This image of phyllosilicates and olivine in the Nili Fossae region of
Mars was taken by the Compact Reconnaissance Imaging Spectrometer for Mars
(CRISM) at 0731UTC (3:31 a.m. EDT) on October 4, 2006 near 20.5 degrees
north latitude, 78.5 degrees east longitude. The image was taken in 544
colors covering 0.36-3.92 micrometers, and shows features as small as 18
meters (60 feet) across. The image is about 11 kilometers (7 miles) wide
at its narrowest point.
Nili Fossae is a long, narrow depression comprised of a series of grabens
or down-dropped blocks of crust surrounded by faults. It lies to the
northeast of Syrtis Major (a low and broad shield volcano) and to the
northwest of an impact basin, Isidis Planitia. Nili Fossae stretches some
667 kilometers (415 miles) toward Utopia Planitia, and has been partially
filled by sediments and volcanic lavas.
The top panel in the montage above shows the location of the CRISM image
on a mosaic taken by the Mars Odyssey spacecraft's Thermal Emission
Imaging System (THEMIS). The CRISM data covers relatively flat terrain
with slightly elevated mesas. The lower left image, an infrared false
color image, shows the mineralogical complexity of the region. The
High-Resolution Imaging Science Experiment (HiRISE), which is also onboard
the Mars Reconnaissance Orbiter, has imaged sand dunes in Nili Fossae.
When combined with CRISM data, the HiRISE image revealed olivine-rich sand
dunes atop clay deposits (see PIA09093).
The lower right image offers further evidence for the region's complex
mineralogy. CRISM data reveal olivine (an iron-magnesium containing
igneous mineral) in orange, on top of ferromagnesian phyllosilicates (lime
green). The phyllosilicates, a category of mineral that includes clays,
were exposed during the erosion of overlying rock. The blue areas are
remnants of the overlying cap rock containing the igneous mineral
pyroxene.
CRISM is one of six science instruments on NASA's Mars Reconnaissance
Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory,
Laurel, Md., the CRISM team includes expertise from universities,
government agencies and small businesses in the United States and abroad.
NASA's Jet Propulsion Laboratory, a division of the California Institute
of Technology in Pasadena, manages the Mars Reconnaissance Orbiter and the
Mars Science Laboratory for NASA's Science Mission Directorate,
Washington. Lockheed Martin Space Systems, Denver, built the orbiter.