Scientists have identified sugar molecules within the interstellar medium of the Milky Way for the first time, offering new insights into the chemical origins of life on Earth. The discovery, detailed in a recent paper in Nature Astronomy, reveals the presence of erythrulose, a sugar composed of four carbon atoms, eight hydrogen atoms, and four oxygen atoms, in a nebula near the galaxy’s center.
The research team, led by astrochemist Izaskun Jiménez-Serra at the Center for Astrobiology in Spain, utilized data from two radio telescopes to detect the characteristic radio frequency signatures produced by molecules in space. These signatures arise as molecules rotate and vibrate, allowing researchers to identify specific compounds by comparing observed patterns with laboratory spectra. After extensive analysis, the team found a strong match between the signals from the interstellar medium and those from erythrulose, a sugar also found in raspberries on Earth.
“This is a real, bona fide sugar,” said Brett McGuire, an astrochemist at the Massachusetts Institute of Technology who was not involved in the study. “Their data and analysis support their conclusion that the molecule is there,” he added, noting the rigorous efforts to rule out possible contaminants or alternative explanations. Another external expert, Yoshihiro Furukawa of Tohoku University in Japan, who previously helped identify sugars on asteroid Bennu, also endorsed the findings.
The identification of sugar molecules in the cold, harsh environment between stars supports the hypothesis that essential organic compounds can form in space, prior to the formation of stars and planets. Laboratory experiments have suggested that sugars could arise from chemical processes occurring in icy dust grains within molecular clouds, and this study provides observational evidence consistent with that model.
Understanding how sugars like erythrulose originated is critical, as they are fundamental components of nucleic acids such as RNA and DNA, which carry genetic information in living organisms. The discovery also bolsters theories that some of the organic material necessary for life on Earth may have been delivered by asteroid or comet impacts during the planet’s early history. The researchers estimate that as much as 0.5 to 50 million tons of sugar could have been deposited on Earth during this period.
Interestingly, the team did not detect a smaller sugar molecule with three carbon atoms, which was unexpected given current chemical understanding. “It defies expectations, in some ways, based on the chemistry we understand,” McGuire said, highlighting that the absence of the simpler sugar raises new questions for researchers.
The presence of sugar molecules in the interstellar medium may also have wider implications for astrobiology, as it suggests that other molecular clouds across the galaxy could harbor similar prebiotic compounds, potentially increasing the likelihood of life emerging beyond Earth. “If the interstellar medium is capable of forming these ingredients, it could also be found in other molecular clouds across the galaxy,” Jiménez-Serra said.
This discovery marks a significant step toward unraveling the complex chemistry leading to life's emergence and opens new avenues for exploring the molecular precursors of biology in space.