Billions of years ago, Mars was home to lakes and oceans – but where all the water to transform the planet into a desert rock we know today has become a mystery.
Most of it was thought to have been lost to space, but a new NASA-funded study suggests it went nowhere but is trapped in minerals in the crust.
“We say that the crust forms what we call hydrated minerals, so said minerals that have water in their crystal structure,” said Eva Scheller, lead author of the new paper in Science, ri AFP.
In fact, the Scheller model suggests anywhere between 30 – 99 percent of the original water remains trapped within these minerals.
Early Mars was thought to have enough water to cover the entire planet in about 100 to 1,500 meters (330 to 4,4920 feet) of ocean.
As the planet lost its magnetic field in early history, the feeling was gradually removed, and it was assumed that this was how it lost its water.
But the authors of the new study believe that although some of the rain disappeared, most remained.
Using observations made by Mars rovers as well as meteorites from the planet, the team focused on hydrogen, a key component of water.
There are different types of hydrogen atoms. Most have only one proton in their nucleus, but a small fraction, about 0.02 percent, both proton and neutron, make them heavier. These are called deuterium, or “heavy” hydrogen.
As the lighter type escapes the planet’s atmosphere at a faster rate, the loss of most of the water to space would leave relatively little deuterium behind.
But with the amount of water believed to have started the planet, and the rate of hydrogen escape observed by spacecraft, the normal deuterium-to-hydrogen ratio cannot be explained by the loss of air. -only.
A decorative representation of our assumptions for the Noachian, Hesperian, and Amazonian times. (Scheller et al., Science, 2021)
Permanent call
The study’s authors say there was a combination of two mechanisms: mineral water capture in the planet’s crust as well as water loss to the atmosphere.
“Whenever you have a rock and it interacts with water, there is a series of complex reactions that create a hydrated mineral,” Scheller said.
This process, known as “chemical weathering”, also takes place on Earth – for example, in clay, which is also found on Mars.
But on our planet volcanoes recycle the water back into the atmosphere. However, Mars does not have tectonic plates, making the changes permanent.
According to team symbols, the planet lost most of its water four to 3.7 billion years ago, which means “Mars was pretty much as we see it today. the last three billion years, “Scheller said.
(California Institute of Technology)
She said she was excited about what the Perseverance rover, which landed last month for a multi-year science mission on the planet, could add to the field of research.
“The Perseverance rover is definitely going to study just those processes and reactions that cause water to trap in the bark,” she said.
In the team model there are several scenarios, which they need to compare with new data obtained by the rover.
“We can start by saying, ‘Those parts of the model are not working properly and those parts are’ and that’s going to help us get closer and closer and closer to the answer,” Scheller said. .
© Agence France-Presse