Martian soil proves difficult to process

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’ 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 8-ft-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 Analyzer, to shake the soil in an attempt to break it up.

That didn’t work either. Images beamed down from the site where Mars landed May 25 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, according to William Boynton, the lead scientist for the TEGA instrument.

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 on Monday at the University of Arizona, Boynton said it is 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.

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 in a series of glitches that have set back the mission’s time line. Ideally, Boynton said, by now they would have completed the first analysis of the Martian surface and would 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.

When winter arrives, the lander will be covered in carbon dioxide ice. Without the sun to charge its batteries, the lander will expire before the next spring arrives.
-John Johnson Jr. (LAT-WP)