Researchers at the University of Oxford have made a significant discovery regarding the origin of water on Earth. By studying a meteorite known as an enstatite chondrite, which mimics the composition of early Earth, they found evidence of intrinsic hydrogen in the material. This suggests that the building blocks of our planet had more hydrogen than previously believed.
The meteorite, LAR12252, discovered in Antarctica, was key to this study. The ANSMET Program, along with Case Western Reserve University and the University of Utah, contributed to its discovery. Hydrogen is essential for forming water, and its origin on Earth has been debated for years. Many scientists proposed that asteroids brought hydrogen during Earth's early years, but these new findings challenge this idea, implying the hydrogen required for water was present from Earth's formation.
The research team from Oxford used a technique called X-Ray Absorption Near Edge Structure (XANES) spectroscopy at the Diamond Light Source synchrotron in Oxfordshire to analyze the meteorite. In previous studies, hydrogen was found within organic materials and chondrules in the meteorite, but the source of this hydrogen was unclear, raising the possibility of terrestrial contamination.
The Oxford researchers probed the hypothesis that the meteorite’s sulfur might hold significant hydrogen. They discovered that the matrix surrounding the chondrules was rich in hydrogen sulphide, five times more than in non-crystalline sections. Parts of the meteorite exposed to potential Earthly contamination showed minimal hydrogen, reinforcing the idea that the hydrogen sulphide is not from an Earthly source.
Tom Barrett, a DPhil student who led the study, stated, "We were incredibly excited when the analysis told us the sample contained hydrogen sulphide – just not where we expected! Because the likelihood of this hydrogen sulphide originating from terrestrial contamination is very low, this research provides vital evidence to support the theory that water on Earth is native - that it is a natural outcome of what our planet is made of.”
Associate Professor James Bryson noted, “A fundamental question for planetary scientists is how Earth came to look like it does today. We now think that the material that built our planet – which we can study using these rare meteorites – was far richer in hydrogen than we thought previously. This finding supports the idea that the formation of water on Earth was a natural process, rather than a fluke of hydrated asteroids bombarding our planet after it formed."
Their findings, detailed in the study "The source of hydrogen in earth's building blocks,” were published in the journal Icarus.