The MRO High-Resolution Imaging Experiment (HiRISE) spacecraft's color camera previously captured stunning images of strange circular objects on the Mars, including some of the crescent-shaped dunes; however, the latest batch of images have left officials somewhat starstruck.
"Sand dunes of many shapes and sizes are common on Mars. In this example, the dunes are almost perfectly circular, which is unusual", wrote planetary geologist Alfred McEwen, adding: "They are still slightly asymmetrical, with steep slip faces on the south ends. This indicates that sand generally moves to the south, but the winds may be variable."
Circular Sand Dunes on the surface of Mars
The MRO took pictures of the dunes in late November last year using the HiRISE camera, which is operated by the University of Arizona.
Circular Sand Dunes on the surface of Mars, cover with frost
The NASA MRO is an orbiting spacecraft that studies the geological past and current climate of Mars. Since 2006, it has been studying the atmosphere and topography of the red planet from orbit using high-resolution sensors. It also serves as an important relay station for several Martian missions.