Mars hides its ‘lost’ water beneath the surface, new research suggests

A view of Mars made up of about one hundred Viking Orbiter images.

A view of Mars made up of about one hundred Viking Orbiter images.
Picture: NASA / JPL-Caltech / USGS

The water that used to exist on Mars slowly seeped into space, or at least that’s the current theory. A new role challenges this assumption, offering an alternate scenario where the red planet has latched onto much of its ancient water – we just can’t see it.

An unexpectedly large amount of water is hidden within minerals buried beneath the Martian crust, according to the new research published in Science. The data presented in the new paper, co-authored by Caltech graduate student Eva Scheller, suggests that between 30% and 99% of the original water has been retained on Mars.

At the same time, the authors say that the prevailing theory about the leakage of Martian water into space, a consequence of the planet’s low gravity, is not entirely up to par. and that his new theory solves a key flaw pretty good. These results were presented on March 15 at the 52nd Lunar and Planetary Science Conference..

We know that the Red Planet was once covered in flowing water, as evidenced by the remains of deep ocean basins, lakes, rivers running, and even tremendously huge tsunamis. The total volume of water that used to exist in the ancient martian surface is estimated to half the total volume of the Atlantic Ocean, which barely a trivial amount. Such was the case billions of years ago, but most of this water appears to be gone, and the small amount that remains has been withdrawn to the polar caps and (possibly) some underground reservoir.

But as Scheller explained in a NASA statement, the atmospheric escape of Martian water “does not fully explain the data we have about the amount of water that actually existed on Mars.”

The key to any study of the history of water on Mars is the observed ratio of deuterium to hydrogen (D / H), which is typically used to reinforce the theory of atmospheric escape. Water is made up of hydrogen and oxygen, but there is a very small number of hydrogen atoms such as deuterium, also known as “heavy hydrogen” due to an extra neutron within the atomic nucleus, in addition to the standard proton. Normal hydrogen, which makes up 99.98% of all hydrogen, can easily escape Martian low gravity and leak into space, but that is not the case with deuterium. Consequently, Mars should exhibit a surplus of deuterium, which it does.

The problem is that the currently observed atmospheric water leak rate is too low, according to the study. authors, and this process cannot exclusively account for all that historical loss of water through the atmosphere. Instead, Scheller and his colleagues argue that, in addition to a small leak through the atmosphere, ancient Mars water was trapped in minerals within the planet’s crust. Together, these two mechanisms can explain the observed D / H ratio and lack of water, according to the paper.

Evidence for this hypothesis was obtained from NASA’s Planetary Data System., which serves as a general data repository for past missions. In this case, the authors analyzed Mars-specific data collected by telescopes, satellites, and rovers in order reconstruct historical volumes of water, whether in liquid, vapor or ice form, on Mars and study the chemical composition of the Martian atmosphere and crust.

By running simulations under various conditions, the authors showed that Mars lost much of its water during its Noah period, around 4.1 billion to 3.7 billion years ago, and that 30% to 99% of This ancient water was buried under the crust, the rest is lost in space, in a find that respects the D / H ratio currently observed.

The process responsible for the disappearance of the water on Mars is known as hydration of the crust and it is not as exotic as it seems. Chemical weathering caused by mixing rocks with water produces clays and other soggy minerals. This happens both on Earth and in on Mars, as evidenced by the earth observations manufactured by NASA’s Curiosity rover. However, the fate of these materials developed differently on the two planets.

“Hydrated materials on our own planet are continually recycled through plate tectonics,” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program, in the NASA statement.. “Because we have measurements from various spacecraft, we can see that Mars is not being recycled, so the water is now locked in the crust or has been lost to space,” said Meyer, who is not directly involved in the new research. ..

Kevin Olsen, a fellow at the University of Oxford and an expert on the Martian atmosphere, said the new article makes “bold“But” new and intriguing“Assumptions”.

“Our basis for [making inferences] about the ancient climate of Mars comes from the comparison with Earth, and one aspect of the evolution of Mars that differs from Earth is the silencing of its volcanoes, the largest in the solar system, ”wrote Olsen, who is not affiliated to the new study, in an email. “By modellConsidering how large the exchange is between the water reservoirs near the surface and those in the rocky crust, they have opened up many plausible scenarios where Mars was once much wetter, but it turned out as we see it today. “

“This is a very interesting article, combining many different mechanisms and models to explore the fate of water on Mars,” Geronimo Villanueva, planetary scientist at NASA’s Goddard Space Flight Center, what’s more not involved in the new study, said in an email. “Taking into account the high degree of uncertainty that exists in some of the model parameters, the range of possible scenarios is large, however, it is important that they make verifiable predictions that can be followed in the future.”

Villanueva said the new document will help future research on the history of water on the Red Planet.

Fortunately, the Rover perseverance it could soon contribute to this line of research. NASA’s new Martian rover he will soon begin his scientific work in Jezero Crater, the site of an ancient lake and river delta. Evidence to reinforce this new theory could exist within this ancient extension, which Perseverance will explore over the next two years.

For future Martian colonists, this is good news and bad. This is good news because, well, Mars still has a lot of water, at least in theory. The bad news is that this water, if it exists, is locked up in hydrated materials like clay. Live on mars Be strong enough, but develop the infrastructure to mine, extract and clean the water extracted from these mineral sounds. wildly complicated and expensive.

To quote the “Rime of the Ancient Mariner,” it could be a classic case of, “Water, water, everywhere, And all the tables shrunk; Water, water, everywhere, not a drop to drink. “


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