Meteorites that formed in the early days of the solar system may contain liquid water, according to new research, giving credence to the theory that meteorites brought water and other precursors to life on our planet billions of years ago.
Carbonic chondrites are a special group of meteorites that trace their origins to the formation of the solar system. When pieces of them are found on Earth, they have been found to contain pieces of tempting information, such as minerals that appear only in the presence of water and organic compounds, such as amino acids – some of the building blocks of life.
As a result, carbonic chondrites have become a major candidate for the way water has reached Earth. An excellent way to know for sure would be if a chondrite – which, although rarely among their fallen meteorite compatriots, still has an impact on the Earth regularly – would reach the ground with water on it and we would have been lucky to observe the rock. and recover it.
It’s a high order. The Ryugu asteroid was recent it was found to be dry with water long, long before Japan got there with the spaceship Hayabusa2. Until now, scientists have been aware that the flow of fluids occurred at carbonic chondrites at one time, but did not know how recently this flow could have occurred. Previous dating methods have shown that water was present on these rocks early – about 4.5 billion years ago, shortly after the formation of the Earth.
“All this leads to the hypothesis that any change and any presence of water were very old. So our test was to say, could there have been a young change? “ Simon Turner, an isotope geochemist at Macquarie University in Sydney, Australia, said in a video call. “I mean, there’s still ice on these meteorites.” Turner is the lead author of a new paper describing the flow of liquid in carbonic chondrites, published this week in Scientific Reports.
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A team of researchers from Macquarie University, Florida State University and the Museum of Natural History in Paris have discovered that these carbonic chondrites have had a quantity of fluid in the last few hundred thousand years – very recently, in terms of space and intervals. geological time.
All meteorites fall, but only those who witness falls are called “falls” after that. Turner’s team used only carbonic chondrite falls in their research, because those fresh rocks in space have a clear timestamp when they arrived and the context of what they came in contact with on Earth (ie what they could be contaminated with). The meteorites included in the study came from all corners: one was from Sutter’s Mill, where the California Gold Rush began, while another landed on a frozen lake in Russia, among many other sites around the world.
The research team took samples from these space rocks and gave their water flow with uranium-thorium dating, in which the isotopes of the two elements can be measured to discern age. In this case, the question was not the age of these meteorites themselves, but the age at which the liquid moved in the rock. Uranium is very mobile in fluid, while thorium is not, so seeing when uranium moved inside the meteorite relative to thorium, the team could deduce when the water stirred around.
“If there was ice on the bodies and if there was a reason why the ice melted and moved and produced in the last million years, you should expect a differential behavior of uranium and torus,” Turner said.
In other words, when liquid flows, either on a space rock or along a riverbed, it moves isotopes around, leaving a short-term record of flow. This signature disappears if too much time passes. If the isotopes moved within a million years, specifically, the team would detect this disturbance.
Liquidity of the liquid the movement found in some of the team’s samples is captivating – it means that carbonic chondrites can contain ice very well if they flow liquid just a few hundred thousand years ago.
Edward Young, a geochemist at UCLA who was not affiliated with the recent newspaper, said in an email that the new research was “very interesting” and “elegant.” He noticed that other one scientists have just learned about the wide flow of water on the asteroid Bennu, thanks to NASA Ongoing OSIRIS-REx mission.
A next step would be to test spacecraft that did not fall like a ball of fire through the Earth’s atmosphere, a violent process that hides exactly how the ice on these asteroids melted (evidence from a spacecraft would be helpful). Meanwhile, researchers will throw themselves at the fallen space rocks, watching the sky for new evidence that could collapse.