One perfect barchan on Mars

A piece of Mars: In nature most dunes pile on one another or strongly influence each other. But occasionally, like a perfect flower or crystal, you find a perfectly shaped dune. Here is a crescentic dune, called a “barchan”, formed by winds moving from right to left. (HiRISE PSP_007676_1385, NASA/JPL/Univ. of Arizona)

Sand, wind, and dust

A piece of Mars: This is what dunes look like in the deepest part of Mars, where the air is full of bright dust that constantly settles out onto everything. The wind helps to clear off the sand dunes (blue in this image) in two ways: one is by dust devils that leave crooked tracks

Mars’ moving dunes

A piece of Mars: Today’s image comes courtesy of my postdoc, Simone Silvestro. He’s studying migrating dunes and has made a 3 image movie of a dune moving across the surface of Mars. This one crawls at a rate of ~0.5 m/year, and it isn’t far from where the Curiosity rover will pass when it

Echoes of the past

These dunes are quite unusual for Mars, and difficult to interpret. The thick blue and white stripes are dunes in their current location, but subtle stripes above them seem to indicate former positions of dunes, small pieces that got left behind as the dunes marched toward the bottom of the image. (HiRISE ESP_022645_1505)