Mars lander faces biggest challenge so far

LOS ANGELES, California (AP) -- Scientists troubleshooting the Phoenix lander said Monday that they will try one last shake to get a scoopful of Martian dirt inside a tiny oven in hopes of jump-starting their study of Mars' north pole region.

Phoenix's first science experiment to heat the permafrost soil was delayed after it was discovered that virtually none of it passed through a screen to reach a miniature oven.

The oven is one of eight aboard the spacecraft that will heat soil and sniff the resulting vapors for signs of life-friendly elements.

"This soil is very cohesive, and it's very hard for it to get through the screen," said mission scientist William Boynton of the University of Arizona in Tucson, who is in charge of the oven experiment.

If shaking the oven doesn't work, scientists will try sprinkling dirt through the opening of a new oven or using the lander's 8-foot robotic arm to grind up the dirt first.

It's the biggest challenge faced by Phoenix since landing in the Martian arctic May 25 on a three-month mission to study whether the environment could be habitable for alien life.

Boyton said he was initially more concerned that the robot wouldn't collect enough soil, not its density.

"To be honest, we never thought it would be working so well that we'd have to worry about a riches of just too much," he said. "Now that we see the nature of that soil ... we really are much better off with very small amounts of soil."

Phoenix's single-use ovens are among several instruments that will investigate whether the Martian northern plain has the chemical building blocks of life. The lander cannot directly detect fossils or living things.

In the meantime, Phoenix grabbed another scoopful of soil and planned to deliver it to its microscope this week.

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