A portion of a trough in the Nili Fossae region of Mars is shown in
enhanced color in this image from the High Resolution Imaging Science
Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The
image was taken on March 24, 2007, as part of a campaign to examine more
than two dozen candidate landing sites for the NASA Mars Science
Laboratory rover, which is scheduled for launch in 2009.
The Nili Fossae region has one of the largest exposures of clay minerals
discovered by the mapping spectrometer (called OMEGA for its French name's
acronym) on the European Space Agency's Mars Express orbiter. These
minerals have also been mapped in greater detail by the Compact
Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars
Reconnaissance Orbiter (see http://crism.jhuapl.edu/gallery/featuredImage).
This image covers an area nearly one kilometer (six-tenths of a mile)
wide, at 21.1 degrees north latitude, 74.2 degrees east longitude. North
is up. It is a composite of exposures that HiRISE took in the infrared,
red and blue portions of the spectrum. Color is enhanced beyond the
standard enhancement in HiRISE color images, as this view is excerpted
from a special video treatment of the full-frame image. The purple areas
are basaltic in composition, including sand-sized material that bounces
around in the wind to form dunes. Basalt in the most common type of
volcanic rock on the Earth and other terrestrial planets. Orange areas are
rich in clays. Clay minerals contain water in their mineral structure and
may also preserve organic materials, so there is great interest in
studying these deposits to understand past environments that could have
supported life. The blue-green patches are outcrops of unaltered rocks
rich in the mineral pyroxene.
This is a portion of the full-frame color image catalogued as PSP_003086_2015
in the HiRISE collection. The image was taken at a local Mars time of 3:38
p.m. The scene is illuminated from the west with a solar incidence angle
of 62 degrees, thus the sun was about 28 degrees above the horizon. The
season on Mars was northern autumn.