'NASA probe for clues of life in Mars'

Cape Canaveral, Fla, Aug 3: A NASA probe that will analyze Mars for water and other chemicals needed for life is on track for launch aboard an unmanned Delta rocket on Saturday, NASA officials said.

The Phoenix spacecraft, which will take nine months to reach Mars, is designed to land in the planet's northern polar region and dig into the frozen soil for samples to analyze.

Launch is targeted for 5:26 a m (1456 IST) tomorrow from Cape Canaveral Air Force Station in Florida.

''The launch team is ready,'' NASA launch director Chuck Dovale said in a news conference at the Kennedy Space Center yesterday.

Rain storms have plagued launch preparations but there was an 80 per cent chance of good weather tomorrow, said Air Force meteorologist Joel Tumbiolo.

Any delays could affect NASA's plans to launch the space shuttle Endeavour on Tuesday on a construction mission to the International Space Station.

Earth and Mars will be aligned for Phoenix's launch only until August 24. After that, the planets with take another 26 months to get back into a favorable position.

The mission's primary goal is to ascertain if Mars is, or ever was, suited for life to develop. Previous Mars probes, including the two rovers Spirit and Opportunity, have found geologic and chemical evidence of past water, but did not have the tools for in-depth analysis.

Instead of roaming the planet's surface, Phoenix will zero in on a target zone and scrutinize the terrain on a molecular level. Scientists are particularly interested if organic molecules are present.

The lander has several instruments to analyze soil content, including eight tiny ovens to heat pinches of soil to about 1,800 degrees Fahrenheit. Gas analyzers will then sniff the vapors to determine what chemicals are present.

''If we do find organic molecules, we won't be able to say that they definitely came from life in the past,'' said University of Arizona researcher William Boynton, a lead investigator for one of Phoenix's seven science instruments.

Organic material may have been delivered to Mars by meteorites, for example.

''We really aren't going there to identify life or look for past life,'' Boynton added. ''We're going there to really understand whether conditions were right for life.'' Phoenix's samples will be delivered for analysis inside the lander by a 7.7-foot robotic arm that can burrow through the soil to an ice layer just below the surface.

Scientists feel the best chance to discover if conditions were suitable for microbial life is to look underground, which offers some protection from the harsh radioactive environment.

Phoenix also sports an advanced digital imaging system and a meteorological station built by the Canadian Space Agency.

Scientists are eager to verify remote observations of what appear to be massive amounts of water ice around the planet's polar regions. Before Phoenix can find the answers, however, it has to reach the surface, a tricky maneuver that has doomed about 50 percent of past Mars probes.

Phoenix will use a heat shield, parachutes and thruster rockets to reach the planet's surface. Touchdown is expected on May 25, 2008.

Reuters>