The Compact Reconnaissance Imaging Spectrometer for Mars, a mineral
mapping instrument on NASA's Mars Reconnaissance Orbiter (CRISM), began
observing Mars after its lens cover was opened on Sept. 27, 2006.
This image shows one of the first regions of Mars measured after CRISM's
cover was opened.
CRISM takes images in two basic formats. The first format is a "targeted
image" about 10 kilometers by 10 kilometers (about 6 miles by 6 miles), at
about 18 meters (60 feet) per pixel, in 544 colors covering wavelengths of
0.36 to 3.92 micrometers. The second format is a lower-resolution strip 10
kilometers (6 miles) wide and thousands of kilometers long, at 200 meters
(660 feet) per pixel, in 72 colors. Many thousands of these "multispectral
survey" strips are used to build a global map.
The image is part of the second multispectral survey strip, taken at 22:36
UTC (6:36 p.m. EDT) on Sept. 27, 2006. Only minimal processing of the data
has been done at this early point in the Mars Reconnaissance Orbiter's
mission. The strip crosses part of the north polar region named Olympia
Undae, and stretches between 76.7 north latitude, 141.9 east longitude
and 85.5 north, 115.8 east. From the top, the northern end of the image
crosses layers of dusty and clean ice in the north polar cap. Moving south
the image covers dusty sedimentary deposits, dark sand dunes, and outlying
polar ice deposits. The full-resolution TIFF file can be viewed or downloaded here
PIA08788.tif; the full-resolution JPEG can be viewed or downloaded here
PIA08788.jpg.
This image shows three representations of the 72 colors. The left panel is
a nearly true-color composite in which the blue, green, and red planes are
0.44, 0.53, and 0.60 micrometer light -- nearly as the human eye would
see. The contrast between the bright ice and dark dunes is so large that
the dunes are barely seen. The middle panel is false color constructed
from infrared wavelengths just beyond the range of the human eye. The
blue, green, and red planes cover 0.80, 0.95, and 1.06 micrometer light.
In this rendering of the data the differences between ice- and soil-rich
regions are not as apparent because the colors of ice and dust are similar
in this wavelength region. The right panel uses 1.15, 1.8, and 2.25
micrometer light in the blue, green and red planes and provides a
dramatically different view of the scene. The areas of highest ice content
appear in blue, and those with a mix of dust and ice -- most of the scene
-- appear yellowish. The dunes are now visible against the ice because of
their higher brightness at longer infrared wavelengths, and appear ruddy
brown.
The Compact Reconnaissance Imaging Spectrometer for Mars 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, Calif., manages the Mars Reconnaissance Orbiter mission for
NASA's Science Mission Directorate, Washington.
CRISM's mission: Find the spectral fingerprints of aqueous and
hydrothermal deposits and map the geology, composition and stratigraphy
of surface features. The instrument will also watch the seasonal
variations in Martian dust and ice aerosols, and water content in surface
materials -- leading to new understanding of the climate.
