This image is a wonder. NASA's Mars Reconnaissance Orbiter snapped it while looking down at a series of dark dunes. The shapes of Mars' dunes are usually a clue to wind directions on the planet, but these particular dunes take on an odd shape akin to a Morse-code message. NASA says "a circular depression (probably an old and infilled impact crater) has limited the amount of sand available for dune formation and influenced local winds. As a result, the dunes here form distinct dots and dashes."
The fascinating photo comes from the spacecraft's High Resolution Imaging Science Experiment (HiRise) camera. The orbiter snapped the image in February and NASA released it Friday.
Winds pushing from two directions at right angles force the sand into long dark stretches that make up the linear dunes. The dots are called "barchanoid dunes," and scientists are still working out what causes their formation on the Red Planet. Crescent-shaped barchanoid dunes can also be found on Earth.
The dots and dashes can be translated into letters using Morse code. Planetary scientist Veronica Bray analyzed the dune image and told Gizmodo the code works out to read "NEE NED ZB 6TNN DEIBEDH SIEFI EBEEE SSIEI ESEE SEEE !!" This may be nonsense, or it might be the crab-people of Mars trying to warn us about the wrath of their ancient gods. Or maybe they're just inviting us to come fishing.