Where did Earth`s water come from?
Baku, July 18 (AZERTAC). Researchers examining hydrogen isotope ratios in meteorites appear to have thrown a spanner in the works of the latest models of how elements such as hydrogen and nitrogen reached the early Earth. The finding throws up questions about where all the Earth`s water came from and how life on Earth began.
One big question that remains unanswered about the evolution of the early Earth is how volatiles such as hydrogen, nitrogen and carbon arrived - their presence being crucial to the origins of water and life. The two main candidates for the sources of these elements are asteroids, found between the orbits of Mars and Jupiter, and comets, which come from the colder outer reaches of the Solar System. Current models suggest that at some point in the evolution of the Solar System, a jolt to the orbits of Saturn and Jupiter caused comet-like material in the outer Solar System to be flung inwards into the present-day asteroid belt - eventually arriving at Earth and bringing the crucial volatiles.
Now, a new study led by Conel Alexander at the Carnegie Institution of Washington, US, has taken a significant step towards solving the conundrum. Alexander`s team compared the hydrogen isotope ratios in chondritic meteorites, ancient fragments of asteroids, with those that have been measured in comets. In the outer Solar System, the birthplace of comets, the extreme cold results in frozen water having a higher proportion of deuterium than ice formed in the less cold regions.
The team analysed the hydrogen isotope ratios in 86 meteorites, and showed that the proportion of deuterium to hydrogen was lower than in comets.
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