Winchcombe meteorite holds information about the origin of Earth's oceans

[muriel_volestrangler]

The Winchcombe meteorite, a rare carbonaceous meteorite which crashed onto a driveway in Gloucestershire, has been found to contain extra-terrestrial water and organic compounds that reveal insights into the origin of Earth’s oceans.

A new study led by experts from the Natural History Museum and the University of Glasgow reports the orbital history and first laboratory analyses of the Winchcombe meteorite, which was recovered only hours after its spectacular fireball lit up the skies over the UK in February 2021.
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Crucially, the team were able to quickly measure the ratio of hydrogen isotopes in the water, finding it to closely resemble the composition of water on Earth. Extracts from the Winchcombe meteorite also contain extra-terrestrial amino acids – prebiotic molecules that are fundamental components for the origin of life. As the composition of the Winchcombe meteorite is largely unmodified by the terrestrial environment, these results indicate that carbonaceous asteroids played a key role in delivering the ingredients needed to kickstart oceans and life on the early Earth.

Rapid recovery of the Winchcombe meteorite was enabled by public reports and video footage of the fireball captured by 16 cameras coordinated by the UK Fireball Alliance (UKFAll). By combining the footage with chemical analysis of the meteorite, the team calculated that Winchcombe was blasted off the surface of an asteroid near Jupiter and travelled to Earth within the last million years. Pre-atmospheric orbits – the journey of an object around the Sun before arriving on Earth – are known for less than 0.1% of meteorites in the worldwide collection, with Winchcombe providing the strongest link yet between carbonaceous meteorites and asteroids in the outer regions of the solar system.

https://www.nhm.ac.uk/press-office/press-releases/winchcombe-meteorite-holds-information-about-the-origin-of-earth.html

Abstract

Direct links between carbonaceous chondrites and their parent bodies in the solar system are rare. The Winchcombe meteorite is the most accurately recorded carbonaceous chondrite fall. Its pre-atmospheric orbit and cosmic-ray exposure age confirm that it arrived on Earth shortly after ejection from a primitive asteroid. Recovered only hours after falling, the composition of the Winchcombe meteorite is largely unmodified by the terrestrial environment. It contains abundant hydrated silicates formed during fluid-rock reactions, and carbon- and nitrogen-bearing organic matter including soluble protein amino acids. The near-pristine hydrogen isotopic composition of the Winchcombe meteorite is comparable to the terrestrial hydrosphere, providing further evidence that volatile-rich carbonaceous asteroids played an important role in the origin of Earth’s water.

Introduction

The early solar system comprised at least two isotopically distinct reservoirs separated by a barrier proposed to reflect the orbits of the proto-gas giants and/or location of snow lines (1, 2). Small bodies that accreted late in the outer regions of the solar system and avoided high temperatures and melting are crucial for understanding the initial composition of the protoplanetary disk. Dynamical models and remote sensing observations suggest that primitive, volatile-rich asteroids originating in the outer solar system were scattered inward to the main asteroid belt by the giant planets (3, 4). Carbonaceous chondrite meteorites are likely fragments of these asteroids and have volatile abundances and isotopic compositions that indicate that they played a key role in the delivery of water and biologically important molecules to Earth and other terrestrial planets (5). However, direct links between meteorites and their parent bodies are poorly constrained, with only four carbonaceous chondrite falls with pre-atmospheric orbits having been recovered to date (6–9). Most carbonaceous chondrites are fortuitous finds that lack information about their source region(s) in the solar system.

Recently, JAXA’s Hayabusa2 and NASA’s OSIRIS-REx missions have sampled the surfaces of the carbonaceous near-Earth asteroids Ryugu and Bennu, respectively. Both are rubble-pile asteroids thought to be derived from either the Eulalia or new Polana collisional families that reside in the inner main belt [~2.1 astronomical units (AU) < a < 2.5 AU], although their original parent body(ies) probably formed beyond the orbit of Jupiter (10). Ryugu and Bennu have complex orbital histories and were potentially modified during transport from the outer solar system to their current locations at ~1 AU (11). In comparison, the Winchcombe CM (“Mighei-like”) meteorite is the most widely observed carbonaceous chondrite fall to date and has a well-constrained pre-atmospheric orbit that confirms that it originated from an asteroidal source in the main belt. As the meteorite was recovered soon after landing, it also offers a near-pristine record of the composition of primitive asteroids. This combination of pre-atmospheric data with a fresh sample largely unmodified by the terrestrial environment makes the Winchcombe meteorite comparable to materials returned by space missions. Here, we report the orbital characteristics and results of coordinated laboratory analyses of the petrography and organic composition of the Winchcombe carbonaceous chondrite.

https://www.science.org/doi/10.1126/sciadv.abq3925

I think it's so cool that so much knowledge can come from a find on an average driveway:

"When I heard it drop, I stood up and looked out the window to see what was there," recalled Hannah. "But because it was dark I couldn't see anything.

"It was only the next morning when we went out that we saw it on the drive - a bit like a kind of splatter. And in all honesty, my original thought was - has someone been driving around the Cotswolds lobbing lumps of coal into people's gardens?" she told BBC News.
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In fact, they were inundated with pictures. Most had nothing to do with meteorites, but when Open University planetary scientist Richard Greenwood looked at the Wilcocks' picture, he was blown away.

"It was one of those moments when your legs start going wobbly. I saw this thing; it was like a splat across [the Wilcocks'] drive; and it had all these rays coming off it; and I just thought - that is a meteorite. It was instantaneous," he said.

https://www.bbc.co.uk/news/science-environment-56337876

[Timeflyer]

1. So cool. We are stardust.