On Thursday, Spirit's main assignment is to brush off an area on the rock nicknamed "Adirondack" to prepare for a dust-free examination of its surface. On Friday, controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., plan to have Spirit grind off a small patch of Adirondack’s outer surface and inspect the rock's interior. Spirit may start driving over the weekend toward a crater about 250 meters (about 270 yards) to the northeast.
For Opportunity, halfway around Mars from Spirit, controllers changed plans Thursday morning. They postponed a trenching operation until the rover gets to an area of its landing-site crater where the soil has a higher concentration of large- grain hematite. That mineral holds high interest because it usually forms under wet conditions. The main science goal for both rovers is to find geological clues about past environmental conditions at the landing sites, especially about whether conditions were ever watery and possibly suitable for sustaining life.
Instead of trenching, Opportunity will be commanded after it next wakes up to drive about 1.5 meters (about 5 feet) farther, possibly to within arm's reach of one of the rocks in the exposed outcrop.
Before it began driving on Wednesday, Opportunity finished using its alpha particle X-ray spectrometer for the first time. This spectrometer, which assesses what chemical elements are present, took readings on an area of soil that the rover had previously examined with its microscope.
Each martian day, or "sol," lasts about 40 minutes longer than an Earth day. Spirit begins its 34rd sol on Mars at 3:22 a.m. Thursday, Pacific Standard Time. Opportunity begins its 14th sol on Mars at 3:43 p.m. Friday, PST.
JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Office of Space Science, Washington, D.C. Images and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu.