Cracks on the sides of a Martian volcano

Mars has some of the most impressive volcanoes in the solar system. The European Space Agency’s (ESA) Mars Express has now imaged the cleft, open wing of the second-tallest planet ever: Ascraeus Mons.

This image includes observations from the Mars Express High Resolution Stereo Camera (HRSC).

Ascraeus Mons is the northernmost and tallest of three prominent volcanoes found in the Tharsis region of Mars, a volcanic plateau in Mars’ western hemisphere. It is 18 km in elevation but has gentle slopes, with an average inclination of 7 degrees. This slow climb is reflected in volcanoThe massive base has a diameter of 480 km, giving it a footprint nearly the size of Romania on Earth.

Ascraeus Mons is surpassed in height only by Olympus Mons, which is the tallest volcano not only on Mars but in the entire solar system.

Like ink in water

The image shows the lower south side of Ascraeus Mons. There is quite a difference in height from one side to the other, with the left (south) side of the tire sitting 10km lower than the right (north) side. The volcano’s peak is found to the right (north) of the frame, as seen clearly in the broader context map of the area.

Several similarly dramatic features – collectively called the Ascraeus Chasmata, which include an enormous swath of collapsed terrain more than 70 km in diameter – can be seen across the frame: lava flow And pipes, and drill strings, and channel-like pits, and large cracks stretching tens of kilometers in length.

All these features of different ages and origins, mesh together to form a scene akin to ink trails artfully dispersed in water, or the beautifully intricate root system of a plant as it digs into the soil.

lurking underground

On the right side of the frame lie many crinkly lava flows. This rumpled land then encounters series of “craters”: features where series of circular or semi-circular depressions coalesce to form basins. We see these on Earth too, with a prime example being the dramatic Cenotes found on the Yucatan Peninsula, Mexico. The crater basins and ridges shown here are also grouped together to form a large and striking collapse area.

These chains and troughs are likely to form where there are hidden voids below the surface, causing the Earth to become unstable and collapse – much like a sinkhole. Subsurface voids are thought to be created when the surface layer of a pyroclastic flow cools and hardens rapidly; The lava flow beneath them then stops and recedes over time, leaving tube-shaped pockets several meters underground.

The land to the left of the crater chains is characterized by what are called “winding streams”: smaller, winding, edgeless channels often found at the sides of volcanoes. It’s still not clear how these form, but their formation may involve flows of lava, ash, or water — or a combination of the three.

The left part of the image is dominated by large cracks up to 40 km long. Branching out from these fissures are channels that weave and braid together (“braided canals”), isolating parts of the Martian terrain to form “islands” and terraces. These are likely to have been formed by water – perhaps as snow and ice accumulated on the sides of Ascraeus Mons before later melting.

Mars exploration

Mars Express has been orbiting the Red Planet since 2003, imaging the Martian surface, mapping its minerals, determining the composition and circulation of its tenuous atmosphere, exploring what is beneath its crust, and exploring how various phenomena interact in the Martian environment.

The in-orbit HRSC, responsible for these new images, has revealed plenty of diverse Martian surface features, with images showing everything from wind-sculpted ridges and canyons to impact craters, tectonic faults, river channels and ancient lava pools. Many of the Mars Express images feature the red planet’s supervolcanoes, of which Ascraeus Mons is a great example.