A spaceship capable of detecting the first signs of life on Mars was this weekend being prepared for the final course corrections before its touchdown on the red planet.

Nasa’s Mars Phoenix lander has travelled 420m miles and now has just 2m miles and a few final course adjustments to go before it reaches Vastitas Borealis near the Martian north pole on May 25.

The site was chosen after months of careful prospecting by spacecraft such as Mars Odyssey, which used a gamma ray spectrometer to see if there was water underneath.

Alhough the mission is run by Nasa, British scientists have been closely involved in many key instruments for the most sophisticated science package sent to Mars.

“We are sending them to an area where there is likely to be ice below the surface,” said Peter Smith, professor of planetary science at the University of Arizona and the mission’s principal investigator. “We want to understand the relationships between the water under the ground and in the atmosphere and how water moves from one to the other.”

The details of how water behaves on Mars will be crucial to discovering whether it has ever harboured life. “We may find signs of life but a lot will depend on the nature of the evidence,” Smith said.

For Nasa, however, the biggest question of all is whether the Phoenix will reach the surface safely.

Its landing system will use descent engines for a controlled touchdown rather than making an airbag-cushioned landing.

This method allows for a larger payload of instruments but is more prone to failure and has seen serious losses. It has not been used successfully on Mars since 1976.

If it does make it to the surface, the Phoenix will start by deploying an 8ft arm to dig through the soil to ice believed to lie 3ft down.

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