MIAMI, Aug 9: Nasa prepared an unmanned spacecraft for launch to Mars on Thursday on a quest to learn whether Earth’s neighbouring planet had water long enough to nurture life.

Previous Mars missions have shown that water once flowed across the planet’s surface. Scientists hope data from the Mars Reconnaissance Orbiter will tell them where and for how long Mars had water, whether it ever had life and whether it could support a human outpost.

The two-ton orbiter was earlier scheduled for launch on Wednesday from Cape Canaveral, but weather conditions forced the postponement.

Weather official had however forecast favourable conditions with only a 20 per cent chance that isolated showers would cause a delay, Air Force weather officer Clay Flinn said.

The 21-foot (6.5-meter) spacecraft will ride aloft on a Lockheed Martin Atlas V rocket and is scheduled to reach Mars in March 2006. Using the friction of the planet’s upper atmosphere as a brake, it will slowly dip into a low orbit about 190 miles above the surface of Mars, Nasa said.

Beginning in November 2006, the Mars orbiter will use an array of scientific instruments to zoom in for close-up photos of the Martian surface, analyze mineral deposits, search for subsurface water and shorelines of ancient seas, trace dust and water distribution in the atmosphere and monitor the planet’s weather through a full cycle of Martian seasons.

Previous Mars probes have literally only scratched the surface, project manager Richard Zurek told journalists during a teleconference.—Reuters