And it’s not a lens artifact, nor is it just a hill that might kinda look like a face from one particular angle. It’s weird streaks that reappear on certain Martian slopes during warm months, detected by the HiRISE camera currently orbiting Mars aboard NASA's Mars Reconnaissance Orbiter. The observations are detailed in the new issue of Science.Most likely, it’s water, specifically gross, briny water, explains the University of Arizona's Alfred McEwen. (Though, there’s no way to confirm that based on the HiRISE observations.) The streaks range from a half meter to a few meters wide and appear to be hundreds of meters long. They aren’t the first weird streaks seen on Martian slopes — gullies, possibly caused by recent liquid flow, have also been observed — but they’re the first that change seasonally, suggesting current surface liquid or at least liquid very close to the surface. Why the flows are just in these places remains to be seen.From a University of Arizona news release:The flows lengthen and darken on rocky equator-facing slopes from late spring to early fall. Favoring warm areas and times suggests a volatile material is involved, but which volatile? The settings are too warm for carbon-dioxide frost and, at some sites, too cold for pure water. This suggests the action of brines with their lower freezing points. Salt deposits indicate brines have been abundant in Mars’ past. These recent observations suggest they may form near the surface today in rare times and places.The slopes were checked for water with the orbiter’s Compact Reconnaissance Imaging Spectrometer for Mars, and they came up dry. Note, however, that just because the surface isn’t technically wet doesn’t mean that water isn’t drying quickly on it, rearranging the grains of sand to leave the marks, or flowing just under the surface.Check it out:Are they teaming with life? Probably not, but they could hold clues for what life once was — if it was — or could be on Mars.Reach this writer at michaelb@motherboard.tv.
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