Samples from the asteroid Bennu, brought to Earth by NASA's OSIRIS-REx mission in 2023, hold a new clue about the origin of the molecules that made life possible. In a study published in the journal Communications Earth & Environment, researchers at Penn State analysed the amino acid beta-alanine in those samples and in the Murchison meteorite, which fell to Earth in 1969, and concluded that the molecules may have formed through the same chemical process — but in very different regions of the Solar System.
The discovery changes how we read the history of life's building blocks. Until now, most studies measured the distribution and quantity of amino acids in samples. The team led by Ophélie Mcintosh, then a postdoctoral researcher in Penn State's Department of Geosciences, went further: it measured carbon and nitrogen isotopes at every position inside the beta-alanine molecule.
A fingerprint inside the molecule
To do this, the researchers developed an intramolecular isotope measurement technique, which shows how isotopes are distributed within a single molecule instead of just calculating an average. The work used two instruments: the pico-CSIA, which exists only at Penn State and measures isotope averages from minuscule amounts of material, and a modified GC-Orbitrap, which measures isotope composition at different positions in the molecule.
“Being able to analyse the isotope values for each carbon and nitrogen within the beta-alanine molecule is a dream for geochemistry,” said Christopher House, professor of geosciences and co-author of the study, noting that the analysis was done on a pristine sample returned to Earth by NASA.
Same averages, different stories
The most surprising result came from comparing Bennu and Murchison. On average, the carbon isotope values of beta-alanine in the two samples are practically identical — within the margin of error. But looking inside the molecule, the patterns are completely different: of beta-alanine's three carbons, one is heavily enriched in neutrons and the other two are heavily depleted, with distinctly different values between the samples. Bennu's enriched carbon recorded the largest isotope anomaly ever observed in an organic molecule from space.
Despite the differences, the isotope structure is similar in both samples, suggesting a related underlying chemistry — the same formation process, in different places in the Solar System. “One of the main things we discovered, for both glycine and beta-alanine, is that they might have formed in different environments or places in the Solar System,” Mcintosh said. “This broadens our understanding of the type of environments where you can form those very important molecules for prebiotic chemistry.”
A cold environment, not a warm sea
Beta-alanine is not one of the 20 amino acids that build proteins, but it is naturally produced by the human body, can combine with other amino acids to form peptides, and is one of the most abundant amino acids in asteroid and meteorite samples. In earlier work, the same team had already found that Bennu's glycine — the simplest and most abundant amino acid — may have formed in a harsh, cold environment, contradicting the prevailing idea that life's building blocks arose in warm, wet conditions.
For Katherine Freeman, Penn State professor and principal investigator on the project, the preservation of such striking differences is a sign of the molecules' primordial nature. “I was genuinely astonished by the enormous isotope difference between two neighbouring atom positions within the same molecule,” she said. “We are working with molecules formed at the dawn of the Solar System, possibly even before the formation of Earth.”
The OSIRIS-REx mission has concluded, but work on the amino acids in the samples continues. The next step, according to the team, is to understand how space environments — such as exposure to water — can alter the isotope signature of molecules over time. The asteroid Bennu is now more than 200 million miles (322 million kilometres) from Earth.
Image credit: the featured image shows the rocky surface of the asteroid Bennu, captured by NASA's OSIRIS-REx spacecraft. Credit: NASA / OSIRIS-REx, via SciTechDaily.
Sources
- Phys.org — Bennu asteroid analysis suggests unexpected origins for organics in space (November 11, 2026)
- Communications Earth & Environment — Mcintosh et al. (2026), DOI: 10.1038/s43247-026-04084-9
Transparency: this article was produced with the assistance of artificial intelligence, based on the original scientific paper and specialist coverage, with the facts checked against the sources listed above. See the original sources for more details.
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