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Four billion years ago, Mars had water equivalent to half the Atlantic Ocean, according to a study published by the journal “Science”, which estimates that much of that water was trapped in the planet’s crust.
About four billion years ago, Mars had enough water to cover the entire planet, in an ocean between 100 and 1500 meters deep, a volume roughly equivalent to half the Atlantic Ocean on planet Earth, according to research by the Institute. of California Technology (Caltech) and NASA’s Jet Propulsion Laboratory (JPL).
The same research maintains that between 30% and 99% of the missing water on Mars is trapped in the planet’s crust.
A billion years later, the planet was already as dry as it is today and current theories consider that water has escaped into space due to the planet’s low gravity, an idea that, according to the new study, cannot explain the most of this. lost.
The team studied the amount of water on Mars over time in all its forms – gas, liquid and solid – and the chemical composition of its current atmosphere and crust.
In particular, they focused on the relationship between two elements: deuterium and hydrogen.
Water is made up of hydrogen and oxygen, but not all hydrogen atoms are the same.
The lighter one has a greater facility to escape the planet’s gravity into space than its heavier counterpart.
For this reason, the flight of water from a planet through the upper atmosphere would leave an tell-tale mark on the ratio of deuterium to hydrogen in the planet’s atmosphere.
However, according to research, the loss of water through the atmosphere alone cannot explain the signs of deuterium and hydrogen seen in the Martian atmosphere.
Instead, the study proposes that a combination of two mechanisms, the retention of water in minerals in the planet’s crust and the loss of water in the atmosphere, may explain the signal observed in the Martian atmosphere.
When water interacts with rocks, the chemical climate forms clays and other minerals that contain water as part of their mineral structure.
Atmospheric leakage “clearly played a role” in the loss of water, but the discoveries of the last decade from the Mars missions pointed to the fact that there was this huge reserve of ancient hydrated minerals whose formation “certainly decreased the availability of water with time. “said Bethany Ehlmann of Caltech.
All that water “got stuck very early and then never came out again,” added Eva Scheller, lead study author.
The research, based on data from meteorites, telescopes, satellite observations and samples analyzed by Mars explorers, illustrates the importance of having multiple ways of probing the planet, the authors said.
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