London, April 18th, Xinhua News Agency (reporter Shuang Guo) - For a long time, it has been generally believed on Earth that water comes from asteroid impacts on Earth. However, British researchers recently published a paper in the American journal "Icarus", saying that they have discovered important evidence that may overturn this theory, and the water on Earth might be "native".
Hydrogen is an essential element of water and a key condition for the formation of life on Earth. The origin of hydrogen and water on Earth has always been controversial. The popular view holds that during the first approximately 100 million years after the formation of Earth, asteroids carrying ice water collided with the surface, injecting the source of life into this blue planet.
However, researchers at the University of Oxford and other institutions found that Earth may have had the hydrogen required to form water when it initially formed. This supports an important viewpoint, which is that the formation of water on Earth was a natural process rather than caused by the accidental collision of asteroids after Earth's formation.
The researchers introduced that enstatite chondrite meteorites are a rare type of meteorite whose composition is similar to early Earth 4.55 billion years ago. A team led by French researchers previously discovered traces of hydrogen in the non-crystalline part of the chondrite (millimeter-sized spherical objects within the meteorite) while studying these meteorites, but could not confirm whether these hydrogen traces were due to terrestrial contamination.
In the latest study, the researchers used the UK's "Diamond Light Source Synchrotron" scientific equipment to analyze the elemental composition of enstatite chondrite meteorites by irradiating them with powerful X-ray beams. They found that the material composed of sub-micron materials surrounding the chondrites was rich in hydrogen sulfide, with concentrations even reaching five times that of the non-crystalline parts. By contrast, hydrogen content was very low or nonexistent in the cracks of the meteorites or in areas obviously contaminated by terrestrial sources.
The researchers said this suggests that the hydrogen sulfide detected in the meteorites is extremely unlikely to originate from Earth. Since early Earth was composed of materials similar to enstatite chondrite meteorites, this indicates that when the forming Earth became large enough to be impacted by asteroids, it had already accumulated sufficient hydrogen to form water. (End)
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