Botox for rocks: Tiny abrasion tool could help reveal Mars geology

The rock abrasion tool, or RAT, is part of the Athena science-instrument package. NASA/JPL/Cornell/Honeybee Robotics

By Kate Becker

Facelifts can sag. Botox is temporary. But modern science has a new way to return youth to weathered faces: the rock abrasion tool (RAT). If your dermatologist hasn't heard of it, ask your local Mars scientist.

Billions of years of exposure to the sun, atmosphere and extremely fine Martian dust has given Mars rocks a weathered "rind," or exterior layer. The RAT, part of the Athena science-instrument package carried by the two Mars rovers, Spirit and Opportunity, uses a diamond-tipped robotic grinding tool to scrape away this weathered exterior, revealing a fresh surface.

"Clearing away the dust and a weathered layer gives the science instruments access to the part of the rock that hasn't changed since it was formed billions of years ago," said Cornell alumnus Paul W. Bartlett '99. An employee of New York engineering firm Honeybee Robotics, Bartlett has been working on the RAT since the first concept drawings from professor of astronomy and Athena principal investigator Steven Squyres arrived in his fax machine three years ago.

Access to the pristine rock interior is critical to understanding the history of the geology of Mars and to answering what Bartlett describes as the "big questions" to be solved by the rovers: did water -- or even an environment suitable for life -- once exist on the red planet?

These big questions might be answered by a very small machine: the RAT weighs only 1 1/2 pounds and uses less power (30 watts) than most light bulbs. It is about the size of a soda can.

The RAT occupies the turret, or "hand," of the rover's robotic arm, along with other Athena instruments for rock analysis: a microscopic imager and Mössbauer and alpha particle X-ray spectrometers. The agile arm, which has shoulder, elbow and wrist joints just like a human arm, presses the RAT up against a rock's surface.

In just two hours, the RAT's grinding wheel can shave off a disk about twice the diameter and thickness of a nickel from a hard rock surface. Two brushes sweep the resulting dust away from the hole to provide a clean surface for an up-close view.

Once the fresh surface is exposed, the imager and the spectrometers take over, peering through the abraded opening to perform a detailed analysis of the rock's interior. So that scientists can learn about the processes that might have weathered the rock, the rover also records temperature and current readings from the RAT's three motors while they grind away the exterior layer.

Bartlett notes that the breadth of his work on the RAT, which spans design, fabrication, assembly, testing and mission operations, "is a rare opportunity in engineering."

And working with Athena scientists also has stood out among his other assignments for Honeybee. One was building a robot for an art installation at Manhattan's Whitney Museum of American Art. He discovered, he said, that "planetary scientists and avant-garde architects speak very different languages."