MARS:IN A series of manoeuvres that sounds more like cooking class than research on Mars, scientists said yesterday they would try one more time to shake bits of the clumpy Martian soil into a test oven on Nasa's Phoenix lander before switching to a backup strategy that calls for dribbling the soil into the oven.
Scientists so far have failed twice to inject soil from the Martian north pole into one of eight tiny ovens that are designed to test for organic compounds that would prove Mars's suitability for life.
The problem is, the opening to the oven is about the thickness of a pencil lead. The Martian soil is proving to be much clumpier - cemented, in scientific terms - than expected.
Late last week, the lander's nearly 8ft-long robotic arm dumped a cup full of soil on top of oven No 4, but none of the particles fell through the guard screen and into the oven.
Over the weekend, the science team at the University of Arizona and the Jet Propulsion Laboratory in La Canada Flintridge, California, ordered the instrument containing the ovens, the Thermal Evolved-Gas Analyser, to shake the soil to try to break it up.
That didn't work either. Images beamed down from the site where Mars landed on May 25th showed that the shaking had shifted the mound of soil. While a few tiny particles fell into the oven, the sample was too small to test, William Boynton, the lead scientist for the instrument, said.
The clumpiness could be caused by any one of several factors, including the presence of water. Ice is thought to lie only inches below the lander. Another condition that could cause soil adhesion is the presence of salts in the dirt, possibly laid down millions of years ago when liquid water flowed on the surface of Mars.
At a media briefing yesterday at the University of Arizona, Mr Boynton said it was too soon to start worrying that the instrument, one of the key elements of the $420 million mission, would not be able to do its job.
The scientists now think the robotic arm simply delivered too much soil in too big a lump.
Mr Boynton said the science team will try again to shake the soil into the oven before switching to a strategy of dribbling the soil out in a narrow stream.
The problem with the oven is the latest glitch to delay the mission. Ideally, Mr Boynton said, by now they would have completed the first analysis of the Martian surface and be well on the way to digging into the ice layer.
Unlike Nasa's twin Mars rovers, Spirit and Opportunity, which are in their fourth year of operation, Phoenix is designed to last only three months. - (LA Times-Washington Post service)