By Tariq Malik
After surviving near fatal dust storms on Mars, NASA's Opportunity rover is gearing up for its long-awaited trek inside an expansive crater on the red planet's surface.
Opportunity could begin descending down into Mars' giant Victoria Crater by Sept. 11 after spending two months hunkered down to wait out sunlight-blotting storms that nearly starved the solar-powered rover and its robotic twin, Spirit. The rover spent this week rolling ever closer to entry point into Victoria Crater.
"Opportunity might be ready for that first 'toe dip' into the crater as early as next week," said John Callas, project manager for the Mars rover mission at the Jet Propulsion Laboratory in Pasadena, Calif., in a Friday statement.
Victoria is the largest crater visited by Opportunity during a 43-month trek across its Meridiani Planum landing site. A bright layer of exposed rock inside the 2,400-foot wide (730-meter wide) crater may yield tantalizing clues of interactions between Mars' surface and atmosphere millions of years ago, mission researchers said.
To prepare for the descent into Victoria Crater, Opportunity's handlers will send the rover to an entry point that will allow clear access to the bright band of rock about 40 feet (12 meters) blow the depression's rim. The rover will then back out a bit to check how much it may slip during the descent.
"We chose a point that gives us a straight path down, instead of driving cross-slope from our current location," said JPL rover driver Paolo Bellutta. "The rock surface on which Opportunity will be driving will provide good traction and control of its path into the 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 explores its Gusev Crater landing site.
Health checks planned
But before Opportunity can begin its crater descent, scientists on Earth will check the health of two vital instruments to ensure the months-long martian dust storms haven't crippled their ability to collect data.
If the dust storms 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 mirror reflects infrared light into the rover's Miniature Thermal Emission Spectrometer (Mini-TES), allowing scientists to determine the minerals present on the martian surface. Some data from the spectrometer's last use hinted that the mirror, which can also swivel to cover a mast opening as a dust guard, may not be moving properly.
"It would be the first permanent loss of an instrument on either rover," said rover science principal investigator Steven Squyres, of Cornell University in Ithaca, N.Y. "But we'll see."
The dust woes of Opportunity and Spirit began in late June, when astronomers spotted growing dust storms on the red planet's surface. The storms swelled to blot out much of the sunlight on the planet's surface, leading some mission managers to worry that the solar-powered rovers could starve from lack adequate energy supplies.
By late August, the storms had subsided enough to allow Opportunity and Spirit to once more explore Mars. Opportunity, which weathered the storms while perched on the rim of Victoria, resumed preparations to enter the crater.
All-weather rovers
Originally slated to spend three Earth months exploring Mars, Spirit and Opportunity are now in their fourth year of red planet roving. The two robots have uncovered evidence of the planet's ancient watery past, scaled hills and studied a martian meteorite among their many scientific exploits.
While dust is still settling from Mars' recent storms, wind gusts have been aiding Opportunity's recovery by blowing away dust particles from its solar arrays almost as fast as they are deposited, mission managers said.
"These rovers are tough," said Alan Stern, NASA's associate administrator for science missions, in a Friday statement. "They faced dusty winds, power starvation and other challenges--and survived."
