Spirit, the robot on wheels that reached the top of a Martian hill this summer after an epic climb, is heading back down toward its next target for exploration.

After two months at the summit of Husband Hill (search), the six-wheeled rover is descending to a basin where the scientific instruments it carries will examine an outcrop dubbed "home plate" because from orbit it looks like home on a baseball field.

Spirit's yearlong climb to the peak was a major feat for the Mars rover (search), which along with its twin, Opportunity, landed on opposite sides of the Red Planet in January 2004.

Last month, scientists released the first full-color panoramic photo of the landscape taken by Spirit from the 270-foot-high summit. It shows the rover's distinct tracks in the dust, the flat plains of the surrounding Gusev Crater region and distant plateaus on the crater rim.

Spirit also has been studying rocks and using its robotic arm to sift the soil to determine how the hill formed. The leading theory is that Husband Hill became uplifted as a result of crater impact.

Mission scientists say a comparison of the summit rocks reveal similar geologic features to those found on the side of the hill. In both cases, the rocks' makeup reveal they have been altered by water.

It will take about two months for Spirit to make it all the way down Husband Hill, which is named after Rick Husband, the commander of the space shuttle Columbia that broke apart as it was returning from Earth orbit in 2003.

Meanwhile, Opportunity is in good health again after recovering from a recent computer glitch while surveying the Meridiani Planum (search) region.

The rovers, operated by NASA's Jet Propulsion Laboratory in Pasadena, have long outlasted their primary, three-month missions.