NASA Spacecraft Sees Ice on Mars Exposed by Meteor Impacts

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Dwayne Brown 202-358-1726
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News release: 2009-148 Sept. 24, 2009

NASA Spacecraft Sees Ice on Mars Exposed by Meteor Impacts

PASADENA, Calif. -- NASA's Mars Reconnaissance Orbiter has revealed frozen water hiding
just below the surface of mid-latitude Mars. The spacecraft's observations were obtained from
orbit after meteorites excavated fresh craters on the Red Planet.

Scientists controlling instruments on the orbiter found bright ice exposed at five Martian sites
with new craters that range in depth from approximately half a meter to 2.5 meters (1.5 feet to 8
feet). The craters did not exist in earlier images of the same sites. Some of the craters show a thin
layer of bright ice atop darker underlying material. The bright patches darkened in the weeks
following initial observations, as the freshly exposed ice vaporized into the thin Martian
atmosphere. One of the new craters had a bright patch of material large enough for one of the
orbiter's instruments to confirm it is water-ice.

The finds indicate water-ice occurs beneath Mars' surface halfway between the north pole and
the equator, a lower latitude than expected in the Martian climate.

"This ice is a relic of a more humid climate from perhaps just several thousand years ago," said
Shane Byrne of the University of Arizona, Tucson.

Byrne is a member of the team operating the orbiter's High Resolution Imaging Science
Experiment, or HiRISE camera, which captured the unprecedented images. Byrne and 17 co-
authors report the findings in the Sept. 25 edition of the journal Science.

"We now know we can use new impact sites as probes to look for ice in the shallow subsurface,"
said Megan Kennedy of Malin Space Science Systems in San Diego, a co-author of the paper and
member of the team operating the orbiter's Context Camera.

During a typical week, the Context Camera returns more than 200 images of Mars that cover a
total area greater than California. The camera team examines each image, sometimes finding dark
spots that fresh, small craters make in terrain covered with dust. Checking earlier photos of the
same areas can confirm a feature is new. The team has found more than 100 fresh impact sites,
mostly closer to the equator than the ones that revealed ice.

An image from the camera on Aug. 10, 2008, showed apparent cratering that occurred after an
image of the same ground was taken 67 days earlier. The opportunity to study such a fresh
impact site prompted a look by the orbiter's higher resolution camera on Sept. 12, 2009,
confirming a cluster of small craters.

"Something unusual jumped out," Byrne said. "We observed bright material at the bottoms of the
craters with a very distinct color. It looked a lot like ice."

The bright material at that site did not cover enough area for a spectrometer instrument on the
orbiter to determine its composition. However, a Sept. 18, 2008, image of a different mid-
latitude site showed a crater that had not existed eight months earlier. This crater had a larger
area of bright material.

"We were excited about it, so we did a quick-turnaround observation," said co-author Kim Seelos
of Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Everyone thought it
was water-ice, but it was important to get the spectrum for confirmation."

Mars Reconnaissance Orbiter Project Scientist Rich Zurek, of NASA's Jet Propulsion Laboratory,
Pasadena, Calif., said, "This mission is designed to facilitate coordination and quick response by
the science teams. That makes it possible to detect and understand rapidly changing features."

The ice exposed by fresh impacts suggests that NASA's Viking Lander 2, digging into mid-
latitude Mars in 1976, might have struck ice if it had dug 10 centimeters (4 inches) deeper. The
Viking 2 mission, which consisted of an orbiter and a lander, launched in September 1975 and
became one of the first two space probes to land successfully on the Martian surface. The Viking
1 and 2 landers characterized the structure and composition of the atmosphere and surface. They
also conducted on-the-spot biological tests for life on another planet.

NASA's Jet Propulsion Laboratory in Pasadena manages the Mars Reconnaissance Orbiter for
NASA's Science Mission Directorate in Washington. Lockheed Martin Space Systems in Denver
built the spacecraft. The Context Camera was built and is operated by Malin Space Science
Systems. The University of Arizona operates the HiRISE camera, which Ball Aerospace &
Technologies Corp., in Boulder, Colo., built. The Johns Hopkins University Applied Physics
Laboratory led the effort to build the Compact Reconnaissance Imaging Spectrometer and
operates it in coordination with an international team of researchers.

To view images of the craters and learn more about the Mars Reconnaissance Orbiter, visit
http://www.nasa.gov/mro or http://marsprogram.jpl.nasa.gov/mro/ .

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