NASA's newest Mars spacecraft — carrying the
APL-built Compact Reconnaissance Imaging Spectrometer for
Mars — 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 spacecraft'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, the first week of
observations from low orbit, the instruments provided a
good test of their capabilities by viewing dozens of sites
that reflect different episodes in Mars' history. 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
midaltitude 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 Chasma Boreale, a vast valley that juts into the
north polar ice cap, the 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 APL spectrometer, called CRISM for short, 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 APL's Scott Murchie, CRISM principal investigator.
"These layers are geologically young — on the order
of thousands or millions of years — and may hold
clues about climate cycles."
CRISM also examined a lower-latitude target named
Mawrth Vallis. A previous spacecraft discovered ancient
deposits of clay minerals that could form only if water was
present for a long time at Mawrth Vallis. CRISM now 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, which, during testing week, imaged 64
areas including Victoria Crater, has shown unprecedented
detail. "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, Alfred McEwen of the
University of Arizona, Tucson.
Another observation of an unnamed southern crater
shows relatively young gullies that look like those seen in
many Mars locations viewed by NASA's Mars Global Surveyor
orbiter. In the new observations, braided channels
characteristic of sediment-rich streams are visible. This
reinforces the interpretation that these geologically young
gullies formed at least in part from erosion by flowing
The Mars Reconnaissance Orbiter is managed by the Jet
Propulsion Laboratory, Pasadena, Calif., for NASA's Science
Mission Directorate, Washington.
For more on the orbiter, go to www.nasa.gov/mro.
For more on CRISM, go to