New software developed at Carnegie Mellon University will allow the Mars rovers -- Spirit and Opportunity -- to explore the red planet more efficiently.

Or as NASA claims, it will teach old rovers new tricks.

Tony Stentz, research professor in CMU's Robotics Institute, developed the software with student David Ferguson, now with Intel.

NASA tested the software on earthbound rovers before uploading the software to Opportunity and Spirit last summer. Tests done Wednesday on Opportunity worked well, said Mark Maimone, a NASA rover mobility engineer who earned his doctoral degree at CMU.

Several more tests will be conducted before the rovers begin using the software full time.

"It's making the robot smarter about getting around things that get in its way," Dr. Maimone said.

Although each rover already is autonomous and progresses under its own control, the old software made it capable of avoiding only isolated obstacles. But Mars is full of geological obstacles. The rovers often got stuck amid rocks and were unable to find their way out without human assistance from NASA's Jet Propulsion Laboratory in Pasadena, Calif.

But CMU software will help the rovers negotiate their way through mazes and retreat from rocky cul-de-sacs, Dr. Stentz said. The software allows them to remember terrain and create maps of obstacles they can rely on to make their escape.

"I think basically we've improved its capability," Dr. Stentz said. "It will get stuck less often and be able to continue making forward progress with fewer human interventions."

Expected to last about three months, the rovers have been exploring the Martian surface for four years and counting.

To date, Opportunity has traveled about 10,000 meters and Spirit has traveled 7,000 meters on Mars.

The rovers have sent 200,000 images of Mars back to earth, Dr. Maimone said.