Newsgroups: sci.space.shuttle
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: shuttle escape systems
Message-ID: <1989Oct15.035238.12688@utzoo.uucp>
Organization: U of Toronto Zoology
References: <538.252A3A3B@mamab.FIDONET.ORG> <SHAFER.89Oct11081832@drynix.dfrf.nasa.gov> <2430@hydra.gatech.EDU> <1989Oct12.021826.7915@utzoo.uucp> <2521@hydra.gatech.EDU>
Date: Sun, 15 Oct 89 03:52:38 GMT

In article <2521@hydra.gatech.EDU> ccsupos@prism.gatech.EDU (SCHREIBER, O. A.) writes:
>>... Its use would probably be practical only
>>after [SRB] thrust termination..."
>
>... The escape system should be designed
>to function before SRB thrust termination.

In case it hasn't penetrated yet:  THIS IS VERY HARD.  By far the simplest
solution to that problem, which kills several other birds with the same
stone, is to junk the damned roman candles and use liquid-fuel boosters.

>>>I think this type of vehicle, without an escape system can never
>>>be safe enough.
>>Can you elaborate on why you think this?  The men who know the hardware
>>obviously disagree with you.
>
>The families of the victims, even without mentioning that
>of the teacher who was not an astronaut might agree with my statement.

Christa McAuliffe undoubtedly knew more about the safety issues than you
or I; she volunteered.  Note that her backup, who would be the person in
line to fly the next such mission, has *not* withdrawn.  The families
of the Challenger astronauts are not astronauts, and do not necessarily
understand the hardware.  Moreover, I don't see any great post-Challenger
exodus of astronauts from the program; I doubt that most astronauts would
ignore their families' wishes in the matter.

Note also my posting earlier today, observing that ESA's astronauts are
*against* putting an escape system into Hermes.

>Why I think this way is because it is a vertical take off vehicle and a
>3000 tons vehicle. The thrust put into play is thus very difficult
>to manage and puts the crew at greater risk than that of an ailiner
>or a fighter jet aircraft...

Have you figured out the thrust required for a 3000-ton airliner or
fighter?  It's less, but not an order of magnitude less.  Vertical vs.
horizontal takeoff simply does not make that much difference in the
required thrust, especially for a supersonic aircraft.  Concorde has
thrust a couple of orders of magnitude greater than a typical private
plane; which would you feel safer riding in?  What matters is the
competence of the engineers who design the engines, and the constraints
put on them, not the size of the nozzles.

As for comparative risks, have you looked at accident statistics for
jet fighters?  Any significant air force has to allow for steady
attrition of its fighter force, even in peacetime -- they simply crash
with some regularity.  In 1986, far more people died in USAF jet fighters
than in NASA space shuttles.

>>How much risk FOR WHAT GAIN is the question...
>If you think that a 2.5 year delay in manned space operations is
>a GAIN, then of course the risk is ok. 

The 2.5 year delay was irrational, pure and simple.  2.5 years after
an equally-ugly disaster hit Project Apollo, there were men walking
on the Moon.  I thought we were talking about technology, not politics.

>Still,  NASA may not want in the future 
>to take the responsibility of sending non astronauts with that kind
>of risk level, even volunteers like you.

NASA has never wanted to fly non-astronauts, ever, under any circumstances.
They were delighted to have an excuse to put the "citizen in space" program
on indefinite hold.  They'd probably have done it even if the Challenger
crew had survived.
-- 
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
