Where Did Earth's Water Come From And When?
Credit: Illustration by Jack Cook, Woods Hole Oceanographic Institution
“The answer to one of the basic questions is that our oceans were always here. We didn’t get them from a late process, as was previously thought,” said Adam Sarafian, the lead author of the paper published Oct. 31, 2014, in the journal Science and a MIT/WHOI Joint Program student in the Geology and Geophysics Department.
One school of thought was that planets originally formed dry, due to the high-energy, high-impact process of planet formation, and that the water came later from sources such as comets or “wet” asteroids, which are largely composed of ices and gases.
“With giant asteroids and meteors colliding, there’s a lot of destruction,” said Horst Marschall, a geologist at WHOI and coauthor of the paper. “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.”
The study’s authors turned to another potential source of Earth’s water— carbonaceous chondrites. The most primitive known meteorites, carbonaceous chondrites, were formed in the same swirl of dust, grit, ice and gasses that gave rise to the sun some 4.6 billion years ago, well before the planets were formed.
“These primitive meteorites resemble the bulk solar system composition,” said WHOI geologist and coauthor 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.”
In order to determine the source of water in planetary bodies, scientists measure the ratio between the two stable isotopes of hydrogen: deuterium and hydrogen. Different regions of the solar system are characterized by highly variable ratios of these isotopes. The study’s authors knew the ratio for carbonaceous chondrites and reasoned that if they could compare that to an object that was known to crystallize while Earth was actively accreting then they could gauge when water appeared on Earth.
To test this hypothesis, the research team, which also includes Francis McCubbin from the Institute of Meteoritics at the University of New Mexico and Brian Monteleone of WHOI, utilized meteorite samples provided by NASA from the asteroid 4-Vesta. The asteroid 4-Vesta, which formed in the same region of the solar system as Earth, has a surface of basaltic rock—frozen lava.
The measurements show that 4-Vesta contains the same hydrogen isotopic composition as carbonaceous chondrites, which is also that of Earth. That, combined with nitrogen isotope data, points to carbonaceous chondrites as the most likely common source of water.
“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.
While the findings don’t preclude a late addition of water on Earth, it shows that it wasn’t necessary since the right amount and composition of water was present at a very early stage.
“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.”
This research was supported by a Harriett Jenkins NASA graduate fellowship, an Andrew W. Mellon Foundation Award for Innovative Research, and a NASA Cosmochemistry award. The Northeast National Ion Microprobe Facility is supported by the National Science Foundation Instrumentation and Facilities Program.
The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment.
Contacts and sources:
WHOI Media Office
Woods Hole Oceanographic Institution
Source: http://www.ineffableisland.com/2014/11/where-did-earths-water-come-from-and.html
Anyone can join.
Anyone can contribute.
Anyone can become informed about their world.
"United We Stand" Click Here To Create Your Personal Citizen Journalist Account Today, Be Sure To Invite Your Friends.
Please Help Support BeforeitsNews by trying our Natural Health Products below!
Order by Phone at 888-809-8385 or online at https://mitocopper.com M - F 9am to 5pm EST
Order by Phone at 866-388-7003 or online at https://www.herbanomic.com M - F 9am to 5pm EST
Order by Phone at 866-388-7003 or online at https://www.herbanomics.com M - F 9am to 5pm EST
Humic & Fulvic Trace Minerals Complex - Nature's most important supplement! Vivid Dreams again!
HNEX HydroNano EXtracellular Water - Improve immune system health and reduce inflammation.
Ultimate Clinical Potency Curcumin - Natural pain relief, reduce inflammation and so much more.
MitoCopper - Bioavailable Copper destroys pathogens and gives you more energy. (See Blood Video)
Oxy Powder - Natural Colon Cleanser! Cleans out toxic buildup with oxygen!
Nascent Iodine - Promotes detoxification, mental focus and thyroid health.
Smart Meter Cover - Reduces Smart Meter radiation by 96%! (See Video).