NASA's Mars Exploration Rover Opportunity used its navigation camera during the rover's 1,278th Martian day, or sol, (Aug. 28, 2007) to take the images combined into this view.

Aftersurviving near fatal dust storms on Mars, NASA's Opportunity rover is gearingup for its long-awaited trek inside an expansive crater on the red planet'ssurface.

Opportunity could begin descending down into Mars'giant Victoria Crater by Sept. 11 after spending two months hunkered down to waitout sunlight-blotting storms that nearly starvedthe solar-powered rover and its robotic twin, Spirit. The rover spent thisweek rolling ever closer to entry point into Victoria Crater.

"Opportunitymight be ready for that first 'toe dip' into the crater as early as nextweek," said John Callas, project manager for the Mars rover mission at the JetPropulsion Laboratory in Pasadena,Calif., in a Fridaystatement.

Victoria isthe largest crater visited by Opportunity during a 43-month trek across its MeridianiPlanum landing site. A bright layer of exposed rock inside the 2,400-foot wide(730-meter wide) crater may yield tantalizing clues of interactions betweenMars' surface and atmosphere millions of years ago, mission researchers said.

To preparefor the descent into Victoria Crater, Opportunity's handlers will send the rovertoan entry point that will allow clear access to the bright band of rockabout 40 feet (12 meters) blow the depression's rim. The rover will then backout a bit to check how much it may slip during the descent.

"Wechose a point that gives us a straight path down, instead of drivingcross-slope from our current location," said JPL rover driver PaoloBellutta. "The rock surface on which Opportunity will be driving will provide good traction and control of its path intothe crater."

Spirit,meanwhile, climbed atop a rock plateau dubbed "Home Plate' on Wednesday.The plateau had been a long-time destination for Spirit as the rover exploresits Gusev Crater landing site.

Healthchecks planned

But beforeOpportunity can begin its crater descent, scientists on Earth will check thehealth of two vital instruments to ensure the months-long martian dust stormshaven't crippled their ability to collect data.

If the duststorms have not impacted a microscope-like camera on Opportunity's robotic arm,mission managers will use it to inspect a crucial mast-mounted mirror.

The mirrorreflects infrared light into the rover's Miniature Thermal EmissionSpectrometer (Mini-TES), allowing scientists to determine the minerals presenton the martian surface. Some data from the spectrometer's last use hinted thatthe mirror, which can also swivel to cover a mast opening as a dust guard, maynot be moving properly.

"Itwould be the first permanent loss of an instrument on either rover," saidrover science principal investigator Steven Squyres, of Cornell University inIthaca, N.Y. "But we'll see."



The dust woes of Opportunity and Spirit began in late June, when astronomers spottedgrowing dust storms on the red planet's surface. The storms swelled to blotout much of the sunlight on the planet's surface, leading some mission managersto worry that the solar-powered rovers could starve from lack adequate energysupplies.

By lateAugust, the storms had subsided enoughto allow Opportunity and Spirit to once more explore Mars. Opportunity, which weatheredthe storms while perched on the rim of Victoria, resumed preparations to enterthe crater.

All-weatherrovers

Originallyslated to spend three Earth months exploring Mars, Spirit and Opportunity arenow in their fourth year of red planet roving. The two robots have uncoveredevidence of the planet's ancient watery past, scaled hills and studied amartian meteorite among their manyscientific exploits.

While dustis still settling from Mars' recent storms, wind gusts have been aidingOpportunity?s recovery by blowing away dust particles from its solar arraysalmost as fast as they are deposited, mission managers said.

"Theserovers are tough," said Alan Stern, NASA's associate administrator forscience missions, in a Friday statement. "They faced dusty winds, powerstarvation and other challenges--and survived."