The largest known canyon in the solar system gets the star treatment in new images from the European Space Agency’s Mars Express orbiter.
As it whizzed past in Martian orbit, the spacecraft captured a pair of caves in the planet’s surface that form part of the Valles Marineris, a system of canyons known as the Grand Canyon of Mars.
However, the Martian Grand Canyon makes the Earth version seem like a canyon for ants.
At 4,000 kilometers (2,485 miles) long and 200 miles wide, Valles Marineris is nearly 10 times longer and 20 times wider than the vast canyon system found in North America. Earth has nothing close to compare with Valles Marineris, making the feature intensely interesting to planetary scientists.
The Mars Express segment images include parts of two chasmata, Ius on the left and Tithonium on the right. Close study of the details of these incredible natural structures can help scientists understand Mars’ geology and geological history.
For example, Mars appears to be tectonically extinct now, with its crust fused into one distinct layer encasing the planet’s interior. This is in contrast to the Earth, whose crust is divided into plates that can shift around, with a whole range of consequences.
Valles Marineris, scientists believe, was formed back when Mars had tectonic plates. Recent research has suggested that the canyon system was formed as a result of a widening rift between the plates a long time ago. This makes Valles Marineris very interesting.
The images from Mars Express make the canyon look relatively shallow, but the two chasmata are incredibly large; the full resolution version is about 25 kilometers per pixel. Ius Chasma stretches 840 kilometers in length in its entirety, and Tithonium Chasma 805 kilometers.
The orbiter is also equipped with 3D imaging capabilities, which reveal that in this image the canyon reaches about as deep as it can go—about 7 kilometers, five times deeper than the Grand Canyon.
There are several noticeable features that the images reveal in the two chasmata. Within Ius, a range of jagged mountains probably formed as the two tectonic plates pulled apart. Since it was some time ago, these mountains are quite eroded.
Tithonium is partially colored a darker shade in the upper part of the image. This may have come from the nearby volcanic region of Tharsis to the west of the chasma. Paler mounds arise from this dark sand; these are actually mountains that are more than 3 kilometers high.
However, the mountain tops have been scoured off thanks to erosion. This suggests that whatever material the rock is made of is softer and weaker than the rock around it.
However, that rock is not impenetrable. To the lower right of the more visible of the mountains, features suggest a recent slide of the canyon wall to the right.
Interestingly, Mars Express has discovered sulfate-bearing minerals in some of the features of Tithonium Chasma. This has been interpreted as evidence that the Chasma was once (at least partially) filled with water.
The evidence is far from conclusive, but recent detections of hydrogen in the chasma suggest that much water may be bound to minerals below the surface.
As with most Martian science, it is difficult to draw conclusions with any certainty, since we are forced – at least for the moment – to study it remotely. But identifying areas of interest could help in the planning of future Mars missions, both manned and unmanned; sending a rover to Valles Marineris would certainly help scientists answer some of the burning questions that have emerged.
Images like these are scientifically useful because they help formulate and sometimes answer these questions. But they are also just spectacularly gorgeous.
The images are published on ESA’s website.