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From: wab@yoda.Rational.COM (Bill Baker)
Newsgroups: sci.space.shuttle
Subject: Re: MANY QUESTIONS (Shuttle cabin survival)
Message-ID: <923@igor.Rational.COM>
Date: 15 Mar 91 22:43:04 GMT
References: <0566B3896080344E@splava.cc.plattsburgh.edu> <1991Mar13.045435.3817@zoo.toronto.edu>
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In article <1991Mar13.045435.3817@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
>[Transliterated to lower case to make it at least semi-readable!  Please
>don't post long articles in SCREAMING UPPERCASE.]
>
>In article <0566B3896080344E@splava.cc.plattsburgh.edu> LONGWJ@SPLAVA.CC.PLATTSBURGH.EDU writes:
>>4.  more morbid curiosity...since the challenger explosion has there been any
>>effort to redesign the shuttle orbiter so that the crew cabin could be used in
>>an emergency splashdown?  maybe something like the present crew cabin with its
>>own parachute system and heat sheild? ...
>
>The idea is not ridiculous, but it would require massive redesign, and
>the extra mass might well wipe out the shuttle's payload entirely.  The
>ESA designers working on Hermes came to the same conclusion as NASA:
>bringing the whole cabin down is difficult and costly, and probably
>not worth it.  (ESA has gone for ejection seats on Hermes, over the
>protests of the astronauts, who think the correct solution is not
>to fit an escape system at all.)

I've wondered about this since the post-Challenger redesign began.
Given that the cabin is designed to be much more robust than the rest of the
orbiter and given that the cabin of the Challenger did emerge from the
initial break-up somewhat intact and some circumstantial evidence that
the crew survived the break-up if not the impact:  Why not include
some rudimentary survival system that might save the cabin after a
high to medium altitude catastrophic failure?  It might be nothing
more than a hellacious parachute built into the rear wall of the
cabin, deployed only by command of one of the "pilots."  This presumes
someone surviving to hit the button, but this may have been the case
with the Challenger and if a large parachute had been deployed from
the cabin at the top of its ballistic arc after break-up wouldn't it
have had a reasonable chance of maintaining structural integrity
during a parachute-aided landing?  Presuming the crew survived the
blast and other effects (I suppose high-gee spin might leave you fatally
concussed or disoriented), couldn't they reasonably expect to survive
such a landing inside the cabin?  Of course, if you were landing in
water you might as well have died in the explosion, but...

That's a lot of caveats, but actually wouldn't this scenario cover
most of the worst contingencies?  The Challenger break-up is about 
the most catastrophic possible scenario, no?  And the cabin survived whole
(sort of, maybe), so there is a likelihood of cabin survival in the
worst of circumstances (and therefore in all the less catastrophic
instances, too).  Now, what are the floor and ceiling of practical
cabin survival with some sort of parachute detente system?  Too low
and it has no time to deploy.  Too high and, I guess, it's destroyed
by reentry effects (just to define a broad rubric).  Wouldn't this
actually be a pretty wide spread?  From how many nautical miles up
could the cabin theoretically descend and the crew survive if it
maintained pressure and had a robust detente system.  It would
probably take a series of drogue ribbons and 'chutes ala Apollo
reentry, but it doesn't seem technologically unreasonable.  Wouldn't such
a "window" actually comprise the majority of time in which the shuttle
is likely to fail?  

Extend this further and accept more (but perhaps still minimal)
increases in systems complexity, cost, and weight:  Design a system to
separate the cabin in the case of non-catastrophic failure (my bet for
the next shuttle crash:  A couple turbo-pumps fail in mid-ascent, the
shuttle loses two engines and can't make orbit).  Instead of going
down the pole with a chute and a prayer or trying to separate and land
the shuttle, include an ejection "ring" at the juncture of the cabin
and the rest of the orbiter body that would blow the cabin away from a
doomed stack, sort of the way that stages separate in multi-stage
rockets.  Obviously, a survivable separation at high speed is 
more than a minor problem, but it's better than nothing.  Include a
backup computer inside the cabin that monitors altitude, change of
attitude, telemetry status, etc. and matches it against a data profile
of likely system failure (e.g., We're a hundred thousand feet up,
we're experiencing extremely high roll rates, I'm receiving no ground
telemetry, no data from the rest of the orbiter, and all of these
things have happened simultaneously. Conclusion: We've blown up).
Have it control firing the emergency separation charges, chutes, etc.
in case the crew is unconscious but not dead (e.g., Challenger).  Maybe it
all works and they survive to have grandchildren.  Even over water,
maybe they ride cabin-with-parachute down to a reasonable altitude and
then jump with their own 'chutes (the latter part is already an
accepted escape method from the shuttle).  At least they'd have a
chance for, perhaps, a small tradeoff in payload.

Even as wacky as these scenarios seem, the likelihood that we are
going to watch more cabins coming down whole seems pretty good.
NASA's saying something like 1 out of 80 shuttle flights will suffer a major
failure, and it seems to me that most of these will be pad failures,
mid-ascent failures, and reentry failures.  In the last two catgories
I can well imagine that an orbiter will again go to pieces and leave the
fly-boys hurtling to Earth in a titanium bathysphere.