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D. P. Glavin, Jason P. Dworkin, C. M. O'd. Alexander | Nature Astronomy | (2025)
Primary Link Pubmed DOI Openalex Full text (OA)

Abstract

Organic matter in meteorites reveals clues about early Solar System chemistry and the origin of molecules important to life, but terrestrial exposure complicates interpretation. Samples returned from the B-type asteroid Bennu by the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer mission enabled us to study pristine carbonaceous astromaterial without uncontrolled exposure to Earth's biosphere. Here we show that Bennu samples are volatile rich, with more carbon, nitrogen and ammonia than samples from asteroid Ryugu and most meteorites. Nitrogen-15 isotopic enrichments indicate that ammonia and other N-containing soluble molecules formed in a cold molecular cloud or the outer protoplanetary disk. We detected amino acids (including 14 of the 20 used in terrestrial biology), amines, formaldehyde, carboxylic acids, polycyclic aromatic hydrocarbons and N-heterocycles (including all five nucleobases found in DNA and RNA), along with ~10,000 N-bearing chemical species. All chiral non-protein amino acids were racemic or nearly so, implying that terrestrial life's left-handed chirality may not be due to bias in prebiotic molecules delivered by impacts. The relative abundances of amino acids and other soluble organics suggest formation and alteration by low-temperature reactions, possibly in NH<sub>3</sub>-rich fluids. Bennu's parent asteroid developed in or accreted ices from a reservoir in the outer Solar System where ammonia ice was stable.

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Plain English Takeaway

Scientists found that samples from the asteroid Bennu contain lots of ammonia and many types of molecules needed for life, showing that space rocks can carry important building blocks for life to planets like Earth.

Study Aim

The main goal of this study was to analyze organic molecules in samples from the asteroid Bennu, which were collected by the OSIRIS-REx mission and kept free from Earth's contamination. The researchers wanted to find out what kinds of carbon- and nitrogen-rich compounds, especially those important for life, are present in Bennu. They also aimed to compare Bennu's chemistry to other meteorites and asteroids, and to understand how these molecules might have formed in space. Simply put: The study set out to see what life-related molecules are in Bennu and how they got there.

Study Design

Researchers examined four bulk samples from Bennu, including fine and mixed-size particles, using advanced laboratory techniques. They used mass spectrometry (a method to identify molecules by their mass), chromatography (a way to separate chemicals), and isotope analysis (measuring different forms of elements) to detect and measure organic compounds. The team compared Bennu's chemistry to other meteorites and asteroid samples, and took special care to avoid contamination from Earth during collection and analysis. Simply put: Scientists carefully tested Bennu dust for different molecules using sensitive lab tools, making sure nothing from Earth mixed in.

Findings

The study reveals that Bennu samples are rich in volatile compounds, with higher amounts of carbon, nitrogen, and ammonia than most meteorites and samples from asteroid Ryugu. The researchers detected about 10,000 nitrogen-containing molecules, including 14 of the 20 amino acids used by life on Earth, all five DNA and RNA nucleobases, and many other organic compounds. Most amino acids were found in equal left- and right-handed forms, suggesting that life's preference for left-handed amino acids did not come from space rocks like Bennu. The chemical makeup and isotopic signatures indicate these molecules formed in cold, ammonia-rich environments, possibly in the outer Solar System. The findings suggest that asteroids like Bennu could have delivered key ingredients for life to early Earth. Simply put: Bennu has lots of life's building blocks, showing that space rocks can bring these important molecules to planets.

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Apr 18, 2026 2:32 AM

Dang the Connolly paper (Glavin, 2025) seems really groundbreaking – in that it (if I got it right) basically proved that this diverse organic matter (life building blocks?) does exist (probably more abundantly than previously thought?) in space, independently of from just earth.

Neil's point which you flagged makes sense i.e. if this organic material is very abundant, then perhaps it's more likely that earth itself had this material as well (vs earth received the material from space). But thinking about it, it almost seems arbitrary (whether the material came from earth or space) – since earth itself is formed from "space material" – so it's basically all the same stuff!

But yes in general, it seems important to know that these building blocks are far from unique to earth!

StarTalk

Season 17, Episode 22: Asteroid Bennu and the Origin of Life in the Solar System

Hey StarTalkians! Neil and Chuck sat down with Professor Harold Connolly Jr. for season 17, episode 22, talking about his work on the OSIRIS-Rex mission and the asteroid Bennu. After covering the basics of the mission, they briefly discussed what it could mean for the origin of life in the solar system: 

Secrets of Asteroid Bennu with Harold Connolly Jr. - StarTalk Radio

(From 53:55)

The discussion touches on the “panspermia” hypothesis. The overall idea is unlikely, to say the least, but a limited form of it could be more promising.

What They Found on Bennu

As Professor Connolly explains in the podcast, the asteroid Bennu contained a lot of organic materials.

One paper he co-authored describes what they found on the carbon-rich asteroid. Most importantly, this included 14 out of 20 terrestrial amino acids, the building blocks of life. Interestingly, these may have been formed in low-temperature reactions involving ammonia ice, unlike previous cases that depended on mild temperatures and liquid water.

Another paper added a 15th terrestrial amino acid, noting that such prebiotic molecules could have been deposited onto the young Earth by asteroid impacts.

The Panspermia Hypothesis

This leads into Chuck’s question about “lithopanspermia,” a variant of the panspermia hypothesis. This is the idea that the earliest forms of life may have developed away from the Earth, eventually being delivered to our planet by asteroid impact events (hence “litho”) and evolving terrestrially.

This hypothesis isn’t super likely, though. After all, could life really survive the journey through space and the impact itself? And the whole thing requires extra-terrestrial life to exist in the first place.

Pseudo-lithopanspermia – A Viable Alternative?                              

Instead of living microbes making the unlikely journey through space, the more likely “pseudo-panspermia” hypothesis posits that prebiotic organic molecules arrived on Earth that way. If this came from an asteroid like Bennu, we might call this “pseudo-lithopanspermia.”

Professor Connolly’s research shows that such molecules certainly exist. Additionally, modelling suggests that plenty of material from other bodies ends up on Earth – including 21 million landing from Mars alone over 3.5 billion years.

This removes a lot of problems with panspermia, and it’s definitely an interesting possibility. However, Neil’s point in the podcast pours cold water ammonia over this: why would we need extra-terrestrial amino acids if they seem to form everywhere anyway?

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