The high-resolution stereo camera (HRSC) aboard ESA’s Mars Express orbit captured a fascinating landscape near the vast gorge system of Valles Marineris on the Red Planet.
This image from the High Resolution Stereo Camera (HRSC) aboard ESA’s Mars Express shows craters, valleys and chaotic terrain in the Pyrrhae Region, Mars. Chaotic terrain forms as a shifting subsoil of melting ice and sediment causes the surface above to collapse. In the chaotic terrain seen here, ice melted, the resulting water flowed away and a number of disparate broken blocks were left in now empty cavities (which once offered ice). This image consists of data collected by HRSC on 3 August 2020. Image credit: ESA / DLR / FU Berlin / CC BY-SA 3.0 IGO.
Valles Marineris is a vast gorge system that runs along the Mars equator just east of the Tharsis region.
It is 4,000 km long and reaches depths of up to 7 km – about 10 times longer and five times deeper than the Grand Canyon in Arizona.
It consists of numerous smaller cracks, channels, outflows, fractures and signs of flowing material (such as water, ice, lava or debris).
Valles Marineris is an impermissible scar on the face of Mars, and is thought to have formed as the Earth’s crust was stretched by nearby volcanic activity, causing it to rupture and burst open before falling into the deep craters we see today.
These bins were further formed and eroded by water currents, landslides and other erosion processes, with spacecraft, including Mars Express spy plates that water existed in parts of Valles Marineris in the relatively recent past.
Perspective view of chaotic terrain in Pyrrhae Region, Mars. Image credit: ESA / DLR / FU Berlin / CC BY-SA 3.0 IGO.
The new image of Mars Express’ HRSC instrument shows’ chaotic terrain ‘in Pyrrhae Region – a region south of Eos Chasma, an eastern branch of the Valles Marineris system.
To the left of the frame, a distribution of impact craters, formed as incoming bodies from space, collides with the surface of Mars.
The floor of the largest and upper basin stretches for about 40 km and contains fractures and marks that formed just after the crater itself.
It is suspected that hot, molten rock was thrown up during the crater-forming collision, after which it cooled and sank to form the scar-like features visible here.
Towards the middle of the frame, the surface is relatively smooth and distinctive – however, two wide channels have worked through the landscape and can be seen as winding, branching notches in the surrounding terrain.
The valleys are attached to their right to the true star of the image: a sunken, uneven, scarred ground known as chaotic terrain.
Chaotic terrain, as the name implies, seems irregular and cluttered, and it is presumably when ice and sediment on the surface begin to melt and shift.
This shifting layer causes the surface above to collapse – a collapse that can occur quickly and catastrophically if water flows away quickly through the Mars regolith.
This can cause ice to melt due to events such as volcanic lava flows, subterranean magmatism, pushing by large meteorites or changes in climate.
In the chaotic terrain seen here, ice melted, the resulting water flowed away, and a number of disjointed broken blocks were left standing in now empty cavities.
Strikingly, the floors of these cavities lie about 4 km below the flatter ground near the craters on the left.