More than two-thirds of Earth's surface is covered by water, but its actual origins are not known yet. Since long, scientists have been uncertain whether water was there at the time of the planet’s formation, or if it has arrived afterwards, probably along with comets and meteorites.

Now, with the help of advanced ion-microprobe instrumentation, researchers from the University of Hawaii at Manoa discovered that rocks from Baffin Island in Canada have proof that water was present on Earth from the beginning. The study has been published in the journal Science’s November 13 issue.

A cosmochemist Dr. Lydia Hallis, then a postdoctoral fellow at the UH NASA Astrobiology Institute (UHNAI) and presently Marie Curie Research Fellow at the University of Glasgow, Scotland, headed the research team.

The ion microprobe proved useful for the researchers as it helped them in focusing on tiny pockets of glass inside these scientifically significant rocks, and in the detection of the small amounts of water present in it. It was the ratio of hydrogen to deuterium in the water that gave the researchers valuable new clues related to its origins.

The atomic mass of Hydrogen is one while the atomic mass of deuterium, an isotope of hydrogen also called ‘heavy hydrogen’ is two. Scientists have discovered that in our solar system, water from different types of planetary bodies have different hydrogen to deuterium ratios.

Dr. Hallis explained, “The Baffin Island rocks were collected back in 1985, and scientists have had lot of time to analyze them in the intervening years. As a result of their efforts, we know that they contain a component from Earth's deep mantle”.