The European Space Agency (ESA) has published images of the Deuteronilus Cavus depression taken by the Mars Express spacecraft. They are accompanied by a mock recipe for creating such formations, involving asteroid bombardment, streams of liquid water, and volcanic eruption.
Deuteronilus Cavus is located in the Northern Hemisphere of Mars in the transition zone between the Southern Highlands and the Great Northern Plain. Its diameter is about 120 kilometers. The depression was formed over a long period of time, preserving details of volcanic, glacial, water and wind activity over its four billion years of existence.
The almost circular shape of the depression indicates that it all started with a crater. It probably formed about 4.1-3.7 billion years ago, when the planet was regularly bombarded by asteroids and comets. Over time, the effects of water and ice changed the shape of the original crater, nearly doubling its size.
The rim of the crater is riddled with outflow channels. They were probably cut by streams of water that once flowed across the surface of Mars. It is also possible that water flowed underground, collapsing the weakened surface.
The grooved surface texture in some of the channels and depressions carved into the crater rim indicates pre-existing ice. Because Deuteronilus Cavus is located in the mid-latitudes of Mars, glaciers are thought to have formed in this region when the planet’s axis was tilted much more than now.
Linear furrows indicate that boulders frozen into the base of the glacier dragged along it, gouging out the depressions visible today. So-called “debris aprons” are visible around the base of the inner crater walls. These smooth, tongue-shaped ends were formed when ice mixed with rock fragments during glaciation and slowly slid down the slope.
Inside the crater is a haphazard mixture of hillocks, table mountains, channels and smoother plains. The stronger rock blocks resisted erosion better and survived, while the surrounding material gradually collapsed. It is possible that they could be remnants of the collapsed central peak of the crater.
Much of the interior surface of the crater is covered with a dark plaque. It appears to be wind-blown volcanic ash. The brighter sediments that show through the darker material contain clay minerals formed by the mixing of ash and water. This suggests that the eruptions occurred at a time when water streams were still flowing on the surface of Mars.
Further evidence of past volcanic activity is provided by the “wrinkled ridges” that crisscross the smoother terrain surrounding the crater. They were formed by the cooling and compression of lava flows.
A recipe for creating a Martian crater
Thus, the recipe for creating a crater according to ESA is as follows:
- Throw an asteroid at Mars to form a classic round base;
- Cover it with molten lava;
- Make channels with liquid water;
- Refrigerate to form ice, and then freeze-thaw several times to slowly expand the edges of the crater;
- Sprinkle generously with volcanic dust and leave to solidify;
- Serve the hungry Mars fans!
Recall that earlier Mars Express photographed a white Christmas on Mars.
According to ESA
