Opportunity's Arm, Steering Malfunctioning; Spirit's Scraping Tool Worn

When the Spirit rover landed on the Martian surface on January 3, 2004, not even the most wide-eyed optimist in the NASA community believed that the rover would still be functioning nearly two years later. After all, the rover was built for a mission expected to last only 90 days, with stress tests for only three times that number.

But here we are, with Spirit having roamed 5.5 km over the Martian surface, and it's still chugging along. It's companion rover, Opportunity, landed after Spirit, but has travelled a kilometer further it is journeys. Spirit just celebrated its one-year anniversary on the Martian surface (a Martian year is 687 days long) on November 20th, and Opportunity has its one-year anniversary coming up next week.

As can be expected, though, both rovers are increasingly showing their age. NASA reports that Spirit's scraping tool is worn out after collecting 15 rock scraping samples (it was designed for only 2-3 scrapings). Apart from that, though, the oldest rover is in remarkably good health.

Opportunity is fairing less well. Although still mobile, one of the rover's steering actuators has stopped operating -- NASA speculates the motor's lubricant has begun to break down, after lasting seven times it's design intent. More troubling, however, is an inoperable shoulder joint on rover's robotic collection arm. The arm (shown in the photo below, taken by Spirit) retracts into a special housing when not in use, and the joint issue might prevent the arm from being extended again.

"If it has failed, it will be a significant hit. It is the contact arm of the mission," said John Callas, deputy project manager for the NASA Mars Exploration Rovers project, according to media reports.

However, scientists are still optimistic the elbow of the arm can be jolted out of the T-shaped protective housing, which would allow enough mobility to allow the golf-cart-sized rover to continue to collect samples.

It's only a matter of time, however, before the rovers do shut down... a fact NASA is very aware of.

"We drive it every day as if there were no tomorrow," said Stephen Squyres, a Cornell University professor and the principal investigator on the rover project.

The probes' continued operations have allowed NASA to gather a significant amount of information on the Red Planet, including the discovery of nine different types of rocks on the Martian surface.

Squyres, though, added that the two vehicles have brought a wealth of information about the planet back to Earth. A climb up the Columbia Hills on Mars, for instance, has revealed an astounding variety of rocks in a small area.

Scientists have also been able to obtain nighttime observations from the Mars surface, including a shot of a probable meteor shower. Most significantly, however, soil samples taken by the rovers have shown existence of a clay-like consistency, evidence of the possible existence of water sometime in its history -- and maybe even today.

FMI: www.nasa.gov/vision/universe/solarsystem/mer_main.html