SCIENTISTS yesterday hailed the discovery of water ice on Mars as a major breakthrough in the search for life on the planet.
The find, by Nasa's Phoenix probe, brought them a step closer to being able to say whether organisms could have existed on Mars.
Dr David Catling of the University of Bristol is among the 36-strong team of researchers assessing the probe's results
from a base in Arizona.
"It's really exciting," he said. "Wherever you find liquid water on Earth, you also find life in some form.
"It doesn't matter if it's tiny pockets of sea water in ice or if it's close to boiling point in some volcanic vent, there will be molecules living."
He said the team was examining whether the ice could have taken liquid form at any stage in the past.
The probe touched down on May 26 and has since used its eight-foot-long robot arm to dig trenches in the Martian soil.
Satellite scans had previously indicated the presence of the ice under the surface, near its north pole.
Mission controllers became excited when the excavation exposed chunks of white material last Sunday.
It was still present the following day, but was confirmed as ice four days later when it had vaporised.
Scientists say the disappearing chunks could not have been carbon dioxide ice, which would not have been stable for even one day as a solid.
Scientists will now use a range of instruments to determine whether organic compounds are present that could provide the building blocks of life.
The probe is designed to look for conditions which might be suitable for life, but is not equipped to find evidence of life itself.
Dr Catling, from Bristol's Earth Sciences department, is looking at the way the Martian polar weather interacts with the ground surface.
It is believed that during the northern summer, water vapour is driven off ice at its polar cap and enters the atmosphere. He said: "Most people think life on Mars would be pretty difficult today because of the cold and dry nature of the planet.
"But in ice we have found one substance in which signs of life could be preserved."
The ice was in a trench to the north-west of the lander.
More hard material, possibly more ice but darker in colour, has been detected in a second trench on the probe's north-east side.
Scientists are to direct Phoenix to collect and analyse surface soil from a third trench near the second one, and later to probe and sample the hard layer.
The full article contains 436 words and appears in Scotland On Sunday newspaper.
