A new study suggests that the water came to Earth earlier than thought previously. In fact, water flooded the Earth 100 million years ago than previously believed by many scientists, courtesy to meteorites containing ice and gases. Nearly 25% of Earth’s water came from meteorites, according to a new study led by scientists at the Woods Hole Oceanographic Institution (WHOI).
Some scientists believed that planets originally formed dry, due to high energy and high impact process of planet formation all the water on the planet would have dried up. “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,” says Adam Sarafian of MIT and the Woods Hole Oceanographic Institution, who was the lead author of a study published in the journal Science.
The most primitive known meteorites, Carbonaceous chondrite, were formed in swirl of dust, grit, ice and gases and contains a lot of water in them. “These primitive meteorites resemble the bulk solar system composition,” said WHOI geologist and co-author Sune Nielsen. “They have quite a lot of water in them and have been thought of before as candidates for the origin of Earth’s water.”
To determine the age and source of water present in a planet scientists measure ratio of hydrogen and its isotope deuterium (heavy hydrogen due to one extra neutron). For the study researchers were looking for an object that crystallized while Earth was actively accreting so that they can find age of water on ‘Blue Planet’ by comparing its ratio of hydrogen isotopes to already known hydrogen isotopic composition of Carbonaceous chondrite. For the research, NASA provided sample of asteroid 4-Vesta that formed in the same region in the solar system as Earth. Thus, 4-Vesta asteroid contains similar ratio of hydrogen and deuterium as Earth. Also, they are just 14 million years younger than our solar system which makes them ideal for the research.
“The study shows that Earth’s water most likely accreted at the same time as the rock. The planet formed as a wet planet with water on the surface,” Marschall said.
Researchers observed that water formation began much earlier than thought previously, this also means life forms might have evolved earlier. “An implication of that is that life on our planet could have started to begin very early,” added Nielsen. “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.”