JM Marineris It is the wide valley system that runs along the Martian equator east of Tharsis.
It is 4,000 kilometers (2,500 miles) long and reaching depths of 7 kilometers (4 miles) – about 10 times longer and 5 times deeper than the Grand Canyon in Arizona.
They are composed of countless small cracks, channels, outflows, fractures, and signs of flowing material (such as water, ice, lava, or debris).
Vallis Marineris is an unmissable scar on the face of Mars, and it is believed to have formed when the planet’s crust was stretched by nearby volcanic activity, causing it to rupture and crack before collapsing into the deep basins we see today.
These basins have been further formed and eroded by water flows, landslides, and other influencing processes, with spacecraft including Mars Express spying signs indicating the presence of water in parts of Valles Marineris in the relatively recent past.
The new image from the HRSC instrument from Mars Express shows “chaotic terrain” of Pyrrhae Regio – an area south of Eos Chasma, the eastern branch of the Valles Marineris system.
Scattering craters, which were formed when objects from space collided with the surface of Mars, can be seen to the left of the frame.
The floor of the largest and highest basin extends about 40 kilometers (25 miles), and contains some fractures and markings that formed immediately after the crater itself.
The hot molten rock is thought to have been thrown away during the collision that formed the crater, and then cooled and stabilized to form the scar-like features visible here.
In the center of the frame, the surface is relatively smooth and virtually flat – however, two broad channels made their way through the landscape, and can be seen as jagged and branching indentations into the surrounding terrain.
The valleys at their right end are connected to the image’s true star: a sunken, uneven, lumpy spot from the ground known as the chaotic terrain.
The chaotic terrain, as the name suggests, is irregular and mixed, and it is believed to form when subsurface ice and sediments begin to melt and shift.
This changing layer causes the surface above to collapse – a collapse that can happen quickly and catastrophically as the water drains away rapidly through Martian regolith.
Ice melt can be induced by heating events such as pyroclastic flows, underground magma, impacts of large meteorites, or changes in climate.
In the chaotic terrain we see here, the ice melted, the resulting water was washed away, and a number of scattered broken blocks remained standing in now empty hollows.
Significantly, the floors of these pits are located about 4 kilometers (2.5 mi) under flat ground near craters on the left.