QUESTION:
I was thinking that after slowing down and entering
orbit things might have been bounced around a bit.  In all that buffeting,
maybe, just maybe, the large antenna may have fixed itself.  Has anybody at
JPL thought of checking it out again?

ANSWER from Todd Barber on January 10, 1996:
Thanks for the very intriguing question!  We have thought about what
effect orbit insertion would have had on the high gain antenna.
Unfortunately, when you figure out the g-forces that the spacecraft
experienced due to the engine firing, it turns out to be around 1/50
of one g (0.2 m/s/s).  Therefore, there is little chance that the
antenna moved at all.  Of course, there would be another chance
THEORETICALLY that the antenna could have been jostled loose if some
kind of resonant driving frequency were applied to the spacecraft,
perhaps through the engine firing.  But, again, this has been looked
at in detail with no positive results anticipated.

As far as buffeting goes, there really has been none to speak of since
the second Earth flyby in December, 1992, since we have not flown near
enough to any planetary atmosphere in the ensuing three years to
experience this effect.  To get the kind of "air resistance" forces
necessary to free the high gain antenna would probably lead to severe
frictional heating of portions of the spacecraft (not to mention a
large disturbance to the trajectory due to the associated
aerobraking).

Despite our high confidence that the antenna is stuck for the
duration, we are planning in March a high gain antenna motor
"hammering" activity as a last-ditch effort to deploy the antenna.
This is being done simply on the off-chance that somehow the
pin-binding friction has been reduced sufficiently to allow some rib
deployment.  This "hammering" will be performed shortly after the last
use of the main engine in mid-March, which is executed to keep Galileo
out of the strongest radiation fields of Jupiter on subsequent closest
approaches.  You may be wondering how we could tell that the antenna
had fully deployed if the hammering activity were successful.  The
attitude control personnel are able to identify small changes in
Galileo's wobble; such changes would occur due to the minute change in
the mass properties of the spacecraft with the ribs fully deployed!

It should be mentioned that a fantastic orbital mission is possible on
the low gain antenna, given the tireless work of many of my coworkers
here at JPL.  We fully anticipate 70% of the original science
objectives to be met, including 100% of the probe mission objectives.
Like you, I simply cannot wait for the probe results and the first
high-resolution images of the Jovian satellites, which will be
released this summer.  Thank you for your interest and support of the
Galileo mission!