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NASA Space Place

A Rock Hound is Born

Patrick Barry

Opportunity spots a rock with its NavCam that its AEGIS software says meets all the criteria for further investigation.


It’s tough to be a geologist when you can’t tell one rock from another. Is that a meteorite or a chunk of lava? A river rock or an impact fragment? Houston, we have a problem!

It’s a problem Spirit and Opportunity have been dealing with for the past six years. The two rovers are on a mission to explore the geology of the Red Planet, yet for the longest time they couldn’t recognize interesting rocks without help from humans back on Earth.

Fortunately, it is possible to teach old rovers new tricks. All you have to do is change their programming–and that’s just what NASA has done.

“During the winter, we uploaded new software to Opportunity,” says Tara Estlin, a rover driver, senior member of JPL’s Artificial Intelligence Group, and the lead developer of AEGIS, short for Autonomous Exploration for Gathering Increased Science. “AEGIS allows the rover to make some decisions on its own.”

Estlin and her team have been working for several years to develop and upload increasingly sophisticated software to the rovers. As a result, the twins have learned to avoid obstacles, identify dust devils, and calculate the distance to reach their arms to a rock.

With the latest upgrade, a rock hound is born.

Now, Opportunity’s computer can examine images that the rover takes using its wide-angle navigation camera (NavCam) and pick out rocks with interesting colors or shapes. It can then center its narrower-angle panoramic camera (PanCam) on targets of interest for close-up shots through various color filters. All this happens without human intervention.

The system was recently put to the test; Opportunity performed splendidly.

At the end of a drive on March 4th, the rover settled in for a bit of rock hunting. Opportunity surveyed the landscape and decided that one particular rock, out of more than 50 in the NavCam photo, best met criteria that researchers had set for a target of interest: large and dark.

“It found exactly the target we would want it to find,” Estlin says. “It appears to be one of the rocks tossed outward onto the surface when an impact dug a nearby crater.”

The new software doesn’t make humans obsolete. On the contrary, humans are very much “in the loop,” setting criteria for what’s interesting and evaluating Opportunity’s discoveries. The main effect of the new software is to strengthen the rover-human partnership and boost their combined exploring prowess.

Mindful that Opportunity was only supposed to last about six months after it landed in 2004, Estlin says “it is amazing to see Opportunity performing a brand new autonomous activity six years later.”

What will the rock hounds of Mars be up to six years from now? Stay tuned for future uploads!

Learn more about how the AEGIS software works at If you work with middle- or high-school kids, you’ll find a fun way to explore another kind of robot software–the kind that enables “fuzzy thinking”–at

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.


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