Status Report

Mars Odyssey THEMIS Image: Spallanzani Crater

By SpaceRef Editor

July 18, 2002

Filed under Daily Themis Pictures, Mars Odyssey THEMIS, US

Image Context:

Context image credit: NASA/Mars Orbiter Laser Altimeter (MOLA) Team

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The craters on Mars display a variety of interior deposits one of which
is shown here. Spallanzani Crater is located far enough south that it
probably experiences the seasonal growth and retreat of the south polar
cap. During the southern hemisphere winter, CO2 frost condenses out of
the atmosphere onto the surface and probably brings with it small
amounts of dust and even water ice. It is this sort of depositional
process that is thought to have produced the polar layered deposits.
The layered deposit in Spallanzani Crater shares some similarities with
the polar deposits. Whatever the origin of the layered materials, they
likely filled the crater at one time. Note how the interior slope of
the northern rim displays layered material of similar if less distinct
morphology as the main deposit on the floor. The process that filled
the crater with sediment has been replaced by the opposite process.
Erosion has taken over, leaving behind spectacular stair-stepped mesas
and bizarre, contorted landforms. Unlike the interior crater deposits
in the equatorial latitudes, the erosional process has not produced the
yardang features that indicate wind erosion. It may be that ice was one
of the cementing agents of the sediment and perhaps the sublimation of
that ice has left the sediment susceptible to erosion. The details of
the deposition and erosion of this interesting deposit remain to be
discovered.

[Source: ASU THEMIS Science Team]

Note: this THEMIS visual 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