Dunes near Ulyxis Rupes
Date: 24 August 2018
Satellite: Trace Gas Orbiter
Depicts: Dune field on Mars
Copyright: ESA/Roscosmos/CaSSIS, CC BY-SA 3.0 IGO
This beautiful dune field lies inside a crater near the south polar region of Mars.
The image was taken by the ExoMars Trace Gas Orbiter's Colour and Stereo Surface Imaging System, CaSSIS, on 18 May 2018, at the beginning of martian southern spring, when a thin layer of seasonal carbon dioxide ice was still covering the surface. Over the winter, the ice grains in this thin layer appear to grow enough that the ice becomes almost transparent, letting light through and heating up the surface from the bottom of the ice. As the ice begins to sublimate from the bottom up, pressure builds up, and it is released through instabilities and cracks in the ice layer, in what scientists think are geyser-like processes of carbon dioxide gas that push out martian sand. The black streaks seen all across this image are examples of the darker sand being propelled out through the ice cracks and down the slip face of the dunes.
The ExoMars programme is a joint endeavour between ESA and Roscosmos.
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 IGO License. 
