What is the big deal with the upper stage, it's mentioned in the Bill and the 130mt figure can't be reached without it so it's not going to be forgotten. The Ares I upper stage could be finished and used now if it's such a big deal but I suspect time will be taken to get some commonality with ULA especially in light of any future propellant depots. Using SSMEs will allow that commonality. The SLS's first task is also clear, to fully support ISS, and it doesn't need an upper stage for that. To think that MSFC/Shelby will stop at a <100mT vehicle is just silly especially with such a clear Bill mandate on the issue, you will have to try and stop them building a 3 stage version instead and then you go back to complaining about lack of payloads.
Quote from: marsavian on 10/08/2010 04:50 amWhat is the big deal with the upper stage, it's mentioned in the Bill and the 130mt figure can't be reached without it so it's not going to be forgotten. The Ares I upper stage could be finished and used now if it's such a big deal but I suspect time will be taken to get some commonality with ULA especially in light of any future propellant depots. Using SSMEs will allow that commonality. The SLS's first task is also clear, to fully support ISS, and it doesn't need an upper stage for that. To think that MSFC/Shelby will stop at a <100mT vehicle is just silly especially with such a clear Bill mandate on the issue, you will have to try and stop them building a 3 stage version instead and then you go back to complaining about lack of payloads.To be honest: If they don't "stop" at 100mt or less and the budgetary situation really does degenerate further, as some think it will, then they may cause another Ares debacle. That ties in with the entire "mismanage it and no matter how good it is, it still fails" dilemma. We will just have to see.
I have no such argument. Jorge is right. Set a goal out to far, and it's meaningless, including an advanced upper stage. Proponent, you're right that that means no BLEO exploration.
The only answer (to allow BLEO exploration) is to use a cheap upper stage, which basically means one we already have. That's what I think OV-106 has been hinting at. Is that correct?
We will just have to see.
Thats not to say though, that with budgets limited DIVUS, centaur, or even Raptor are not viable options
They have to go up to 130mt. <100mt is for the upper stage less version. Ares I was always hard to justify because it is just EELV Heavy class and asking for tens of billions more for a theoretically higher safety factor is not an easy decision to sell. The SLS is different, it will offer unique lift capability way higher than any commercial vehicle and just as important HLV is seen as essential by all political sides. Any justification for canceling it is just not as clear as it was for Ares I regardless of how big it is.
What is the big deal with the upper stage, it's mentioned in the Bill and the 130mt figure can't be reached without it so it's not going to be forgotten.
The SLS's first task is also clear, to fully support ISS, and it doesn't need an upper stage for that.
Quote. Use what is available until flight rates and proposed payloads require/mandate the development of something more optimal.Heh. The irony of this is delicious.
. Use what is available until flight rates and proposed payloads require/mandate the development of something more optimal.
Quote from: marsavian on 10/08/2010 04:50 amWhat is the big deal with the upper stage, it's mentioned in the Bill and the 130mt figure can't be reached without it so it's not going to be forgotten.If it's not a big deal, then why is it, according to Jorge and kraisee, such a big deal that the future is so uncertain as to prevent us from setting a target date for it?
If you want a date for the upper stage I will give you one 2060.Until then NASA can get on with going to the Moon and Mars.LEO to EML1 manned: Orion with stretched propellant tanks.EML1 to Moon surface: Lunar lander.EML1 to Phobos manned: Mars Transfer Vehicle.Phobos to Mars: Mars lander.LEO to EML1 cargo: SEP tug.EML1 to Phobos cargo: SEP tug.LEO to Moon surface cargo: SEP tug to low lunar orbit with a chemical decent stage. (Optional)
That is a possibly valid architectural option: forgo the very large, capable JUS, and use EML rendezvous with SEP for all mass except Orion. But that probably takes even longer -- HEFT, for example, figured about $7 billion for ~300kW-class SEP, availability in the latter 2020s. We could do a big upper stage before then, or possibly smaller stages refueling at propellant depots. The disadvantage to this approach is that it's not great for lunar. That advantage is that it leaves you well positioned for Mars and main belt missions. -Alex
Attached is a drawing of my entry in the "Affordable Upper Stage for SLS" competition. Inside an 8.5 meter fairing are shown:
It's probably just cheaper to have the DIVHUS stretched; 40mT of prop proposed. Little reason to duplicate what you already have.
articles on NSF pointed towards the possibility of using Centaur, DIVHUS, or a stretched DIVHUS on SDHLV. [...] There might be [..] contracting issues, but I assume [they] can be worked around.
You certainly can build a stage from the AIUS tooling
but if you want to do payload EOR with it, you'll either have to do rapid double-SLS LC-39 A/B launch and immediate rendezvous, or essentially develop ACES independently.
The "standard" 138 t AIUS might not fit well with SLS, but a "long" 172 t version certainly would!