Water on Earth may be 135 million years older than previously believed, according to a new study from the Woods Hole Oceanographic Institution (WHOI).
Astronomers examining the early history of the solar system now believe the water that now covers 70 percent of our globe may have arrived on the planet - as well as to much of the inner solar system - soon after the planets formed from a primordial cloud of gas and dust. Some researchers had previously believed that water came to Earth from comets and "wet asteroids" long after the young planet had cooled and solidified.
"With giant asteroids and meteors colliding, there's a lot of destruction. Some people have argued that any water molecules that were present as the planets were forming would have evaporated or been blown off into space, and that surface water as it exists on our planet today, must have come much, much later - hundreds of millions of years later," Horst Marschall, geologist at WHOI and coauthor of an article announcing the study, said.
Carbonaceous chondrites, the oldest meteorites known, were created along with the planets and moons of the solar system, 4.6 billion years ago. Researchers from WHOI believe these ancient bodies may have brought large volumes of water to the young Earth, pushing back the date the planet may have seen its first oceans - and life.
Deuterium and hydrogen, two stable isotopes of hydrogen, are formed in distinct ratios withing rocky bodies, depending on where in the solar system the object was created. Researchers studied rock from 4-Vesta, one of the great asteroids of the solar system, which formed fairly close to the primitive Earth. A surface layer of basaltic rock, formed from lava, provides samples of some of the oldest-known hydrogen atoms known to science. Small quantities of the substance have fallen to Earth in the form of meteorites called eucrites.
Researchers found the material from 4-Vesta contained the same ratio of deuterium and hydrogen as terrestrial rocks which cooled as the Earth was forming. This suggested to the team at WHOI that chondrite meteorites may have brought water to the Earth 135 million years before previously measured. Isotopes of nitrogen were also examined by the team, lending further evidence to the theory that water may have formed along with our planet, rather than arriving from space at a later date.
"An implication of that is that life on our planet could have started to begin very early. Knowing that water came early to the inner solar system also means that the other inner planets could have been wet early and evolved life before they became the harsh environments they are today," Sune Nielsen of WHOI, and co-author on the study, told the press.
Investigation of the early arrival of water to the Earth was detailed in the journal Science.
