Astronomers Detect First Interstellar Sugar Near Milky Way Center

A team of international researchers has directly detected a complex sugar molecule within the interstellar medium for the first time, demonstrating that essential chemical precursors to life can synthesize in the extreme environments of deep space before the formation of stars and planets.

The findings, published Monday in the journal Nature Astronomy, reveal the presence of erythrulose, a natural four-carbon sugar commonly found in trace amounts in raspberries and utilized commercially in self-tanning cosmetics, within a massive molecular dust and gas cloud located near the center of the Milky Way galaxy.

The research was spearheaded by Dr. Izaskun Jiménez-Serra and Dr. Carlos Briones at Spain’s Centre for Astrobiology (CAB) and the Spanish National Research Council (CSIC). The team directed two Spanish radio telescopes to analyze the molecular cloud designated G+0.693−0.027. The instruments utilized included a radio telescope at the Yebes Observatory north of Madrid and another operated by the Institute for Radio Astronomy in the Millimeter Range (IRAM) in the Sierra Nevada range of southern Spain.

• Molecular Cloud Observed:  G+0.693−0.027

• Telescopes Employed:         Yebes Observatory & IRAM

• Sugar Detected:                   Erythrulose (Four-Carbon Sugar)

• Ambient Temperature:        Approximately -250°C

Astronomers identified the chemical by cross-referencing the molecular radio wave signatures captured from the gas cloud against the exact wavelength patterns of erythrulose established in laboratory environments. The team initially searched for simpler three-carbon sugars but found no trace of them.

“This finding was unexpected, as the prevailing view in astrochemistry is that interstellar molecules grow in size through the sequential addition of carbon atoms,” Jiménez-Serra said in an official statement. “Our discovery demonstrates that relatively complex sugars can already be synthesized in interstellar space, before stars and planets are born.”

According to the study, erythrulose forms at ambient temperatures hovering around -250°C when two abundant organic compounds, glycolaldehyde and ethylene glycol, combine on the surfaces of microscopic, icy interstellar dust grains. While scientists have cataloged more than 340 distinct molecules within the interstellar medium, no sugar compounds had ever been directly observed in these space expanses until this study.

The discovery carries significant implications for pre-biotic chemistry and the understanding of how life originated on Earth. Laboratory simulations have consistently shown that simple sugars do not form easily under the volatile conditions present during the earliest chapters of Earth's history. While sugar-related compounds have previously been identified in primitive meteorites and within samples collected from the asteroid Bennu by NASA’s OSIRIS-REx spacecraft, this finding confirms these molecules originate prior to planetary accretion.

“Sugar and sugar-related compounds have been found in asteroids, but the discovery of these compounds in interstellar space strengthens suggestions that our solar system may have been seeded with pre-existing organic compounds,” said Mark Sephton, a professor in the department of Earth science and engineering at Imperial College London, who was not involved in the research.

The study outlines a delivery model where interstellar sugars are incorporated into forming comets and asteroids, which subsequently impact planetary surfaces. The researchers calculate that between 0.5 million and 50 million metric tons of erythrulose could have been delivered to Earth during the Late Heavy Bombardment, a phase roughly 4 billion years ago when asteroids repeatedly struck the inner solar system, though NASA notes the exact timeline of this bombardment period remains a subject of ongoing scientific debate.

“To have suffered this kind of rain of organics, I think that seems to have been a key step. That material could have contributed to prebiotic soups where the first biomolecules were synthesised.” ,” Jiménez-Serra noted.

Once delivered, simple sugars can undergo chemical transitions to form ribonucleotides, the foundational components of ribonucleic acid (RNA), which served as the precursor to deoxyribonucleic acid (DNA) in early evolutionary biology.

“We have been waiting for an actual detection like this,” stated Professor Yoshihiro Furukawa of Tohoku University’s Department of Earth Sciences, who previously discovered sugars in the Bennu asteroid samples. “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.”

The detection indicates that the chemical building blocks of life are distributed widely across the cosmos rather than being unique to Earth's solar system.

“The detection of erythrulose is very exciting because it opens up the possibility of discovering in space other sugars such as ribose, which is part of RNA, and other important molecules for the origin of life,” said study coauthor Carlos Briones.

Jiménez-Serra added: “The key ingredients for the origin of life could be present in other regions across the galaxy, opening the possibility for life to develop elsewhere in the universe.”