At 1949 GMT, Galileo will burn up from friction as it falls through the atmosphere of largest planet of the solar system.

"After traversing almost three billion miles and being our watchful eyes and ears around Jupiter, we're keeping our fingers crossed that, even in its final hour, Galileo will still give us new information about Jupiter's environment," said Claudia Alexander, director of the Galileo project at the Jet Propulsion Laboratory in Pasadena, California.

"We expect to be collecting science data all the way in," she said Wednesday at a press conference at the headquarters of the National Aeronautics and Space Administration.

At 1942 GMT, seven minutes before its breakup, the probe will send its last dispatch, she said.

"The remaining few minutes of the craft will be spent in darkness, and alone," NASA said on its Web site. "It will rapidly burn up through friction with the atmosphere."

During its 34 fly-bys of the four principal Jupiter moons, Galileo discovered evidence of underground oceans on Europa, Ganymede and Callisto and examined volcanic activity on Io.

Scientists are particularly interested by in the subterranean ocean on Europa, which is covered with a thick pack of ice. They wonder, in particular, about the thickness of the ice.

The presence of water suggests the possibility that some form of life could exist on Europa.

For that reason, NASA decided to prevent Europa's possible contamination with microbes that Galileo may be carrying.

"In order to make sure we do not contaminate that potential source of life, we will vaporize the Galileo spacecraft," said Colleen Hartman, director of NASA's Solar System Exploration Division.

The breakup is necessary because the probe is almost out of fuel, and without fuel it could not be controlled.

Galileo, launched in October 1989, arrived at Jupiter in December 1995. It took about 14,000 pictures during its lifetime, and was the first spacecraft to pass near an asteroid and the first to discover a moon of an asteroid.

The probe's long voyage followed a complex trajectory which enabled it to benefit from the gravitational pulls of Venus and the Earth, and fly over asteroids Gaspra and Ida.

Given the wealth of information collected by Galileo, the US space agency is already preparing a new Jupiter probe.

"Three icy moons, Ganymede, Callisto and Europa, which may harbor subsurface oceans, will be investigated with a new mission that we have already begun to study, Jupiter Icy Moons Orbiter," said Hartman.

She said the orbiter will have "a hundred times more power than Galileo, and will be able to orbit into these moons and investigate the possibility of life on them."

The new probe is expected to be launched in the next decade.

SPACE.WIRE