Status Report

Mars Odyssey THEMIS Image: Maunder Crater

By SpaceRef Editor

May 24, 2002

Filed under Daily Themis Pictures, Mars Odyssey THEMIS, US

Image Context:

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

The Science

The Story

This image is of a portion of Maunder Crater located at about 49 S and
358 W (2 E). There are a number of interesting features in this image. The
lower left portion of the image shows a series of barchan dunes that are
traveling from right to left. The sand does not always form dunes as
can be seen in the dark and diffuse areas surrounding the dune field.
The other interesting item in this image are the gullies that can be
seen streaming down from just beneath a number of sharp ridgelines in
the upper portion of the image. These gullies were first seen by the
MOC camera on the MGS spacecraft and it is though that they formed by
groundwater leaking out of the rock layers on the walls of craters. The
water runs down the slope and forms the fluvial features seen in the
image. Other researchers think that these features could be formed by
other fluids, such as CO2. These features are typically seen on south
facing slopes in the southern hemisphere, though this image has gullies
on north facing slopes as well.

[Source: ASU THEMIS Science Team]

Little black squigglies seem to worm their way down the left-hand side of this image. These land features are called barchan (crescent-shaped) dunes. Barchan dunes are found in sandy deserts on earth, so it’s no surprise the Martian wind makes them a common site on the red planet too. They were first named by a Russian scientist named Alexander von Middendorf, who studied the inland desert dunes of Turkistan.

The barchan dunes in this image occur in the basin of Maunder crater on Mars, and are traveling from right to left. The sand does not always form dunes, though, as can be seen in the dark areas of scattered sand surrounding the dune field.

Look for the streaming gullies that appear just beneath a number of sharp ridgelines in the upper portion of the image. These gullies were first discovered by the Mars Orbital Camera on the Mars Global Surveyor spacecraft. While most crater gullies are found on south-facing slopes in the southern hemisphere of Mars, you can see from this image that they occur on north-facing slopes as well. Comparing where gullies appear will help scientists understand more about the conditions under which they form.

Some researchers are really excited about gullies on Mars, because they believe these surface tracings might be signs that groundwater has leaked out of the rock layers on the walls of craters. If that’s true, the water runs down the slope and forms the flow-like features seen in the image.

Scientists can get into some really hot debates, however. Other researchers think that these features could be formed by other fluids, such as carbon dioxide. No one knows for sure, so a lot of heads will be studiously bent over these images, continuing to study them closely. The neat thing about science is that the way you get closer to the truth is to hypothesize and then test, test, and test again. Debate for scientists is seen as an essential means of making sure that no wrong assumptions are made or that no important factor is left out. It’s what keeps the field interesting and dynamic . . . and sometimes quite loud and entertaining!

[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