Scientists are investigating a huge, mysterious scar spanning the length of Mars, but they don’t know how it formed there.
The incredible formation, which stretches some 600 kilometers (373 miles) — longer than the Grand Canyon at 446 kilometers (227 miles) — was photographed by ESA’s Mars Express spacecraft.
The scar, known as Aganippe Fossa, runs across the lower slopes of Arsia Mons, one of the largest volcanoes on Mars.
The canyon was first discovered in 1930, but this is the first time scientists have been able to see it up close.
The ESA describes it as “a dark, uneven scar cutting through the marble floor at the base of a giant volcano” and a “trench-like groove with steep walls on either side.”
The space agency said Mars Express will be making regular observations of Arsia Mons and its nearby companion mountains in the Tharsis region, where some of Mars’ giant volcanoes are found.
This includes Olympus Mons, the tallest volcano in the solar system.
Mount Arsia itself is 435 km (270 mi) in diameter and rises more than 9 km (5.5 mi) above the surrounding plain.
For comparison, the tallest dormant volcano on Earth, Ojos del Salado on the border between Argentina and Chile, is about 7 km (4.3 miles) high.
“It is still unclear how and when Aganippe Fossa formed, but it is likely that it formed when magma rising beneath the Tharsis volcano’s giant mass stretched and cracked the Martian crust,” the ESA said.
Mars Express has been orbiting the Red Planet since 2003.
It is photographing the Martian surface, mapping minerals, determining the composition and circulation of the tenuous atmosphere, probing beneath the crust, and investigating how different phenomena interact in the Martian environment.
