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Problem Forces Galileo Spacecraft into Standby Mode
By SPACE.com Staff
posted: 05:15 pm ET
17 January 2002
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The Galileo spacecraft has an unknown problem and put itself into a standby mode Thursday while awaiting further instructions from ground controllers, NASA officials said. The $1.4 billion craft, which was approaching Jupiter's moon Io and preparing to take its final photographs, has been in space for seven years and returned many science findings. The images and other data planned for the Io flyby were not collected, and it was unclear late Thursday what the fate of the robotic probe might now be. "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 Eilene Theilig, Galileo project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "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," she said. Mission controllers are sending commands aimed at switching the spacecraft out of standby mode, or "safing" mode as it is also called, for the later portion of the planned encounter period, which lasts into Sunday. Galileo hit its intended flyby point which brought it to within 63 miles (102 km) of Io's volcanic surface. This flyby is the closest and last for Galileo at any of Jupiter's four major moons.One goal of the flyby was to put the craft on course for its grand finale, a September 2003 impact into Jupiter. The intentional collision course with Jupiter was chosen as a way to end the mission before losing control of the spacecraft, which is running low on fuel. At about 8:41 a.m. EST (1341 GMT) today, the spacecraft detected a computer reset and went into standby 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 they'll be able to restore normal spacecraft functioning by transmitting new commands to Galileo to restore data collection, Theilig said. 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.
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