QUESTION:
Why didn't the antenna open all the way up? Is JPL still trying to
open it?

ANSWER from FAQ:
On April 11, 1991, the Galileo spacecraft began to deploy its
high-gain antenna under computer-sequence control.

The antenna -- a 16-foot mesh paraboloid stretched over 18
umbrella-like ribs -- had been furled and hiding behind a small
sunshade for the almost 18 months since launch, in which the
spacecraft came closer to the sun than Earth and briefly closer even
than Venus. Communications, including Venus and Earth-moon
science data return, had been using the low-gain antennas.

Within minutes, Galileo's flight team, watching spacecraft
telemetry 37 million miles away on Earth, could see that something
was wrong: The motors had stalled, something had stuck, the
antenna had opened only part way.

Within weeks, a tiger team had thoroughly analyzed the telemetry,
begun ground testing and analysis, and presented its first report.

They attributed the problem to the sticking of a few antenna ribs
due to friction between their standoff pins and their sockets. The
first remedial action was taken -- turning the spacecraft to warm
and expand the central tower, in hopes of freeing the stuck pins.

In addition to thermal cycling, the tiger team developed other ideas
for loosening the stuck ribs: retracting the second low-gain antenna
(on a pivoting boom), pulsing the antenna motors, and increasing
the spacecraft spin rate to maximum 10 rpm (normally about 3
rpm).

After a nearly two-year campaign to try to free the stuck ribs there
is no longer any significant prospect of deploying the HGA,
though one last attempt will be made in March of 1996. The Project
is proceeding to perform the Galileo Mission with the Low-Gain
Antenna.