Discovery of Erythrulose in Interstellar Space
Astronomers have detected erythrulose, a natural sugar found in raspberries and used in fake tan lotions, in a vast cloud of dust and gas near the center of the Milky Way. This marks the first time a sugar has been directly identified in the interstellar medium, the space between stars.
The discovery, published in Nature Astronomy, demonstrates that compounds essential for life can form in the frigid expanse of space. Erythrulose is produced through chemical reactions on tiny interstellar dust grains, which then may rain down on planets or arrive via comets.
Implications for Life's Origins
Dr. Izaskun Jiménez-Serra at Spain's Centre for Astrobiology near Madrid said, “This is the very first sugar to be detected in interstellar space and it is important because it tells us that these sugars are more common than we previously thought. It opens the possibility for life to develop on other worlds in a similar fashion to what it did on Earth.”
Scientists have long puzzled over how simple sugars became abundant on early Earth, as lab studies suggest they would not have formed easily under young Earth conditions. Previous detections of sugars in ancient meteorites and on the Bennu asteroid hinted at an extraterrestrial source, but direct evidence from interstellar space was lacking.
Observations and Formation Process
Jiménez-Serra and her team used two Spanish radio telescopes to observe the dust cloud G+0.693-0.027. After initially finding no three-carbon sugars, they unexpectedly detected the signature of erythrulose, a four-carbon sugar. “To my surprise, I saw the signals,” Jiménez-Serra said.
The researchers explain that erythrulose can form when glycolaldehyde and ethylene glycol—two organic compounds abundant in space—combine on microscopic dust grains, even at temperatures around -250°C.
Role in Prebiotic Chemistry
Simple sugars like erythrulose can provide energy and react to form ribonucleotides, the building blocks of RNA, likely the first genetic material. As life evolved, DNA emerged as a more stable genetic store, with RNA serving as an intermediary.
The scientists estimate that millions of tonnes of erythrulose could have rained down on Earth during the Late Heavy Bombardment, a period of intense asteroid and comet impacts. “To have suffered this kind of rain of organics, I think that seems to have been a key step,” Jiménez-Serra said. “That material could have contributed to prebiotic soups where the first biomolecules were synthesised.”
Earthly Connections and Expert Reactions
Erythrulose is found in trace amounts in red raspberries and is used in fake tan lotions, where it reacts with amino acids via the Maillard reaction to produce brown polymers.
Prof. Yoshihiro Furukawa at Tohoku University, who discovered sugars on the Bennu asteroid, commented: “We have been waiting for an actual detection like this. Sugars formed in the interstellar medium can reach Earth and other planets via cometary dust … This supply may have helped facilitate the emergence of life, if planetary environments were able to build life from such molecules, although that process itself remains unclear.”
