Mars Rover Digs In for Water Hunt

In its first attempt to see what lies immediately below the Martian surface, NASA’s Opportunity rover spun one of its front wheels in place to excavate a shallow trench near the rock outcropping called Opportunity Ledge.

“We dug a nice big hole on Mars,” said engineer Jeffrey Biesiadecki.

The team at NASA’s Jet Propulsion Laboratory in Pasadena is attempting to determine whether the iron-rich hematite, which led them to choose the Meridiani Planum area as a landing site, lies only in a thin surface layer, or extends much deeper into the soil.

Hematite is often formed in large bodies of water, and understanding how much of it is present at Meridiani and how it got there will help geologists determine whether large quantities of water ever existed on the surface of the now-barren planet.

The trench is a little over 4 inches deep at its deepest point and about 20 inches long, said Cornell University geologist Rob Sullivan. “It came out deeper than I expected,” he said. The trenching took about six minutes of wheel spinning, with stops for picture taking.

So far, the team has characterized the soil only superficially. Along the top of the trench, Sullivan said, the soil is “clotty” and rather coarse. “This is not like the sand in an hourglass.” The soil thrown out of the trench by the rover’s wheel is also brighter than the surface soil, he added.

The team will spend the next day or two studying the subsurface soil before moving on to the spot on the outcrop known as El Capitan. Opportunity, which landed on Mars on Jan. 24, will examine the finely layered rock at that location.

Halfway around Mars at Gusev Crater, the Spirit rover has been slowly making its way to the crater nicknamed Bonneville, stopping frequently along the way to look more closely at the soil and interesting rocks.

Spirit, which landed on Mars on Jan. 3, has now traveled about 356 feet, breaking the unofficial record of 337 feet traversed by the Sojourner rover in 1997. The craft has almost 800 feet to go to reach the rim of Bonneville. The team expects it to reach the crater in 16 days, unless it stops for more science along the way.