There’s more to this image of Mars than first meets the eye: nestled in the detail of the cliff face that cuts through this scene are signs of geology in motion. Zooming in reveals many rocks that had fallen from the cliff edge and left little dimples in the soft material as they slid downslope.
The image was taken by the CaSSIS camera onboard the ESA/Roscosmos ExoMars Trace Gas Orbiter on August 3, 2020, and captures a slice through the maze-like system of the aptly named Noctis Labyrinthus. The cliff-like feature running through the central portion of the image is part of a horst-graben system, which comprises raised ridges and plateaus (horst) either side of sunken valleys (graben) created as a result of tectonic processes that pulled the planet’s surface apart. The entire network of plateaus and trenches making up Noctis Labyrinthus spans some 1200 km, with individual cliffs reaching 5 km above the surface below.
Patches of linear ripples produced by the wind may be found elsewhere in this photograph, particularly on the right-hand side. A few minor impact craters dot the landscape as well.
The image was taken over the easternmost part of Noctis Labyrinthus at 265.8°E/8.70°S in the Phoenicis Lacus Quadrangle, near the intersection with Lus Chasma of Valles Marineris – the ‘grand canyon’ of Mars.
TGO landed on Mars in 2016, and its full science mission began in 2018. Not only is the spacecraft delivering magnificent photographs, but it is also giving the best ever inventory of the planet’s atmospheric gases and mapping the planet’s surface for water-rich locations. It will also provide data relay services for the second ExoMars mission, which will arrive on Mars in 2023 and include the Rosalind Franklin rover and the Kazachok platform.