Engineers working on Galileo camera mystery

Composite picture of Jupiter and its four largest moons. From top to bottom, the moons shown are Io, Europa, Ganymede and Callisto

(CNN) -- Engineers may be close to solving a puzzling problem with a camera on NASA's Galileo spacecraft.

The probe -- launched October 18, 1989 on a mission to study Jupiter and its moons -- sent alarms to its controllers at NASA’s Jet Propulsion Laboratory three times as Galileo passed close to Jupiter from December 28, 2000, to January 1, 2001.

The alarms indicated the probe’s camera was malfunctioning. But JPL said that each time, the camera either fixed itself or was restored by commands from the ground.

Galileo had a similar problem 5 months earlier and both incidents may be due to the cumulative exposure of electronic components to intense radioactivity from Jupiter, said Dr. Eilene Theilig, Galileo project manager at JPL in Pasadena, California.

"We are able to clear the fault by power-cycling the instrument -- turning the power off and on -- and reloading its memory," said Theilig.

The fact that the camera can fix itself without our intervention is puzzling but provides valuable information to analyze what is happening," Theilig said.

Galileo already is working overtime. The spacecraft was designed to orbit Jupiter for 2 years. It arrived at Jupiter in December of 1995 and has endured more than three times the radiation it was designed to withstand.

Engineers have examined some of the camera data collected in late December. The samples indicate more than half of the 120 pictures taken during that period were properly captured, including all the ones taken December 28 as the spacecraft flew by the moon Ganymede during an eclipse.

In pictures taken when the camera was malfunctioning, the images appear over-exposed.

More images will arrive later this month. On May 25, Galileo is scheduled to fly by Jupiter's moon Callisto.

The spacecraft is named in honor of astronomer Galileo Galilei.

Spacecraft flyby paints new picture of Jupiter
December 30, 2000

Galileo Project

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