Scientists at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said Opportunity advanced 44 feet toward the edge of Victoria Crater on Aug. 21. Mission controllers were taking advantage of gradual clearing of dust from the sky while also taking precautions against buildup of dust settling onto the rover.
"Weather and power conditions continue to improve, although very slowly for both rovers," said John Callas, NASA's rover project manager.
Both rovers had become immobilized when a giant dust storm on Mars cut off their solar energy supply. But no new storms have developed during the past two weeks and scientists said skies above both rovers have started to clear, although the process might take several months since there is a lot of very fine material suspended in the Mars' atmosphere.
The improved sky conditions have enabled Spirit and Opportunity to resume their daily communication schedule. Opportunity had previously been conserving energy by going three or four days between communications.
On Spirit, dust on the lens of its microscopic imager has slightly reduced image quality for that instrument., NASA said.