The So-Called 'Face On Mars' In Infrared
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Thanks to Jim Torson.
THE SO-CALLED 'FACE ON MARS' IN INFRARED
ASU THEMIS Science Team
July 24, 2002
This set of THEMIS infrared images shows the so-called "face on Mars"
landform located in the northern plains of Mars near 40° N, 10° W (350 ° E).
The "face" is located near the center of the image approximately 1/6 of the
way down from the top, and is one of a large number of knobs, mesas, hills,
and buttes that are visible in this THEMIS image. The THEMIS infrared camera
has ten different filters between 6.2 and 15 micrometers - nine view the
surface and one views the CO2 atmosphere. The calibrated and geometrically
projected data from all of the nine surface-viewing filters are shown in
this figure. The major differences seen in this region are due to
temperature effects -- sunlit slopes are warm (bright), whereas those in
shadow are cold (dark), The temperature in this scene ranges from -50 °C
(darkest) to -15 °C (brightest). The major differences between the different
filters are due to the expected variation in the amount of energy emitted
from the surface at different wavelengths. Minor spectral differences
(infrared 'color') also exist between the different filters, but these
differences are small in this region due to the uniform composition of the
rocks and soils exposed at the surface.
The THEMIS infrared camera provides an excellent regional view of Mars -
this image covers an area 32 kilometers (~20 miles) by approximately 200
kilometers (~125 miles) at a resolution of 100 meters per picture element
('pixel'). This image provides a broad perspective of the landscape and
geology of the Cydonia region, showing numerous knobs and hills that have
been eroded into a remarkable array of different shapes. In this "big
picture" view the Cydonia region is seen to be covered with dozens of
interesting knobs and mesas that are similar in many ways to the knob named
the "face" - so many in fact that it requires care to discover the "face"
among this jumble of knobs and hills. The 3-km long "face" knob was first
imaged by the Viking spacecraft in the 1970's and was seen by some to
resemble a face carved into the rocks of Mars. Since that time the Mars
Orbiter Camera on the Mars Global Surveyor spacecraft has provided detailed
views of this hill that clearly show that it is a normal geologic feature
with slopes and ridges carved by eons of wind and downslope motion due to
gravity. Many of the knobs in Cydonia, including the "face", have several
flat ledges partway up the hill slopes. These ledges are made of more
resistant layers of rock and are the last remnants of layers that once were
continuous across this entire region. Erosion has completely removed these
layers in most places, leaving behind only the small isolated hills and
knobs seen today.
Note: this THEMIS infrared image has not been radiometrically nor
geometrically calibrated for this preliminary release. An empirical
correction has been performed to remove instrumental effects. A linear shift
has been applied in the cross-track and down-track direction to approximate
spacecraft and planetary motion. Fully calibrated and geometrically
projected images will be released through the Planetary Data System in
accordance with Project policies at a later time.
NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for
NASA's Office of Space Science, Washington, D.C. The Thermal Emission
Imaging System (THEMIS) was developed by Arizona State University, Tempe, in
collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS
investigation is led by Dr. Philip Christensen at Arizona State University.
Lockheed Martin Astronautics, Denver, is the prime contractor for the
Odyssey project, and developed and built the orbiter. Mission operations are
conducted jointly from Lockheed Martin and from JPL, a division of the
California Institute of Technology in Pasadena.
Image Credit: NASA/JPL/Arizona State University
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