NASA Orbiter Reveals New Details of Mars, Young and Old

PASADENA, CALIF. 91109 TELEPHONE 818-354-5011

Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.

Erica Hupp 202-358-1237
NASA Headquarters, Washington

News Release: 2006-131 Oct. 16, 2006

NASA Orbiter Reveals New Details of Mars, Young and Old

During its first week of observations from low orbit,
NASA’s newest Mars spacecraft is already revealing new
clues about both recent and ancient environments on the
red planet.

Scientists hope the Mars Reconnaissance Orbiter will
answer questions about the history and distribution of
Mars’ water by combining data from the orbiter’s
high-resolution camera, imaging spectrometer, context
camera, ground-penetrating radar, atmospheric sounder,
global color camera, radio and accelerometers.

Between Sept. 29 and Oct. 6, science instruments on the
spacecraft viewed dozens of sites that reflect different
episodes in Mars’ history. The diverse sites provide a
good test for the capabilities of the spacecraft
instruments. The orbiter will begin its primary science
mission phase in early November when Mars re-emerges from
passing nearly behind the sun.

The instruments are seeing details in the shapes and icy
composition of geologically young layering near the Martian
north pole. Other views offer details of a mid-latitude
valley whose upper layers have been eroded away, revealing
an underlying clay layer that formed a few billion years ago,
when wet conditions produced the clay. Observations of a
southern-hemisphere crater show fine-scale details of more
recent gullies, adding evidence that they were carved by
flowing water.

“In this opening phase we have tested the instruments, and
they are working perfectly,” said Dr. Steve Saunders, Mars
Reconnaissance Orbiter program scientist at NASA
Headquarters, Washington. “The teams are getting amazing
science data. They are ready to fulfill the mission’s
science objectives and to support other Mars missions. One
image is already helping the Mars Exploration Rover team
choose a route to explore Victoria Crater. Others will help
guide the selection of a safe site for the future Phoenix
Mars Lander.”

In Chasma Boreale, a vast valley that juts into the north
polar ice cap, the orbiter’s spectrometer sees layers that
vary in soil composition and in how much ice is mixed with
the soil. A dark underlying layer contains little ice, but
just beneath it lies ice-rich material resembling higher
layers. The spectrometer takes pictures both in
visible-light and infrared wavelengths useful for
identifying what a target is made of.

“You see more-ice-rich and less-ice-rich layers, which
tells you that conditions changed from the time one layer
was deposited to the time another layer was deposited,”
said Dr. Scott Murchie of Johns Hopkins University Applied
Physics Laboratory, Laurel, Md. Murchie is the principal
investigator for the spectrometer on the spacecraft.
“These layers are geologically young – on the order of
thousands or millions of years – and may hold clues about
climate cycles.”

A lower-latitude target was Mawrth Vallis. The European
Mars Express spacecraft previously discovered ancient
deposits of clay minerals that could form only if water
were present for a long time at Mawrth Vallis. The Mars
Reconnaissance Orbiter’s spectrometer has resolved
smaller-scale compositional features and detected differing
clay mineral content. The clay-rich areas show some of
the best evidence for conditions possibly favorable for
life on ancient Mars, Murchie said.

The mission’s High Resolution Imaging Science Experiment
camera has shown unprecedented detail in orbital images of
Mars. An example was released recently showing the
Opportunity rover at Victoria Crater. The camera imaged 64
areas on Mars during the testing week. “These images are
truly beautiful, and since they resolve features the size
of people, you can visualize yourself hiking around in
these diverse terrains,” said the camera’s principal
investigator, Dr. Alfred McEwen of the University of
Arizona, Tucson.

The high-resolution camera, the imaging spectrometer and
the orbiter’s wider-looking Context Camera all observed
Mawrth Vallis. Details visible in the new observations,
such as small channels, are consistent with past wet
conditions, McEwen said.

Another observation of an unnamed southern crater shows
relatively young gullies, like those seen in many Mars
locations viewed by NASA’s Mars Global Surveyor orbiter.
Braided channels characteristic of sediment-rich streams
are visible in the new observations. This reinforces the
interpretation that these geologically young gullies
formed at least in part from erosion by flowing water.
Original discovery of the many geologically young
gullies on Martian slopes was by Dr. Michael Malin of
Malin Space Science Systems, San Diego.

The Mars Reconnaissance Orbiter is managed by the Jet
Propulsion Laboratory, Pasadena, Calif., for NASA’s
Science Mission Directorate, Washington. For more
information, visit .