Sugars, a Strange Gum-Like Organic, and Supernova Stardust Found in Asteroid Bennu — Clues to Life’s Ingredients

New Analyses of Bennu Samples Reveal Organic Building Blocks and Ancient Stardust

Samples returned to Earth by NASA’s OSIRIS‑REx mission in September 2023 have yielded a string of surprising discoveries about the near‑Earth asteroid Bennu. Three papers, published in Nature Geoscience and Nature Astronomy, report that Bennu contains simple sugars, an unusual nitrogen‑ and oxygen‑rich gum‑like organic material, and an unexpectedly large amount of microscopic stardust with signatures of supernova origins.

Ribose and Other Sugars: Support for an RNA-First World

In a study led by Professor Yoshihiro Furukawa (Tohoku University) and colleagues, researchers detected several simple sugars in the Bennu sample, including ribose — a key component of RNA. While these molecules are not evidence that life existed on the asteroid, their presence indicates that the chemical ingredients for biological molecules were distributed widely across the early solar system. The relative abundance of ribose compared with deoxyribose (a DNA sugar) lends additional support to hypotheses suggesting RNA played a central role in early prebiotic chemistry.

A New Gum-Like Organic Compound

A second paper, led by teams at NASA’s Ames Research Center and the University of California, Berkeley, describes a complex, gum‑like substance rich in nitrogen and oxygen that has not been previously observed in extraterrestrial rocks. This sticky, organic‑rich material could have been a favorable medium for chemical reactions relevant to prebiotic chemistry, and it may offer new chemical markers to guide future astrobiology studies.

Abundant Stardust Traces Supernova Origins

The third study, led by Ann Nguyen (NASA Johnson Space Center), reports that Bennu contains a higher than expected abundance of presolar grains — microscopic stardust whose isotopic signatures point to origins in supernova explosions. These grains provide constraints on the astrophysical environment where Bennu’s parent body formed and carry information about the earliest stages of the solar system.

Important caveat: While these discoveries illuminate how key organic molecules and stardust were distributed in the early solar system, they do not demonstrate that life originated on Bennu or any asteroid.

Taken together, the three studies enrich our picture of the primordial materials that seeded the young Earth and other planetary bodies. Ongoing analysis of the returned samples will refine our understanding of the chemical pathways that could have contributed to life’s emergence and help guide where and how to search for signs of life beyond Earth.