Earth and Planetary Science

A Comprehensive Review of Organic Matter Found in Asteroids (162173) Ryugu and (101955) Bennu

Charis E. Adams

Department of Biological Sciences, Biola University, La Mirada, CA 90639, USA

Hyuna Lee

Department of Biological Sciences, Biola University, La Mirada, CA 90639, USA

DOI: https://doi.org/10.36956/eps.v5i1.3118

Received: 31 January 2026 | Revised: 29 March 2026 | Accepted: 2 April 2026 | Published Online: 16 April 2026

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Abstract

Near-Earth Asteroids (NEAs) are among the planetary bodies that have encountered, and will continue to encounter, our planet. This interaction has provided insights into the composition and origins of asteroids and their relationship to meteorites and other solar system materials. Sample return missions, notably JAXA's Hayabusa2 to Asteroid (162173) Ryugu in 2018 and NASA's OSIRIS-REx to Asteroid (101955) Bennu in 2020, have provided unprecedented access to primitive carbonaceous asteroid material for laboratory analysis. Unlike meteorites, which experience thermal degradation and contamination during atmospheric entry, hermetically sealed asteroid samples preserve a more accurate record of their original chemical state. Analysis of Ryugu samples yielded approximately 20,000 soluble organic compounds, fifteen amino acids including both proteinogenic and non-proteinogenic varieties, and the nucleobase uracil, with subsequent analysis confirming all five canonical nucleobases. These compounds are characteristic of Ivuna-type carbonaceous chondrites, a rare class of meteorites whose bulk elemental abundances approximate solar photospheric composition. The detection of presolar grains in Ryugu samples further indicates the preservation of material predating the formation of our solar system. Bennu samples have corroborated and extended these findings, confirming bio-essential sugars including ribose and phosphate-bearing compounds in addition to containing all five nucleobases, meaning Bennu samples contain representatives of two of the three main structural components of an RNA nucleotide. While the formation pathways and prebiotic significance of these compounds remain subjects of active investigation, these findings prompt broader questions about the relationship between primitive carbonaceous bodies and the molecular history of our solar system.

Keywords: Ivuna‑Type Carbonaceous Chondrite; Hayabusa2; Near‑Earth Asteroid; Prebiotic Chemistry; Nucleobases; Potentially Hazardous Asteroids

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