The European Space Agency’s Mars Express orbiter has captured images of portions of the Martian Valles Marineris, the largest system of canyons in the Solar System. Valles Marineris, like many other geological features on the red planet, dwarfs all terrestrial analogues. The Valles Marineris, in particular, is 4,000 km long, 200 km wide and up to 7 km deep. In comparison, the Grand Canyon in North America is just under 450 km long, 16 km wide and under 2 km deep. While the Grand Canyon was formed by erosion by the Colorado River, the Valles Marineris was formed by tectonic plates moving away from each other.

The Mars Express captured images of two trenches that form part of western Valles Marineris, the 840 km-long Ius Chasma, and the 805 km-long Tithonium Chasma. The images, captured by the orbiter, highlight how the top of the Tithonium is covered with darker sand that may have come from the nearby Tharsis volcanic region.

Other observations from the Mars Express show water-bearing sulphate minerals, parallel lines, and debris piles, which indicate a recent landslide, two 3 km tall mountains surrounding sand dunes around Tithonium whose surface has been sharply eroded. The sulphate minerals are especially interesting for scientists, as they may be evidence of the fact that millions of years ago the chasma was once filled with water.

“The gnarly floor of Ius Chasma is equally fascinating. As tectonic plates pulled apart, they appear to have caused jagged triangles of rock to form that look like a row of shark teeth. Over time, these rock formations have collapsed and eroded,” ESA said on its blog.

The Mars Express arrived on Mars in 2003 and has been continually in service for 18 years and 6 months, the second oldest spacecraft in orbit around a planet other than Earth. The mission was granted an extension till December 31, 2022, due to its valuable science retrieval and the highly flexible mission profile that it has been able to undertake.