Longest canyon in the solar system reveals new secrets — Space photo of the week

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NASA's Mars Reconnaissance Orbiter recently photographed Candor Chasma in Mars' Valles Marineris, the largest canyon in the entire solar system.

The folded layers of eastern Candor Chasma on Mars.

Mars' Valles Marineris stretches nearly a quarter of the way around the planet's equator. (Image credit: NASA/JPL-Caltech/University of Arizona)
QUICK FACTS

What it is: Candor Chasma, a large canyon on Mars

Where it is: Valles Marineris, the biggest canyon network in the solar system

When it was shared: Aug. 14, 2025

This latest photo, taken May 24 and published last week, is of the eastern side of Candor Chasma, one of the largest canyons within Valles Marineris. What it reveals could change how planetary geologists think about Mars' ancient environment.

Using its ability to see detail down to the size of a kitchen table, HiRISE produced an image that shows layered deposits of sediment several meters thick, scientists at the Lunar and Planetary Laboratory at the University of Arizona, which developed and operates the camera, said in a description of the image. Crucially, these layers of sediment must date to after the canyon itself formed, because they appear to have been eroded, warped and bent by tectonic movements.

Related: 32 things on Mars that look like they shouldn't be there

Mars doesn't have plate tectonics like Earth does. Instead, its crust is like one giant plate, according to NASA. But faults and fractures still form in the Martian crust as it cools. Unlike Earth's Grand Canyon, which was carved by a river, Valles Marineris — including Candor Chasma — is thought to have formed by volcanic activity, with landslides, floods and erosion later sculpting it into its present form.

In 2021, the European Space Agency (ESA) revealed that the ExoMars Trace Gas Orbiter, a collaboration between ESA and the Russian space agency, had found water beneath the surface in Candor Chasma. It's thought that up to 40% of the near-surface material in Valles Marineris could be water. That would make it akin to Earth's permafrost regions in Alaska, Canada, Greenland and Siberia, where water ice permanently persists under dry soil because of the constant low temperatures.

With its steep walls and chaotic landscapes, Candor Chasma would be challenging for a Mars rover to explore. However, the German Space Agency's Valles Marineris Exploration project would study the possibility of sending a swarm of autonomous rovers, crawlers and uncrewed aerial vehicles to this treacherous terrain.

For more sublime space images, check out our Space Photo of the Week archives.

Jamie Carter
Jamie Carter
Live Science contributor

Jamie Carter is a Cardiff, U.K.-based freelance science journalist and a regular contributor to Live Science. He is the author of A Stargazing Program For Beginners and co-author of The Eclipse Effect, and leads international stargazing and eclipse-chasing tours. His work appears regularly in Space.com, Forbes, New Scientist, BBC Sky at Night, Sky & Telescope, and other major science and astronomy publications. He is also the editor of WhenIsTheNextEclipse.com.

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