Newsgroups: sci.space.policy
From: henry@spsystems.net (Henry Spencer)
Subject: shuttle boosters (was Re: X-Prize on TLC)
Date: Tue, 2 May 2000 16:48:23 GMT

In article <8e6dhu$gqt$1@nnrp1.deja.com>,  <maxbeerbohm@my-deja.com> wrote:
>> By comparison, segmented SRBs had already been used quite successfully
>> on Titan III, and were felt to be well-understood and reliable
>> technology.
>
>Things that just don't make sense:
>1) Launch vehicles without crew escape in the ascent phase.

Definitely not the best of ideas, at least with systems developed using
conventional rocket practices.  (Concorde does not have an escape system
either, but it's a fault-tolerant design which logged many, many test
flights before it was trusted in operational service.)

Do note that the choice of solid boosters was made on the assumption that
it *would* be possible to terminate booster thrust on command, so that an
RTLS abort (or something similar) could be flown starting at any time.
When it became apparent that thrust termination was impractical, because
the transient loads were too high for the orbiter and ET, it was too late
to change the decision.

>The US has
>the only manned vehicle without such a capability ever built. Don't give
>me the it's impossible/useless line.

Impossible/useless, no.  One can debate whether it is *worthwhile*.  When
the issue came up for ESA's Hermes spaceplane, ESA's astronauts came out
against adding an escape system, on the grounds that it cost a lot of
weight (and hence vehicle capability) and did not increase safety much.

>2) Solids on manned systems.

See above.  I agree it's a bad idea, but it seemed to more or less make
sense at the time.

>3) Hatches on space stations that can't be closed until cables are
>removed. Note: quick release connectors don't count.

Agreed, but the US solution -- external cables which have to be connected
and maintained by EVA -- isn't much better.  And both approaches are
pretty stupid, since the Apollo spacecraft had the correct solution:  put
the connectors within the connecting tunnel but on the tunnel sides of the
hatches, so that the cables cross the module boundary within the tunnel,
but do not go through a hatch.

>5) Thruster systems on a space station that use toxic materials. Perhaps
>we need a billion dollar program to invent H2O2??

If you supply the billion, that's fine.  The station designers *wanted*
to do something more sensible about the thrusters.
--
"Be careful not to step                 |  Henry Spencer   henry@spsystems.net
in the Microsoft."  -- John Denker      |      (aka henry@zoo.toronto.edu)