Recurring Slope Lineae (called "RSL") are seasonally-repeating dark flows that are active at the warmest times of the year. Some of these grow from the <a rel="nofollow" class="external text" href="http://static.uahirise.org/images/2017/details/cut/ESP_049032_1670.jpg">top of the steep slope downwards</a> as expected for liquid or granular flows.
<p>Others show different darkening patterns, which suggests different processes. Although HiRISE has acquired many images to monitor RSL sites, it still is not certain how these features form.
</p><p>The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 25.8 centimeters (10.2 inches) per pixel (with 2 x 2 binning); objects on the order of 51.7 centimeters (20.4 inches) across are resolved.] North is up.
</p>
The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace &amp; Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.
NASA/JPL-Caltech/Univ. of Arizona
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