Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!olivea!oliveb!amdahl!JUTS!duts!haw30
From: haw30@duts.ccc.amdahl.com (Henry A Worth)
Newsgroups: sci.space.shuttle
Subject: Re: Recovering HST from orbit
Message-ID: <31Nb02wq05R.01@JUTS.ccc.amdahl.com>
Date: 8 Feb 91 21:31:25 GMT
References: <6814@harrier.ukc.ac.uk> <1991Feb6.214941.316@abode.wciu.edu>
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Reply-To: haw30@DUTS.ccc.amdahl.com (Henry Worth)
Organization: Amdahl Corporation, Sunnyvale CA
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>In article <6814@harrier.ukc.ac.uk> sss3@ukc.ac.uk (S.S.Sturrock) writes:
>While this seems to be a cost effective method, I was wondering if there were
>some other reason why the HST was not just recovered and the mirror replaced.
>Is it because the Shuttle would not be able to land safely with the added
>weight, or maybe it could land but would be so damaged that it could not
>be re-used?
>

Two Points:

1>
     The Shuttle manifest is somewhat over-subscribed. With shifting
priorities, inconsistent budgets, and technical problems; it is hardly
certain that the HST repair flight will be flown on time -- if at all.
To bring the HST back down to Earth for refurbishment would be to take
a considerable risk that it would never get back into orbit.


2>
     There should be some consideration of cost effectivness.
In the decade++ since the HST was designed there had been MAJOR
advances in active/adaptive optics, mirror casting techniques
(spin casting), electronics, CCD's, image processing and compression,
and other technologies.

     The cost of two shuttle flights and a major refurbishing of
the HST (the solar panels would also have to be replaced, and
while we are at it we might as well replace the batteries, the
troublesome tracking devices, ... ) may well EXCEED the cost to
build a new, superior, space telescope (or even a series) and
launch it with a commercial ELV. Another advantage is that the HST
stays in orbit and continues its work. One cost-saving option
would be to design the new instrument for wide-field work only --
the HST's major weaknes.

     This approach may even be more desirable than the planned
repair mission (has anyone at NASA - or elsewhere -- run the numbers?)

--
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Henry Worth  --  haw30@duts.amdahl.com
No, I don't speak for Amdahl -- I'm not even sure I speak for myself.