GALILEO MILLENNIUM MISSION STATUS
January 17, 2002
While approaching Jupiter's moon Io on Thursday, during
the seventh year of its mission around Jupiter, NASA's Galileo
spacecraft placed itself into standby mode, awaiting further
commands from Earth.
"We're not totally surprised, because Galileo has already
outlived expectations and we knew that it might encounter
additional difficulties from the high-radiation environment on
this flyby," said Dr. Eilene Theilig, Galileo project manager
at JPL. "Galileo has already lasted more than four years past
its original mission and has survived three-and-a-half times
the radiation it was designed to withstand, so it's not
unexpected that this flyby would be interrupted by a problem."
Images and other data were not collected during the
closest phase of the encounter. The Galileo flight team at
NASA's Jet Propulsion Laboratory, Pasadena, Calif., is sending
commands aimed at switching the spacecraft out of standby or
"safing" mode for the later portion of the planned encounter
period, which lasts into Sunday.
Galileo hit its intended flyby point, achieving one of the
encounter's primary goals of using Io's gravity to put the
spacecraft on course for a September 2003 impact into Jupiter.
This flyby is the closest and last for Galileo at any of
Jupiter's four major moons. The spacecraft sped within 102
kilometers (63 miles) of Io's volcanic surface.
At about 13:41 Universal Time (5:41 a.m. Pacific time)
today, the spacecraft detected a computer reset, which caused
Galileo to enter a so-called "safe" mode. In this mode,
onboard fault protection software instructs the spacecraft
cameras and science instruments to stop taking data and places
them in a safe state awaiting further instructions from the
ground. The situation is similar to some that occurred in
previous orbits and appears to result from the radiation
environment near Jupiter.
Engineers remain hopeful that they'll be able to restore
functioning by transmitting new commands to Galileo to restore
data collection, Theilig said.
The path of today's encounter was chosen to use Io's
gravity to put Galileo on course to send it plunging into the
crushing pressure of Jupiter's atmosphere in September 2003.
Galileo is running low on the propellant needed to steer the
spacecraft and keep its antenna pointed toward Earth. The
intentional collision course with Jupiter was chosen as a way
to end the mission before losing control of the spacecraft.
Additional information about the Galileo mission is
available at http://galileo.jpl.nasa.gov .
Galileo was launched from the Space Shuttle Atlantis on Oct.
18, 1989. After a long journey to Jupiter, Galileo began
orbiting the huge planet on Dec. 7, 1995, and successfully
completed its two-year primary mission in 1997. That has been
followed by three mission extensions. JPL, a division of the
California Institute of Technology in Pasadena, manages the
Galileo mission for NASA's Office of Space Science, Washington,