Was earth water always here? Unexpected meteorite structure provides basic evidence


Earth is the only planet with liquid water on its surface, a fundamental feature when it explains the emergence of life. However, was this water always present in the rocks that make up our planet? Alternatively, was it later delivered by asteroids and comets bombarding the Earth? Or did the earth’s water originate from a combination of both sources?

In the magazine ScienceScientists have contributed to the debate by the Center de récherches petrographics et gochimics in Nancy (CNRS / Université de Lorraine) indicating that most of the water on Earth today is probably there from the beginning. And yet the Earth was formed in a region of the Solar System, where the temperature was too high for water to condense and support the hypothesis of long water mixing with other solids in the form of ice. .

Sahara 97096 Meteorite

A roughly 10-centimeter long piece of Sahara 97096 meteorite, one of the studied anestatites. Approximately 0.5% water concentration was measured in it by mass, and some portion of hydrogen was found located in the chondrules (white spheres seen in the photograph). Specimen belonging to the French National Museum of Natural History (Paris). Sincerely: © Christine Fieni / Laurette Piani

However, the amount of water present in the rocks that make up the Earth was never accurately estimated. Scientists focused on meteorites with a composition similar to that of the Earth, called Ensite Chondrites[1], And more specifically on a small number of these which became slightly warmer during their lifetime and thus still exhibit a primitive composition. Using two complementary techniques, they measured their content in hydrogen and determined where it was located.

Their results suggest that the Earth’s primitive rocks probably had enough water to provide at least three times as much water in the Earth’s oceans, and possibly much more.

Furthermore, the isotopic structure of hydrogen in these meteorites is similar.[2] As is the water stored in the Earth’s mantle, while the isotopes of the oceans comprise 95% of the water from the acetate chondrites and only 5% of the water distributed by comets or water-rich asteroids. Therefore, the Earth receives an overwhelming majority of water from its constituents.

notes

[1] These are very rare, making up less than 2% of meteorites. Although thirteen were brought together for this study, some of them were replaced, and only eleven of them were considered their water content.

[2] A molecule of water is made up of two hydrogen atoms and one oxygen. Atom. Like many chemical elements, hydrogen can exist in many different forms called isotopes, which differ in their mass.

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References: “Earth’s water is inherited from the same material as the Anostatite Chondrite meteorite”, Laureate Piani, Yves Marcocchi, Thomas Rigadier, Lionel G. Wachter, by Doreen Thomassin and Bernard Marty, 28 August 2020. Science.
DOI: 10.1126 / science.baba 1948