With hopes raised for a successful last mission, especially after the Columbia space shuttle disaster earlier this year, National Aeronautics and Space Administration technicians are on tenterhooks as Galileo begins its final descent.

The Galileo space probe, running low on fuel, is due to disintegrate in Jupiter's atmosphere at 1947 GMT Sunday. That will enable the probe to beam rare data back to Earth in its last minutes.

One measurement NASA is particularly keen to get could confirm whether rocky debris orbits Jupiter.

However, the craft will have only minutes to take such readings before it bursts into Jupiter's deeper atmosphere at 48.2 kilometers (30 miles) per second.

"It has been a fabulous mission for planetary science, and it is hard to see it come to an end," Claudia Alexander, Galileo project manager at NASA's Jet Propulsion Laboratory, in California, said earlier this week.

"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."

"This is a very exciting time for us as we draw to a close on this historic mission and look back at its science discoveries. Galileo taught us much about Jupiter but there is still much to be learned and for that, we look with promise to future missions," Charles Elachi, director of the JPL, said recently.

Galileo, which has circled Jupiter 34 times, is now being purposefully plunged into its atmosphere rather than risk a collision with Europa, one of Jupiter's four principal moons.

One of Galileo's discoveries was that Europa likely has a subterranean ocean. NASA technicians feared that Galileo could contaminate that ocean with microbes carried from Earth if it collided with Europa, and thus affect a potential source of life and future scientific discovery.

Galileo was named after 17th Century Italian astronomer Galileo Galilei, who discovered Jupiter's four key moons. The probe also discovered oceans on Ganymede and Callisto as well as volcanic activity on Jupiter's fourth moon, Io.

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

It was also the first spacecraft to directly measure with a probe the atmosphere of Jupiter, the largest planet in the Earth's solar system, and was the first to carry out long-term observations from orbit.

SPACE.WIRE