Galileo Millennium Mission Status 7 Dec 2000

NASA’s Galileo spacecraft completes its fifth year of
orbiting Jupiter today, continuing to send home new information
after enduring more than twice the time in orbit and three times
the radiation dosage that it was originally planned to withstand.

It is heading back toward Jupiter after the most elongated
of its 28 loops around the planet since entering orbit on Dec. 7,
1995. As it moves closer to Jupiter, Galileo is making a 14-week
continuous study of the planet’s magnetosphere, a vast bubble of
magnetic force that surrounds the planet and contains its
dangerous radiation belts.

The study began in October while Galileo was still outside
the magnetosphere. The information being collected as Galileo re-
enters it will be paired with measurements taken as the craft
exited the magnetosphere last spring. The study is also part of
collaborative research with NASA’s Cassini spacecraft, which is
flying past Jupiter this month for a gravity assist to reach
Saturn. From a position outside of Jupiter’s magnetosphere,
Cassini is monitoring the solar wind of particles streaming away
from the Sun.

“The data we’re collecting right now are part of a
collaboration with Cassini to understand how the magnetosphere of
Jupiter responds to changes in the solar wind,” said Dr. Duane
Bindschadler, Galileo manager of science operations at NASA’s Jet
Propulsion Laboratory, Pasadena, Calif.

Initial science results from Galileo’s May 20 flyby of
Jupiter’s largest moon, Ganymede, will be presented at the fall
meeting of the American Geophysical Union, beginning Dec. 15, in
San Francisco. On Dec. 28, Galileo will fly by Ganymede once
again, this time while the moon is in eclipse behind Jupiter.
Galileo’s flight team is preparing for more studies of Jupiter’s
volcanic moon Io in 2001 and other possible encounters in a
further extension of the mission.

Several instruments and subsystems have suffered some damage
during the mission, but Galileo is still able to collect valuable
scientific information. “Galileo is showing some signs of battle
fatigue, but it is still a capable spacecraft,” said Jim
Erickson, project manager. Most of the degradation resulted from
cumulative radiation damage, particularly during Io flybys in
1999 and 2000, he said.

JPL, a division of the California Institute of Technology in
Pasadena, manages Galileo for NASA’s Office of Space Science,
Washington, D.C.