Broken wheel unearths evidence of Martian water

NASA scientists have said a broken wheel on a space vehicle has helped them to find some of the strongest evidence yet that ancient Mars was much wetter than it is now and may have been able to support life.

Members of the Mars rover Spirit’s team discovered a patch of soil that was made up of about 90% pure silica — a composition that would have required the presence of water — after one of its six wheels stopped rotating and left a deep track as it dragged through the soil.

NASA scientists said yesterday it was a “remarkable” discovery “which continues to spur the hope that we can show that Mars was once habitable and possibly supported life”.

Spirit has already found other indicators of long-ago water at the site, such as patches of water-bearing, sulphur-rich soil, alteration of minerals and evidence of explosive volcanism, while exploring a low range of hills inside a basin named Gusev Crater.

Albert Yen, a geochemist at NASA’s Jet Propulsion Laboratory in Pasadena, California, said: “This is some of the best evidence Spirit has found for water at Gusev.”

One possible origin for the silica could have been interaction of soil with acid vapours produced by volcanic activity in the presence of water, a NASA spokesman said.

David Des Marais, an astrobiologist said: “What’s so exciting is that this could tell us about environments that have similarities to places on Earth that are clement for organisms.”

The Spirit, and its twin Opportunity, completed their three-month prime missions in April 2004, but continue to operate despite showing signs of age.