UH researchers shed new light on the origins of Earth’s water

Samples from the Earth’s deep mantle suggests water has been around since the formation of the planet, a recent study in Science reports.

In this scenario, before the planets of our solar system formed, the water-rich dust in question was part of a disk around the Sunday.

Study leader, Dr. Lydia Hallis, initially at the University of Hawaii at Manoa and now as a Marie Curie Research Fellow at the University of Glasgow, and colleagues describe how they used advanced ion microprobe technology to analyze a set of rocks from Baffin Island, in Nunavut (a Canadian territory) – Canada’s largest island.

Around 4.6 billion years ago, Earth formed from countless collisions of dust and rocks around the Sunday. Water molecules could have stuck onto dust grains floating in the gas cloud that birthed the sun and planets.

Water sloshes over more than two-thirds of Earth’s surface, giving it the nickname of the Blue Planet. Earth’s surface has altered dramatically over billions of years, but lava churning in the deep mantle remains unchanged from when the planet took shape. Researchers can learn about the origins of water on any planetary body by studying the water’s deuterium/hydrogen (D/H) ratio, the ratio of hydrogen atoms that have one neutron or no neutron, respectively. Aboveground processes such as hydrogen atoms leaking into space can hike deuterium concentrations in the planet’s surface water (SN: 9/5/15, p. 8). These olivine grains contain trapped pockets of glass, known as melt inclusions (image B), and this glass contains tiny amounts of water sourced from the mantle plume.

Other computer models show Earth’s original water may have remained in the atmosphere after the moon-forming impact and then returned to the surface as the planet cooled.

“Water wasn’t added later to Earth”.

UHNAI is a research center that links the biological, chemical, geological and astronomical sciences to better understand the origin, history and distribution of water in the universe, and its relation to life. The evidence lies in the fact that the lavas, now hardened into basalts, still contain a fair amount of light helium isotopes, which would have escaped to space had the rocks spent much time anywhere near the surface. But the water covering Earth did not have the same hydrogen composition, a sort of water fingerprint, as comets that have been tested.

The atomic mass of Hydrogen is one while the atomic mass of deuterium, an isotope of hydrogen also called “heavy hydrogen” is two.

“From an astrobiology point of view, it’s really important because it means that when any rocky body forms in our solar system or beyond, it would retain plenty of water, so it doesn’t need to be hit by water-rich comets after it formed”, Dr Hallis said. In the wake of the big bang, a baseline ratio of hydrogen to deuterium was locked in place.

Traditionally, the main objection to this idea has been that the inner portion of the protosolar nebula, where Earth formed, would have been too hot for water to hang around. Gradually, over time, this water-laden dust was slowly drawn together to form planet Earth.

The new data suggest that the difference is vast.

However, if Hallis and her colleagues turn out to be right, their hypothesis could have major implications for other planets.

More traditional theories suggested that the presence of water of Earth was linked to other astronomical circumstances.

Hallis said lava samples had to come from deep in the mantle because lava closer to the crust may have erupted and mixed with surface matter. “That would make habitable worlds much more likely”, says Marschall. “A new chapter has just begun in our understanding of where Earth-like planets get their water”, Desch said.

Earth is like an avocado, says Steve Mojzsis, a geologist at the University of Colorado Boulder.