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From: karn@petrus.UUCP (Phil R. Karn)
Newsgroups: sci.space
Subject: Re: Space Telescope
Message-ID: <357@petrus.UUCP>
Date: Fri, 17-Oct-86 02:13:26 EDT
Article-I.D.: petrus.357
Posted: Fri Oct 17 02:13:26 1986
Date-Received: Fri, 17-Oct-86 22:16:09 EDT
References: <1322@rayssdb.UUCP> <1250002@hpfcms.HP.COM> <180@ka9q.bellcore.com> <15@cartan.Berkeley.EDU> <8220@sun.uucp>
Organization: Bell Communications Research, Inc
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> ... And since most of the instrumentation was designed by
> researchers from various universities, the space telescope is definitely
> NOT a version of any kind of spysat.

I'm sorry, people seemed to take my quote too literally. By "unclassified
version of a spysat", I understood the original author to mean that the two
spacecraft were of roughly the same physical size, mass, pointing capability
and resolution, not that a surplus KH-11 was actually converted into the ST.
(I'm still trying to dig up the source of this quote; I'm quite sure that I
didn't invent it.)

The ST and the KH-11 are OBVIOUSLY designed for entirely different missions.
The KH-11 operates in an elliptical orbit and probably has orbit-changing
rockets designed to optimize low-altitude coverage of interesting ground
sites; the ST will operate in a circular orbit and doesn't need an
orbit-changing capability.  The ST is designed to optimize both image
resolution and light-gathering power; obviously the KH-11 doesn't need much
of the latter.  Still, if the instrumentation could withstand it (e.g.,
through use of a neutral density filter) the ST would probably make very
nice high-resolution pictures of the earth.

Since it's resolution and not light-gathering power that the spooks are
after, I wonder if they've tried optical aperture synthesis yet.  If they
could figure out a way to coherently combine the photons from two or more
widely separated sets of optics (separated by, say, more than the diameter
of a Titan III payload fairing or the Shuttle cargo bay which would be the
ultimate limit on the diameter of a single-piece objective) then this might
result in much better ground resolution than we've given them credit for.

Phil