This image shows some faint traces of dark flows along the headwall of an impact crater. These are relics of seasonal recurring slope lineae (RSL) that formed on an equator-facing slope.

They are not expected to be active yet, so we’ll have to wait until later in the Martian spring for any changes. However, we like to monitor these sites as they progress through the seasons, and fully formed RSL have been identified at this site before.

That’s because RSL recur each Mars year at the same places, like this crater wall. RSL activity often happens at predicted temperatures approaching minus 20 degrees Celsius (or minus 4 degrees Fahrenheit). An intermittent flow of brines is possible but dry flow of granules is an alternative explanation to explain RSL formation. Because of this uncertainty, the science community is debating whether these regions should be regarded as “special regions” where rovers or others landers are restricted.

Written by: John Bridges (narration: Tre Gibbs)  (25 May 2020)