January 28, 2021

New evidence found that meteorites brought water to Earth

Image of a meteorite

Image of a meteorite

Scientists led by the Department of Chemistry of the Autonomous University of Barcelona (UAB), the Institute of Space Sciences (ICE-CSIC) and the Institute of Space Studies of Catalonia (IEEC) have provided new evidence that a class of Meteorites, known as carbonaceous chondrites, brought water to early Earth.

Carbonaceous chondrites contain minerals capable of retain water and organic matter, which could have played an important role in the enrichment of these components in the early Earth.

The researcher from the Chemistry department of the UAB Albert Rimola recalled that, according to one of the current theses, “these meteorites could have facilitated the transport of these compounds that accumulated in the outer regions of the so-called protoplanetary disk, from which the planets of the solar system were formed more than 4.5 billion years ago“.

“There is a great debate about the origin of water on Earth. A paradigm postulates that much of the water comes from external asteroidal bodies, such as comets and meteorites, which arrived on Earth once it was already formed,” said Rimola. According to the researcher, “another paradigm holds that the Earth was formed by rocky bodies already rich in water and that therefore the origin of water is intrinsic to the formation of the Earth “.

The chemist has explained that carbonaceous chondrites are meteorites that come from bodies that did not merge with the planets, but that formed in the same areas of the protoplanetary disk where the bodies that did give rise to the planets were formed.

“Therefore,” he added, “chondrites are a fossil legacy of the creation of planetesimals (the seeds of the planets, comets and meteorites) that provide first-hand information on the aggregation processes of the first formative blocks of the planets, but also to identify processes that could have happened in the same protoplanetary disk “.

In this study, the researchers analyzed meteorites from the carbonaceous chondrite family from NASA’s Antarctic collection and from meteorite samples from Murchison (Australia, 1968) and Renazzo (Italy, 1824). “The results show that the water possibly present in the protoplanetary disk was retained in the matrices of the parent bodies of certain chondrites, thus corroborating that these meteorites were able to store and transport water efficiently”, Rimola has summarized.

The researcher has specified that “calculations reveal that trillions of tons of carbonaceous chondrites could reach Earth 3.8 billion years ago, coinciding with the so-called ‘Great Bombardment’, when the Earth received a disproportionate amount of meteoritic impacts due to a gravitational destabilization of the main asteroid belt.

The study also points out that the presence of water in carbonaceous chondrites “could activate chemical reactions that led to the formation of complex organic molecules, which could be important in the primordial chemical evolution that ultimately led to the appearance of lifetime”.

The work also highlights the importance of asteroid sample return missions (currently two: OSIRIS-Rex and Hayabusa), “since these samples are not so biased by collisions, as happens to meteorites that impact the Earth’s surface.”


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