New Evidence For A Warmer And Wetter Early Mars
A recent study from ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter (MRO) provides new evidence for a warm young Mars that hosted water across a geologically long timescale, rather than in short episodic bursts – something that has important consequences for habitability and the possibility of past life on the planet.
Although water is known to have once flowed on Mars, the nature and timeline of how and when it did so is a major open question within planetary science.
The findings follow an analysis of a region of relatively smooth terrain, called inter-crater plains, just north of the Hellas Basin. With a diameter of 2300 km, the Hellas Basin is one of the largest identified impact craters both on Mars and within the Solar System, and is thought to have formed some 4 billion years ago.
“These plains on the northern rim of Hellas are usually interpreted as being volcanic, as we see with similar surfaces on the Moon,” said Francesco Salese of IRSPS, Università “Gabriele D’Annunzio”, Italy, and lead author on the new paper. “However, our work indicates otherwise. Instead, we found thick, widespread swathes of sedimentary rock.”
Sedimentary and volcanic (igneous) rocks form in different ways – volcanic, as the name suggests, needs active volcanism driven by a planet’s internal activity, while sedimentary rock usually requires water. Igneous rock is created as volcanic deposits of molten rock cool and solidify, while sedimentary builds up as new deposits of sediment form layers that compact and harden over geologically long timescales.
“To create the kind of sedimentary plains we found at Hellas, we believe that a generally aqueous environment was present in the region some 3.8 billion years ago,” said Salese. “Importantly, it must have lasted for a long period of time – on the order of hundreds of millions of years.”
A volatile adolescence?
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