'Greeley Haven' is Winter Workplace for Mars Rover

NASA's Mars Exploration Rover Opportunity will spend the next several months at a site informally named "Greeley Haven." The name is a tribute to planetary geologist Ronald Greeley (1939-2011), who was a member of the science team for the Mars rovers and many other interplanetary missions.

The site is an outcrop that provides a sun-facing slope to aid in maintaining adequate solar power during the rover's fifth Martian winter. It also provides targets of scientific interest for the rover's robotic arm to examine.

Closer to the equator than its twin rover, Spirit, Opportunity did not need to stay on a sun-facing slope during previous winters. Now, however, Opportunity's solar panels carry a thicker coating of dust than in the previous winters. Unless an unlikely wind cleans the panels in coming weeks, the team will use a strategy employed for three winters with Spirit: staying on a sun-facing slope. For several months of shortened daylight before and after the southern Mars winter solstice on March 30, 2012, the sun will pass relatively low in the northern sky from the rover's perspective, and Opportunity will work on the north-facing slope.

Plans for research at Greeley Haven include a radio-science investigation of the interior of Mars, which began this week; inspections of mineral compositions and textures on the outcrop; and recording a full-circle, color panorama: the Greeley Panorama. Greeley taught generations of planetary scientists at Arizona State University, Tempe, until his death two months ago.

The radio-science investigation studies tiny wobbles in the rotation of Mars to gain insight about the planet's core. It requires many weeks of radio-tracking the motion of a point on the surface of Mars to measure changes in the spin axis of the planet.

The winter worksite sits on the "Cape York" segment of the rim of Endeavour Crater. Opportunity reached the edge of this 14-mile-wide (22-kilometer-wide) crater five months ago after three years of driving from smaller Victoria Crater, which it studied for two years.

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NASA Rover Inspects Next Rock at Endeavour

NASA's Mars Exploration Rover Opportunity is using instruments on its robotic arm to inspect targets on a rock called "Chester Lake."

This is the second rock the rover has examined with a microscopic imager and a spectrometer since reaching its long-term destination, the rim of vast Endeavour crater, in August. Unlike the first rock, which was a boulder tossed by excavation of a small crater on Endeavour's rim, Chester Lake is an outcrop of bedrock.

The rocks at Endeavour apparently come from an earlier period of Martian history than the rocks that Opportunity examined during its first seven-and-a-half years on Mars. More information about the ongoing exploration of Endeavour.

Opportunity and its rover twin, Spirit, completed their three-month prime missions on Mars in April 2004. Both rovers continued for years of bonus, extended missions. Both have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life. Spirit stopped communicating in 2010. NASA will launch the next-generation Mars rover, car-size Curiosity, this autumn for arrival at Mars' Gale crater in August 2012.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for the NASA Science Mission Directorate, Washington.

NASA's Opportunity Tops 20 Miles of Mars Driving

More than seven years into what was planned as a three-month mission on Mars, NASA's Mars Exploration Rover Opportunity has driven more than 20 miles, which is more than 50 times the mission's original distance goal.

A drive of 407 feet (124 meters) completed on July 17 took Opportunity past the 20-mile mark (32.2 kilometers). It brought the rover to within a few drives of reaching the rim of Endeavour crater, the rover's team's long-term destination since mid-2008. Endeavour is about 14 miles (22 kilometers) in diameter, and its western rim exposes outcrops that record information older than any Opportunity has examined so far.

The rover is now about eight-tenths of a mile (about 1.3 kilometers) from the site chosen for arriving at the rim.

"The numbers aren't really as important as the fact that driving so much farther than expected during this mission has put a series of exciting destinations within Opportunity's reach," said Alfonso Herrera, a rover mission manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. who has worked on the rover missions since before launch in 2003.

The latest drive included an autonomous hazard detection portion during which the rover paused at intervals to check for obstacles before proceeding.

Herrera said, "Autonomous hazard detection has added a significant portion of the driving distance over the past few months. It lets us squeeze 10 to 15 percent more distance into each drive."

The milestone-setting drive was on the 2,658th Martian day, or "sol," of the rover's exploration of Mars. Opportunity drove backward. Backward driving is a technique to extend the life of a motor in the right-front wheel that sometimes draws more current than the other five wheels' drive motors.

JPL's Bill Nelson, chief of the mission's engineering team, said, "Opportunity has an arthritic shoulder joint on her robotic arm and is a little lame in the right front wheel, but she is otherwise doing remarkably well after seven years on Mars more like 70 in 'rover years.' The elevated right front wheel current is a concern, but a combination of heating and backwards driving has kept it in check over the past 2,000-plus sols."

Opportunity and its rover twin, Spirit, completed their three-month prime missions on Mars in April 2004. Both rovers continued for years of bonus, extended missions. Spirit finished communicating with Earth in March 2010. Both rovers have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life.