Status Report

Mars Odyssey THEMIS Image: Small Volcano in Terra Cimmeria

By SpaceRef Editor

June 26, 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 Science

The Story

This positive relief feature (see MOLA context) in the ancient
highlands of Mars appears to be a heavily eroded volcanic center. The top
of this feature appears to be under attack by the erosive forces of the
martian wind. Light-toned streaks are visible, trending northeast to
southwest, and may be caused by scouring of the terrain, or they may be
dune forms moving sand. The northeast portion of the caldera area looks as
though a layer of material is being removed to expose a slightly
lighter-toned surface underneath. The flanks of this feature are slightly
less cratered than the surrounding terrain, which could be explained in two
ways: 1) this feature may be younger than the surrounding area, and has
had less time to accumulate meteorite impacts, or 2) the slopes that are
observed today may be so heavily eroded that the original, cratered
surfaces are now gone, exposing relatively uncratered rocks. Although most
of Terra Cimmeria has low albedo, some eastern portions, such as shown in
this image, demonstrate an overall lack of contrast that attests to the
presence of a layer of dust mantling the surface. This dust, in part, is
responsible for the muted appearance and infill of many of the craters at
the northern and southern ends of this image

[Source: ASU THEMIS Science Team]

This flat-topped volcano pops out from the surface, the swirls of its ancient lava flows running down onto the ancient highlands of Mars. Its smooth top appears to be under attack by the erosive forces of the martian wind.

How can you tell? Click on the image above for a close-up look. You’ll see some light-toned streaks that run in a northeast-southwest direction. They are caused either by the scouring of the terrain or dunes of moving sand. Either way, the wind likely plays upon the volcano’s surface. Look also for the subtle, nearly crescent shaped feature at the northeast portion of the volcano’s cap. It looks as if a layer of material has been removed by the wind, exposing a slightly lighter-toned surface underneath.

The sides of the volcano are less cratered than the rest of the terrain. Perhaps that means it is younger than the surrounding area and has had less time to accumulate meteorite impacts. On the other hand, perhaps erosion has scrubbed away the original cratered surfaces. It’s a little hard to tell which possibility holds the key to the history of this area.

Although most of Terra Cimmeria can look relatively darker (has a low albedo or low “reflective power”) than some other Martian areas, its eastern portions sometimes have an overall lack of contrast as seen in the above image. A layer of dust blankets the surface here, causing it to look muted. Many of the craters in the northern and southern ends of the image also seem subdued, as dust has partly filled in the stark holes they once created.

The Cimmerians who give their name to this region were an ancient, little-known people of southern Russia mentioned in Assyrian inscriptions and by Homer.

[Questions? Email marsoutreach@jpl.nasa.gov]

[Source: NASA/JPL Mars Outreach]

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