Opportunity self-portrait reveals dusty solar panels

A newly-released mosaic from the Opportunity rover shows a coating of rust-colored dust on the robot's solar panels, visual evidence of the mobile science outpost's eight years exploring the treacherous plains of Mars.

Opportunity's panoramic camera collected images for the mosaic over three days from Dec. 21 to Dec. 24 of last year, according to NASA's Jet Propulsion Laboratory.

The dust reduces the efficiency of the rover's solar panels. Previous dust build-ups were cleared by wind storms.

Concerned the dust layer could threaten the six-wheeled vehicle's ability to generate electricity during the Martian winter, managers decided to park Opportunity on a north-facing slope at a location called Greeley Haven, an outcrop near the rim of Endeavour crater, the rover's current work site.

The parking spot gives Opportunity a 15-degree tilt toward the north, allowing the vehicle to collect more sunlight and keep its batteries charged. Opportunity is exploring a region in the southern hemisphere of Mars, but its position is near the equator, and the rover kept driving during other winters.

With more dust accumulating on Opportunity, officials opted to park the rover this time. As of Feb. 14, solar energy production was at 274 watt-hours, according to an update posted on the mission website.

The southern Mars winter solstice is March 30, then the sun will rise higher in the sky each day, giving the rover more power to resume driving and conduct more ambitious scientific studies.

Officials are using Opportunity's limited power to collect imagery for a full-circle panorama and measure textures and compositions of nearby rocks.

Researchers are also taking advantage of Opportunity's static location to measure tiny wobbles in the planet's rotation, revealing insights into the Martian core. The investigation requires months of precise Doppler tracking of Opportunity's position on Mars and cannot be accomplished with the rover on the move.

Opportunity landed on Mars in January 2004 and has driven more than 21 miles across the red planet's surface. Opportunity's twin, the Spirit rover, succumbed to low power levels and cold temperatures in 2010.

The images below compare Opportunity's solar panels in views from December 2011 and September 2007.