Opportunity rolled off her lander and onto the dark red Martian soil at Meridiani Planum early Saturday morning, at about 1:50 a.m., Pacific Standard Time, just one week after the robot field geologist arrived on the Red Planet.
When the rover returned the first signal indicating she had begun her journey, mission control center erupted in cheers, as the strains of The Who's "Going Mobile" rocked the room.
Confirmation that Opportunity had safely navigated the 10-foot (3 meter) drive straight down the lander ramp and onto the surface came about an hour and 10 minutes later from data relayed by Mars Odyssey at 3:01 a.m. PST.
The first picture she returned, taken by the rear hazard camera, shows the now empty lander and the set of rover tire tracks leading away from it, much as the image returned by Spirit when she rolled off her lander a little more than two weeks ago.
Opportunity's mission is to explore the planet's geological history and search for signs of water, and already she has confirmed the presence of hematite, the iron oxide that on Earth usually forms in processes involving water. The robot geologist's mini-thermal emission spectrometer -- Mini-TES -- recorded the spectral signature of hematite in the layer of coarse ground materials covering the bedrock that lies in the rim of the crater into which she rolled last Saturday.
An enormous amount of hematite had been measured at Meridiani Planum from the thermal emission spectrometer on Mars Global Surveyor a couple of years ago, and the gray crystalline mineral is the prime reason the site was chosen for exploration. It is possible, however, for hematite to form from volcanic ash without water.