A satellite orbiting Mars has captured the best images yet of a gigantic “scar” etched into the red planet’s surface. The dark ravine, which is accompanied by unusual zebra-like stripes, is probably the result of extreme volcanic activity millions of years ago.
The striking surface feature, named the Aganippe Fossa, is a graben—”a moat-like groove with steep walls on either side,” according to European Space Agency (ESA). Astronomers first spotted it as early as 1930, but officially named it only in 1976, according to US Geological Survey.
The graben is incomplete, with various cracks in the groove from end to end, but is believed to be a single structure that stretches for about 375 miles (600 kilometers). That’s longer than the Grand Canyon, which is 277 miles (446 km) from end to end, according to National Park Service. However, the structure is still significantly shorter than that of Mars Valles Marineris — the largest canyon in the Solar System, stretching more than 4,000 km along the Red Planet’s equator.
ESA’s Mars Express orbiter took the newly released photos on December 13, 2023. The satellite has been circling the Red Planet in an elliptical orbit for more than two decades.
One of the most interesting things about the photo is the surrounding landscape, which is different on either side of the giant rift. To the left the ground appears to be very uneven and contains several ridges, furrows and ridges. But to the right, the ground looks smooth and is painted with “zebra-like” rocky stripes, ESA officials said.
This marked difference was likely due to historical wind erosion to the right of the graben, which wore away the planet’s surface in that region. However, it is not clear why the rest of the surrounding landscape was untouched.
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Aganippe Fossa is located near the base of Arsia Mons, a 12-mile-high (20 km) extinct volcano on the Tharsis Plateau on Mars. The area contains two other large volcanoes, Pavonis Mons and Ascraeus Mons, and together the three dead peaks form an almost perfect line perpendicular to the planet’s equator. The Trinity is flanked by Olympus Mons the highest peak in the solar systemwhich lies just outside Tharsis and stands over 25km above the surface – about three times higher than Mount Everest.
The scar was likely caused by a large plume of magma that once gathered beneath Arsia Mons, pushing the planet’s crust upward and tearing the surface, ESA representatives wrote.
It is currently unclear how old Aganippe Fossa is, but NASA previously estimated that the volcano stopped erupting about 50 million years ago. However, scientists have recently discovered evidence of Volcanic eruption on Mars up to 50,000 years agosuggesting that volcanic activity on the Red Planet is not as old as we previously thought.
Similar grabens also exist in Noctis Labyrinthus (meaning “Labyrinth of the night“in Latin) – a massive canyon the size of Italy, located between Tharsis and Valles Marineris.
The area around Tharsis is one of the most geologically interesting areas on the Red Planet. The region also caught the attention of researchers earlier this year after the discoveries of a a giant volcano hidden next to Noctis Labyrinthus and more than 150,000 tons of frozen water over the peaks of the three Tharsis volcanoes.