ESA has published new images of the region of the planet Mars called Deuteronilus Mensae captured by its Mars Express space probe’s High Resolution Stereo Camera (HRSC) instrument that show a territory sculpted by the movements of glaciers that created formations such as those known as mesas. That’s a particularly interesting region because already in the last decade traces of ice still there were discovered. In the past, there was perhaps a regional ice cap in that area of which Deuteronilus Mensae represents the remains.
The Deuteronilus Mensae (Image ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO) is a boundary region between the two hemispheres of Mars studied over the years thanks to detections carried out by various space probes. Detections carried out in 2008 by NASA’s Mars Reconnaissance Orbiter space probe’s SHAllow RADar (SHARAD) instrument already provided indications of the presence of ice in parts of that region.
An ancient ice cap may have formed in Deuteronilus Mensae region when the inclination of Mars axis was very different, a phenomenon due to the fact that it changes considerably over time because its moons are too small to keep it stable. These changes affect environmental conditions with consequences for the climate. Frozen carbon dioxide can sublimate, ending up in the atmosphere.
A water ice sheet can change shape and move under its own weight, causing considerable erosion on its way. Mesas are a type of geological formation that can be created on both Earth and Mars because of such processes. On the red planet a particular set of geological elements that include canyons, mesas, cliffs and more still exists in some regions and was called “fretted terrain”.
The conformation of the territory in Deuteronilus Mensae suggests that there were several glacial phases, even in geologically recent times, which means less than a million years ago. Many impact craters in the region have very eroded rims and were almost completely filled with materials brought to them and subsequently deposited by glaciers. In some places they can still be seen as circular structures with flat bases, in other craters only the central peak partially protrudes from the sediments.
Today the ice is probably present only in Deuteronilus Mensae’s subsoil after the ice on the surface evaporated or even sublimated. These formations so young from a geological point of view are a change from the much older ones found in so many other regions of Mars, even in the vicinity such as in the one just south, known as Arabia Terra, where there are traces of water that flowed well before Deuteronilus Mensae’s glaciation phases.
Perhaps in so many other areas of Mars there are still large amounts of water ice underground, covered with thick protective layers of dust and other materials. Some are similar to Deuteronilus Mensae and were already studied, others may be older and more eroded or may look different due to different geological processes.
To better understand Mars history and its transformation from a planet similar to the Earth to today’s desert, ESA, together with the Russian space agency Roscosmos, is developing the various phases of the ExoMars mission. The Trace Gas Orbiter space probe is orbiting Mars and in 2021 the arrival of the Rosalind Franklin rover is scheduled together with a surface scientific platform.