Interim Cryogenic Propulsion Stage (ICPS) for SLS

[sdsds]

Short answer:  because NASA does not wish to launch Orion to low-Earth orbit.  NASA wants to launch Orion beyond low-Earth orbit.  To do that, Orion and a fully-fueled, large cryogenic stage need to get up there together.  NASA does not wish to depend on LEO rendezvous for this, much less propellant transfer.  Ergo, Delta-IV Heavy is not sufficient for NASA's "needs."

[Jim]

There goes NASA rushing forward again at the speed of a slug on Valium!  Will it really need to take the better part of 8 months to react to the response they get to this?  (To be fair, iCPS probably isn't anywhere near the SLS critical path.)

Yes, because the beginning of the fiscal year

[spectre9]

But NASA does wish to launch Orion to LEO.

ISS lifeboat capability is written into the law is it not?

[spectre9]

I've been thinking. Orion can't launch straight to Mars anyway can it?

So the real point in building the SLS is to do Apollo Mk II and get as much on the one launch as you can?

Big rockets are really expensive.

Like I've already said before SLS makes sense for Mars but not the moon.

I guess it's up to the people designing missions to make it make sense for lunar exploration.

[strangequark]

I've been thinking. Orion can't launch straight to Mars anyway can it?

So the real point in building the SLS is to do Apollo Mk II and get as much on the one launch as you can?

Big rockets are really expensive.

Like I've already said before SLS makes sense for Mars but not the moon.

I guess it's up to the people designing missions to make it make sense for lunar exploration.

So are big planes. This is why all intercontinental flight is done with Cessnas (i.e. Look at per kilogram cost).

[93143]

What an EELV Heavy can launch to LEO, SLS Block 1 can launch to an L-point.  (Roughly.)  Sounds to me like it could be useful for all sorts of exploration to be able to treat cislunar space the way we treat LEO now...

[long rant removed and placed in storage; I'm not sure I want to hit the thread that hard right now...]

[spectre9]

Aww did I miss the juicy stuff?

C'mon it can't be worse than my ranting.

There are policies there are assumed.

Things like :

1. Orion must be launched to the moon all up.

2.  SLS will use old SSMEs, 5 seg solids and ICPS but this hardware will not in any way be part of the real evolution of the vehicle. New boosters, new engines and a new upper stage are required.

3. SLS will have some huge 130mt payloads TBD. It's written in the law. 130mt and no less.

4. Orion can only be launched on SLS.

5. SLS will be aiming to get down to about 1.2 bill recurring launch cost.

Much of this just seems unrealistic to me but it's the way things are to be done.

Is NASA wrong?

Am I wrong?

No wonder people bang on about Senate Launch System and are big supporters of EELV. I can finally understand all the stuff I've been reading over the last few months.

No longer will I be an SLS loving sheep.

[Ben the Space Brit]

Is NASA wrong?

Am I wrong?

I think that the thing to remember is that, to a greater extent, NASA is an instrument of the policies of the government of the United States of America.  Because of this, it is required to do things to impliment these policies that do not make obvious scientific, engineering or economic sense.  That's because those issues are not necessarily more important than implimenting those policies in them manner in which it has been instructed.

In this case, this means SLS with the specified capabilities (even though the 'why' is 'TBD') and using the bits specificed ('wherever practicable'), even though this isn't necessarily the best or cheapest way to do it.  It is about political requirements more than anything else.

The way I see things, at least for NASA, it is going to be a case of SLS or an end to non-Commercial-to-LEO-only HSF.  I think that is why it has the (at least grudging) support of so many.

[Patchouli]

Thanks for linking that article.

"Delta IV not getting human rated"

Just because it keeps getting said doesn't mean it's true.

Or at least not that I will believe it anyway.

DIV-H will launch the Orion safer, cheaper with a real rocket and without a 300ft+ crew access tower.

I know the solution, LIBERTY!!!! 

I can really understand EELV fanboys because these rockets are real and do exist.

Every plan to build a new rocket to do something one that already exists can do just makes me ask WHY?

I'm not trying to troll, I seriously don't know why.

The reason why shuttle was so expensive is because it was a massive cost just to launch a few astronauts.

SLS wants to do the same and not do it until 2021.

WHY!!!!!!!!!!!!!!!!!!!     

in defense in the EELV crowd the Delta IV is probably over all a safer vehicle then Soyuz and Long March despite being a hotrod.

With ICPS possibly being the DCSS and the fact the RS-68A already includes half the man rating requirements proposed for  the RS-68B man rating the Delta IV may not be as far fetched an idea now as it was.

[93143]

1. Orion must be launched to the moon all up.

Who ever said that?

It could be a useful capability, though - Orion is neither large nor complex, as spacecraft go; it's just a capsule (the phrase "all up" is rather silly in this case IMO).  Getting Orion out of LEO by itself doesn't need to be a big production with a propellant launch campaign and the better part of a week spent chasing a depot and doing prox ops; just stick it on an SLS and fire away.  If you've already got a reusable personnel lander at an L1 depot, or a Mars transfer vehicle at L2, you can just go there directly.  Treat cislunar space the way we treat LEO now.

2.  SLS will use old SSMEs, 5 seg solids and ICPS but this hardware will not in any way be part of the real evolution of the vehicle. New boosters, new engines and a new upper stage are required.

You are misrepresenting the situation with the SSMEs.  The "new" engine will basically be the SSME Block III with some reusability features removed.  If more Block IIs are required in the interim, we can make them.  The change is purely a cost-reduction exercise, and a lot of the work has been done already as part of the intended Block III upgrade for Shuttle.

Also, the booster competition was something a lot of SLS opponents were pushing for.  Now that it's happening, they complain that it's a waste of time and money.  Looks like someone didn't think things through...

The upper stage - of course SLS needs a new upper stage.  No existing upper stage is remotely large enough to properly complement the capabilities of the SLS core.  Neither does any existing cryo stage have anything like the required in-space lifetime to support a deep space mission.

That's not to say that the iCPS will definitely be retired, though.  It seems to have its uses, depending on the architecture...  they were talking about a stretched version in some of the documents; that could be helpful, and it would be a shame to only use it once or so...

3. SLS will have some huge 130mt payloads TBD. It's written in the law. 130mt and no less.

The law only says SLS needs to be expandable to carry payloads that heavy, not that they will necessarily be built.  This is because Mars mission designs have a strong tendency to converge on 130 tons or so as the largest single chunk in LEO.

4. Orion can only be launched on SLS.

Believe it or not, this was an attempt to protect Commercial Crew - Orion on Atlas V Heavy was seen as unfair government competition.  IIRC this was said by 51D Mascot, who was in on the proceedings...

It's also technically incorrect; the first Orion launch is supposed to be on a Delta...

5. SLS will be aiming to get down to about 1.2 bill recurring launch cost.

Where did you get this?  If you mean marginal costs on top of the fixed cost of owning the system, you're high by something like a factor of 3 or 4.  If you mean total cost divided by launches per year, well, that depends on launch rate, which is not known.

[spectre9]

1. Good response.

2. So expendable SSME will be cheap? Cheapest core stage engine in the world?

I think it's a waste of time and money to design SLS for 2 boosters just so you can use the old solids. Vehicles with more than 2 boosters are much more flexible. Maybe there's a reason why you can't have more if there is I don't know.

3. Going to Mars? Keep the dream alive I guess but not for a long long time after the law says the SLS needs to carry 130mt.

4. Only launched manned on SLS? It is a manned capsule isn't it?

5. Yes this was for multiple launches 3-4 possibly. 1-2 makes for a more expensive SLS.

[Robotbeat]

...
2. So expendable SSME will be cheap? Cheapest core stage engine in the world?...

Only in NSF fantasyland.

[93143]

1. Good response.

Thanks.

2. So expendable SSME will be cheap? Cheapest core stage engine in the world?

Cheap compared with RS-25D, yes.  Compared with Merlin 1D, probably not.  But it's a very high-performance engine.  Its cost should be roughly similar to that of a hypothetical regeneratively-cooled RS-68, and there should be a lot of commonality between the RS-25, RL-10 and J-2X lines.

As I recall, the cost of RL-10s shot way up when the Shuttle program closed down...

I think it's a waste of time and money to design SLS for 2 boosters just so you can use the old solids. Vehicles with more than 2 boosters are much more flexible. Maybe there's a reason why you can't have more if there is I don't know.

The rule is to use what you have.  What we have is the nearly-finished 5-seg SRB.  I'd personally have preferred AJAX (we also have the Atlas V CCB, even though they use Russian engines), but oh well.  As I recall, Downix had an idea for using multiple boosters on a single attach point using a rack mount - bit of a waste of mass IMO, but for boosters that's less important, and I'm not sure how big the mass hit would actually be...

3. Going to Mars? Keep the dream alive I guess but not for a long long time after the law says the SLS needs to carry 130mt.

The law doesn't say anything about when the 130 ton capability is supposed to be available.  It just says that SLS has to be designed so that it can reach that number at some point.  The only actual date given is for the 70-ton version.

4. Only launched manned on SLS? It is a manned capsule isn't it?

Yes, but now you've added a word.  I said technically, didn't I?

...Be aware that I have a totally baseless aversion to using smileys.  It's a matter of honour...

Besides, what would you do with it on a different launcher?  Send it to the ISS?  Given that you already have SLS for BEO exploration and thus have to pay the fixed costs anyway, adding a core-only flight is cheaper than buying an EELV Heavy (as far as I can tell from currently-available numbers).  And the hope is that we won't have to do that.

5. Yes this was for multiple launches 3-4 possibly. 1-2 makes for a more expensive SLS.

By my calculations, based on the Budget Integration document, the SLS program cost for one flight per year should be between $1.5B and $2B in modern dollars.  That's the 130-ton version.

Adding a flight of the 70-ton version with iCPS (EDIT: iCPS inclusion has been questioned and is not positively certain) every year raises the price by $270M or so.  Including the 21CGS costs (which are for more than just SLS) adds a little over $400M.  (These costs don't all seem to inflate at the same rate; it's a bit of a confusing document.)  The whole shebang, including Orion and its fixed costs, is under $4B in 2023 dollars, or between $2.4B and $3B in 2012 dollars.

Where are you getting your numbers?

[Robotbeat]

The $270 million figure doesn't include the iCPS.

[93143]

Based on what?  The description of the flights says MPCV BEO.  You can't do that without a kick stage, and there's no separate budget line for one.