The origin of water on earth
In a recent study ... scientists found the origin of water on Earth.
 |
| origin of water |
Was the earthling dry or wet? A question that baffled scientists for a long time, and because our planet was relatively close to the scorching heat of the sun 4.5 billion years ago, the belief has remained that the Earth was born dry and that it later obtained its water, which constitutes 70% of its area, from the collision of asteroids and comets from the cold and icy depths of the outer solar system.
However, in a new study published in the journal Science on August 28, 2020. A French research team reported that they identified space rocks as the source of this water and that our planet has been humid since its formation.
Hydrogen-laden rocks.
Researchers from the Center for Petrographic and Geochemical Research at the University of Lorraine (CRPG, CNRS) analyzed 13 different enstatite chondrites, a class known to look like space rocks that merged to form the Earth more than 4 years ago, 5 billion years.
The researchers found that this type of rock contains a lot of hydrogen, indicating that our planet was not born dry, as the team's calculations indicate that the rocks that formed the Earth were home to at least 3 times the amount of water. held by the current oceans of the planet.
"Our discovery shows that the building blocks of the Earth may have contributed significantly to the Earth's water," said study author Laureate Bayani. "Materials containing hydrogen were present in the inner solar system when the rocky planet was formed, even though the temperatures were too high for water to condense."
Ann Bessler, a researcher at NASA's Johnson Space Center in Houston, commented in a companion article in the same issue of Science, saying, "Maybe Earth's water was just coming from nebulous matter." Where the planet is from. "
Prevailing theory.
Bayani says the results contradict the prevailing theory that water was originally brought to dry Earth by far-reaching comets or asteroids.
And that, according to the first models of the appearance of the solar system, the large disks of gas and dust revolving around the sun and forming the inner planets were very hot, which would explain the arid conditions on Mercury, Venus and Mars; But our blue planet, with its vast oceans and wet faces, is not.
Scientists, therefore, assumed that the water came after the formation of the earth and that the main source - according to the scientists - was meteorites called carbon chondrites rich in minerals from the water. The problem, however, was that its chemical makeup did not closely match that of the rocks on our planet.
It is the opposite of a group of meteorites, "enstatite chondrite" (EC), which has a much closer chemical match to rocks on Earth and contains similar isotopes of oxygen, titanium, and calcium, indicating that they were the building blocks of the Earth and other inner planets.
Amazing results.
To test if the chondritic enstatite rocks are as dry as thought due to their formation near the sun or the source of rich water on Earth, Bianni and his colleagues used a technique called "mass spectrometry." to measure the hydrogen content of anastatic chondrite.
The team found that rocks contain enough hydrogen to provide Earth with three times the mass of water in its oceans, and possibly much more.
They also found that the isotopic composition of enstatite chondritic hydrogen is similar to that found in water stored in the Earth's mantle.
The isotopic composition of oceanic waters corresponds to a mixture containing 95% of the water from anastatic chondrites and only 5% of water is carried by comets or asteroids rich in water.
Bayani says the research also does not rule out that there are other sources of water on Earth such as comets. But he points out that enstatite chondrites made a significant contribution to the Earth's water balance at the time of its formation.