Oxford Researchers Reveal New Clues to Earth’s Water Origins from Ancient Meteorite

The meteorite used in this study – LAR12252 – when it was discovered in Antarctica. Credit: The ANSMET (ANtarctic Search for METeorites) Program, Case Western Reserve University and the University of Utah. (Credit: The ANSMET (ANtarctic Search for METeorites) Program, Case Western Reserve University and the University of Utah.)

A groundbreaking study by scientists at the University of Oxford has uncovered compelling evidence that Earth’s water may have originated from the planet’s original building materials, rather than from asteroid impacts as previously believed.

The research focused on enstatite chondrites—rare meteorites with a chemical makeup similar to that of early Earth, dating back 4.55 billion years. Researchers discovered that these meteorites contain intrinsic hydrogen, a vital component for the formation of water molecules. This hydrogen, they confirmed, was not the result of contamination, but an inherent part of the meteorites themselves.

These findings suggest that the material Earth was formed from was significantly richer in hydrogen than previously thought. This overturns a long-held theory that hydrogen—and thus water—was delivered by water-rich asteroids during the planet’s formative years.

Since hydrogen is a fundamental building block of water and essential for life, this discovery provides critical insight into how Earth developed the conditions necessary to support life. The study not only reshapes our understanding of the origin of water on Earth but also has implications for the study of habitability on other rocky planets.

To investigate the origin of hydrogen found in the Antarctic meteorite LAR 12252, a research team conducted elemental analysis using X-Ray Absorption Near Edge Structure (XANES) spectroscopy* at the Diamond Light Source synchrotron in Harwell, Oxfordshire. Previous work by a French team had identified hydrogen within organic materials and non-crystalline regions of chondrules, but the source remained ambiguous. The Oxford team hypothesized that substantial hydrogen might be associated with the meteorite’s significant sulphur content. Employing the synchrotron, they directed a powerful X-ray beam at the meteorite to identify sulphur compounds. While initially examining the hydrogen-bearing non-crystalline chondrule sections, a chance analysis of the fine-grained matrix material adjacent to a chondrule revealed it to be remarkably rich in hydrogen sulphide—five times more concentrated than in the previously studied areas. Conversely, regions showing signs of terrestrial contamination, like cracks and rust, contained little to no hydrogen. This contrast strongly indicates that the discovered hydrogen sulphide compounds are indigenous to the meteorite.

Tom Barrett, DPhil student in the Department of Earth Sciences at the University of Oxford, who led the study, said: “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.”

Co-author Associate Professor James Bryson (Department of Earth Sciences, University of Oxford) added: “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.”