New scientific findings show that much of the Red Planet’s water is trapped in its crust instead of escaping into space.
Billions of years ago, according to geological evidence, enough water flowed over Mars and accumulated into pools, lakes and deep oceans. New research, funded by NASA, shows that much of its water – between 30 and 99% – is trapped in minerals in the planet’s crust, challenging current theory, such as due to the low pressure of the Red Planet, its water fled into space.
Early Mars was thought to have enough water to cover the entire planet in an ocean about 100 to 1,500 meters (330 to 4,920 feet) deep – a volume equal to half the Atlantic Oceans on Earth. Although some of this water disappeared from Mars through air escape, the new findings, published in the latest issue of Science, conclude that it does not account for mostly water loss.
The results were presented at the 52nd Lunar and Planetary Science Conference (LPSC) with lead author and Caltech Ph.D. candidate Eva Scheller with co-authors Bethany Ehlmann, professor of planetary science at Caltech and associate director for the Keck Institute for Space Studies; Yuk Yung, professor of planetary science at Caltech and senior research scientist at NASA’s Jet Propulsion laboratory; Danica Adams, Caltech graduate student; and Renyu Hu, JPL research scientist.
“Air escape will not fully explain the data we have for the amount of water that once existed on Mars,” said Scheller.
Using a wealth of cross-mission data stored in NASA’s Planning Data System (PDS), the research team inputted data from multiple NASA Mars Exploration Program missions and meteorite lab work. In particular, the team studied the amount of water on the Red Planet over time in all forms (valves, liquids, and ice) and the chemical combination of the planet’s normal atmosphere and crust, looking to particularly on the ratio of deuterium to hydrogen (D / H).
While water is made up of hydrogen and oxygen, not all hydrogen atoms are created equal. Most hydrogen atoms have just one proton inside the atomic nucleus, and contain a small fraction (about 0.02%) such as deuterium, or so-called “heavy” hydrogen, which has a proton and a neutron . The lighter weight hydrogen escapes the planet’s gravity into space much more easily than its denser counterpart. As a result, the loss of planetary water through the upper atmosphere would leave a clear sign on the ratio of deuterium to hydrogen in the planet’s atmosphere: There would be a lot of deuterium left.
However, water loss alone through the atmosphere cannot explain both the deuterium-to-hydrogen signal seen in the Martian atmosphere and much water in the past. Instead, the study suggests that a combination of two mechanisms – mineral water capture in the planet’s crust and loss of water to the atmosphere – can explain the deuterium-to-hydrogen signal seen in the Martian atmosphere. .
When water interacts with rock, chemical weathering creates clays and other hydrous minerals in which water is part of their mineral structure. This process takes place on Earth as well as Mars. On Earth, old crusts melt into the mantle and form new crusts at plate boundaries, recycling water and other molecules back into the atmosphere through volcanism. However, Mars does not have tectonic plates, so the “drying” of the surface, once it occurs, is permanent.
“The hydrated materials on our own planet are regularly recycled through plate tectonics,” said Michael Meyer, chief scientist for NASA’s Mars Exploration Program at the agency’s headquarters in Washington. “Because we have measurements from multiple spacecraft, we can see that Mars is not recycling, so water is now trapped in the crust or lost to space.”
The main goal of NASA’s Perseverance rover 2020 mission on Mars is astrobiology, including detecting signs of microbial age. The rover will mark the geology of the planet and the climate of the past, pave the way for human study of the Red Planet, and will be the first mission to collect Martian rock and regolith and accumulate (broken rock and dust). Scheller and Ehlmann in operations with the Perseverance rover will assist in the return of those samples that will be returned to Earth through the Mars Sample Return program, which will allow further much-anticipated research into the reasons for change. Mars climate. Understanding the evolution of the Martian environment is an important context for understanding results from analyzes of the returned samples as well as understanding how living capacity changes over time. rocky planets.
The research and conclusions outlined in the paper highlight the contribution of early career scientists to contributing to the broadening of our understanding of the solar system. Similarly, the research, which relied on data from meteorites, telescopes, satellite observations, and samples surveyed by rovers on Mars, shows the importance of multiple approaches for the Planet Examine red.
This work was supported by the NASA Habitable Worlds award, the NASA Earth and Space Science Alliance (NESSF) award, and the NASA Future Explorer in NASA Earth and Space Science and Technology (FINESST) award.
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Gray Hautaluoma / Alana Johnson
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Anndra Math
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