Mars dried up a billion years later than they thought
Mars dried up a billion years later than they thought –
A new study by American scientists shows that water was still flowing on the surface of Mars 2-2.5 billion years ago, and that it dried up much later than previously thought.
This conclusion was reached based on the study of Martian salt-bearing rocks by NASA’s Mars Reconnaissance Orbiter (MRO). Previously, it was generally accepted that water in liquid form on Mars only existed about 3 billion years ago.
Elaine Liske of the Johns Hopkins Laboratory of Applied Physics and Bethany Elman of the Caltech used data from the Mars Compressed Reconnaissance Imaging Spectrometer, a visible and near-infrared spectrometer aboard the MRO, to map chloride salts in the mud-rich mountains. Southern Hemisphere regions of Mars – a region riddled with shock craters.
“Our results focus on deposits of chloride salt left by the evaporation of meltwater that flowed through this land,” the study authors wrote. “Although the outlines of some Martian valleys have already hinted that water could flow on Mars not so long ago, these salt deposits provide the first confirmatory evidence for the existence of such liquid water and depend on the mineral composition of the rocks.”
At the same time, craters became one of the keys to the dating of salt deposits, because the fewer craters were found on a particular surface, the younger it was considered. By calculating the number of craters on a given landscape, planetary scientists can estimate its age.
It also turns out that many of the salt deposits lie in depressions that were once small ponds located in volcanic plains. Nearby are winding dry channels – former streams that were fed by running surface water during the sudden melting of glaciers or permafrost.
The researchers used images captured by two MRO cameras, the Context Camera and High Resolution Imaging for Scientific Experiment (HiRISE), to create digital elevation maps.
This discovery raises new questions about how long microbial life can survive on Mars.
