Astronomers have detected the sugar erythrulose in a molecular cloud near the center of the Milky Way, marking the first time a four-carbon sugar has been identified in interstellar space. The discovery suggests that complex organic molecules essential for life may form more readily in space than previously understood.
Detection in the Galactic Center
Researchers identified the signature of erythrulose within a dense dust cloud designated G+0.693-0.027, located near the center of the Milky Way. The detection was made using two radio telescopes in Spain: the 40-meter telescope at Yebes and the 30-meter telescope at Granada. While the team had previously searched for three-carbon sugars in the same region without success, the identification of this four-carbon molecule came as a significant development.
While simple sugars like glycolaldehyde—the first sugar ever detected in space—have been known to exist in the interstellar medium for years, the presence of a more complex, four-carbon sugar suggests a broader chemical complexity in deep space than astronomers had previously confirmed.
Chemical Formation on Interstellar Dust
The synthesis of erythrulose occurs under extreme conditions, with temperatures in the cloud hovering around -250C. The process involves the combination of two simpler organic compounds: glycolaldehyde and ethylene glycol. These precursors are already known to be abundant in various corners of the galaxy.
This process of grain-surface chemistry is a critical area of study for understanding how organic material eventually reaches planetary surfaces. Once formed, these molecules can be incorporated into comets or asteroid dust, which may later impact planets like Earth. The researchers hypothesize that such a mechanism could have contributed to the prebiotic soups that existed on early Earth, potentially providing the raw materials needed for the first biomolecules to emerge.
Implications for the Origins of Life
The detection of erythrulose carries weight for the study of abiogenesis—the transition from non-living matter to life. Simple sugars can react to form ribonucleotides, which are the fundamental building blocks of RNA. In early biological models, RNA is believed to have served as the primary genetic material before the emergence of more stable DNA.
The presence of these sugars in the interstellar medium suggests that the “rain” of organic materials from space might have been a consistent feature throughout the history of planetary formation.
Historical Context and Future Research
The role of extraterrestrial delivery systems has been a subject of intense scientific debate. Previous analysis of samples from the Bennu asteroid and ancient meteorites had already hinted at the presence of bio-essential sugars, but direct detection in a gas cloud confirms that these molecules exist independent of planetary or asteroidal bodies. Prof. Yoshihiro Furukawa of Tohoku University, who discovered sugars in samples from the Bennu asteroid, emphasized the importance of this finding.
Photo: Theguardian
“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.”
Photo: Nature
Prof. Yoshihiro Furukawa, Tohoku University
While the detection confirms that the “ingredients” are available, scientists remain cautious about the next steps. The jump from the presence of sugars in space to the development of complex life is a massive one, and the specific environmental conditions required to catalyze these sugars into functional biological machinery remain a subject of active research. For now, the discovery of erythrulose serves as a confirmed link in the chain, demonstrating that the chemistry of life is not unique to Earth’s surface but is a fundamental component of the galaxy’s molecular inventory.
