A comparison of images taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter in November 2010 and May 2013 reveal the formation of a new gully channel on a crater-wall slope in the southern highlands of Mars.

Gully or ravine landforms are common on Mars, particularly in the southern highlands. This pair of images shows that material flowing down from an alcove at the head of a gully broke out of an older route and eroded a new channel. The dates of the images are more than a full Martian year apart, so the observations did not pin down the Martian season of the activity at this site. Before-and-after HiRISE pairs of similar activity at other sites demonstrate that this type of activity generally occurs in winter, at temperatures so cold that carbon dioxide, rather than water, is likely to play the key role.

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A New Gully Channel in Terra Sirenum, Mars
This pair of before (left) and after (right) images from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter documents the formation of a substantial new channel on a Martian slope between Nov. 5, 2010, and May 25, 2013.

The location is on the inner wall of a crater at 37.45 degrees south latitude, 222.95 degrees east longitude, in the Terra Sirenum region. Gully or ravine landforms are commonly found in the mid-latitudes on Mars, particularly in the southern highlands. These features typically have an alcove at the upper end, feeding into a channel and an apron of debris that has been carried from above. Researchers using HiRISE have discovered many examples of gully activity likely driven by seasonal carbon-dioxide frost (dry ice).

The changes visible by comparing the 2010 and 2013 observations at this site formed when material flowing down from the alcove broke out of an older route, eroded a new channel and formed a deposit on the apron. Although this pair of observations does not pin down the season of the event, locations HiRISE has imaged more often demonstrate that this sort of event generally occurs in winter, when liquid water is very unlikely. Despite their resemblance to water-formed ravines on Earth, carbon dioxide may play a key role in the formation of many Martian gullies.

The image on the right is one product from a HiRISE observation catalogued as ESP_032011_1425. Other products from the same observation are available at http://uahirise.org/ESP_032011_1425 . The image on the left is from observation ESP_020051_1420. A May 14, 2009, observation of the same slope is at http://uahirise.org/ESP_013115_1420.

HiRISE is one of six instruments on NASA’s Mars Reconnaissance Orbiter. The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter and Mars Science Laboratory projects for NASA’s Science Mission Directorate, Washington. Image Credit: NASA/JPL-Caltech/Univ. of Arizona

For more information about HiRISE, see http://hirise.lpl.arizona.edu . For more information about the Mars Reconnaissance Orbiter, visit http://www.nasa.gov/mro .

Posted by: Soderman/SSERVI Staff
Source: NASA JPL

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