AFP – Water covers 70 percent of the Earth’s surface and is known to be crucial to life, but how it got here has long been the subject of scientific debate.
On Thursday, a French team reported in the Science Journal that they had discovered which space rocks were responsible, and the puzzle suggested that our planet has been wet ever since it was formed.
Cosmo-chemist Lauret Piani, who led the research, told AFP that the findings contradicted the prevailing theory that water was initially brought to dry land by distant comets or asteroids.
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Asteroids are rocky celestial bodies that orbit the Sun; Comets are made of ice and dust, and also orbit the sun; And meteor ids are many small objects objects, mostly fragments of asteroids and comets.
According to early models of how the solar system came to be, large disks of gas and dust that revolved around the sun and eventually formed inner planets were too hot to sustain the ice.
This will explain the desolate conditions on Mercury, Venus and Mars – but not our blue planet, with its vast oceans, humid atmosphere and well-hydrated geology.
Scientists therefore theorized that water came later, and the main suspects were meteorites known as carbonaceous chondritis, rich in hydros minerals.
But the problem was that their chemical composition did not match closely with the rocks of our planet.
The outer solar system also contains carbonaceous kitendrites, making them less likely to cause silver on early Earth.
The stars move in the night sky during the Perseoid meteor shower at Lake Pinios near the village of Velanidi in the Peloponnese, Greece. (AP Photo / Petros Giannacoris)
Planetary building blocks
Another group of meteorites, called anastatite chondritis, is a very close chemical match, consisting of similar isotopes or types, containing oxygen, titanium, and calcium.
This suggests that they were obstacles to the formation of the Earth and other inner planets.
However, because these rocks formed near the sun, they were thought to be too dry to take into account the rich reservoirs of the earth.
To test whether this was indeed true, Piani and colleagues at the Center de Richters Petrographics at Geochemicals (CRPG, CNRS / University de Loren) used a technique called mass spectrometry to measure the hydrogen content in 13 instantite chondrites.
Rocks are now fairly rare, accounting for only two percent of the known meteorites in the collection, and they are hard to find in ancient, uncontrolled conditions.
The team found that the rocks contained enough hydrogen to provide the Earth with at least three times as much water as its oceans – and possibly much more.
They also measured two isotopes of hydrogen, as their relative proportions vary greatly from one celestial body to another.
Comparing the DNA match, Piani said, “We found that the hydrogen isotopic composition of anastatite chondritis is similar to that of water stored in the terrestrial mantle.”
The isotopic composition of the oceans has been found to be consistent with that of 95 percent of the aquatic mixtures of encyclopedic chondrites – further evidence is responsible for much of this Earth’s water.
The authors further discovered that nitrogen isotopes from anastatite chondritis are similar to Earth – and suggested that these rocks may also be the source of the most abundant component of our atmosphere.
Piani added that the research does not exclude the subsequent addition of water by other sources like Dharmoketu, but indicates that Anasite chondrites made a significant contribution to the Earth’s water budget at the time of the planet’s formation.
The work “brings a decisive and glorious element to this puzzle,” wrote Anne Paslier, a NASA planetary scientist, in an editorial.
