NASA's Mars rover Opportunity, fresh from a spring cleaning courtesy of the Red Planet's wind, has snapped a "selfie" of its own shadow with an onboard camera.

Thanks to winds that have blown dust off the rover's solar panels and longer spring days providing more sunlight time for charging, the rover is operating at higher power levels, the space agency's Jet Propulsion Laboratory reported.

The "selfie" of Opportunity's shadow was captured March 20 by the rover's rear hazard avoidance, JPL scientists reported.

The shadow fell on a slope of a western escarpment of Endeavor Crater where the rover is analyzing rock strata for evidence of the character of ancient Martian environments.

The output level of electricity from the rover's solar arrays improved by around 10 percent last week as Martian winds partially removed dust from them.

A number of recent wind events and the increasing length of spring days have improved the solar panel's output to more than 70 percent in the last two months, JPL said.

Opportunity has been operating on the Red Planet for more than a decade, touching down on Jan. 25, 2004 after its July 2003 launch.

Its landing came three weeks after its twin, the rover Spirit, touched down on the Martian surface on the other side of the planet.

Both rovers were intended to conduct scientific work for just 90 Mars days, known as sols, as part of NASA's Mars Exploration Rover Mission.

A sol is 24 hours, 39 minutes and 35.244 seconds in Earth time.

Just two months into its original mission period, Opportunity found evidence suggesting liquid water flowing on the Martian surface billions of years in the past.

Having spent two years studying an area around Victoria Crater, the rover arrived at Endeavour crater on August 9, 2011.

The longevity of both rovers has both surprised and pleased scientists; Opportunity for its part has operated 40 times longer than its designed called for.

Although Spirit ceased being mobile due to problems with its wheels in 2009 and stopped communicating with Earth in 2010, Opportunity is still going strong, as its recent selfie proves.

Powered by the sun through its solar panels, Opportunity stand 4.9 feet high, weighs about 400 pounds and gets around on six wheels, with each wheel being powered by its own electric motor.

At full speed, the rover can move over the Martian surface at 2 inches per second.

In Opportunity's selfie, the far rim of the 14-mile-wide Endeavour crater can be seen.