Crater floor ‘veins’

The ESA-Roscosmos ExoMars Trace Gas Orbiter captured this image of the floor of the 400 km Antoniadi impact crater on 25 March 2020. This crater is located in the northern hemisphere of Mars in a region named Syrtis Major Planum.

The image was taken with the orbiter’s CaSSIS camera. The blue colour of this image does not represent the real colour of the crater floor but highlights the diversity of rock composition inside.

In the centre of the image are dendritic structures which look like veins on oak leaves. These structures are evidence of ancient river networks in this region. The structures stand up above the surface, whereas channels are usually depressions. This is because the channels were filled with harder material – possibly lava – and over time the softer rocks surrounding these branching channels has been eroded, leaving an inverted imprint of this ancient river system.