Mars rovers to rove into September, without worry about 'fare'

A false-color image looking toward the rover Spirit's long-term target, the Columbia Hills, about 2.5 kilometers distant. The journey will establish the benchmark for long-distance driving on Mars, taking the vehicle one to two months to complete. NASA/JPL/Cornell

By David Brand

The two Mars rovers, Spirit and Opportunity, which bounced down on the Martian surface in January, will continue to roam their areas of the red planet until at least mid-September, a considerable extension of the mission that originally was planned for only 90 days. NASA has approved a budget of $15 million to make the longer mission possible.

Cornell astronomy professor Steven Squyres, who is leading the science team in charge of the science instruments and cameras carried by the two rovers, says that it's impossible to say how long the mission will last. "We have begun to realize that the power system on the rover, which could have been a limiting factor, is likely to hold out for a very long time. If power isn't the limiting factor, then something else will be," he said. "It could be that electronic parts will fail, or that mechanisms will wear out, and that sort of thing is very difficult to predict. What is important about the extension of the mission by NASA is that it means that the limiting factor will not be having the funding run out." The mission's original cost was $820 million.

Squyres

Speaking at a press briefing at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., April 8, Mars exploration manager Firouz Naderi said the mission could be extended even beyond September. "If we do have healthy rovers at the end of September, we will entertain another extension," he said.

As Naderi spoke, the rover Spirit was heading towards its long-term target, dubbed Columbia hills, about 2.5 kilometers (1.5 miles) away, a journey that will establish the benchmark for long-distance driving on Mars, taking the vehicle one to two months to complete. New auto-navigation software downloaded by the rovers' computers in recent days will add 20 to 22 meters (66 to 72 feet) a day to the rovers' current daily range.

Each rover was given a "success criteria" for the mission -- a sort of Martian "warranty" period -- of operating on the planet for 90 days and traveling 600 meters (1,969 feet). On April 3 and 5, Spirit, which landed in Gusev crater on Jan. 3, met the "warranty" requirements, setting a short-lived record for Martian driving with a single-day's driving distance of 50.2 meters (165 feet) that pushed the odometer total to 617 meters (2,024 feet).

Two days later, Opportunity shattered that mark with a 100-meter (328-foot) drive. Opportunity, which landed three weeks after Spirit, on Jan. 24, on the opposite side of Mars in Merediani Planum, will complete its "warranty" period when it finishes a 90th Martian day of operations April 26. A Martian day, or "sol," is 39 minutes and 35 seconds longer than an Earth day.

The mission extension more than doubles exploration for less than a 2 percent additional investment, if the rovers remain in working condition, NASA officials said.

Spirit is heading to the hills in pursuit of further geological evidence that water once flowed on Mars -- one of the seven objectives for the extended mission. Opportunity has a parallel objective: to seek geologic context for the rocky outcrop in its landing-site area, Eagle crater, by reaching other outcrops in Endurance crater 750 meters (2,460 feet) distant, and perhaps elsewhere.

Other science objectives are to continue atmospheric studies at both sites to encompass more of Mars' seasonal cycle and to calibrate and validate data from Mars orbiters for additional types of rocks and soils examined on the ground.

Three new engineering objectives are to traverse more than a kilometer (0.62 mile) to demonstrate mobility technologies, to characterize solar-array performance over long durations of dust deposition at both landing sites, and to demonstrate long-term operation of science robots on another planet.

During the past two weeks, rover teams at JPL, which include several researchers from Cornell, have been switching from living on Mars time to regular Pacific time schedules. The changeover is designed to be less stressful and more sustainable over the longer mission period.