Water `present during Earth`s birth`

Researchers claim to have found evidence that water was present during the birth of our planet.

Updated: May 14, 2010, 11:53 AM IST

London: What could make scientists rethink their understanding of how Earth formed, researchers claim to have found evidence that water was present during the birth of our planet.

An international team, led by Manchester University, has discovered that volatile elements - most likely to include water - were present during the violent process of the Earth`s birth between 30 and 100 million years after the solar system was created -- a minute period in geological terms.

According to the researchers, the findings mean that comets and asteroids were unlikely to have brought the bulk of volatile elements to Earth -- as commonly thought.

They have based their findings by using high precision equipment to measure abundances of Silver isotopes contained in rocks. The readings showed the moderately volatile element Silver was present in large amounts towards the final stages of the Earth`s formation, the `Science` journal reported.

The radioactive isotope Palladium 107 decays to Silver 107, which was present during the formation of the solar system. The decay of Palladium 107 creates anomalies in the abundances of Silver isotopes, which can be measured and used for dating, even though Palladium 107 is no longer present on Earth, say the researchers.

The findings give a new boost to a 30 year old model, which suggests that volatile elements were already present in the final stages of the Earth`s birth. How much of these elements were lost during impacts like the one that formed the moon, however, is still not well known.

Lead researcher Dr Maria Schonbachler said: "The sensitive equipment we use works in much the same way as when you might carbon date a rock or artifact -- but on a scale which enables us to go back billions of years.

"And those measurements allow us to detect transition from volatile-depleted to volatile-enriched building blocks as the accumulation of Earth proceeded. As we know what happened to the moderately volatile Silver, it`s very likely that the same thing happened to the highly volatile water.

"Though I accept that about 85 percent of the Earth`s
mass was built without volatile elements the rest of it was
and that`s quite an important difference in our understanding
of the Earth`s geological history.

"We don`t now need any theories about how water came
to Earth -- such as comets and asteroids -- it was most likely
here almost from the beginning. And water is, what made Earth
habitable for life."