Christmas on Mars

Scientists are dreaming of a white Christmas on Mars once this latest robotic explorer is launched next August on a nine-month voyage to the Martian Arctic. The Phoenix lander will touch down near the north polar cap of Mars during the Arctic summer in May of 2008, but engineers hope it will survive long enough to take spectacular photographs as it is buried under two metres of snow during the onset of the Arctic winter.

There are many ways in which a planetary spacecraft can end its life – burning up in the atmosphere, crashing onto an alien surface, drained of battery life or even sinking beneath the Atlantic Ocean in a failed launch attempt. But this will be the first time in history that a robot has been buried up to its antenna mast in snow.

Mars is a cold desert planet with no liquid-water on its surface, but in the Martian Arctic water-ice lurks just below the surface. America's Mars Odyssey has discovered vast amounts of sub-surface water-ice in the northern Arctic plain. The Phoenix lander will touch down in this circumpolar region and use a robotic arm to dig through the top layers of soil to the water-ice beneath. It will then bring both soil and water-ice to the lander platform for sophisticated scientific analysis.

According to the ancient Greeks, the phoenix lives in Arabia, near a cool well, and sings a beautiful morning song. It lives 500 years or longer with only one phoenix existing at any time. When the bird's death approaches it bursts into flames and a new bird springs from the pyre.

This Phoenix mission “raises from the ashes” of two previous unsuccessful attempts to explore the Red Planet: the Mars Polar Lander (MPL) and the Mars Surveyor 2001 Lander. MPL disappeared without trace over the Martian Antarctic in December 1999, and Mars Surveyor was mothballed as a result until scientists at the University of Arizona's Lunar and Planetary Laboratory suggested the Phoenix project.

The mission is a partnership of universities from the US, Canada, Switzerland and Germany; America's space agency (Nasa); the Canadian Space Agency; and private industry. The $325m NASA contract is more than six times larger than any other single research grant in the history of the University of Arizona.

According to its chief scientist, Peter H Smith, Phoenix has the potential to change the way we think about the origins of life on other worlds. Even though the northern plains of Mars are thought to be too cold now for water to exist as a liquid, periodic variations in the Martian orbit allow a warmer climate to develop every 50,000 years. During these periods the ice can melt, dormant organisms could come back to life (if they exist) and evolution could proceed.