"The high gain antenna has been successfully deployed," Jim Erickson told reporters at the Jet Propulsion Laboratory here.

The rover had been connected to Earth through a pair of satellites orbiting the red planet: Mars Global Surveyor and Mars Odyssey.

Opportunity became this weekend the second US rover to land on Mars. Its twin, Spirit, was deployed on the other side of Mars.

NASA scientists said the Mars Exploration Rover tended to overheat, but it was still too early to imagine "the worst case scenario," Erickson said.

Engineers have yet to paste together all of the color pictures Opportunity has already sent, which will create a 360-degree panoramic view of its landing site, in the Meridiani Planum.

NASA has released the first image, in three dimensions, of nearby rocks, which look surprisingly familiar.

"Many of you looking at that scene would say, 'I have things a lot like that in my backyard'," mission scientist Andrew Knoll said.

Opportunity landed in a small crater, 20 meters (65 feet) in diameter, which geologists said is promising from a scientific point of view.

Knoll said two hypotheses could explain the origin of rocks found on the Martian surface: They resulted from a volcanic event or were formed from sediments carried by wind or water.

NASA scientists are also interested in another, larger crater about one kilometer (half a mile) away. The crater could yield a peek at what lies below the surface without having to dig.

The soil of Meridiani Planum looks to be covered with hematite, a common iron oxide, which not only gives Mars its red color, but is often formed in the presence of water.

In weeks to come, the robot is to examine the soil and rocks around the landing site, NASA scientist Steve Squyres said. However, Opportunity's will not begin work for another 10 days, he said, which is the amount of time it will take to test all the systems.

Repair work continued on Spirit, whose on-board computer crashed Wednesday, after its flash memory was overloaded with data, including digital photographs it had taken.

Engineers plan to delete some of the many files created during the six-month voyage from Earth to Mars.

SPACE.WIRE