Dark, seasonal flows emanate from bedrock exposures at Palikir Crater on Mars in this image from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. These flows, now documented at several places on Mars, form and grow during warm seasons when surface temperature is warm enough for salty ice to melt, and then fade or completely disappear in the colder season.
The location of this site is about 41.6 degrees south latitude, 202.3 degrees east longitude. The season was summer on southern Mars when this image was taken on June 27, 2011. Three arrows point to bright, smooth fans left behind by flows. The scale bar at lower right indicates 50 meters (164 feet). North is up.
These dark, warm-season flows are called "recurring slope lineae" or RSL. Researchers are using observations from Mars orbiters to study the possibility that RSL result from action of salty liquid water. Examples of RSL sites observed over a sequence of seasons are at PIA14472 and PIA14475.
This image, included in a paper by Lujendra Ojha of the Georgia Institute of Technology, Atlanta, and co-authors in Geophysical Research Letters, is one product from the HiRISE observation cataloged as ESP_023045_1380. Other products from the same observation are available at http://uahirise.org/ESP_023045_1380.
Image credit: NASA/JPL-Caltech/University of Arizona
Note: For more information, see NASA Mars Orbiters See Clues to Possible Water Flows.