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 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,” says Cornell University alumnus
Paul Bartlett. An employee of New York engineering firm Honeybee
Robotics, Bartlett has been working on the RAT since the first
concept drawings from Cornell professor of astronomy Steven Squyres
arrived in his fax machine three years ago.

Spirit is scheduled to land on Mars on Jan. 3 at 11:35 p.m. EST.
Opportunity will touch down on Jan. 25 at 12:05 a.m. EST.

The Jet Propulsion Laboratory in Pasadena, a division of the
California Institute of Technology, manages the Mars Exploration
Rover project for NASA’s Office of Space Science, Washington, D.C.
Cornell, in Ithaca, N.Y., is managing the science instruments carried
by the two rovers, with Squyres as principal investigator.

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 rover science 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

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 Mars 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 says, that “planetary scientists and avant-garde
architects speak very different languages.”

This release was prepared by Cornell News Service science-writer
intern Kate Becker

Rock Abrasion Tool