Rover missions extended again as Mars emerges from behind Sun

This map shows the traverse of NASA's Mars Exploration Rover Opportunity through the rover's 205th martian day, or sol (Aug. 21, 2004).

Both rovers successfully completed their primary three-month missions on the surface of Mars in April and have already added about five months of bonus exploration during the first extension of their missions.

Neither rover drove during a 12-day period this month, while radio transmissions were unreliable because of the Sun's position between the two planets. Daily planning and commanding of rover activities recommenced Sept. 20 for Opportunity and Sept. 21 for Spirit.

"Although Spirit and Opportunity are well past warranty, they are showing few signs of wearing out," said Jim Erickson, project manager for both rovers at NASA's Jet Propulsion Laboratory. "We really don't know how long they will keep working, whether days or months. We will do our best to continue getting the maximum possible benefit from these great national resources."

Rover science team members will spend less time at JPL during the second mission extension. They are able to attend daily planning meetings by teleconferencing from their home institutions in several states and in Europe. Workstations researchers used at JPL are at their home institutions. Planning tools include video feeds, workstation display remote viewing, and audio conferencing.

"Before, the way it worked was that they would just walk around ant talk to everybody [and decide what the rover would do the next day]. Now that's all done by telephone and video conference and e-mail." explained Jonathan Joseph, a member of the PanCam team headed by Cornell professor of astronomy Jim Bell. Once research plans for a day are set, Cornell team members program the panoramic cameras on the rovers. These commands and those for other instruments are uploaded to Mars by engineers at JPL.

Besides reducing costs, remote operations allow scientists to spend more time at home. "We get back to more normal lives, back to our families, and we still get to explore Mars every day," said Dr. Steve Squyres, Cornell professor of astronomy and leader of the science team.

The complete traverse of NASA's Mars Exploration Rover Spirit through the rover's 238th martian day, or sol (Sept. 3, 2004).

It is also Martian winter, when less solar energy is available to recharge the rovers' batteries, so another change in operations is a shift from seven days per week to five days per week from October through December. The rovers' reduced energy supply during the rest of the Martian winter makes the inactive days valuable for recharging batteries. By January, the energy situation will have improved for the solar-powered rovers, provided they are still operating.

As Mars emerges from behind the Sun, Spirit is partway up the west spur of highlands called the "Columbia Hills," a drive of more than 3 kilometers (2 miles) from its landing site. Opportunity is inside stadium-size "Endurance Crater," headed toward the base of a stack of exposed rock layers in "Burns Cliff," and a potential exit route on the crater's south side.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Science Mission Directorate, Washington.

Compiled from NASA and local reports.

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