the possibility of an IU-EDS for single-launch SLS CaLV missions.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/14/2011 07:05 pm
And here they are, talking about 140 ton versions already, in direct written, willful, contradiction of the clear language of the Act.

Have they actually changed the design to make that happen?  Or is it just a better performance estimate?

Perhaps their initial design was intended to definitely, without fail, achieve at least 130 t, so as not to break the law by not trying hard enough.  Now that their analysis has been refined and some margins have been removed, they find that the design will probably do better.

Just guessing...

...

I am also rather disappointed in the current upper stage plan.  Perhaps there's time to refine it...  or perhaps there's a good reason they're doing things this way; I'm not an expert at launch vehicle design or mission design...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/14/2011 07:19 pm
Just a little aside sdsds, under what you just described, if there is only ONE crewed BEO mission per year, then we are talking two (2) launches per year, one crew and one mission spacecraft, correct? Hmm. I seem to recall someone on the previous page going on about how there wouldn't be 2 launches per year. I think he was confusing launches with a 2-launch mission :)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: TrueBlueWitt on 11/14/2011 07:20 pm
And here they are, talking about 140 ton versions already, in direct written, willful, contradiction of the clear language of the Act.

Have they actually changed the design to make that happen?  Or is it just a better performance estimate?

Perhaps their initial design was intended to definitely, without fail, achieve at least 130 t, so as not to break the law by not trying hard enough.  Now that their analysis has been refined and some margins have been removed, they find that the design will probably do better.

Just guessing...

...

I am also rather disappointed in the current upper stage plan.  Perhaps there's time to refine it...  or perhaps there's a good reason they're doing things this way; I'm not an expert at launch vehicle design or mission design...

Current upper stage plan might be just fine.. if they never build the J-2X powered 2nd stage.. make CPS 8.4m and forget about the Barrel stretch and 5th SSME on the core!
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/14/2011 07:24 pm
Have they actually changed the design to make that happen?  Or is it just a better performance estimate?

My sources tell me that it's better analysis being done - the design was not changed in order to do 140 tonnes. It just turns out it can. From a design/development pov that's the right approach because historically the launch mass will only increase. By the time they get aroud to actually flying the SLS, they will still be targeting 130 tonnes in spite of the increased liftoff mass.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Khadgars on 11/14/2011 07:26 pm

If we are all very lucky, we won't have very many more uber super cheap, cheap, cheap Congresses like we currently are being forced to painfully endure. Like the rest of the country, there are too many legislators with Champagne  tastes but want to satisfy that on a beer budget. Sooner or later they will wake up, smell the coffee, and write the checks. For the sake of the United States HSF program I hope it is sooner rather than later.

Hmmm...
No offense Chuck, but I find this statement stunning.  We currently have a Congress and a White House that spends $1.5 trillion dollars more than it takes in.  Any attempts to lessen that has been met with attacks and demagoguery.  If this is what you consider an uber cheap Congress, I shutter to think at what you consider a "normal" congress, much less a "spend thrift" Congress.

How much over budget do they have to be before you wouldn't consider them "cheap".  ;-)

Good grief...

PS:  I agree their priorities are all out of whack.  Note that we take in about $2.2 trillion now, and spend about $3.8 trillion.
If NASA's budget is $18 billion, then that's about 0.8% of what they take in, or about 0.47% of what we spend. 
In FY1999, we managed about that same budget for NASA, and took in only $1.8 trillion, and spent only $1.7 trillion.  So there's absolutely no reason we can't live well within $2.2 trillion in revenue, and have money for NASA at least at their exisitng budgets, if not a little more.

Also note, that we are taking in $2.2 trillion despite being in one of the worst recessions in history.  FY1999 took in $1.8 trillion, and that was at the height of one of the best economic growth periods in history. 
During FY2007, we were taking in about $2.7 trillion, during that good economy. 
So we are actually flush with money despite what many partisons tell you, but we'd doubled our spending over the past decade on apparently non-essential things, because in 1999, the Federal Government seemed to run just fine on $1.7 trillion, and people weren't starving in the streets and old people weren't eating dog food, or whatever else they say will happen if we don't keep up this insane level of spending.

No, we could cut $1.6 trillion from -next year's- budget, and fund NASA and the world woudn't come to an end. 
That wouldn't be "uber cheap" that'd be "responsible".

:-)




Just to clarify, during the last decade, many items were left off the budget including the cost of the wars in Iraq and Afghanistan and the then new Department of Homeland Security and Medicare Part D even though we continued to pay for them.  This created an artificially lower overall budget.  Once we put them on budget, our budget swelled to what it is today but should have been for most of the last decade.

A better indicator is federal spending compared to GDP, which has in fact remained fairly consistent between 20%-30% for the last 60 years. 
Back on topic, I don't see NASA's budget being cut drastically but I doubt we'll get an increase of any kind for the foreseeable future as well.  With that kind of funding I don't see anything beyond Block IA being developed, which may be a blessing in disguise?
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/14/2011 07:35 pm

So no, I am not fine with that. NASA is once again thumbing their nose at what is practical and pulling out all the stops to go for the BFR because everybody likes shiney new monster rockets, right? They are addicted. They have totally lost the mental capacity to think straight, just like an addict. Look at their eyes when they talk about the SLS. They are all glazed over. Tell me they're not high! :)

Well, I think the NAA2010 set the table for this by specifying 130mt to LEO.  Had they done just a bit of research into Direct, and saw where the optimum performance came out to with the existing hardware, they could have specified 70mt evolving to say, 110mt. (or they could have just added 1 mt to whatever Saturn V's LEO, and then they could say it's the most powerful rocket every...if only by 1mt...because there are those who think that's a big deal).
By keeping it around 110mt, you could have stuck with a J-241 basically, and just tweaked it to get a bit more.  Kept the core the same length.  Go with ATK's new 5-seg boosters,  less the middle segment for the first few launches.  ATK can comete with ULA, SpaceX and Orbital for the final booster.  The requirement would be whatever thrust would get you to 111mt to LEO or whatever it is, so you tweak up the boosters rather than screw with the non-stretched core plus 3 or 4 RS25's.  The upper stage would use a single J2X.

So, for those who want the most powerful rocket in history, they have it.

For those who want a "NASA rocket" (rather than a commercial rocket), they have it.

For those who want the most efficient use of the existing 8.4m core and RS25 engines, they have it.

For those who wanted the J2X contract, they have it.

Perhaps not quite as ideal of just picking Direct 4 years ago, but it would pretty much hit all the political buttons, without needing to grow everything to hit that 130mt mark....that's arbitrary and not needed. 

A win-win.  :-)
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: clongton on 11/14/2011 07:37 pm
Just to clarify, during the last decade, many items were left off the budget including the cost of the wars in Iraq and Afghanistan and the then new Department of Homeland Security and Medicare Part D even though we continued to pay for them.  This created an artificially lower overall budget.  Once we put them on budget, our budget swelled to what it is today but should have been for most of the last decade.

A better indicator is federal spending compared to GDP, which has in fact remained fairly consistent between 20%-30% for the last 60 years.  We do have a spending problem, but we have a bigger revenue problem, too many wealthy are able to escape paying taxes.

Back on topic, I don't see NASA's budget being cut drastically but I doubt we'll get an increase of any kind for the foreseeable future as well.  With that kind of funding I don't see anything beyond Block IA being developed, which may be a blessing in disguise?

That's correct. During the entire Bush Administration, all 8 years (8 federal budgets), there was never a line item in the federal budget for any of those things. Instead they were all funded by Supplemental Appropriation bills after the fact. It is misleading to compare the federal budget from then with now because among the few things the Obama Administration did correctly was insist that all those things be included in the federal budget, thus taking all those billions of dollars out of the shadows and letting the people see what the feds were "really" spending. And then the bottem fell out while the presidential campaign was still going on in 2008 and George Bush was still president. Mind you I am not fixing blame here, just rehearsing the history.

The shock wave was nearly instantaneous and the result was the Tea Party movement. I wonder where all those people would have been during the Bush years if they knew what was *actually* being spent in their name, and hidden from them? After all, none of us really knew the extent of the deficit until we were made aware of what was actually being spent, and that didn't become common knowledge until after Obama put *everything* in the federal budget. That's when everything hit the fan.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Khadgars on 11/14/2011 07:45 pm
Didn't Chris have an article where they are contemplating going with the upgraded Block IA to 90mt and staying with that?  And they could keep with the law because it would be "evolvable" to 130mt even though they may never do it
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Ronsmytheiii on 11/14/2011 10:24 pm
interesting info on the RS-25E:

Quote
RS-25E development should be well under way when the first SLS flight with the surplus RS-25Ds occurs at the end of 2017.

Quote
Changes include adopting the hot isostatic pressing technique PRW uses to bond the combustion chamber to its structural jacket on the RS-68 and J-2X to the RS-25D, and using modern manufacturing techniques for engine flex joints. The program also hopes to gain cost savings from supply-chain changes.

also mentions the switch to the J-2X controller, which would save cost

http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/awst/2011/11/14/AW_11_14_2011_p39-392423.xml&headline=NASA%20Fleshes%20Out%20SLS%20Development%20Schedule&next=10
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Lobo on 11/15/2011 12:20 am
Just to clarify, during the last decade, many items were left off the budget including the cost of the wars in Iraq and Afghanistan and the then new Department of Homeland Security and Medicare Part D even though we continued to pay for them.  This created an artificially lower overall budget.  Once we put them on budget, our budget swelled to what it is today but should have been for most of the last decade.

A better indicator is federal spending compared to GDP, which has in fact remained fairly consistent between 20%-30% for the last 60 years.  We do have a spending problem, but we have a bigger revenue problem, too many wealthy are able to escape paying taxes.

Back on topic, I don't see NASA's budget being cut drastically but I doubt we'll get an increase of any kind for the foreseeable future as well.  With that kind of funding I don't see anything beyond Block IA being developed, which may be a blessing in disguise?

That's correct. During the entire Bush Administration, all 8 years (8 federal budgets), there was never a line item in the federal budget for any of those things. Instead they were all funded by Supplemental Appropriation bills after the fact. It is misleading to compare the federal budget from then with now because among the few things the Obama Administration did correctly was insist that all those things be included in the federal budget, thus taking all those billions of dollars out of the shadows and letting the people see what the feds were "really" spending. And then the bottem fell out while the presidential campaign was still going on in 2008 and George Bush was still president. Mind you I am not fixing blame here, just rehearsing the history.

The shock wave was nearly instantaneous and the result was the Tea Party movement. I wonder where all those people would have been during the Bush years if they knew what was *actually* being spent in their name, and hidden from them? After all, none of us really knew the extent of the deficit until we were made aware of what was actually being spent, and that didn't become common knowledge until after Obama put *everything* in the federal budget. That's when everything hit the fan.

Both Parties had there fingers in it over the last decade, I never want to insinuate otherwise.  Remember, during the Bush years, the Repbulicans only had the Senate for 4 of those year, and the House for 6.  Then The Dems had everything for two years.  And hidden costs or not, the Dems increased spending a fair amount when we were in a major recession.   Maybe some of the Tea Party's angst is misplaced.  *shrug*
Both sides have power at various times and chose not to do anything to curb the spending.

Chuck,
Perhaps I misunderstood you, if you meant this Congress has been uber cheap in terms of NASA funding, then I -can- buy that.  As the old saying goes, "Water, water everywhere, but not a drop to drink..."  With nearly $4 trillion in spending, they can't see fit to push a few sheckles NASA's way?  When so many other Federal department have seen budget increases anywhere from 10-50%?  NASA's cut is such a drop in the bucket, but good lord!  we just don't have an extra couple of billion for them!  We just don't have a penny anywhere else to cut!
If that's what you meant, then I'm with you.  I find it funny, yet not funny, that Congress can take a dump and loose $10 billion dollars, and have no idea where it even went.  But increase NASA's budget by $5 billion?  Man...just no money for that...

;-)

Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: spectre9 on 11/15/2011 01:04 am
The shuttle isn't even dead yet until next year as far as redirecting the budget money for it.

This was the only real way to get a new rocket off the ground.

Trying to develop new technology while still supporting the shuttle and the massive workforce that goes with it was not going to happen.

2012 onwards is the real test.

Will the American people sit by while NASA gets peanuts and slowly develops a rocket as their lives go by?  ::)

That is the question that I want to know. Will be pretty sad if we're waiting until the 20s for SLS and to the 30s before Mars is even on the table.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Jorge on 11/15/2011 01:29 am
Guys, get it back on topic, which is SLS with 4xRS-25 on the core. And no, mentioning the NASA budget once every three paragraphs is not sufficiently on-topic.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Chris Bergin on 11/15/2011 01:30 am
^^What he said.

On topic please.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: JohnFornaro on 11/15/2011 02:05 pm
Quote from: Mark
140 tons is authorized within the "or more" part.

Oh. My. Garnet.

I had totally forgotten that.  The sky is indeed the limit then.  I'm pretty sure it won't be flying year after year then.  'Cause the first one will be the 180 ton implementation.  Gotta have "margin", right?  And no, it's just a proposal for 140 ton version, AFAIK.  I have no idea as to the validity of the calculations getting to that point.

As to the upper stage.  Got any links for me to read up on?

Quote from: Lobo
So you'd either need a 2nd stage that's married to every SLS launch, or you'd have to find a way for the core to do the EDS burn...which I don't think would be possible?

Well, the core should be able to get any of that burned into LEO orbit.  Right?

Quote from: Chuck
But perhaps ... they could still obey the law if they field a depot in LEO. Then they could expend the upper stage propellant getting to orbit, refuel at the depot and use that same stage as an earth departure stage. If they planned it that way then there would not be any need for the in-space CPS, which NASA is currently targeting as the EDS.

Fine, except that I'd say that the LV should be able to get the EDS to a LEO depot, at least to the point where prox ops become necessary.  It would be full when it got there.  Maybe it would be a dual purpose piece of hardware; could it find utility as part of the cis-lunar tug?

Quote
And to Matt's question about why the 5th SSME, it is all related. SLS needs the upper stage *and* a CPS EDS because that 5th SSME needs to consume more propellant, which causes the barrel stretch, which increases the core propellant load which increases the lift-off mass and decreases the IMLEO which consumes all the propellant in that upper stage – none left for the TLI burn without a depot.

Which sounds like some kind of point of diminishing returns, accompanied by a long rightward schedule shift, followed by a chance of cancellation in the morning.  Too big.  Start small, and start using it.

Three SSME's is what the "legacy" is.  Anything else is clean sheet.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/15/2011 10:04 pm
So you'd either need a 2nd stage that's married to every SLS launch, or you'd have to find a way for the core to do the EDS burn...which I don't think would be possible?

Seems a separate CPS that SLS can fly with or without, would be the more flexible design, doesn't it?

False dichotomy.

CPS is a payload.  As far as I can tell it's designed so that it doesn't burn to orbit.  The Constellation EDS was an upper stage.  It was assumed to be part of every launch of an Ares V.

However, there is no reason you couldn't design an upper stage that could burn to orbit, without requiring it to be on every launch.  That's what the JUS was - an optional upper stage.  That was the key point of DIRECT, and you're just papering over the possibility.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/15/2011 10:09 pm
So you'd either need a 2nd stage that's married to every SLS launch, or you'd have to find a way for the core to do the EDS burn...which I don't think would be possible?

Seems a separate CPS that SLS can fly with or without, would be the more flexible design, doesn't it?

False dichotomy.

CPS is a payload.  As far as I can tell it's designed so that it doesn't burn to orbit.  The Constellation EDS was an upper stage.  It was assumed to be part of every launch of an Ares V.

However, there is no reason you couldn't design an upper stage that could burn to orbit, without requiring it to be on every launch.  That's what the JUS was - an optional upper stage.  That was the key point of DIRECT, and you're just papering over the possibility.
CPS can be designed to burn to orbit. That is the case in the other thread about SLS alternatives.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/15/2011 10:18 pm
CPS can be designed to burn to orbit. That is the case in the other thread about SLS alternatives.

Where in the other thread?  I don't recall anything about that.

I know it can be, since it's just powerpoint right now and could easily change.  But as far as I recall it isn't currently baselined for that.  It fits into the LEO payload of the 1.5-stage SLS - meaning that even if it could burn to orbit, it's suboptimal as an upper stage for LEO launch, and it's too small to take advantage of depot availability.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/15/2011 10:31 pm
CPS can be designed to burn to orbit. That is the case in the other thread about SLS alternatives.

Where in the other thread?  I don't recall anything about that.

I know it can be, since it's just powerpoint right now and could easily change.  But as far as I recall it isn't currently baselined for that.  It fits into the LEO payload of the 1.5-stage SLS - meaning that even if it could burn to orbit, it's suboptimal as an upper stage for LEO launch, and it's too small to take advantage of depot availability.
As you said, it's still at the powerpoint stage. So saying it's too small to take advantage of depot availability is also premature. In fact, it could function as a depot itself with a capacity of over 230 metric tons of propellant, even if launched on a non-SLS launch vehicle. (Here's the link, by the way: http://images.spaceref.com/news/2011/21jul2011.pdf ) Obviously, if designed to launch on SLS with the capability for refueling on orbit, it could be even larger.

We're going to have to get one of these things anyway because a second stage with a bunch of J-2Xs on it is too heavy to have optimal TLI performance, and we most definitely need CPS for Mars and very likely for many asteroid missions. If it's a choice between a second stage using 3 J-2x engines and CPS, the best choice seems pretty obvious.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/16/2011 02:46 am
We're going to have to get one of these things anyway because a second stage with a bunch of J-2Xs on it is too heavy to have optimal TLI performance

Have you seen the mass fraction for CPS?  Also, the US can go down to one J-2X.

Depending on the mission, that could still end up being too much thrust...

I don't really like the SLS-US either.  It's a battleship stage.  I guess my main problem is that I got enamoured of the ACES/WBC technology proposed for the JUS, and the relatively primitive conservative CPS and US concepts are comparing poorly.

Quote
and we most definitely need CPS for Mars

Why?  Weren't you a huge fan of SEP a while back?  (I like advanced nuclear (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110009914_2011009270.pdf) myself.)  Mars is 20 years in the future; we could be using Polywells by then.  Cryo storage?  Definitely.  CPS specifically?  I don't see it...
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: Robotbeat on 11/16/2011 03:23 pm
Right, the CPS may have a bad mass fraction, but its low-boiloff technology is needed for chemical Mars missions.

SEP would work even if you went SEP for almost all the propulsion needs of the exploration stack, but I see a hybrid approach as much cheaper and realistic. For instance, using a SEP tug that has only a small fraction of the power of a full SEP propulsion stack to push the whole exploration stack to a Lagrange point or a high Earth orbit where it is met by a crew launched in Orion (or possibly some commercial crew-derived craft). Or even using SEP tugs to pre-place mission elements in Mars orbit or on its surface (obviously using EDL of some sort). Hybrid approach works well because it allows you to trade time for delta-v very deeply and because it's not necessarily on the "critical path" and is used only for pre-placing mission elements before any crew launches from Earth. Hybrid approach works best if you already have elements which can withstand long-duration spaceflight with very low-boiloff, like CPS.
Title: Re: SLS trades lean towards opening with four RS-25s on the core stage
Post by: 93143 on 11/18/2011 08:45 pm
Personally I like hydrogen as a VASIMR propellant.

I didn't say low-boiloff wasn't necessary.  In fact I specifically said it was.  But this does not imply that a stage identical to the proposed CPS is "most definitely" needed for Mars, which is what you said and what I was objecting to.  ACES, for instance, does low-boiloff too, with what appears to me to be a more sophisticated approach, and it can be sized for SLS.

I guess I'll let things evolve and see where this goes...