After seven years of working on the surface of Mars, NASA's Mars rover Opportunity has been upgraded to allow it to make some of its own decisions.

NASA announced Tuesday that its engineers this winter uploaded artificial intelligence software to enable the Mars rover to decide on its own whether it wants to stop and analyze rocks spotted during its travels across the Martian surface. The space agency noted that the upgrade will provide a good test of robotic autonomy, which it hopes to use more fully in future NASA space missions.

"We spent years developing this capability on research rovers in the Mars Yard here at the Jet Propulsion Laboratory," said Tara Estlin, a senior member of the Artificial Intelligence Group at the NASA Jet Propulsion Laboratory, in a statement. "Six years ago, we never expected that we would get a chance to use it on Opportunity."

NASA has two rovers on Mars -- Spirit and Opportunity. The twin rovers have been slowly trekking across the planet's surface for years, sending images and data back to NASA scientists.

The robots are among the most advanced technology ever built at the Jet Propulsion Lab, said Bruce Banerdt, a project scientist for the Mars Exploration Rovers, said in an earlier interview.

Overall, Opportunity rover has had better luck than its counterpart, Spirit.

In January, NASA announced that Spirit is permanently stuck in Martian dirt. Nonetheless, NASA scientists hope that Spirit can conduct experiments from where it sits.

Meanwhile, Opportunity, is still mobile.

The artificial intelligence software is designed to Opportunity's computer system recognize rocks that meet specified, pre-programmed criteria, such as a rounded shape or certain color. If the object meets specific criteria, the rover then will use its narrower-angle panoramic camera to take multiple images of it.

"It's a way to get some bonus science," said Estlin.

The new software is called Autonomous Exploration for Gathering Increased Science, or AEGIS.

Previously, scientists at NASA would have to determine when rocks needed more analysis after studying photos sent back from the rover.

Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, or subscribe to Sharon's RSS feed . Her e-mail address is sgaudin@computerworld.com.