Mars hides an ancient ocean beneath its surface

For decades, scientists have speculated about what will become of all water on Mars, believed to have been a significantly wetter planet centuries ago. Some water can be found frozen in the polar ice caps of Mars, but new research indicates there is also a shocking amount of water in Mars. The discovery could have a major impact on developing plans to harvest water for a future human presence on the red planet.

It is largely believed that when the ancient atmosphere of Mars was gradually drawn into space, much of the surface water went with it. But a new NASA-backed study suggests that a significant portion of all that Mars moisture is still on the planet, trapped in the crust.

“Atmospheric escape does not fully explain the data we have on how much water once existed on Mars,” said Caltech Ph.D. candidate Eva Scheller said in a statement. Scheller is lead author of the study published Tuesday in the journal Science.

Scheller and colleagues looked at models that quantify the amount of water on Mars in various forms over time, as well as current data on the chemical composition of Mars’ atmosphere and Earth’s crust. They found that atmospheric escape theory could not fully explain the conditions we see above and below the surface of our neighboring world today.

“Atmospheric escape clearly played a role in water loss, but findings from the last decade of Mars missions have indicated that there was a huge reservoir of ancient hydrated minerals whose formation over time certainly reduced the availability of water,” explains Bethany Ehlmann, CalTech. professor of planetary science.

When water and rock interact, a chemical weathering process can occur that creates materials such as clays that contain water in their mineral structure. This process takes place on Earth, but the geological cycle eventually sends moisture trapped in rocks back into the atmosphere via volcanism. However, Mars appears to have little or no volcanic activity, causing all that water to get stuck in the crust.

“All this water was kept in isolation quite early and never cycled back after that,” says Scheller.

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The team found that 4 billion years ago, Mars had enough water to cover the entire planet with an ocean between 100 and 1,500 meters deep, and that between 30% and 99% of that water is now trapped in minerals. in the crust.

Scheller and Ehlmann will be the Mars 2020 Perseverance rover team in collecting rock samples from Mars for eventual return and study here on Earth to test the theory.

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