Jupiter probe dodges moon, resumes mission

Galileo spied the volcanic region of Culann Patera during an earlier pass over Io.

By Richard Stenger
CNN Sci-Tech

(CNN) -- The Galileo spacecraft resumed normal operations on Friday, the day after it unexpectedly shut down while darting dangerously close to Jupiter and its most volatile moon.

The aging robot ship dove within 62 miles (100 kilometers) of Io on Thursday during its final and closet flight over a large jovian satellite.

The orbiter was to take a series of pictures of the volcano-riddled moon, but during the approach, which brought it perilously close to the radiation belts of Jupiter, it suddenly went into safe mode and turned off its instruments.

"At this time we think the problem resulted from the radiation environment near Jupiter," said NASA mission scientists in a statement on Friday.

The glitch prevented Galileo from making scientific observations as it passed directly over Io. Afterward, flight engineers coaxed the ship to recover in time to squeeze out some last-minute research.

This weekend, the orbiter should snap a picture of the small moon Amalthea, which it is scheduled to visit in November; take its final picture of the icy moon Europa, on the side that faces Jupiter; and focus on Jupiter, particularly on chaotic storm clouds near the Great Red Spot.

Launched in 1989, the $1.4 billion robot ship has spotted an asteroid with a moon, a comet striking Jupiter and dozens of molten cauldrons on Io, the most volcanic body in the solar system.

Galileo has taken more than 10,000 images, many documenting puzzling and stunning features on Io, Europa and the other major jovian moons, Ganymede and Callisto.

Among its achievements: providing convincing evidence that Europa possesses a deep saltwater ocean under its frozen exterior.

Jagged ridges of Callisto resemble nothing Galileo has seen on other jovian moons.

One year ago, the vessel took part in an unprecedented collaboration, conducting joint observations with the Saturn-bound Cassini probe during its brief stopover in the Jupiter system.

Despite the Thursday glitch, mission engineers achieved their main objective with the Io flyby, pushing Galileo along on an orbital path that will eventually lead to its destruction.

An inhabitant of the Jupiter system for six years, the NASA probe has survived four years longer than expected, endured more than three times the radiation it was designed to withstand and has nearly exhausted its fuel supply.

The finale is expected in September 2003, when it will plunge into the crushing atmosphere of Jupiter. The suicide run is to ensure the probe does not strike and contaminate Europa, which scientists speculate could harbor microbial life.