Incredible Images Show What’s Inside the Biggest Canyon in the Solar System

A Mars orbiter has captured stunning pictures of the largest canyon in the solar system, called Valles Marineris. It stretches across 2,500 miles of the red planet’s equator, a distance that is roughly equivalent to the diameter of the continental United States.

Mars Express, a European Space Agency (ESA) mission that arrived at Mars in 2003, recently imaged the deepest reaches of this epic canyon, where its slopes descend more than four miles into the Martian surface, which is five times deeper than the Grand Canyon, according to an ESA statement. 

The observations reveal two massive “chasma,” or trenches, that run parallel along the western portion of Valles Marineris, known as Tithonium Chasma in the south and Ius Chasma in the north. These trenches are each about 500 miles in length, making them twice as long as the Grand Canyon—and they encompass only about a fifth of Valles Marineris’ full extent.  

Mars Express snapped these shots of the chasma in April with its High Resolution Stereo Camera, during its 23,123th orbit around the planet. The images are so sharp that ESA scientists used them to generate close-up perspectives of Tithonium Chasma that resemble aerial photographs. The pictures show dark dunes, huge mountains, and the fallout of landslides within the chasma, which are annotated in an accompanying map.

Canyons on Earth are usually whittled out by the flow of rivers over millions of years, but scientists believe Valles Marineris was formed by tectonic activity on Mars more than 3 billion years ago. 

While the immense rift is dry today, scientists recently detected surprising stores of water ice under its surface. Valles Marineris may have also hosted liquid water billions of years ago, when Mars was wetter, warmer, and potentially habitable. NASA’s Perseverance rover is currently looking for signs of past life on Mars in Jezero Crater, an ancient lakebed, but scientists have also speculated that Valles Marineris may have also hosted aliens in the past.