Space Topics: Mars Reconnaissance Orbiter
The Year in Pictures: 2007
Mars Reconnaissance Orbiter: Nili Fossae Trough
Credit: NASA / JPL / U. Arizona / JHUAPL |
The blooming purples and greens in this image of the west wall of Nili Fossae,
northwest of Mars' Isidis basin, map the signatures of minerals in the Martian
bedrock that scientists hope to sample with a future rover. The image represents
the best that two of Mars
Reconnaissance Orbiter's instruments—CRISM
and HiRISE—have to offer. Together, these instruments are performing
detailed mapping of all the potential landing
sites for the 2009 Mars Science
Laboratory. Nili Fossae Trough is just one of half
a dozen sites being considered.
The
HiRISE camera is taking photos of Mars with resolutions as high as 25 centimeters
(about 10 inches) per pixel. With such sharp images, planners for future landed
missions can name every large rock in their landing site before they even arrive
at Mars. This image reveals the floor of Nili Fossae (lower right) paved with
volcanic materials; "shark's-tooth" dunes of dark basaltic sand march
parallel to the northwest wall of the trough. An ancient flooding event cut
into that wall, carving a landscape of mesas and buttes and exposing ancient
bedrock.
At the same time, the CRISM imaging spectrometer is slicing the colors
of Mars into an unprecedented 544 different bands of the electromagnetic spectrum.
Because of such high spectral resolution, CRISM workers can search for the
fingerprints of specific minerals on the Martian surface. For instance, in
this image, the blues and magentas map locations where CRISM
sees the spectral signature of phyllosilicates, minerals that form when igneous minerals such
as pyroxene are altered in the presence of water. Greenish colors imply the
presence of low-calcium pyroxene, a mineral that formed very early in Mars'
history with the hottest volcanic activity. A lander sent to one of these greenish
areas has the potential to sample Mars' youth.
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