Galileo Space Mission Hits Snag
JANE E. ALLEN
Jul. 23, 1998
LOS ANGELES (AP) _ The spacecraft Galileo has hiccuped again.
A computer subsystem aboard the unmanned craft turned itself off this week during a flyby of Jupiter's frozen moon Europa. Engineers, however, said they were confident of getting the mission back on track.
``We should be back in normal operations next week, including replaying the data we did take before this happened,'' said Jim Erickson, project manager for the Galileo Europa Mission at NASA's Jet Propulsion Laboratory.
Because of the glitch, the spacecraft lost all data collected Monday from its fifth near-pass of Europa, where scientists are aiming instruments in search of a suspected hidden ocean that could harbor life.
On Wednesday, the JPL team was ``just about to finish'' bringing back up the onboard command and data subsystem that shut itself off.
The subsystem, which is a network of three computers and hardware, went into ``safe mode'' Monday when it detected a problem during the pass within 1,141 miles of the moon.
A backup subsystem also detected a problem, but remained on. Ground controllers were able to receive basic data from the spacecraft.
``It looks like we've started to see a recurrence of something we thought was long gone,'' Erickson said. ``We had a series of about nine of these events where the spacecraft's main command and data subsystem would get an erroneous signal that it was getting a power-on reset,'' something like pushing a reset button on a personal computer.
The first time was shortly after launch; the most recent in 1993.
Erickson said the problem stems from electrical shorts in components called slip rings, caused by wear-and-tear on the metal, and that controllers probably will have to live with it.
The Galileo Europa Mission is scheduled to make three more near-passes of Europa, the next one on Sept. 26. Galileo, launched in 1989, arrived at Jupiter in December 1995 and completed its initial mission last year.