Mars Rovers Resume Driving

After six weeks of hunkering down during raging dust storms that limited solar power, both of NASA's Mars Exploration Rovers, Spirit and Opportunity, have resumed driving.

Opportunity advanced 13.38 meters (44 feet) toward the edge of Victoria Crater on Aug. 21. Mission controllers were taking advantage of gradual clearing of dust from the sky while also taking precautions against buildup of dust settling onto the rover.

"Weather and power conditions continue to improve, although very slowly for both rovers," said John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif, project manager for the rovers. With the improved energy supplies, both rovers are back on schedule to communicate daily. Opportunity had previously been conserving energy by going three or four days between communications.

No new storms have been lifting dust into the air near either solar-powered rover in the past two weeks. Skies are gradually brightening above both Spirit and Opportunity. "The clearing could take months," said rover Project Scientist Bruce Banerdt. "There is a lot of very fine material suspended high in the atmosphere."

As that material does settle out of the air, the powdery dust is accumulating on surfaces such as the rovers' solar panels and instruments. More dust on the solar panels lessens the panels' capacity for converting sunlight to electricity, even while more sunlight is getting through the clearer atmosphere.

Opportunity's daily supply of electricity from its solar panels reached nearly 300 watt-hours on Aug. 23. That is more than twice as much as five weeks ago, but still less than half as much as two months ago. It is enough to run a 100-watt bulb for three hours.

One reason the rover team chose to drive Opportunity closer to the crater rim was to be prepared, if the pace of dust accumulation on the solar panels increases, to drive onto the inner slope of the crater. This would give the rover a sun-facing tilt to maximize daily energy supplies. The drive was also designed to check performance of the rover's mobility system, so it included a turn in place and a short drive backwards.

The next day, a favorable wind removed some dust from Opportunity's solar panels, providing a boost of about 10 percent in electric output. This forestalled the need to hurry to a sun-facing slope. The team is still excited to get Opportunity inside Victoria Crater to examine science targets on the inner slope that were identified in June, shortly before dust storms curtailed rover activities. An estimate of how soon Opportunity will enter the crater will depend on assessments in coming days of how dust may be affecting the instruments and of how much energy will be available.

On Spirit, dust on the lens of the microscopic imager has slightly reduced image quality for that instrument, although image calibration can compensate for most of the contamination effects. The team is experimenting with ways to try dislodging the dust on the lens. Spirit's solar arrays are producing about 300 watt hours per day as dust accumulation on them offsets clearing skies. Spirit drove 42 centimeters (17 inches) backwards on Aug. 23 to get in position for taking images of a rock that it had examined with its Moessbauer spectrometer. The rover team is planning additional drives for Spirit to climb onto a platform informally named "Home Plate."

Source: NASA

Related stories:

Phoenix probe lands on Mars (Update 4)
NASA's Phoenix spacecraft landed in the northern polar region of Mars Sunday to begin three months of examining a site chosen for its likelihood of having frozen water within reach of the lander's robotic arm.
Foot-dragging Mars rover finds Yellowstone-like hot spring deposits
Deposits of nearly pure silica discovered by the Mars Exploration Rover Spirit in Gusev Crater formed when volcanic steam or hot water (or maybe both) percolated through the ground. Such deposits are found around hydrothermal vents like those in Yellowstone National Park. That's the conclusion of planetary scientists working with data collected by the rover's Miniature Thermal Emission Spectrometer (Mini-TES), developed at Arizona State University.
New lunar south polar maps from SMART-1
Newly-released images of the lunar south-polar region obtained by ESA’s SMART-1 are proving to be wonderful tools to zero-in on suitable study sites for potential future lunar exploration missions.
Mars rovers find new evidence of 'habitable niche'
Inch by power-conserving inch, drivers on Earth have moved the Mars rover Spirit to a spot where it has its best chance at surviving a third Martian winter -- and where it will celebrate its fourth anniversary (in Earth years) since bouncing down on Mars for a projected 90-day mission in January 2004.
Mars Rover Investigates Signs of Steamy Martian Past
Researchers using NASA's twin Mars rovers are sorting out two possible origins for one of Spirit's most important discoveries, while also getting Spirit to a favorable spot for surviving the next Martian winter.
Mars Rovers Survive Severe Dust Storms, Ready for Next Objectives
Two months after sky-darkening dust from severe storms nearly killed NASA's Mars exploration rovers, the solar-powered robots are awake and ready to continue their mission. Opportunity’s planned descent into the giant Victoria Crater was delayed, but now the rover is preparing to drive into the half-mile diameter crater as early as Sept. 11.
Images show threat the rovers face in giant Martian dust storm
The mighty Mars rovers Spirit and Opportunity continue to persevere in brutal conditions, as revealed in images of the sun they are sending home. The images show how opaque the Martian atmosphere has been in the face of a raging, two-month dust storm.
Martian Skies Brighten Slightly
Slight clearing of still-dusty Martian skies has improved the energy situation for both Spirit and Opportunity, allowing controllers to increase the rovers' science observations. Spirit is even being commanded to move its arm for the first time in nearly three weeks.

News discussion:

Space & Earth science news