The chemical composition of a meteorite could overturn scientists' understanding of how Earth obtained its water.
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Researchers have detected traces of hydrogen sulfide in a type of meteorite similar to those that formed the young Earth. If these rocky bodies contain abundant hydrogen when in space, it is possible that Earth formed with the necessary materials to produce water, rather than relying primarily on random collisions with asteroids and meteorites during its early history. The findings were published April 16 in the scientific journal Icarus.
Earth's chemical composition is similar to that of barren rocky bodies called enstatite chondrites, suggesting that the planet may have formed from such materials. For years, scientists thought that meant that the water had to come from bodies in the outer solar system that collided with Earth. Such collisions are generally considered unlikely, as they depend on the specific geometry of our solar system and the gravitational influence of Jupiter, which pushes comets and meteorites inward, explains Alessandro Morbidelli, an expert on planet formation at the Collège de France in Paris, who was not involved in the recent research.
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A study showed that, although enstatite chondrites do not contain water, they do contain hydrogen. In theory, hydrogen could have reacted with oxygen on the young Earth to form abundant water. However, it was unclear in what form this hydrogen was present. James Bryson, a planetary scientist at the University of Oxford and an author of the study, and his colleagues suspected that the hydrogen might have been bound to sulfur in the meteorites.
Using a technique known as X-ray near-edge spectroscopy (XANES), the researchers looked for traces of hydrogen bound to sulfur inside an enstatite chondrite found in Antarctica in 2012. They found more hydrogen than expected, in the form of hydrogen sulfide, dispersed throughout the meteorite's fine-grained matrix. The presence of abundant hydrogen suggests that Earth may have contained hydrogen from its formation, Bryson wrote in an email to Live Science.
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The findings suggest that rocky planets in our inner solar system — and possibly in other planetary systems — could form with much of the hydrogen needed to form water oceans already present. However, some scientists remain skeptical.
Source: livescience
