Asteroid news: Space rock study suggests Earth’s water originated ‘from inner solar system

The conclusion contrasts with prior theories water come from comets or asteroids. The findings suggest our planet may have always been ‘wet’.

Researchers from the Centre de Recherches Petrographiques et Geochimiques (CRPG, CNRS) determined a type of meteorite contains sufficient hydrogen to deliver at least three times the amount of water in the Earth’s oceans.

Our discovery shows that the Earth’s building blocks might have significantly contributed to the Earth’s water

Lead author Laurette Piani

Enstatite chondrites meteorite are made-up of of material from the inner solar system.

This is essentially the same matter that originally made up the Earth.

Lead author Laurette Piani, a researcher at CPRG, said: “Our discovery shows that the Earth’s building blocks might have significantly contributed to the Earth’s water.

“Hydrogen-bearing material was present in the inner solar system at the time of the rocky planet formation, even though the temperatures were too high for water to condense.”

The findings from this study are all the more unexpected because the Earth’s building blocks are often presumed to be dry.

They originate from inner zones of the solar system where temperatures were too high for water to condense and form other solids during planet formation.

The meteorites offer tantalising evidence water did not necessarily come from far away.

Lionel Vacher, a postdoctoral researcher at Washington University, said: “The most interesting part of the discovery for me is that enstatite chondrites, which were believed to be almost ‘dry’, contain an unexpectedly high abundance of water.

Enstatite chondrites are rare, making up only about 2 percent of known meteorites in collections.

However, their isotopic similarity to Earth make them particularly compelling.

Enstatite chondrites have similar oxygen, titanium and calcium isotopes as Earth.

This landmark new study revealed their hydrogen and nitrogen isotopes are also similar to Earth’s.

In the study of extraterrestrial materials, the quantity of an element’s isotopes are a distinctive signature to identify where the element originated.

Dr Vacher said: ”If enstatite chondrites were effectively the building blocks of our planet—as strongly suggested by their similar isotopic compositions—this result implies that these types of chondrites supplied enough water to Earth to explain the origin of Earth’s water, which is amazing!”

The researchers also suggest a large amount of the atmospheric nitrogen in the Earth’s atmosphere could have come from the enstatite chondrites meteorites.

Dr Piani said: “Only a few pristine enstatite chondrites exist: ones that were not altered on their asteroid nor on Earth.

“In our study we have carefully selected the enstatite chondrite meteorites and applied a special analytical procedure to avoid being biased by the input of terrestrial water.”

Coupling two analytical techniques—conventional mass spectrometry and secondary ion mass spectrometry (SIMS)—allowed researchers to precisely measure the content and composition of the small amounts of water in the meteorites.

Dr Pianisaid prior to this study, “it was commonly assumed that these chondrites formed close to the sun.

She added: ”Enstatite chondrites were thus commonly considered ‘dry,’ and this frequently reasserted assumption has probably prevented any exhaustive analyses to be done for hydrogen.”

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