But I do think that the rocket is a big part of the problem too. More specifically, the problem is what the architecture choice does to NASA's budget.
jml - 22/4/2008 9:56 PMShuttle-C may save some initial development and infrastructure costs, but side mount payload implies a need for an EELV to serve as crew launcher.
The Shuttle-derived options considered were of two configurations: (1) a vehicle configured much like today’s Shuttle, with the Orbiter replaced by a side-mounted expendable cargo carrier, and (2) an in-line configuration using an ET-diameter core stage with a reconfigured thrust structure on the aft end of the core and a payload shroud on the forward end. The ogiveshaped ET LOX tank is replaced by a conventional cylindrical tank with ellipsoidal domes, forward of which the payload shroud is attached. In both configurations, three SSMEs were initially baselined. Several variants of these vehicles were examined. Four- and five-segment RSRBs were evaluated on both configurations, and the side-mounted version was evaluated with two RS–68 engines in place of the SSMEs. The J–2S+ was not considered for use in the CaLV core due to its low relative thrust and the inability of the J–2S+ to use the extended nozzle at sea level, reducing its Specific Impulse (Isp) performance below the level required. No variant of the side-mount Shuttle-Derived Vehicle (SDV) was found to meet the lunar lift requirements with less than four launches. The side-mount configuration would also most likely prove to be very difficult to human rate, with the placement of the CEV in close proximity to the main propellant tankage, coupled with a restricted CEV abort path as compared to an in-line configuration. The proximity to the ET also exposes the CEV to ET debris during ascent, with the possibility of contact with the leeward side TPS, boost protective cover, and the LAS. The DDT&E costs are lower than the in-line configurations, but per-flight costs are higher—resulting in a higher per-mission cost. The side-mount configuration was judged to be unsuitable for upgrading to a Mars mission LEO capability (100 to 125 mT).
jml - 23/4/2008 1:04 AMMy understanding is that a side mount SDLV places the CEV in the same location as the Shuttle crew cabin, which is unacceptable after Challenger and Columbia. This would put the CEV right in the potential debris field from rapid unscheduled disassembly of the ET or an SRB. Even with a launch abort system to pull the CEV away from a disintegrating LV stack, the risk to crew is higher than with the CEV mounted atop the LV.Of course, I may well be wrong. Anyone have in-line vs. side-mount SDLV LOC numbers from ESAS handy?
OV-106 - 23/4/2008 12:43 PMNever said Shuttle-C config was optimal but it is not impossible and would not have to drive seperate crew and cargo launchers. Challenger and Columbia do not really apply since shuttle has no escape system anyway and the CEV will be protected by the LAS. The heat sheild will have multiple layers of protection. The LAS engines would probably have to be canted, etc for a shuttle-C config. The point is this would be another design trade but saying it automatically drives a two launch vehicles I don't believe is valid.
Jim - 23/4/2008 11:54 AMIt is valid.
MarkWhittington - 23/4/2008 1:38 PMWingo's piece is, unfortunately, riddled with factual errors and analytical fallacies. For one thing, any article that quotes Barney Frank as the voice of both the Congress and the people cannot be taken seriously.
Jim - 23/4/2008 12:43 PMQuoteMarkWhittington - 23/4/2008 1:38 PMWingo's piece is, unfortunately, riddled with factual errors and analytical fallacies. For one thing, any article that quotes Barney Frank as the voice of both the Congress and the people cannot be taken seriously.instead of slinging muck due to your personal differences with Dennis, point out and list the errors
psloss - 23/4/2008 1:08 PMQuoteMarkWhittington - 23/4/2008 1:38 PMWingo's piece is, unfortunately, riddled with factual errors and analytical fallacies. For one thing, any article that quotes Barney Frank as the voice of both the Congress and the people cannot be taken seriously.I don't think Barney's presence in the discussion makes a strong argument either way, even if Rep. Frank himself is a polarizing figure. Didn't some "anti-Mars" language make it all the way to the President's pen in the FY 2008 omnibus appropriations bill? If so, that implies there is likely bipartisan "support" for this particular position. All he's basically saying is "I don't want to spend lots of money on that," which is much easier to support than what to actually fund.I agree with Jim -- I'd be interested in your rebuttal if it enumerates and explains those errors and fallacies.
MarkWhittington - 23/4/2008 2:16 PMOn the Mars language, it actually originated with House Democrats. While annoying, it did not rise to the level of being a sufficient reason to veto the bill and cause a government shut down.
MarkWhittington - 23/4/2008 9:16 PMQuotepsloss - 23/4/2008 1:08 PMDidn't some "anti-Mars" language make it all the way to the President's pen in the FY 2008 omnibus appropriations bill? If so, that implies there is likely bipartisan "support" for this particular position. On the Mars language, it actually originated with House Democrats. While annoying, it did not rise to the level of being a sufficient reason to veto the bill and cause a government shut down.
psloss - 23/4/2008 1:08 PMDidn't some "anti-Mars" language make it all the way to the President's pen in the FY 2008 omnibus appropriations bill? If so, that implies there is likely bipartisan "support" for this particular position.
kraisee - 23/4/2008 5:29 PMBut that was followed up a while later by comments to the exact opposite by both Dr. Hinners and (IIRC) by Rep. Nick Lampson.Rohrabacher's comments were not the only opinions presented at that hearing.
MarkWhittington - 23/4/2008 11:13 AMThe main fallacy of the article, and that seems to be a common one for critics of VSE, is that it assumes that it is NASA's job to create a commercial transportation infrastructure. Does anyone remember how the space shuttle came to be? The proper way NASA could help enable a translunar transportation system is through a lunar version of COTS. But, of course, that can't happen until there is an actual lunar base to go to.
The Congress declares that the general welfare of the United States requires that the National Aeronautics and Space Administration (as established by title II of this Act) seek and encourage, to the maximum extent possible, the fullest commercial use of space.