The Deepest Known Canyon in the Solar System, Seen From Space

Solar system worlds beyond Earth have amazing surface features. Thanks to planetary science missions, we see images of canyons, craters, and cliffs across a variety of worlds. Someday, those places will give mountain climbers and hikers new challenges. In particular, Mars will be a favored destination. Future hikers and mountain climbers will be spoiled for choice, even if they must wear space suits to get their thrill on.

For example, there’s the Valles Marineris canyon region. It’s the largest known such feature in the solar system, many times larger than the Grand Canyon here on Earth. The European Space Agency’s Mars Express orbiter just returned breathtaking images of this rift canyon.

Mars and the Mars Express Images

The latest view from Mars Express focused on two trenches—called “chasma”—in western Valles Marineris. They’re Ius Chasma and Tithonium Chasma, the deepest parts of the canyons. The whole system looks complex and intricate. That’s because it formed from tectonic activity instead of the erosion process that created the Grand Canyon. Think of it like a crack in the crust. It likely formed as infant Mars cooled. The region was also affected by changes in the crust of the Tharsis region to the west. Then, as the gap widened, erosion took over. Those processes created the canyon system we see today. It’s a giant set of canyons 4,000 km long, 200 km wide, and up to 7 km deep in places.

This mapped image shows the regions of Ius and Tithonium Chasmata, which Mars Express imaged. These two areas form part of Mars’s Valles Marineris canyon structure. The area outlined by the bold white box indicates the area imaged by the Mars Express High Resolution Stereo Camera on 21 April 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 sends back data about the atmosphere and can probe beneath the crust. The spacecraft uses the High Resolution Stereo Camera (HRSC) to create detailed images of the surface. Through that camera, planetary scientists have seen spectacular views of everything from wind-sculpted ridges and grooves, to impact craters and channels that once carried liquid water. They’ve also studied volcanoes, tectonic faults, river channels, and ancient lava pools.

Hiking The Martian Canyons

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

At the top of Tithonium, there are deposits of dark material that could be windblown volcanic sand from the west. After you clear those, you cross a couple of 3,000-meter-tall mountains that have been eroded by the Martian winds. The descent continues through areas that may once have been flooded with some sort of liquid. And, of course, there are landslide areas and other rough terrains to get through before you reach the bottom.

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

Things don’t get any easier in Ius Chasma, with rugged slopes to traverse. Once you get to the canyon floor, though, there’s a wealth of rock formations to explore. It will be many years before recreational hiking is available on Mars. Maybe by then, geologist-created trails will make things easier.

For now, however, science is the primary reason for exploration. Both these canyons offer clues to Mars’s geological past, showing evidence of tectonic activity, volcanism, and wind erosion and deposition. Those processes result in the giant “rifts” splitting the surface. They also deposit sands across the surface, and create layered rock deposits.

Superlatives in other Places

If hiking canyons isn’t your thing, there’s always Olympus Mons to consider. It’s the tallest mountain in the solar system, rising up nearly 22 kilometers over the surrounding Martian landscapes. Skiers would love this mountain (if there was enough snow) because it would be a really long run from the caldera to the base. Of course, it would be a rough run. This thing is a shield volcano, and thousands of eruptions have molded and carved the landscape. They give way to a fairly steep cliff that drops down 8 kilometers.

Olympus Mons from orbit. Credit: NASA

Speaking of cliffs, the tallest one in the solar system its not on Mars. It’s actually on the moon Miranda, which orbits distant Uranus. This huge cliff is called Verona Rupes and it rises up more than 20 kilometers above the surface. Folks at NASA calculated that, with Miranda’s low gravity, someone jumping from the top (presumably with airbag protection), would have a 12-minute ride to the bottom. They’d reach a terminal velocity of about 200 kilometers per hour. Provided they survived, Verona Rupes jumpers could boast of an amazing thrill ride.

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

Not to be outdone, the minor planet 4 Vesta, boasts a crater called Rheasilvia, which measures 500 kilometers across. That’s about 90 percent 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, you’d have to drop down into the crater over an escarpment. Then, you’d hike across a fairly rough landscape to get to the peak. The very low surface gravity means it will be a fairly easy hike, albeit a long one.

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

Planetary Exploration Spinoffs

Missions like Mars Express, the Voyagers, Dawn, and others reveal spectacular landscapes across the solar system. They’re sent to give planetary scientists a detailed look at distant worlds. The images they send are evocative and inspirational. It may be a while before anybody gets to hike these places, but the images certainly do inspire dreams of individual exploration.

For More Information

Dawn Mission Overview
Mars Express Peers into Mars’s ‘Grand Canyon’
Olympus Mons
Verona Rupes: Tallest Known Cliff in the Solar System

Carolyn Collins Petersen

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