U.S. scientists have discovered the remains of an ancient lake on Mars.
Billions of years ago, Mars was full of lakes and oceans, but the once-vast red planet has since become a barren, rocky planet; where the original water went has always been a mystery.
The Central News Agency (CNA) reported on March 16 that it is generally believed that most of the water on Mars escaped into space, but a new study funded by the National Aeronautics and Space Administration (NASA) said that the water did not go anywhere, but only seeped into the minerals of the Martian crust.
The new report was published in the journal Science, and lead author Eva Scheller told AFP, “We are showing that the crust forms so-called water-bearing minerals, so there is actually water in the mineral crystals.”
In fact, Scheller’s model shows that between 30 and 99 percent of the water from early Mars is still present in minerals today.
Scientists believe there was enough water to cover the entire planet in the early days of Mars, about 100 to 1,500 meters deep; since Mars lost its magnetic field early on and its atmosphere gradually escaped, scientists used to assume that the reason for the disappearance of water on Mars was because of atmospheric escape.
But this new report says that although some of the water in the early days of Mars has indeed disappeared, most of the water still exists today.
The team used observations from the Mars Exploration Rover and observations of Martian meteorites to focus on hydrogen, an important component of water.
There are different types of hydrogen atoms, most of which have only one proton in the nucleus; however, about 0.02% of hydrogen atoms have both protons and neutrons, so they are heavier, which is called “deuterium,” or “heavy” hydrogen.
Since lighter hydrogen escapes into the atmosphere at a faster rate, the Martian surface loses most of its water to the atmosphere, leaving a relatively large amount of deuterium behind.
However, considering that Mars is believed to have had a significant amount of water in its early days, and the present-day hydrogen escape rate observed by spacecraft, atmospheric escape alone cannot explain the current deuterium-to-hydrogen ratio.
Therefore, the authors of the study say that two mechanisms have combined to make Mars what it is today: both water seeping into the minerals of the Martian crust and water escaping into the atmosphere.
Scherer said, “As long as there are rocks, and the rocks and water interact, a very complex series of reactions will occur to form water-bearing minerals.”
This process is the “chemical weathering” that also occurs on Earth, like clay, which is also found on Mars.
But while Earth’s volcanoes circulate water into the atmosphere, Mars’ crust is not broken into several plates, so once the water is gone, the change is permanent.
According to the team’s simulations, Mars lost the most water 3.7 to 4 billion years ago. In other words, Scherer said, “Mars looked pretty much the same as we see it now over the last 3 billion years.”
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