From: VonBraun@Dodgeit.com   
      
   Anybody out there with some thoughts on the best approach for the CEV?   
      
   Simple capsule vs. some sort of aero vehicle?   Myself, I lean towards   
   the capsule just to keep things simple and lightweight, so that it can go   
   to ISS without something bigger than an EELV-Heavy or a single SRB+upper   
   stage.   
      
      
   TPS system?   
   I read LockMart wants to use titanium.   Seems like overkill to me.   
   They advocate reusability... didn't we learn from Shuttle that reentry is   
   rather hard on a spacecraft, so you end up spending tons of money to   
   ensure it's still OK to fly again.   Just make them disposable, I say...   
   and keep tweaking the design over time.   
      
      
   What about propellants?   We want something that's:   
      
   Non-toxic (no NTO, MMH, UDMH, etc)   
   I know the old storables did a great job, but in today's environmental   
   age, it's time to find a non-toxic solution.   
      
   Relatively dense (no hydrogen)   
      
   Doesn't boil off or freeze easily   
   What's the typical thermal environment??   Obviously LH2 sucks, and LCH4   
   and LO2 are a little difficult, but what about Propane or some of the   
   other very soft cryos?   Don't the storables need heaters in space??   So   
   I would think mild cryos might be right at home on long duration   
   missions.   
      
   Stable and safe   
   Peroxide is a fad that comes and goes... great density, ok performance,   
   but everyone who toys with it ends up blowing hardware up sooner or   
   later.   I hear it's out of favor with NASA at the moment.   What's the   
   performance of Nitrous Oxide like in a biprop engine?   What about other   
   hydrocarbons?   Ethanol?   Leave no stone unturned!   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)