Sugars are central to life. They help form the structural backbone of DNA and RNA and participate in essential metabolic reactions.

They are also thought to have been necessary for the formation of the earliest nucleic acids. Yet researchers studying life’s origins still face a major puzzle: laboratory experiments indicate that prebiotic conditions on early Earth would not have produced enough sugar.

Ribose and glucose have been found in meteorites and asteroid material, raising the possibility that some sugars formed in the ancient molecular cloud that gave rise to the Solar System. Until now, however, no sugar had been identified directly in interstellar space.

A four-carbon sugar appears in space
An international group led by CAB researcher Izaskun Jiménez-Serra has detected erythrulose, the first sugar identified in the interstellar medium. Erythrulose is the only possible ketose containing four carbon atoms. On Earth, it occurs naturally in raspberries and is also used in sunless tanning products.

Researchers found it toward G+0.693−0.027, a molecular cloud near the center of the Milky Way. The detection relied on highly sensitive broadband spectroscopic surveys conducted with the 40-m Yebes radio telescope and the 30-m telescope operated by the Institute for Radio Astronomy in the Millimeter Range (IRAM).