How should NASA evolve the SLS?

[Ben the Space Brit]

Bolden didn't have to "ignore" the legislation. All he had to do was drag his feet so long that all the necessary things expired. That's exactly what he did.

Why did he do that?

That falls into the realm of politics, I think.  My guess is that you have to look at the stated policies of the persons to whom Administrator Bolden is ultimately answerable.

[JohnFornaro]

Bolden didn't have to "ignore" the legislation. All he had to do was drag his feet so long that all the necessary things expired. That's exactly what he did.

Why did he do that?

That falls into the realm of politics, I think.  My guess is that you have to look at the stated policies of the persons to whom Administrator Bolden is ultimately answerable.

I'd agree that it's probably political.  But there is no statement from the President answering the question, "Why drag NASA's feet"?  The delay of the reports, etc.

[clongton]

This is not  an effort to re-start DIRECT. It's time has past.
But I offer a little more about my “too big” statement, just for illustrative purposes.

The Jupiter-130 would easily put 70 tonnes (+) into LEO. To do that it needed:
       Standard STS length Core stage
       2x 4-segment SRB’s
       3x RS-25 engines
       No upper stage at all
       This LV had an additional 15% margin built in that is not reflected in its IMLEO number

The SLS can also put 70 tonnes (+/-) into LEO. To do that it needs:
       Stretched Core stage
       2x 5-segment SRB’s
       4x RS-25 engines
       Modified Upper Stage from the Delta-IV
       This LV does not have DIRECT’s additional 15% margin reflected in its IMLEO number

I understand and accept that Jupiter’s opportunity has gone. After all, the STS 4-segment SRB is no longer manufacturable, as well as several other things that were needed, made by companies that are no longer in business.  This is provided just to help some on this board keep the lift capacity of SLS in context, and to show why I have said on so many occasions that the SLS is too damn big.

As to how to evolve the SLS I would offer that unless the country is willing to wait an additional 4-5 years to re-establish some of the STS industrial base that was allowed to expire that the only practical way to evolve it would be to allow the LRB's to replace the SRB's when they become available and fly it just like that, without an upper stage. At that point we'd be looking at ~100 tonnes to LEO and I cannot believe we couldn't do a robust exploration program with that. Even Mike Griffin was happy with that capacity for the Ares-V until Ares-I's shortcomings forced him to increase the HLV's capacity. That's where the 130 tonne figure came from, not from an exploration need. SLS has been sized to match the Ares-V capacity that was making up for an anemic Ares-I. There is simply no justifiable reason for that continuance. Go with the LRB's when they become available and be satisfied with the 100 tonnes to LEO. We can do anything we want to with that.

[Ben the Space Brit]

Bolden didn't have to "ignore" the legislation. All he had to do was drag his feet so long that all the necessary things expired. That's exactly what he did.

Why did he do that?

That falls into the realm of politics, I think.  My guess is that you have to look at the stated policies of the persons to whom Administrator Bolden is ultimately answerable.

I'd agree that it's probably political.  But there is no statement from the President answering the question, "Why drag NASA's feet"?  The delay of the reports, etc.

He made clear during the 2008 campaign that he favoured a 5-year hold on HLV development and a focus on technology development, education and 'inspiration' by NASA.  Here we are, five years on, and the HLV project is only now starting to seriously get under way and flyable results are unlikely during his second term.  His campaign pledge has been fulfilled.

[MP99]

The SLS can also put 70 tonnes (+/-) into LEO. To do that it needs:
       Stretched Core stage
       2x 5-segment SRB’s
       4x RS-25 engines
       Modified Upper Stage from the Delta-IV

Not that I disagree with your basic point (PL111-267 even directs to continue existing contracts to ease the transition), but the ICPS is not needed for a LEO mission, eg crew-to-ISS backup role, or even if a SEP stage would perform TLI.

If you're thinking of the circ burn, yes that would need to be done by payload (because the core has no disposal hardware), but it doesn't have to be anything big. Of course, if the payload doesn't naturally have it's own propulsion, the development of circ hardware would be an extra expense.

cheers, Martin

Edit: extended first sentence.

[MP99]

This is not  an effort to re-start DIRECT. It's time has past.
But I offer a little more about my “too big” statement, just for illustrative purposes.

...

I understand and accept that Jupiter’s opportunity has gone. After all, the STS 4-segment SRB is no longer manufacturable, as well as several other things that were needed, made by companies that are no longer in business.

It's easy to forget how much of the proposal was trying to make a quick, smooth transition over from Shuttle (with further evolution later, once Shuttle stuff was used up), rather than the relatively clean-sheet we now seem to have.

cheers, Martin

[clongton]

The SLS can also put 70 tonnes (+/-) into LEO. To do that it needs:
       Stretched Core stage
       2x 5-segment SRB’s
       4x RS-25 engines
       Modified Upper Stage from the Delta-IV

Not that I disagree with your basic point (PL111-267 even directs to continue existing contracts to ease the transition), but the ICPS is not needed for a LEO mission, eg crew-to-ISS backup role, or even if a SEP stage would perform TLI.

If you're thinking of the circ burn, yes that would need to be done by payload (because the core has no disposal hardware), but it doesn't have to be anything big. Of course, if the payload doesn't naturally have it's own propulsion, the development of circ hardware would be an extra expense.

cheers, Martin

Edit: extended first sentence.

Martin: The Boeing documentation states:

To briefly summarize, the SLS Block 1 utilizes the initial Cryogenic Propulsion Stage (iCPS) as its second stage (Delta-IV upper stage derivative; 5.0m dia, 70klb mass, O2/H2 single RL-10 engine)

I was comparing the IMLEO of Jupiter-130 to the SLS Block-1 as defined.
I probably should have specified "Block-1".

[Chris Bergin]

I don't care if you think you're responding to someone else. Do not drag threads off topic or into political crap.

This is a dodgy thread at best and on very shaky ground in the first place. Just give me one more excuse to get rid of it.

[Hyperion5]

https://info.aiaa.org/Regions/SE/HSV_AIAA/Downloadable%20Items/AIAA-Chilton_18Oct2012_Final2.pdf

So to sum up, here's how capacity would grow along the evolution paths outlined. 

SLS Bloc I
Core Stage (4 SSMEs)+iCPS (Modified Delta IV 2nd stage with 1 RL-10B-2)
Payload to LEO: 70 mt (Ed Kyle's estimate: 90 mt)
BEO Payload: 19 mt
Year available: 2017

SLS Bloc IA
Core Stage+advanced boosters (appears to be LRBs)-upper stage
Payload to LEO: 105 mt
BEO Payload: 0 mt
Year available: 2022 (if advanced booster program is funded)

SLS Bloc IB
Core stage+8.4 m CPS (8.4 m stage with four RL-10 engines)
Payload to LEO: 118 mt
BEO Payload: 43 mt
Year available: 2019 (if upper stage is funded)

SLS Bloc II
Core stage+8.4 m CPS (from Bloc IB)+advanced boosters (LRBs)
Payload to LEO: 155 mt
BEO Payload: 61 mt
Year available: 2022 (if boosters+CPS are funded)

SLS Bloc IIA
Core stage+8.4 m J-2X stage+advanced boosters (LRBs)
Payload to LEO: 178 mt
BEO Payload: 58 mt
Year available: 2027 (if boosters+J-2X stage funded)


Looking at all of this, it appears the likeliest evolution of the SLS is the SLS Bloc IB.  Even if we estimate the Bloc I is putting up 90 mt instead of 70 mt, the IB would still put up 31% more into LEO.  I think the best argument for the SLS Bloc IB is the BEO capability, which is 2.26X the capability of the Bloc I.  I know some have said just flying the Bloc I is the best option, but is it really if we could have the Bloc IB by 2019 or 2020?  It sure seems like we could get a lot more done both in terms of manned missions and unmanned missions with an LV that has 2.26X the BEO capability of the Bloc I. 

I think the really interesting thing is the possibility of a 3.5 stage SLS seems to have disappeared according to this evolution path.  The SLS Bloc II appears an almost exact match for what I was previously advocating--taking an SLS Bloc IB and adding advanced LRBs.  I am surprised at just how soon it could be made available: 2022.  That would give the most BEO capability (61 mt, or 3.21X the Bloc I's) and have way more than enough LEO capability (155 mt) for all but the biggest Mars missions.  A Bloc II SLS like that could do almost anything NASA wants, including a one-launch mission to Martian orbit and back.  It'd certainly be the quickest and easiest way to meet Congress' 130 mt mandate if that mandate holds up. 

Supposing however that NASA somehow needed more than 155 mt to LEO for future Mars missions, there might be a way to keep the CPS' engine-out capability and fine maneuvering while adding capacity.  Instead of using the J-2X stage, you lengthen the CPS and either add more RL-10/NGEs OR perhaps the ESA+Ariane might volunteer the Vinci hydrolox engine.  If you were to take 4-5 of those you could create an Bloc III SLS that should lift around 180 mt to LEO & have around a 70 mt+ BEO capability for single launch missions.  Of course that's completely speculative and I'm not sure it'd be allowed by French national security laws, let alone ours.  But it'd sure make it easy to build an SLS meant for higher-capability Mars missions. 

[JohnFornaro]

One thing seems clear:  That SLS Block 1 could perform a lunar landing mission in three launches.  The LV is sufficiently evolved.

[Hyperion5]

One thing seems clear:  That SLS Block 1 could perform a lunar landing mission in three launches.  The LV is sufficiently evolved.

True, but wouldn't there be some difficulties for a triple SLS mission?  I don't doubt that if we pushed hard, we could surge production and make 3 of them in a short period.  What I doubt is the current launchpad setup could handle that.  AFAIK only one of the shuttle pads is currently set up to handle the SLS, along with only one MLP.  In this case, you'd need to stow not one but two SLS Bloc Is in the VAB, which I'm not totally sure is possible.  Even then you'd have to launch them in quick succession, and it'd be difficult work preparing each for launch off the same pad if you've only just used it. 

The alternative of refurbishing the other pad and building a new MLP to handle a second SLS would mean more expense but you could launch two of them in quick succession that way.  The third SLS would then be brought up from the VAB, one of the pads would be refurbished, and you'd launch the crew up on it I'm assuming.  Still, the expense and difficulty of making a triple-SLS lunar mission might not be worth it.  You could do it, it's just it'd be a big pain for not a lot of capability. 

I think a dual-launch SLS mission would be more feasible with the current setup, John.  This is why I'd develop an SLS Bloc IB and dual-launch those for an "Apollo on steroids"-type mission like envisioned during Constellation.  It'd probably be less expensive to develop the SLS Bloc IB and dual-launch two of them than use three Bloc Is for an even less capable lunar mission.  Plus you'd be cutting the flight risk substantially while still mounting a mission far more capable than those seen during the days of Apollo. 

There's one final reason why I prefer the SLS Bloc IB: BEO capability.  It has 2.26X the capability of the SLS Bloc I, which means it'd be able to do just about any science mission you could think of to Mars and the outer planets.  Want to put an orbiter around Europa in 2022?  It could do that.  Want to land a rover on Titan in 2030?  No problems for the SLS BLoc IB at least.  The SLS Bloc I would have a great deal of difficulty with at least some of the missions an SLS Bloc IB could do with ease.  It seems to me the SLS Bloc IB is the best near-term option NASA has for the unmanned and manned missions it wants to do (like Mars sample return).  It's hard to argue with 43 mt of BEO capability being available in 2019. 

[USFdon]

Impressive numbers for the SLS Block 1b with the RL-10's, though I'm wondering if the j-2x will still win out due to political reasons. Does anyone have the approx numbers on an eds/ISP optimized j-2x or are they sticking with the performance perameters of Ares 1?

[anonymous]

SLS Bloc IB
Core stage+8.4 m CPS (8.4 m stage with four RL-10 engines)
Payload to LEO: 118 mt
BEO Payload: 43 mt
Year available: 2019 (if upper stage is funded)

So Block 1B would have the same payload to LEO as Saturn V (118 tonnes), but payload to TLI would be a bit less - Saturn V's is quoted as 45 or 47 tonnes.

[Hyperion5]

SLS Bloc IB
Core stage+8.4 m CPS (8.4 m stage with four RL-10 engines)
Payload to LEO: 118 mt
BEO Payload: 43 mt
Year available: 2019 (if upper stage is funded)

So Block 1B would have the same payload to LEO as Saturn V (118 tonnes), but payload to TLI would be a bit less - Saturn V's is quoted as 45 or 47 tonnes.

I was thinking about that and I think they mean the maximum escape velocity payload with the SLS Bloc IB would be 43 mt.  Which should mean its TLI capability would be higher I think.  When Spacex originally gave their estimates on the Falcon Heavy's numbers, the translunar capability was listed at 16 mt while the transmartian capability was listed at 14 mt.  If the SLS Bloc IB were anywhere near the same ratio, its TLI capability should be nearing 50 mt.  Any actual rocket scientist is welcome to clear this up.   

[spectre9]

It must come back to Griffin's challenge.

"We should be able to build bigger than Saturn V"

MSFC has made this their motto imho. Just not publicly 

I really don't know what else to say.

NASA really thinks they're doing the right thing. No flight rate, no payloads, no funding increases. It's like banging your head against a brick wall. 

[RocketmanUS]

https://info.aiaa.org/Regions/SE/HSV_AIAA/Downloadable%20Items/AIAA-Chilton_18Oct2012_Final2.pdf

So to sum up, here's how capacity would grow along the evolution paths outlined. 

SLS Bloc I
Core Stage (4 SSMEs)+iCPS (Modified Delta IV 2nd stage with 1 RL-10B-2)
Payload to LEO: 70 mt (Ed Kyle's estimate: 90 mt)
BEO Payload: 19 mt
Year available: 2017

SLS Bloc IA
Core Stage+advanced boosters (appears to be LRBs)-upper stage
Payload to LEO: 105 mt
BEO Payload: 0 mt
Year available: 2022 (if advanced booster program is funded)

SLS Bloc IB
Core stage+8.4 m CPS (8.4 m stage with four RL-10 engines)
Payload to LEO: 118 mt
BEO Payload: 43 mt
Year available: 2019 (if upper stage is funded)

SLS Bloc II
Core stage+8.4 m CPS (from Bloc IB)+advanced boosters (LRBs)
Payload to LEO: 155 mt
BEO Payload: 61 mt
Year available: 2022 (if boosters+CPS are funded)

SLS Bloc IIA
Core stage+8.4 m J-2X stage+advanced boosters (LRBs)
Payload to LEO: 178 mt
BEO Payload: 58 mt
Year available: 2027 (if boosters+J-2X stage funded)


Looking at all of this, it appears the likeliest evolution of the SLS is the SLS Bloc IB.  Even if we estimate the Bloc I is putting up 90 mt instead of 70 mt, the IB would still put up 31% more into LEO.  I think the best argument for the SLS Bloc IB is the BEO capability, which is 2.26X the capability of the Bloc I.  I know some have said just flying the Bloc I is the best option, but is it really if we could have the Bloc IB by 2019 or 2020?  It sure seems like we could get a lot more done both in terms of manned missions and unmanned missions with an LV that has 2.26X the BEO capability of the Bloc I. 

I think the really interesting thing is the possibility of a 3.5 stage SLS seems to have disappeared according to this evolution path.  The SLS Bloc II appears an almost exact match for what I was previously advocating--taking an SLS Bloc IB and adding advanced LRBs.  I am surprised at just how soon it could be made available: 2022.  That would give the most BEO capability (61 mt, or 3.21X the Bloc I's) and have way more than enough LEO capability (155 mt) for all but the biggest Mars missions.  A Bloc II SLS like that could do almost anything NASA wants, including a one-launch mission to Martian orbit and back.  It'd certainly be the quickest and easiest way to meet Congress' 130 mt mandate if that mandate holds up. 

Supposing however that NASA somehow needed more than 155 mt to LEO for future Mars missions, there might be a way to keep the CPS' engine-out capability and fine maneuvering while adding capacity.  Instead of using the J-2X stage, you lengthen the CPS and either add more RL-10/NGEs OR perhaps the ESA+Ariane might volunteer the Vinci hydrolox engine.  If you were to take 4-5 of those you could create an Bloc III SLS that should lift around 180 mt to LEO & have around a 70 mt+ BEO capability for single launch missions.  Of course that's completely speculative and I'm not sure it'd be allowed by French national security laws, let alone ours.  But it'd sure make it easy to build an SLS meant for higher-capability Mars missions. 

1 ) SLS Block I
2 ) SLS Block IB ( stop there and wait for commercial , see #3 )
     ( the CPS (8.4 m stage with four RL-10 engines) can be used also with the advanced boosters too )

3 ) If and when block I launches have commercial develop LRB's for the advanced boosters and the TSTO with the US powered by a J-2X.

If they do get the advanced boosters and TSTO then there would be the J-2X in production to use for a new US for SLS for high mass to LEO

Block IB will be enough for Lunar and Mars for exploration missions.

If there is to be advanced boosters then let commercial pay for them. They would start on them only after the SLS was flying if they have to pay for the development. This would keep NASA focused on using the Block IB for Lunar missions for now and Mars to follow. The advanced boosters when ready would allow for greater mass of volume payloads to be put in orbit and or sent BLEO to possible enhance BLEO missions.

So how should NASA evolve SLS? Only as they need to for future missions when there is the funding for it. Other wise lets use what we should have by 2019 Block IB.

[Lars_J]

One thing seems clear:  That SLS Block 1 could perform a lunar landing mission in three launches.  The LV is sufficiently evolved.

Three? It should be possible in just two, if you build a smaller lander rather than the massive CxP Altair type lander. Or?

[anonymous]

SLS Bloc IB
Core stage+8.4 m CPS (8.4 m stage with four RL-10 engines)
Payload to LEO: 118 mt
BEO Payload: 43 mt
Year available: 2019 (if upper stage is funded)

So Block 1B would have the same payload to LEO as Saturn V (118 tonnes), but payload to TLI would be a bit less - Saturn V's is quoted as 45 or 47 tonnes.

I was thinking about that and I think they mean the maximum escape velocity payload with the SLS Bloc IB would be 43 mt.  Which should mean its TLI capability would be higher I think.  When Spacex originally gave their estimates on the Falcon Heavy's numbers, the translunar capability was listed at 16 mt while the transmartian capability was listed at 14 mt.  If the SLS Bloc IB were anywhere near the same ratio, its TLI capability should be nearing 50 mt.  Any actual rocket scientist is welcome to clear this up.   

I had thought that TLI was almost exactly the same as escape velocity, while TMI was quite a bit more. Looking it all up, LEO is about 7.8 km/s, while TLI is 10.8 km/s, escape velocity is 11.2 km/s and TMI is 11.8 km/s - respectively 3 km/s, 3.4 km/s and 4 km/s more than LEO.

If the "BEO" figure refers to escape velocity, then Saturn V was capable of 44.5 tonnes (98,000 lbs) to escape velocity, according to the payload planner's guide. http://www.scribd.com/doc/46779714/Saturn-V-Payload-Planner-s-Guide

I think the 47 tonnes quoted by some sources was for TLI and the 45 tonnes quoted by others may be for escape velocity. If the same ratios apply for SLS Block 1B (and Saturn V is a closer comparison than Falcon Heavy), then it would be capable of about 45 tonnes through TLI.

I think the reason why SLS Block 1B would be slightly less capable than Saturn V for TLI, when it's equally capable for LEO, is because Saturn V was using a third stage, whereas SLS would be using the second stage that helped it get into orbit, so there would be more deadweight to carry.

[JohnFornaro]

One thing seems clear:  That SLS Block 1 could perform a lunar landing mission in three launches.  The LV is sufficiently evolved.

Three? It should be possible in just two, if you build a smaller lander rather than the massive CxP Altair type lander. Or?

Talk to Boeing.

I'm not the expert.

[JohnFornaro]

One thing seems clear:  That SLS Block 1 could perform a lunar landing mission in three launches.  The LV is sufficiently evolved.

True, but wouldn't there be some difficulties for a triple SLS mission?

We'll call the triple launch "My Theory", in order to protect the engineers at Boeing.  [Rolls eyes.]

Absolutely there would be technical difficulties.  Particularly the issue of loiter time as it relates to the succesion of quick launches.

Neither is there a question in my mind that, in theory, two 130 ton launches would be "easier" than three 70 ton launches.  We'll call that, "That Theory". 

"That Theory" seems to offer mostly the benefit of reducing the number of quick launches at the considerable expense in time and money of everything else.

"That Theory" does not accomodate the cost of design, testing, and implementing itself.  Neither does it include the calendar time required, which must necessarily be longer than "My Theory", due mostly to the far later availability of the 70 130 ton LV.  [Edit:  Nice scuttling there, Lar.]

In addition, to properly compare "My Theory" with "That Theory", one would have to accomodate the station/prop depot, the landers, yada yada.  It would take a large amount of "optimism" to posit that all of those things would cost less for "That Theory" than they would cost for "My Theory".

SLS evolution is complete, I say.  The Boeing plan should be funded to the next level.  They do need to aim for the poles, BTW.

Want to put an orbiter around Europa in 2022?  It could do that.

First, no, I don't want to.  Second, no, it could not.

Not, at least, per any announced time schedule, much less funding profile.  True, the decadal survey prioritization opines that JEO is second to MSR:

The second-highest-priority flagship mission for the decade 2013-2022 is the Jupiter Europa Orbiter (JEO).

If, well:

If NASA’s planetary budget is augmented, then the program will also carry out the first in-depth exploration of Jupiter’s icy moon Europa.

What universe would it be that you conceive of, where NASA's budget is sufficiently "augmented", so that MSR and JEO are completed by 2022?

No.  SLS Block 1B will assuredly not put anything in orbit around Europa by 2022.