An article published in the journal “Science” describes the discovery of eight areas on the planet Mars where soil erosion revealed the presence of large glaciers. A team of researchers located and studied the areas thanks to NASA’s Mars Reconnaissance Orbiter (MRO) space probe’s High Resolution Imaging Science Experiment (HiRISE) camera. The slopes generated by erosion offer new information on those glaciers’ stratified structure and consequently on the red planet’s climate history.
The abundance of water on Mars has been known for some time, the problem is that generally deep geological studies are needed to find traces left a few billion years ago by rivers, lakes and seas because under the conditions existing on the planet today water is frozen and above all is buried. Sometimes the analysis of the photos and other data detected by the space probes orbiting Mars allow to discover ice deposits such as at the poles, at Utopia Planitia or in the Colles Nili but there’s a whole planet to examine.
This time, a team led by Colin Dundas of the U.S. Geological Survey’s Astrogeology Science Center analyzed the images captured by the MRO space probe at different times detecting the presence of glaciers exposed due to soil erosion. The fractures are widening because today Mars’ atmosphere is thin so even at the very low temperatures that are found at the mid-latitudes of the studied areas the exposed ice sublimates, albeit slowly.
Those glaciers probably formed with a progressive accumulation of almost pure water following snowfall in ancient time but not too ancient considering that in those areas there are not many craters. Those glaciers are normally covered by a layer of one or two meters of rock and dust mixed with ice, which acts like a kind of cement creating a cap. The atmosphere is thin but the strong winds still cause the erosion of the ground and in these cases they ended up sweeping away the upper layer.
The exposed slopes have an unclear origin but are likely to widen due to the ice sublimation. In some cases, the thickness of the exposed water ice deposits exceeds one hundred meters. The nature of the exposed material was confirmed using the MRO space probe’s Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument while the Thermal Emission Imaging System (THEMIS) instrument allowed to control temperatures in those areas to make sure that it wasn’t just a thin crust of ice on the ground.
The different colors with streaks detected in the exposed glaciers indicate that they’re formed of distinct layers. On Earth that type of stratification allows to carry out studies on the ancient climates thanks, for example, to the analysis of the contents of the various layers. On Mars it’s not yet possible to carry out samplings to perform direct examinations on that ice but the examination of their colors’ variations could provide at least some climatic data.
According to NASA, those glaciers could be a source of water for astronauts in future missions to Mars. The ice exposed on the surface would be easy to take in large amounts and those areas have less adverse environmental conditions than the polar ice caps.