Dust devil frenzy

This remarkable image was taken in the Terra Sabaea region of Mars, west of Augakuh Vallis, by the Colour and Stereo Surface Imaging System (CaSSIS) onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter. This mysterious pattern sits on the crest of a ridge, and is thought to be the result of dust devil activity – essentially the convergence of hundreds or maybe even thousands of smaller martian tornadoes.

This image is a colour-composite representation where features that are bluer compared to the average colour of Mars are shown in bright blue hues. In actual colour, the streaks would appear dark red. Dust devils churn up the surface material, exposing fresher material below.

The reason why the streaks are so concentrated on the ridges is not known at present, but a relationship to orographic lift as masses of carbon dioxide air flow uphill and converge with other air masses is one possibility.

The image was taken on 8 February 2019 and is centred at 26.36ºN/56.96ºE. North is up.