Satgen241  Hubble Space Telescope Repair Mission by GM4IHJ       6 Nov 93
BID of this msg is SGEN241  Please use this BID if you retransmit the msg

On December 2nd 93 NASA plan to launch STS 61, the long awaited mission to
repair the Hubble Space Telescope. Soon after launch in April 1990 it was
discovered that a lens manufacturing defect made it impossible to get an
accurate focus on the telescope and despite some super human efforts using
computer de-blurring, the telescope has not met any of its builders hopes
, so far. All that may change if this mission can successfully instal a
box carrying correction lenses, thereby allowing us to really look deep
into space at those places Stephen Hawking and others talk about , but
from which we have very little practical information.
In addition to the lens correction , Hubble has several other problems
which need attention. Its giant solar panels wobble as they expand when
the telescope comes into sunlight, 3 of its 6 stabilizing gyroscopes have
failed leaving it just barely controlable on the remaining three, and two
of its magnetometers are defective. So the Shuttle astronauts plan at
least 5 and possibly 7 long EVAs. Their rough programme is :-
Day 2  Go alongside the telescope , catch it with the remote arm , and
attach it to a platform in the shuttle cargo bay.
Day 3  Replace two gyros and one magnetometer, then start undoing the old
solar panels.
Day 4  Fit new solar arrays
Day 5  Fit Wide field and Planetary camera
Day 6  Fit corrective optics to Faint object cameras
Day 7  Fit new solar array electronics, the 2nd magnetometer ,get all 6
gyros working and fit a Coprocessor in the telescopes computer.
Day 8 and 9 Complete outstanding work then put Hubble back on remote arm
whilst ground control ,unroll and check out solar panels. Then lift Hubble
completely clear of the Shuttle and release it.
Day 10 is a spare day and Day 11 return to Earth.

Clearly this will be a most exciting mission . Long EVAs should give good
listening and viewing for ground observers ( the old EVA frequencies were
Primary 296.8 ; Secondary 259.7 and Low power reserve 279.0 MHz ) NASA TV
has been carried on GE Satcom F2R on C Band 3960 Mhz which is on the UK
western horizon at geostation 72 West. Polarisation is vertical and audio
is 6.8 MHz sub carrier. Intel sats have also carried NASA TV at times (
watch UK packet radio bulls for more info when STS 61 flies )

Unfortunately the Hubble orbit is Inclination 28.5 degrees and its
altitude is 575 kms. This gives it Earth ground coverage to latitude 52
north and south ( 28.5 inclination 23.5 degrees footprint ). So Shuttle
listeners and watchers in Canada, northern UK, Holland, North Germany,
Scandinavia, north Poland and northern Russia will be below the Shuttle
horizon. Stations on the Canada US border , southern England and others
near 50N latitude may just hear or see brief horizon passes once or twice
per day. But such will be the interest in this flight it will probably be
given some national TV coverage everywhere.

So lets wish NASA all the luck in the world . It is vitally important that
this mission should succeed. It goes without saying however that the
intense programme being carried out may preclude any chance of SAREX
operating. 73 de GM4IHJ @ GB7SAN