The deepest known canyon in the solar system, seen from space

The worlds of the solar system beyond Earth have amazing surface features. Thanks to planetary science missions, we see images of canyons, craters, and cliffs across a variety of worlds. One day these places will give mountaineers and hikers new challenges. In particular, Mars will be a preferred destination. Future hikers and mountaineers will be spoiled for choice, even if they have to wear spacesuits to experience the thrills.

For example, there is the Valles Marineris canyon area. It is the largest known feature of its type in the solar system, several times larger than the Grand Canyon here on Earth. The European Space Agency’s Mars Express orbiter has just returned stunning images of this rift canyon.

Mars and Mars Express images

The last view from Mars Express focused on two trenches – called “chasma” – in western Valles Marineris. These are Ius Chasma and Tithonium Chasma, the deepest parts of the canyons. The whole system looks complex and complex. This is because it formed from tectonic activity instead of the erosional process that created the Grand Canyon. Think of it as a crack in the crust. It probably formed when baby Mars cooled. The region has also been affected by changes in the crust of the Tharsis region to the west. Then, as the gap widened, erosion took over. These processes created the canyon system we see today. It is a giant set of canyons 4,000 km long, 200 km wide and up to 7 km deep in places.

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This mapped image shows Ius and Tithonium Chasmata, which the orbiter photographed in April.  These two areas are part of the Valles Marineris de Mars canyon structure.  The area bounded by the bold white box indicates the area imaged by the Mars Express High-Resolution Stereo Camera on April 21, 2022 during orbit 23123. Courtesy Mars Express/NASA/MGS/MOLA Science Team
This mapped image shows the regions of Ius and Tithonium Chasmata, which Mars Express imaged. These two areas are part of the Valles Marineris de Mars canyon structure. The area bounded by the bold white box indicates the area imaged by the Mars Express High-Resolution Stereo Camera on April 21, 2022 during orbit 23123. Courtesy Mars Express/NASA/MGS/MOLA Science Team

The Mars Express orbiter has been circling the Red Planet since 2003. Its main job is to image and map the surface and minerals. It returns data about the atmosphere and can probe under the crust. The spacecraft uses the High Resolution Stereo Camera (HRSC) to create detailed images of the surface. Using this camera, planetary scientists have seen spectacular views of everything from wind-carved ridges and grooves to impact craters and channels that once carried liquid water. They also studied volcanoes, tectonic faults, river channels and ancient lava pools.

Hike the Martian Canyons

Images of Martian surface terrain from Mars Express and other missions inspire dreams of exploration. For adventurers, they also suggest long treks across the Red Planet. So imagine walking to the edge of Tithonium Chasma, for example, and looking down into the canyon. It is large and deep enough to dwarf some of the tallest mountains on Earth. And it won’t be an easy hike.

At the top of Tithonium there are deposits of dark material that could be volcanic sand blown in by the west wind. After clearing them, you cross some 3,000 meter high mountains that have been eroded by Martian winds. The descent continues through areas that may have been flooded with some kind of liquid. And, of course, there are landslide areas and other rough terrain to traverse before you hit bottom.

This oblique perspective view of Tithonium Chasmata, part of Mars' Valles Marineris canyon structure, was generated from the digital terrain model and nadir and color channels of the High-Resolution Stereo Camera on Mars Express from the ESA.
This oblique perspective view of Tithonium Chasmata, part of Mars’ Valles Marineris canyon structure, was generated from the digital terrain model and the nadir and color channels of the High-Resolution Stereo Camera on Mars Express from the ESA.

Things don’t get any easier at Ius Chasma, with rugged slopes to traverse. Once you get to the bottom of the canyon, however, there are plenty of rock formations to explore. It will be many years before recreational hiking is available on Mars. Maybe until then, the trails created by the geologists will make things easier.

For now, however, science is the main reason for exploration. These two canyons offer clues to Mars’ geological past, showing evidence of tectonic activity, volcanism, wind erosion and deposition. These processes result in giant “fissures” that divide the surface. They also deposit sand on the surface and create layered rock deposits.

Superlatives elsewhere

If canyon hiking isn’t your thing, there’s always Olympus Mons to consider. It is the tallest mountain in the solar system, rising nearly 22 kilometers above the surrounding Martian landscapes. Skiers would love this mountain (if there was enough snow) because it would be a very long distance from the caldera to the base. Of course, it would be a tough race. This thing is a shield volcano, and thousands of eruptions have shaped and sculpted the landscape. They give way to a fairly steep cliff that descends for 8 kilometers.

Olympus Mons from Orbit
Olympus Mons from orbit. Credit: NASA

Speaking of cliffs, the tallest in the solar system is not on Mars. It’s actually on the moon Miranda, which orbits distant Uranus. This huge cliff is called Verona Rupes and rises more than 20 kilometers above the surface. The NASA folks calculated that with Miranda’s low gravity, someone jumping from the top (presumably with airbag protection), would have a 12 minute ride down. They would reach a terminal speed of around 200 kilometers per hour. Provided they survived, the Verona Rupes jumpers could boast of an incredible thrill ride.

Not a canyon, but a cliff, the highest in the solar system: Verona Rupes, on the Uranian moon Miranda. Courtesy of NASA.

Not to be outdone, minor planet 4 Vesta has a crater called Rheasilvia, which is 500 kilometers in diameter. That’s about 90% of Vesta’s diameter! The crater has a central peak that rises 23 km above the crater floor. To get to the mountain for a good climb would require descending into the crater above an escarpment. Then you will cross quite a rugged landscape to reach the top. The very low surface gravity means this will be a fairly easy hike, albeit a long one.

A still image (top) from the Dawn mission imagery of Vesta’s south pole, with the peak of the Rheasilvia crater centered. The bottom view is a colorized view, showing variations in height. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Benefits of planetary exploration

Missions like Mars Express, Voyagers, Dawn and others reveal spectacular landscapes across the solar system. They are sent to give planetary scientists detailed insight into distant worlds. The images they send are evocative and inspiring. It may be a while before anyone can hike these places, but the images certainly inspire dreams of individual exploration.

For more information

Dawn Mission Preview
Mars Express Peers into Mars’ “Grand Canyon”
Olympus Mons
Verona Rupes: the highest known cliff in the solar system

Arline J. Mercier