Chair Force Engineer

Friday, May 26, 2006

Everyday I Write the Book

Congratulations to Mark Wade on the tenth anniversary of Encyclopedia Astronautica, the internet's most authoritative and wide-ranging reference on all things space.

Still, it appears there are some gaps in his latest updates. No mentions of the New Horizons launch (Atlas V,) the FalconSat2 + Falcon I failure, GOES-N (Delta IV,) or COSMIC (Minotaur I.) Perhaps, in time, Encyclopedia Astronautica will become like Wikipedia, and rocket nerds across the internet will be able to update it.

Mr. Wade has been quite prolific in updating his blog, though. A few of his points are worth commenting on.

--His point about designing the CEV before selecting a mode is very good. As I've said before, I prefer an L1 rendezvous over the current plan to perform one rendezvous in earth orbit and a second one in lunar orbit. (Yes, it's occurred to me that you'll have to rendezvous twice at L1 if you want to bring the crew back home. I still like it better than the current ESAS plan.)

--His insistence that hit-to-kill interceptors can't work consistently isn't a fair assessment. The Air-Launched Miniature Vehicle, dropped from an F-15 in 1985, successfully destroyed the Solwind target satellite. It was politics, not technical challenges, that killed ALMV. Of course, it's much easier to hit a satellite in a predictable orbit than it is to kill a reentry vehicle from a ballistic missile. Still, not much can be said about the PAC-3 based on its performance in Operation Iraqi Freedom, aside from the fact that it's very good at killing Tornado GR.4's and F/A-18's.

--Another excellent point is made about the CLV upper stage. Why can't NASA order a stretched version of Delta IV's upper stage (or Atlas V's dual-engine Centaur, for that matter?) I think it has everything to do with crew comfort during aborts (see below.) Insufficient thrust might also be a problem.

--I totally agree that NASA's "crew comfort" requirements for aborting a launch are totally bunk. Aborting a manned spaceflight might hurt like a bitch, but that's okay as long as the crew survives. The same holds true for ejection seats in military jets. Crews often break arms and legs during ejections, but 100% of these people will tell you that they'd rather survive with broken limbs than perish inside the cockpit.

--Mr. Wade asks the question, "Why a thumpdown?" In reference to the lack of steerable parafoils on the CEV, it's because steerable parafoils are really heavy--far more so than standard parachutes. In the end, I'd like to see a comparison between the weight of the CEV's parachute+rocket landing system versus a parasail and skids, but I'm confident that parachute+rocket will come in at a lighter weight.

I should probably add that the rumored weight problems which dictated the "Walmart" lunar lander are being addressed with the increased girth of the CaLV (which enhances the amount of cargo it can put in LEO.) Still, if the weight problems persist, NASA should seriousuly look into a nuclear-thermal rocket for the Earth Departure Stage.