"Brian Thorn" wrote in message
...
On 7 Sep 2006 01:09:51 -0700, "Stephen Horgan"
wrote:

Of course the SRB has only failed once in STS operation,
but that was enough to cause the Challenger catastrophe.

And part of the liquid propulsion system (the External Tank) caused
the Columbia accident. Call it a wash.

True, but that one is easy to avoid. Stick your sensitive payloads above
the tanks with SOFI, just like Saturn V and the proposed Aries designs.

So, does the use of the SRB for Ares make sense or not?

Off the shelf, 4 segment SRB possibly, if only minimal changes are
necessary.

New roll control package, redesign of the top of the SRB to support payloads
on the top rather than the side, elimination of the SRB separation motors,
etc.

The 5-segment booster now planned makes no sense
whatsoever. It's pork for Utah, plain and simple. When Ares 5 jumped
to 5-segments and dumped the SSME, NASA should have cut its losses and
switched to one of the EELVs.

Agreed. Also, while the planned J-2X is based off the venerable J-2, and
follow-on development done previously, it's not a flight proven engine. I
would have felt better if NASA had picked an engine being flown today, not
one where they pretty much have to scour storage facilities and museums for
hardware to examine. :-P


But all of that is beside the point. Aries I/V are designed to keep the
shuttle infrastructure intact. As such, it's going to be yet another NASA
only, high fixed cost, low flight rate vehicle that has little to no chance
of being economical and little to no chance of anyone outside of NASA ever
using it. That's not a recipe that will help the US launch industry in any
way, shape, or form.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)