Discovery of Sugar Molecules in Interstellar Space Revealed

For decades, the elusive question of how life’s fundamental building blocks emerged has captivated scientists, particularly the genesis of sugars that form the backbone of DNA and RNA. While laboratory experiments have struggled to replicate prebiotic sugar synthesis on early Earth, recent space-based discoveries indicate these essential biomolecules may have extraterrestrial origins. Now, an international team led by researcher Izaskun Jiménez-Serra from the Centro de Astrobiología (CAB) has identified the first-ever four-carbon sugar, erythrulose, in interstellar space, marking a significant breakthrough in astrobiology.

Erythrulose, a ketose sugar commonly found in raspberries and some skin products on Earth, was detected in the molecular cloud G+0.693−0.027 near the Milky Way’s Galactic Center. Using ultra-sensitive, broadband spectroscopic data obtained from the 40-meter Yebes radio telescope in Spain and the 30-meter IRAM telescope in the French Alps, the team matched 12 distinct spectral lines to the laboratory spectrum of erythrulose recorded at the University of the Basque Country.

The discovery challenges prevailing astrochemical notions that larger interstellar molecules form primarily through the sequential addition of carbon atoms. Erythrulose’s abundance was found to be at least eight times greater than three-carbon sugars, none of which were detected in the same region. This unexpected finding hints at alternative chemical pathways for sugar formation in star-forming molecular clouds.

Collaborating with chemists from the University of Extremadura and Radboud University in the Netherlands, the researchers propose that erythrulose may form on interstellar ice grains through reactions involving simpler two-carbon alcohols and aldehydes. These ices act as chemical factories in space, facilitating the synthesis of complex organic molecules under cold, irradiated conditions.

Based on the measured concentrations, the team estimates that between 0.5 and 50 million tonnes of erythrulose could have been delivered to Earth’s surface during the Late Heavy Bombardment period approximately 4.1 to 3.8 billion years ago. This implies that interstellar sugar delivery may have contributed to the prebiotic chemical inventory necessary for the origin of metabolic and replication processes, laying the groundwork for life.

“This detection opens the exciting possibility of finding other critical sugars such as ribose, an integral component of RNA, in interstellar space,” says co-author Carlos Briones. The direct observation of sugars beyond our Solar System not only bridges gaps in understanding prebiotic chemistry but also strengthens the hypothesis that life’s molecular precursors are widespread throughout the cosmos.

This landmark study opens promising avenues for future astrochemical searches for biologically relevant molecules and deepens our grasp of how life might arise elsewhere in the universe. It underscores the importance of combining high-resolution astronomical observations with laboratory spectroscopy and chemistry to uncover the molecular complexity of space environments.

Keywords

Astrobiology, interstellar molecules, sugars, erythrulose, molecular clouds, Galactic Center, prebiotic chemistry, spectroscopic surveys, origin of life, astrochemistry