The Next Four Weeks on Galileo March 25 – April 21, 2002
Cruise activities continue for Galileo during our long, nearly 10 month
period between encounters. During this time, the distance from the
spacecraft to Jupiter increases from 290 to 320 Jupiter radii (20.7 million
to 22.9 million kilometers or 12.9 million to 14.2 million miles). This
breaks our previous distance record of nearly 290 Jupiter radii set in
September 2000 during our 28th orbit of the giant planet.
The third of five cruise sequences of commands will be transmitted to the
spacecraft on April 1, and these commands will control the activities on
the spacecraft until June 2.
Routine hardware maintenance activities for the spacecraft this month
include two exercises of the propulsion thruster system on March 29 and
April 19, and an exercise of the tape recorder on April 12.
Tape playback of the final bits of data recorded during the January Io
flyby and during the recent calibration activity should be complete by the
April 12 tape maintenance. At the end of this activity, the tape recorder
will be parked with the read/write heads near the center of the tape. This
minimizes the stress on the spring that maintains the correct tension on
the tape, and allows the tape to sit quietly and safely for long periods
without moving. Except for monthly exercises of the tape to check its
status, there are no further plans to use the tape recorder until the
November Amalthea flyby.
On April 3 a test of the on-board gyroscopes is performed. These gyroscopes
provide the spacecraft with information about its attitude in space when we
perform turns and maneuvers. The electronics associated with the gyros have
shown significant degradation over the years of exposure to the harsh
radiation environment near Jupiter. However, when the spacecraft spends
time farther away from Jupiter, the electronics have shown some tendency to
heal themselves somewhat from these radiation effects, or anneal. This test
will provide engineers with data about how much self-healing takes place
after 2-1/2 months far from the radiation damage.
On April 11 the spacecraft will turn in place by 2.4 degrees to keep the
communications antenna pointed towards the Earth.
With the spacecraft well outside the magnetosphere of Jupiter on the
sunward side of the planet, continuous data collection by the Magnetometer,
the Dust Detector, and the Extreme Ultraviolet Spectrometer instruments
provides scientists with information about the interplanetary medium during
this time.
For more information on the Galileo spacecraft and its mission to Jupiter,
please visit the Galileo home page at one of the following URL’s:
