Nov. 12, 2004 — A new image, taken by the European Space Agency's Mars Express spacecraft, focuses in on the Martian moon Phobos, revealing fine details of the planet's largest satellite.

One of the highest-resolution pictures ever taken of Phobos, the image shows the side of the moon that faces Mars.

Phobos, one of two Martian moons, is spiralling ever closer to Mars' surface at a rate of 1.8 meters every hundred years.

It will either crash into Mars in 50 million years or break up into a ring around the planet, according to NASA.

The moon's most noticeable feature is a huge crater dubbed Stickney. Mars Global Surveyor observations of the crater showed it to be filled with dust, with boulders apparently sliding down its sides.

Opportunity in Crater
Meanwhile, on the surface of Mars, the rover Opportunity is pacing Endurance Crater, looking for a way out.

"We've done a careful analysis of the ground in front of Opportunity and decided to turn around," said Jim Erickson, rover project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif., in a NASA press release on Friday. "To the right, the slope is too steep — more than 30 degrees. To the left, there are sandy areas we can't be sure we could get across."

But before going back the way it came, Opportunity will dwell a few more days in the crater, where it has been since June 8. Geologists want the rover to examine the rock layers in a 10-meter-high (33 feet) cliff, named Burns Cliff, to determine whether some of the layers were created by wind, instead of water.

"We have pushed the vehicle right to the edge of its capabilities, and we've finally reached a spot where we may be able to answer questions we've been asking about this site for months," said Steve Squyres, rover principal investigator at Cornell University, Ithaca, N.Y., in the release.

"But after we're done here, it'll be time to turn around. Going any farther could cut off our line of retreat from the crater, and that's not something anybody on the team wants to do," he said.

Opportunity's sister rover, Spirit, is ready to move on after engineers resolved a problem with its steering brakes. The brakes keep the rover's wheels on course while it's under way.

After testing, engineers decided that the brakes were actually working fine; it was the mechanism that monitors the brakes that was sending a false message.

"We're going back to using the full steering capabilities of Spirit," Erickson said.

Opportunity and Spirit successfully completed their three-month missions in April. NASA extended their missions for a second time on Oct. 1 because the rovers are still in good condition and returning sound science results.