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The Hubble Repair Mission
Dick Babish was Technical Director in the Optical Group and
instrumental in
the development of Perkin-Elmer's share of the Hubble.....the
Optical
Telescope Assembly and the Fine Guidance System. Here in his own
words, he
chronicles his toughts about the recent repair mission and his
observations
on what the program has meant to him.
"Working on the Hubble Space Telescope has proven to be one of the
most
prideful activities in my working life.
I had the privilege of participating in much of the activities from
the
early days even before the final proposal when we were engaged in
conceiving solutions to what were even then known to be critical
advances
in technology.
We knew we would have to improve on many of the technologies at
which we
were already quite competitive. These would include spectroscopy,
metrology, optical and mechanical design and fabrication that
would have
to perform to much better than usual in uncommon pressure and
thermal
environments.
While I had the privilege of participating in a number of pertinent
Research and Development Programs, both under contract and
internally
funded, I had the distinct privilege of working directly on
improving the
accuracy of the optical polishing process. We were already engaged
in
developing the Computer Controlled Polishing Process and had twice
attempted to demonstrate its capability on a sixty inch primary
mirror
when the time and funding had run out. I was assigned to aid
this
talented and very capable crew to refine the process. Meeting the
requirements, the picture of the final interferogram appeared on
the
front cover of the Perkin-Elmer Annual Report for that year.
With instruction on only the very first polishing cycle, the
partially
new crew was able to complete the HST primary to unprecedented
accuracy
of figure to the null corrector with unusual smoothness. Without
this
accuracy and smoothness it would not have been possible to correct
the
error introduced by the small spacing error in the null corrector
so
that even with the addition of the extra corrective elements the
Hubble
Space Telescope now meets every performance requirement
originally
specified.
As a result, the HST lives up to expectations in most dramatic
fashion,
leading to unexpected new questions about the universe as well as
answers
to older ones. While these questions are answered by the numbers
generated by its unusually high resolution both spectroscopically
and
metrically and can keep astronomers busy for years to come, its
spectacular imagery is what has made it so popular to the
layman. He
can see results and he can understand the astronomers
explanations.
Both have reasons to believe in HST. Both can understand why it
might be
advisable to keep it going.
Among the reasons this prevails is that the originators of this
device
understood why it was necessary to provide multiple instruments
with
multiple capability and to provide a capability to replace failed
units
despite redundancy. They also desired to be able to replace
instruments
when new discoveries demonstrated the need for newer capabilities
or when
technology had progressed to provide newer or better capabilities.
Implied is the requirement that it should be in an accessible
orbit. We
have seen instances of all these circumstances.
Now that we are retiring the only shuttle, this last mission
attempts to
extend the useful life as much as possible while attaching devices
that
will permit attachment of re-entry devices that will gracefully
guide it
to plunge into the sea safely.
Hopefully by then it will have provided all that it was capable
of, will
have been replaced by even more capable and versatile
instrumentation, or
that a replacement for the Shuttle will exist.
Much hope is placed on its successor, the Webb Telescope, now in
construction. However it will require unusual erection in space
and
will not be repairable, because of inaccessibility. Knowing the
history
of the Hubble, and that unusual and unexpected failure is
possible, we
wonder if the HST should be maintained until the Webb is
operational.
It will be a sad day when the Hubble will meet its inevitable end
yet it
will culminate a prideful period in my life having spent so much
of it on
its evolution."
Dick Babish
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