This broad field of barchan sand dunes – dunes with crescent shapes – in the Olympia Undae region near Mars’ northern polar cap was imaged by NASA’s Mars Odyssey orbiter. The image, showing a small segment of the dune field, was taken during summer when the surface was free of frost. The dunes cover an area of some 470,000 square kilometres (181,000 square miles), larger than the U.S. state of California, and surround about a quarter of the northern polar cap. It is the most expansive continuous field of dunes on Mars.
Nitrogen, in the form of nitric oxide (one nitrogen atom and one oxygen atom), has been detected for the first time on the surface of Mars by a team of researchers using the Sample Analysis at Mars (SAM) instrument suite aboard NASA’s Curiosity rover, adding to the growing speculation that life could have once flourished on ancient Mars.