Mars probe digs into scientific preserve

NASA's Mars Phoenix Lander began digging a new trench in the "national park" region that the mission's scientists have been saving for science.

The first scoop of Mars dirt from the new trench, called Snow White, was excavated early Tuesday. While digging this pit, Phoenix's robotic arm did not reach the hard white material, possibly ice, that it exposed previously in the first trench it dug.

This was to be expected, scientists said, because the Snow White trench is near the middle of a polygonal-shaped region named Cheshire Cat where scientists think the white material would be buried under a thicker layer of the sand and dirt scientists call regolith.

Phoenix has been digging away since the $420 million spacecraft landed on Mars on May 25. So far it has found no liquid water in its first soil samples.

The Snow White trench is about three-quarters of an inch (2 centimeters) deep and about a foot (30 centimeters) long. The Phoenix team plans at least one more day of digging deeper.

In the future, scientists plan to dig another trench in the center of the Cheshire Cat polygon. They hope to study the soil structure of Snow White to decide how deep to collect samples in the next pit.

Phoenix's Thermal and Evolved-Gas Analyzer oven instrument is still working on baking previously collected soil samples to look for volatile ingredients, such as water.