Galileo bows out in blaze of glory

The Galileo mission came to a spectacular conclusion on Saturday as the space probe was crashed into Jupiter at around 108,000 mph.

The spacecraft had been purposely put on a collision course with Jupiter to eliminate any chance of an unwanted impact between the spacecraft and Jupiter's moon Europa, which Galileo discovered "is likely to have a subsurface ocean".

The long-planned impact was necessary as the onboard propellant was nearly depleted. Without propellant, the spacecraft would not be able to point its antenna toward Earth or adjust its trajectory, so controlling the spacecraft would no longer be possible.

Speaking ahead of the impact, Dr Claudia Alexander, Galileo project manager at NASA's Jet Propulsion Laboratory, said: "It has been a fabulous mission for planetary science, and it is hard to see it come to an end.

"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."

Although scientists are hopeful to get every bit of data back for analysis, the team said that the likelihood of getting anything is unknown because the spacecraft has already endured more than four times the cumulative dose of harmful Jovian radiation it was designed to withstand. The spacecraft will enter an especially high-radiation region again as it approaches Jupiter.

Launched in the cargo bay of Space Shuttle Atlantis in 1989, the mission has produced a string of discoveries while circling the solar system's largest planet, Jupiter, 34 times. Galileo was the first mission to measure Jupiter's atmosphere directly with a descent probe and the first to conduct long-term observations of the Jovian system from orbit.

It found evidence of subsurface liquid layers of salt water on Europa, Ganymede and Callisto and it examined a diversity of volcanic activity on Io. Galileo is the first spacecraft to fly by an asteroid and the first to discover a moon of an asteroid.

The prime mission ended six years ago, after two years of orbiting Jupiter but NASA extended the mission three times. The mission was possible because it drew its power from two long-lasting radioisotope thermoelectric generators provided by the Department of Energy.

From launch to impact, the spacecraft has travelled 4,631,778,000 kilometres - about 2.8 billion miles.

(gmcg)