Earth may have had water from day one

IN THE beginning, there was water. Earth's life-sustaining liquid came from the dust from which the planet was born, a new look at these particles suggests, and not simply from collisions with objects that later crashed into the planet from space.

The origin of the oceans has long been a mystery. Earth's birthplace in the dusty nebula around the young sun should have been hot enough to keep any water vaporised. So it seemed clear that the dust that coalesced to create Earth was bone dry, and that water somehow arrived later.

Ice-rich comets or asteroids from farther out in the solar system could have supplied it, but that raises a further problem. Comets are richer in deuterium, a stable heavy isotope of hydrogen, than Earth's oceans. And asteroids should have brought more platinum and other rare elements than have been found. These mismatches are difficult to explain if most of Earth's water came from impacts.

Now, it seems that water may after all have been present in Earth's building blocks. Simulations by Nora de Leeuw of University College London and colleagues suggest that the dust grains from which Earth formed had such a tenacious grip on water that they could have held onto the molecules despite the high temperatures.

Earth may have had water from day one - space - 05 November 2010 - New Scientist