Opening image: Image of Noctis Mons, taken by the European space probe Mars Express. The striking “crater” in the center is a relatively recent geological depression in the landscape; The flat, circular area directly below is the eroded caldera of the newly discovered volcano. © European Space Agency/German Aerospace Center/Vu University Berlin
The base of Noctis Mons (“Night Mountain”), as it has been provisionally named, has a diameter of 450 km, and its towers rise 9 km above the “average” surface of Mars. The planet has no surface water, so there is no “sea level.”
The fact that the giant volcano has remained unnoticed all this time is mainly due to its intense erosion and it is located in a geologically complex landscape: Noctis Labyrinthus (“Labyrinth of Night”), an area of deep valleys and high mountains. At the western end of the Valley of Mars is the giant Valles Marineris.
Pascal Lee of the SETI Institute and Saurabh Shubham of the University of Maryland presented their discovery at the 55th Lunar and Planetary Science Conference in Texas. They identified, among other things, the eroded remains of a caldera (the crater at the top of a shield volcano) and a relatively recent 5,000 square kilometer volcanic deposit, under which a large glacier almost certainly exists.
Noctis Mons is located on the eastern edge of the Tharsis Plateau, a vast plateau on Mars that is home to three other (and larger) volcanoes: Ascraeus Mons, Pavonis Mons, and Arsia Mons. Much further away is Olympus Mons, 24 kilometers high, the largest volcano in the solar system.
It is not even clear when Noctis Mons was active. Given the high degree of erosion, it is certain that they actually formed in Mars’ distant geological past.
According to Lee and Chobham, underground icy deposits (on the southeastern side of the volcano) are an interesting target for future Mars landings – fossil traces of microorganisms can be found here. Shortly after its formation, Mars looked more like Earth and may have harbored life.
