Comet-bound probe passes Mars

A European Space Agency probe bound for a distant comet successfully passed within 250 kilometres of Mars over the weekend.

The Rosetta space probe used Martian gravity to adjust itscourse and slow its speed en route to Comet Churyumov-Gerasimenko.

The planetary flyby was a concern for the space agency because the probe would lose contact with ground controllers for 15 minutes as it passed behind Mars. The probe also had to rely solely on battery power instead of its solar panels for 25 minutes as it traversed a Martian solar eclipse.

The successful flyby is part of a 7.1-billion kilometre journey to the comet, a billion-euro project that began with the launch of the probe on March 2, 2004.

To correctly navigate a path to the comet, Rosetta will have passed Earth three times and Mars once. It firstpassed by Earth in 2005 and will pass the planet again later this year and in 2009.

The ultimate goal of the probe is to land on Churyumov-Gerasimenko in 2014 to analyze its surface.

Like the planets, comets are thought to have spun out of the sun during the formation of the solar system 4½ billion years ago. But unlike planets, comets have remained largely unchanged in composition, making them a unique time capsule of the process and elements at work during the formation of the planets.

NASA has crashed a probe into the comet Tempel 1 to study the dust and ice released during the collision. The Stardust spacecraft obtained dust samples from the Wild 2 comet by flying close by. But no spacecraft has ever attempted to land on a comet.