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NASA tries to revive Jupiter probe
By Richard Stenger
(CNN) -- After a daring dive into the radiation belts of Jupiter knocked out Galileo, NASA engineers were to send up radio commands Friday in an attempt to wake the aging probe gently. The $1.4 billion craft, conducting its final scientific mission, went into "safe mode" Tuesday as it flew within 44,500 miles [71,500 km] of Jupiter's visible cloud tops. Mission technicians plan to beam transmissions in the coming days to begin diagnosing Galileo's onboard systems and slowly revive the craft from its slumber. "It's sort of incremental as far as getting it back into operational condition," said Guy Webster, a spokesman for NASA's Jet Propulsion Laboratory, which manages the Galileo project. The Pasadena, California-based lab was to begin the long-distance diagnostic tests Friday "but will not try to get it back into normal operations until Wednesday next week at the earliest," Webster said. Galileo shuts down automatically when faced with high radiation levels, a reflexive response called "safe mode" that is intended to protect its sensitive electronics. The bus-sized craft has survived about four times the radiation it was designed to endure during its seven-year stay around Jupiter. It has entered safe mode during other dives into the turbulent, radioactive environment near the king of planets. JPL technicians have always revived the $1.4 billion probe, but its current slumber is much deeper than previous snoozes. The dip subjected it to twice as much radiation as any previous descent. "This was a series of safety triggers, so it may take longer (to wake up). There were three different safing events that happened in rapid succession," Webster said.
The dangerous dive was intended to squeeze out final data about Jupiter's magnetosphere, inner rings and a tiny inner moon before the craft ceased scientific operations. "We knew this would be a challenging encounter for Galileo, so we are not surprised to have some things go awry," said Eilene Theilig, Galileo project manager. During its descent Tuesday, the robot ship flew within 100 miles (160 km) of Amalthea, an oddly shaped satellite about 155 miles (250 kilometers) long. Now receding from Jupiter and safely outside the radiation belts, Galileo, should it be restored, will send back data from this week's mission during the next two months. Whether it wakes or not, the spacecraft will remain on a collision course with Jupiter. The death dive in 2003 will ensure that it does not strike and contaminate the large Jovian moon Europa, which scientists think could harbor microbial life.
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