Mars didn’t dry up all at once, study finds

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The results are based on data from NASA’s Curiosity Mars rover which continues to explore the base of Mount Sharp on the Red Planet.

“One of the main goals of the Curiosity mission was to study the transition from the habitable environment of the past to the dry, cold climate of Mars,” said Roger Wiens, document co-author and scientist at Los Alamos National. Laboratory, where he is in the ChemCam team.

“These rock layers recorded this change in great detail,” Wiens said.

ChemCam is the rock vaporizing laser that sits on the mast of the Curiosity rover and analyzes the chemical composition of Martian rocks.

William Rapin, CNRS researcher, led the study published in the journal Geology.

Using ChemCam’s long-range camera to make detailed observations of the rugged terrain of Mount Sharp, a team including Wiens and other Los Alamos researchers found that the Martian climate alternated between dry and wetter periods before becoming completely dry.

Spacecraft orbiting Mars had previously provided clues to the mineral makeup of the slopes of Mount Sharp.

Now ChemCam has succeeded in making detailed observations of the sediment beds on the planet’s surface, revealing the conditions under which they formed.

Going up the field, Curiosity has observed that bed types change dramatically.

Above the clays deposited on the lake that form the base of Mount Sharp, layers of sandstone show structures indicating their formation from wind-formed dunes, suggesting long dry climatic episodes, according to the study.

Higher still, thin alternating brittle and tough beds are typical of river floodplain deposits, signaling the return of wetter conditions.

These changes in terrain show that Mars’ climate underwent several large-scale fluctuations between wetter and drier periods, until the generally arid conditions seen today set in.