The Mars Express offers truly epic views of the largest canyon in the solar system

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 passed Mars orbit, the spacecraft captured a pair of gullies on the planet’s surface that are part of the Valles Marineris, a system of canyons known as the Grand Canyon of Mars.

The Martian Grand Canyon, however, makes Earth’s version look like a canyon for ants.

At 4,000 kilometers (2,485 miles) long and 200 miles wide, Valles Marineris is almost 10 times longer and 20 times wider than the vast canyon system of North America. Earth has nothing that comes close to comparison with Valles Marineris, which makes the feature extremely interesting to planetary scientists.

Segment images by Mars Express include sections 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 the geology and geologic history of Mars.

The location of the two chasmata. (NASA/MGS/MOLA Science Team)

For example, Mars appears to be tectonically extinct now, with its crust fused into a discrete layer that shrouds the planetary interior. This contrasts with Earth, whose crust is split into plates that can move, with a whole range of consequences.

According to scientists, Valles Marineris was formed when Mars had tectonic plates. Recent research has proposed that the canyon system formed as a result of a widening crack between the plates a long time ago. This makes Valles Marineris very interesting.

Mars Express images make the canyon look relatively shallow, but both chasmata are incredibly tall; the full resolution version is about 25 kilometers per pixel. Ius Chasma is 840 kilometers long in its entirety, and Tithonium Chasma is 805 kilometers long.

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.

Topography of Ius and Tithonium ChasmataThe topography of the two chasmata. (ESA/DLR/FU Berlin)

There are several noteworthy features that the images reveal in both chasmata. In Ius, a row of jagged mountains probably formed when the two tectonic plates pulled apart. As it was a while ago, these mountains are quite eroded.

The tithonium is partially stained with a darker shade in the upper part of the image. This may be from the nearby volcanic region of Tharsis to the west of the chasm. Paler mounds rise from this dark sand; they are in fact mountains that rise more than 3 kilometers high.

However, the tops of the mountains have been eroded by erosion. This suggests that whatever material the mountain is made of is softer and weaker than the rock around it.

This rock is not waterproof either. Lower right of the most visible of the mountains, features suggest a recent landslide of the canyon wall on the right.

annotated map of chasmataAn annotated map showing various features in the chasmata. (ESA/DLR/FU Berlin)

Interestingly, Mars Express has detected sulfate-containing minerals in some of the Tithonium Chasma features. 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 sinkhole suggest that a large amount of water may be bound to minerals below the surface.

As with most Mars science, it’s hard to draw conclusions with certainty, as we’re forced — currently, at least — to study it from a distance. But identifying areas of interest could help plan future Mars missions, manned and unmanned; Sending a rover to Valles Marineris would certainly help scientists answer some of the burning questions that have arisen.

Images like these are scientifically useful because they help formulate and sometimes answer these questions. But they are also spectacularly gorgeous.

The images have been published on the ESA website.

Arline J. Mercier