The hypothesis is not new but, little by little, it is becoming almost a certainty. If we know that Mars once had lakes and rivers, as revealed by numerous observations, particularly in the Jezero crater, the Red Planet would also have had a vast ocean, which could have covered a third of its surface.
Many small clues indeed point towards this hypothesis, and in particular data collected by the Chinese roverChinese rover Zhurong who had landed in thenorthern hemispherenorthern hemisphere of the planet in 2021, at the end of a vast flat area called Utopia Plains. The results of this mission were presented in a previous article and were based in particular on the analysis of sedimentary rockssedimentary rocks presenting formations typical of a marine environment subject to the action of the tides. The Zhurong landing site could therefore, in the distant past, have corresponded with an ancient shore.
Multiple clues that suggest the presence of an ocean 3.5 billion years ago
In a study recently published in the journal Naturea team of researchers led by Bo Wu from the Hong Kong Polytechnic University revisits these results by adding new observations obtained by satellite. There geomorphologygeomorphology of the region is in fact in agreement with the hypothesis of an ancient ocean and the data acquired in the field by the rover.
All of this has led researchers to propose that this Martian ocean was formed at the end of the Noachian, between 3.65 and 3.68 billion years ago. The ocean would have been “mature” around 3.5-3.42 billion years ago, including the development of deep and shallow areas. It would have ended up freezing, then evaporating during the Amazonian before disappearing completely and definitively 3.4 billion years ago.
New field analyzes will be necessary
A relatively precise scenario which leaves some scientists skeptical, as revealed in this interview with Benjamin Cardenas carried out by AFP. Although he recognizes that the hypothesis of a Martian ocean is probable, for this researcher the team behind this new study has not sufficiently considered the impact that wind erosion can have on the landscape. Martian in the very long term. The geomorphological observations interpreted here as evidence of the presence of an ancient ocean could in reality be linked to the action of ventvent.
New missions will therefore be necessary to be able to affirm that an ocean occupied Utopia Plains 3.5 billion years ago and to know if Martian life was able to take advantage of this to develop there.
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