Life saver? The spacecraft Galileo will plunge into Jupiter's atmosphere to protect Europa (left). Credit: NASA

A US National Academy of Sciences panel last week endorsed plans to send NASA's Galileo spacecraft on a suicide mission into Jupiter's atmosphere. The move is a bid to avoid contaminating the planet's potentially life-harbouring moons, in particular Europa.

At the same time, the Committee on Planetary and Lunar Exploration, part of the academy's Space Studies Board, agreed to get as much science as possible out of the spacecraft before its navigation systems fail. Galileo was originally launched in 1989 and has been orbiting Jupiter since 1995.

The spacecraft is scheduled to complete a series of fly-bys of Io, one of Jupiter's moons, delaying the craft's destruction by a year. But this is not thought likely to increase the chance of an accidental crash into Europa. Some believe that this moon has a liquid ocean under its ice crust that could contain simple life-forms. Any terrestrial organisms still alive on Galileo could potentially contaminate the moon.

“The probability of total loss of control during this extra year is relatively small,” concludes the report. “Moreover, the chances of total failure can be mitigated by prudent monitoring of the spacecraft's health and by a commitment on the part of NASA to retarget Galileo onto a Jupiter-bound trajectory following the loss of redundancy in any major command and control subsystem.”