Friday, October 31, 2014

Earth's Water Existed 135 Million Years Earlier

An illustration of the early solar system shows proto-Earth, proto-Mars, Vesta within the asteroid belt, and proto-Jupiter. 

The dashed white line represents the "snow line" boundary for water ice in the solar system. 

Credit: Jack Cook, Woods Hole Oceanographic Institution

The water that supports life on Earth may have been on the planet much earlier than scientists previously thought, new research suggests.

While the environmental conditions in Earth's early years made it impossible for water to remain on the planet's surface, scientists have found evidence that the ingredients for water were protectively stored inside rocky bodies near our planet, and maybe inside Earth itself.

The new findings suggest that there was water in the inner solar system 135 million years earlier than previous evidence had shown.

"Our findings show the earliest evidence of water in the inner solar system," said Adam Sarafian, a Ph.D. student at the Woods Hole Research Center in Massachusetts and lead author of the new study.

This image of the giant asteroid Vesta was captured by NASA's Dawn spacecraft on Sept. 5, 2012.

Credit: NASA

Meteorites from an asteroid
The smoking gun appears inside meteorites that once belonged to the asteroid Vesta, one of the largest members of the asteroid belt that sits between Jupiter and Mars. Meteorites from Vesta, dark chunks of cooled magma often as big as grapefruits, continue to be found in Antarctica.

Previous analysis found no water or water-forming ingredients in those meteorites, but Sarafian and his colleagues zoomed in on the molecular contents of the meteorites, and found trace amounts of hydrogen-oxygen molecules.

More than 4.5 billion years ago, or about 15 million years after solid bodies began to form around the young sun, water existed in the outer, cooler parts of the solar system, previous studies have shown.

But in the inner solar system, where Vesta and a young Earth resided, temperatures were far too hot and solar winds would send any water vapor to the outer regions of the solar system.

While the Earth grew and changed over the next 4 billion years or so, Vesta remained frozen in time, according to Sarafian.

"Vesta gives us a snapshot of what Earth maybe looked like when it was first forming," Sarafian said.

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