A team of researchers from the United States and Japan has analyzed an extract from a sample of the near-Earth asteroid (101955) Bennu collected by NASA’s OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft and identified several bio-essential sugars, including ribose (RNA sugar) and glucose (metabolism substrate).
This mosaic image of asteroid Bennu is composed of 12 images collected on December 2, 2018 by OSIRIS-REx’s PolyCam instrument from a range of 15 miles (24 km). Image credit: NASA / NASA’s Goddard Space Flight Center / University of Arizona.
“The OSIRIS-REx mission delivered 121.6 g of regolith (unconsolidated granular material) collected from Bennu to Earth on September 24, 2023, under carefully controlled conditions,” said Tohoku University researcher Yoshihiro Furukawa and colleagues.
“The samples were curated under high-purity nitrogen at NASA’s Johnson Space Center.”
“Early studies showed that Bennu has similar mineralogical and elemental characteristics to carbonaceous chondrites; is enriched in carbon and nitrogen compared to most meteorites, but resembles ungrouped carbonaceous chondrites; and experienced extensive aqueous alteration.”
“The Bennu samples analysed to date contain soluble organic compounds, including amino acids, amines, carboxylic acids, aldehydes, nucleobases, polycyclic aromatic hydrocarbons and a diverse mixture of soluble molecules composed of carbon, hydrogen, nitrogen, oxygen and sulfur.”
“We took advantage of this pristine asteroidal material to search for extraterrestrial bio-essential sugars.”
The authors found the five-carbon sugar ribose and, for the first time in an extraterrestrial sample, six-carbon glucose.
Although these sugars are not evidence of life, their detection, along with previous detections of amino acids, nucleobases, and carboxylic acids in Bennu samples, show building blocks of biological molecules were widespread throughout the Solar System.
Furukawa et al. discovered the bio-essential sugars ribose and glucose in samples of the near-Earth asteroid Bennu that were collected by NASA’s OSIRIS-REx mission. Image credit: NASA / Goddard / University of Arizona / Dan Gallagher.
For life on Earth, the sugars deoxyribose and ribose are key building blocks of DNA and RNA, respectively.
DNA is the primary carrier of genetic information in cells. RNA performs numerous functions, and life as we know it could not exist without it.
Ribose in RNA is used in the molecule’s sugar-phosphate ‘backbone’ that connects a string of information-carrying nucleobases.
“All five nucleobases used to construct both DNA and RNA, along with phosphates, have already been found in the Bennu samples brought to Earth by OSIRIS-REx,” Dr. Furukawa said.
“The new discovery of ribose means that all of the components to form the molecule RNA are present in Bennu.”
“The discovery of ribose in asteroid samples is not a complete surprise.”
“Ribose has previously been found in two meteorites recovered on Earth.”
“What is important about the Bennu samples is that researchers did not find deoxyribose.”
“If Bennu is any indication, this means ribose may have been more common than deoxyribose in environments of the early Solar System.”
The researchers think the presence of ribose and lack of deoxyribose supports the ‘RNA world hypothesis, where the first forms of life relied on RNA as the primary molecule to store information and to drive chemical reactions necessary for survival.
“Present day life is based on a complex system organized primarily by three types of functional biopolymers: DNA, RNA, and proteins,” Dr. Furukawa said.
“However, early life may have been simpler. RNA is the leading candidate for the first functional biopolymer because it can store genetic information and catalyze many biological reactions.”
“The Bennu samples also contained one of the most common forms of ‘food’ (or energy) used by life on Earth, the sugar glucose, which is the first evidence that an important energy source for life as we know it was also present in the early Solar System.”
A paper on the findings was published this week in the journal Nature Geosciences.
_____
Y. Furukawa et al. Bio-essential sugars in samples from asteroid Bennu. Nat. Geosci, published online December 2, 2025; doi: 10.1038/s41561-025-01838-6
