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Angel Mojarro, José C. Aponte, Jason P. Dworkin | Proceedings of the National Academy of Sciences | (2025)
Primary Link Pubmed DOI Openalex Full text (OA)

Key Takeaways

Sample Definition And Size

The study analyzed a homogenized powder of an aggregate sample (unsorted particles <0.5 cm in size; OREX‑800107‑0) and homogenized powders of fragments from three distinct stones—angular (OREX‑800055‑3), hummocky (OREX‑800088‑3), and mottled (OREX‑800023‑2)—representing different boulder types observed on Bennu. No explicit sample mass counts are given beyond noting that aggregate sample mass was up to ~5 mg and stone fragments were less than 1 mg each. ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC12704803/?utm_source=openai))

Study Type

Observational laboratory analysis of returned asteroid samples using pyrolysis and wet‑chemistry techniques coupled with gas chromatography–triple quadrupole–mass spectrometry (GC‑QqQ‑MS); this is an empirical analytical study of extraterrestrial material. ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC12704803/?utm_source=openai))

Conflicts Of Interest

No conflicts of interest are declared in the accessible metadata (PubMed entry and PMC full text). ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/41284850/?utm_source=openai))

Results Summary

Key findings include detection of the five canonical nucleobases and 14 of the 20 standard α‑amino acids in the aggregate sample, with a tentative detection of a fifteenth α‑amino acid, tryptophan, not previously observed in extraterrestrial materials. Distributions of insoluble (IOM) and soluble (SOM) organics differ among the three stone types, indicating heterogeneous aqueous alteration within Bennu’s parent body. Alkylated polycyclic aromatic hydrocarbons (PAHs) resemble those in aqueously altered carbonaceous chondrites, consistent with abiotic aqueous origins. ([pmc.ncbi.nlm.nih.gov](https://pmc.ncbi.nlm.nih.gov/articles/PMC12704803/?utm_source=openai))

Abstract

NASA's OSIRIS-REx mission characterized the asteroid Bennu and delivered pristine samples of its regolith to Earth. Coordinated analyses of this primitive, carbonaceous material are elucidating the abiotic formation and inventory of prebiotic organic compounds in the early Solar System. Using pyrolysis and wet-chemistry techniques, we analyzed aggregate (unsorted particulate) material and three distinct stones that appear to correspond to different boulder types observed by the spacecraft. Results from the aggregate were consistent with previous work that detected the five canonical nucleobases and 14 of the 20 α-amino acids utilized by life to synthesize proteins. However, our analytical approach tentatively uncovered trace signals of a fifteenth α-amino acid, tryptophan, which has not been detected previously in extraterrestrial materials. Further, we found that the distributions of insoluble and soluble-derived organics differ between distinct stones, suggesting heterogeneous geologic processing within Bennu's parent body. The distributions of alkylated polycyclic aromatic hydrocarbons resemble those in aqueously altered carbonaceous chondrites and are consistent with an abiotic origin through aqueous reactions. Our findings expand the evidence that prebiotic organic molecules can form within primitive accreting planetary bodies and could have been delivered via impacts to the early Earth and other Solar System bodies, potentially contributing to the origins of life.

Referenced In

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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