NASA's Mars Rover Opportunity Climbing Out Of Crater

It Just Keeps Going, And Going... And GOING...

Attention, anyone who may have written off NASA's Mars Exploration rover Opportunity -- designed to last a mere 90 days on the Martian surface -- at anytime over the past... sheesh, 54 months.

The Little Rover That Could has shaken off everything from Martian dust storms, to power spikes and balky arms -- even an extremely ill-considered NASA budget cutback proposal -- and is now heading back out to the Red Planet's surrounding plains nearly a year after descending into a large crater to examine exposed ancient rock layers.

"We've done everything we entered Victoria Crater to do and more," said Bruce Banerdt, of NASA's Jet Propulsion Laboratory in Pasadena, CA. Banerdt is project scientist for Opportunity and its rover twin, Spirit.

Having completed its job in the crater, Opportunity is now preparing to inspect loose cobbles on the plains. Some of these rocks, approximately fist-size and larger, were thrown long distances when objects hitting Mars blasted craters deeper than Victoria into the Red Planet. Opportunity has driven past scores of cobbles but examined only a few.

"Our experience tells us there's lots of diversity among the cobbles," said Scott McLennan of the State University of New York, Stony Brook. McLennan is a long-term planning leader for the rover science team. "We want to get a better characterization of them. A statistical sampling from examining more of them will be important for understanding the geology of the area."

Opportunity entered Victoria Crater on September 11, 2007, after a year of scouting from the rim. Once a drivable inner slope was identified, the rover used contact instruments on its robotic arm to inspect the composition and textures of accessible layers.

The rover then drove close to the base of a cliff called "Cape Verde," part of the crater rim, to capture detailed images of a stack of layers 6 meters (20 feet) tall. The information Opportunity has returned about the layers in Victoria suggest the sediments were deposited by wind and then altered by groundwater.

"The patterns broadly resemble what we saw at the smaller craters Opportunity explored earlier," McLennan said. "By looking deeper into the layering, we are looking farther back in time." The crater stretches approximately 800 meters (half a mile) in diameter and is deeper than any other seen by Opportunity.

Engineers are programming Opportunity to climb out of the crater at the same place it entered. A spike in electric current drawn by the rover's left front wheel last month quickly settled discussions about whether to keep trying to edge even closer to the base of Cape Verde on a steep slope. The spike resembled one seen on Spirit when that rover lost the use of its right front wheel in 2006.

Opportunity's six wheels are all still working after 10 times more use than they were designed to perform, but the team took the spike in current as a reminder that one could quit.

"If Opportunity were driving with only five wheels, like Spirit, it probably would never get out of Victoria Crater," said JPL's Bill Nelson, a rover mission manager. "We also know from experience with Spirit that if Opportunity were to lose the use of a wheel after it is out on the level ground, mobility should not be a problem."

Opportunity now drives with its robotic arm out of the stowed position. A shoulder motor has degraded over the years to the point where the rover team chose not to risk having it stop working while the arm is stowed on a hook. If the motor were to stop working with the arm unstowed, the arm would remain usable.

Spirit has resumed observations after surviving the harshest weeks of southern Martian winter. The rover won't move from its winter haven until the amount of solar energy available to it increases a few months from now. The rover has completed half of a full-circle color panorama from its sun-facing location on the north edge of a low plateau called "Home Plate."

"Both rovers show signs of aging, but they are both still capable of exciting exploration and scientific discovery," said JPL's John Callas, project manager for Spirit and Opportunity.

The team's plan for future months is to drive Spirit south of Home Plate to an area where the rover last year found some bright, silica-rich soil. This could be possible evidence of effects of hot water.

Both rovers arrived at the red planet within weeks of each other in January 2004. The rovers were originally supposed to last a mere 90 days.

FMI: www.nasa.gov/rovers

Part II

Opportunity Successfully Ascends Out Of Victoria Crater

Erstwhile Rover Back On Flat Ground

NASA announced Friday its Mars Exploration Rover Opportunity has climbed out of the large crater that it had been examining from the inside since last September.

"The rover is back on flat ground," an engineer who drives it, Paolo Bellutta of NASA's Jet Propulsion Laboratory, announced to the mission's international team of scientists and engineers.

Opportunity used its own entry tracks from nearly a year ago as the path for a drive of 6.8 meters (22 feet) bringing the rover out over the top of the inner slope and through a sand ripple at the lip of Victoria Crater. The exit drive, conducted late Thursday, completed a series of drives covering 50 meters (164 feet) since the rover team decided about a month ago that it had completed its scientific investigations inside the crater.

"We're headed to the next adventure out on the plains of Meridiani," said JPL's John Callas, project manager for Opportunity and its twin Mars rover, Spirit. "We safely got into the crater, we completed our exploration there, and we safely got out. We were concerned that any wheel failure on our aging rover could have left us trapped inside the crater."

The Opportunity mission has focused on Victoria Crater for more than half of the 55 months since the rover landed in the Meridiani Planum region of equatorial Mars. The crater spans about 800 meters (half a mile) in diameter and reveals rock layers that hold clues to environmental conditions of the area through an extended period when the rocks were formed and altered.

The team selected Victoria as the next major destination after Opportunity exited smaller Endurance Crater in late 2004. The ensuing 22-month traverse to Victoria included stopping for studies along the route and escaping from a sand trap. The rover first reached the rim of Victoria in September 2007. For nearly a year, it then explored partway around the rim, checking for the best entry route and examining from above the rock layers exposed in a series of promontories that punctuate the crater perimeter.