Xref: utzoo sci.space:10697 sci.space.shuttle:2861
Newsgroups: sci.space,sci.space.shuttle
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: space news from Feb 20 AW&ST
Message-ID: <1989Apr12.155922.20978@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1989Apr12.030151.7181@utzoo.uucp> <19530@iuvax.cs.indiana.edu>
Date: Wed, 12 Apr 89 15:59:22 GMT

In article <19530@iuvax.cs.indiana.edu> cdaf@iuvax.cs.indiana.edu (Charles Daffinger) writes:
>>...  Some of the [RL10] upgrades are derived
>>from work done on the late, lamented Shuttle-Centaur program.
>
>What was the Shuttle-Centaur program, and why did it croak?

Since the demise of the Space Tug early in shuttle development, any
shuttle payload that wants to go beyond low Earth orbit has needed an
upper stage of some kind.  The Inertial Upper Stage (nee Interim Upper
Stage) is okay for many things, but is short on performance for seriously
demanding missions, like large deep-space missions and boosting really
heavy loads into Clarke orbit.  So NASA undertook to develop a version
of Centaur optimized for the shuttle cargo bay.  (Basically this meant
fatter tanks.)  This would give much higher performance, since Centaur
is oxygen/hydrogen against IUS's solid fuel.  Originally Shuttle-Centaur
was earmarked to launch Galileo, Ulysses, Magellan I think, and at least
some USAF payloads.  There were some complications, like needing a way
to dump the Centaur fuel if an emergency landing was needed, but things
were more or less on track for Galileo and Ulysses in late spring 1986.

Then Challenger exploded.

In the safety hysteria that followed, Shuttle-Centaur was cancelled on
the grounds that having cryogenic fuels in the payload bay somehow
presented safety problems that were utterly beyond NASA's ability to
solve.  What this really meant was that NASA didn't feel like solving
them just then, and the people who needed Shuttle-Centaur didn't have
enough political clout to keep the program alive.  Some of the other
post-Challenger safety restrictions have since been relaxed, but the
momentum was lost on Shuttle-Centaur and there is no chance of reviving
it now.  (If there were no other way to launch Galileo, the situation
might be different, but the Galileo people have found that by making
some sacrifices, they can use an IUS.)
-- 
Welcome to Mars!  Your         |     Henry Spencer at U of Toronto Zoology
passport and visa, comrade?    | uunet!attcan!utzoo!henry henry@zoo.toronto.edu