The European Space Agency’s Mars Express has found evidence that underground water use to exist during the first billion years of Mars’ existence.
ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter zoomed in on craters in part of the region of the ancient southern highlands called Tyrrhena Terra.
Scientists were able to identify 175 sites bearing minerals formed in the presence of water by focusing in on the chemistry of rocks embedded in the crater walls, rims, and central uplifts.
ESA said impact craters offer natural windows into the history of a planetary surface, and the deeper the crater, the further back in time scientists can see.
“The large range of crater sizes studied, from less than 1 km (.62 miles) to 84 km (52-miles) wide, indicates that these hydrated silicates were excavated from depths of tens of meters to kilometers,” Damien Loizeau, lead author of the study, said in a press release.
“The composition of the rocks is such that underground water must have been present here for a long period of time in order to have altered their chemistry.”
ESA said that although the material excavated by impacts appears to have been in close contact with water, there is little evidence for rocks on the surface lying between the craters having been altered by water.
“Water circulation occurred several kilometers deep in the crust some 3.7 billion years ago, before the majority of craters formed in this region,” co-author Nicolas Mangold said in the release.
“The water generated a diverse range of chemical changes in the rocks that reflect low temperatures near the surface to high temperatures at depth, but without a direct relationship to the surface conditions at that time.”
Mawrth Vallis, which is one of the largest identified clay-rich regions of Mars, displays a more uniform aqueous mineralogy than Tyrrhena Terra, according to the space agency.
“The role of liquid water on Mars is of great importance for its habitability and this study using Mars Express describes a very large zone where groundwater was present for a long time,” Olivier Witasse, ESA’s Mars Express project scientist, said in a press release.