Ugh. As soon as anybody mentions Helium-3 it's time to change the channel.
Senate Hearing Link
Stafford mentions that SLS is essential because it is not possible to use many small rockets because of the boiloff of LH2.
Quote from: yg1968 on 04/23/2013 07:50 pmStafford mentions that SLS is essential because it is not possible to use many small rockets because of the boiloff of LH2.So I guess that's the new B$ excuse de jour for not following an affordable space exploration plan that actually has any chance of getting us anywhere. I'm getting sick of playing whack-a-mole with lame anti-depot FUD.To be clear, I'm not trying to insult Stafford, just sort of annoyed at dismissive answers like that when research we've been discussing here on NSF.com over the past several years pretty clearly shows ways of dealing with the problem. ~Jon
Senator Cruz said that he wanted to explore ways to increase commercial activity in space. But none of the witnesses made any suggestions in that regard. Stafford said that NASA has always done everything commercially. NASA never builds anything, the work is contracted to commercial companies. [..]Cook was not entirely clear on what he considers commercial. But he gave Dynetics an example of a commercial company that is successful.
Stafford said that NASA has always done everything commercially. NASA never builds anything, the work is contracted to commercial companies.
He said that a LH2 upper stage stage was essential because of its higher ISP over LOX or solids.
QuoteHe said that a LH2 upper stage stage was essential because of its higher ISP over LOX or solids.I actually agree with this part. I just think that the "we have to use SLS because of boiloff" argument is lame and unsupported FUD. Is boiloff an issue that shouldn't be ignored when dealing with LH2? Of course. Is it some sort of magic showstopper? No. Not anymore than "EELV black zones" were for crew launch.~Jon
I forgot to mention that both Stafford and Cook said that it would be a huge mistake to move away from the 2010 NASA Authorization Act. These witnesses are invited because the Senators know that they will answer what they want to hear. Although to be fair, I think that both Senators Cruz and Nelson are pro-commercial crew and cargo.
What about a methane upper stage as SpaceX is contemplating?
Quote from: yg1968 on 04/24/2013 12:09 amWhat about a methane upper stage as SpaceX is contemplating?I think that while Methane isn't as bad as storables or solids, I'm not convinced it's actually better than LH2 except in some limited situations (like when you can easily make Methane via ISRU such as on Mars). Especially with XCOR's comments that LH2 doesn't seem to be the Cryogenic Satan Juice that some people make it out to be, my take is that LH2 still makes a lot of sense for in-space large-deltaV-propulsion.That said, while I think LH2 makes more sense, CH4 isn't as bad as most of the other alternatives, and might even win out in some corner cases.~Jon