Mars' Tattoo Tear

More cool pictures from the Mars Express Orbiter.

New Scientist: Dark, rippling dunes of volcanic ash - similar to Hawaii's black sand beaches - cast a teardrop shape in an ancient Martian crater, reveal the latest images from Mars Express. Wind is likely to have carved the 12-kilometre-long tear shape a million or more years ago when the Martian atmosphere was thicker, says Gerhard Neukum, principal investigator of the High Resolution Stereo Camera on Europe's Mars orbiter. Now, the atmosphere has thinned so much that the dune's shape is likely to remain fixed for at least hundreds of thousands of years, he says. [...] Right now the camera is taking images for just 10 minutes during each of Mars Express's seven-hour orbits. That is because the closest part of the spacecraft's orbit, which takes an elliptical path around the planet's poles, changes with time. Now the closest approach is relatively far from the planet and occurs over the planet's night side, limiting photo opportunities. But the geometry will begin to improve again in September.