Jupiter probe back on track

Galileo has already provided images of Callisto

A Nasa space probe has completed its closest flyby of one of Jupiter's moons.

The spacecraft Galileo passed about 138 kilometres (86 miles) above the surface of Callisto, the second largest of Jupiter's 28 known moons.

This incredible spacecraft has come through for us again

Nasa's Eilene Theilig

The craft has made 30 previous flybys of the moons - taking pictures, measuring magnetic forces, and studying dust and smaller particles in clouds.

Nasa scientists say Galileo's camera system appears to be working again, after earlier problems.

Eilene Theilig, Galileo project manager at Nasa's Jet Propulsion Laboratory in Pasadena, California, said the camera appeared to be working well as it approached the heavily cratered moon.

"This incredible spacecraft has come through for us again," said Dr Theilig.

But she added that on Thursday the camera appeared to be malfunctioning and probably did not capture some intended images taken of another moon, Io, from a greater distance.

Mission exceeded

Nasa scientists operating the spacecraft are eager to capture as many images as possible.

But they say the spacecraft has more than fulfilled its mission, which was originally due to end in 1997.

Galileo has been orbiting Jupiter for more than five years and survived radiation exposure of more than three times what it was built to withstand.

We're proud that this workhorse of a spacecraft has kept performing well enough that we can ask it to keep serving science a little longer

Nasa's Jay Bergstralh

Its mission has previously been extended twice and during that time it has returned a wealth of scientific information, including evidence of a sub-surface ocean on Jupiter's moon Europa.

"We're proud that this workhorse of a spacecraft has kept performing well enough that we can ask it to keep serving science a little longer," said Jay Bergstralh, Acting Director of Solar System Exploration at Nasa headquarters in Washington, DC.

After three more encounters with Jupiter's moon Io and the small inner moon Amalthea, Galileo's mission will end in dramatic style.

In 2003, the spacecraft is due to plunge into Jupiter's dense atmosphere, descending through the thick clouds until the pressure crushes it out of existence.