The Associated Press

LOS ANGELES -- NASA's Mars Global Surveyor has been out of contact with Earth for nearly a week and engineers tried Friday to re-establish communication with the craft, which may be showing its age after 10 years in space.

The space agency's Jet Propulsion Laboratory in Pasadena lost contact with the probe for two days last week, then received a weak carrier signal with no data on Sunday. Since then, Surveyor has not confirmed receiving a command to point one of its transmitters to Earth, project manager Tom Thorpe said.

The Global Surveyor was launched on Nov. 7, 1996, to map Mars while orbiting the Red Planet. It has operated longer than the other Martian exploration craft.

Carrying a powerful camera that has returned thousands of images, the spacecraft has discovered features suggesting water once flowed on the desert world, and it has looked at potential landing sites for future exploration.

Surveyor is one of four spacecraft orbiting Mars. Its companions include NASA's Mars Reconnaissance Orbiter and Mars Odyssey, and the European Space Agency's Mars Express. On the surface, the NASA rovers Spirit and Opportunity continue operating.

Surveyor was originally launched as a $247 million mission to last for nearly two years. The mission has received extensions since then.