First True Sugar Discovered in Interstellar Space

What makes this discovery significant is not just the identity of the molecule, but its abundance. Erythrulose appears to be at least eight times more abundant than simpler three-carbon sugars (like glycolaldehyde) in the same region, making it the dominant sugar species detected in interstellar space .

How It Was Discovered

The team used two of the most sensitive radio telescopes in Spain — the Yebes 40-meter telescope and the IRAM 30-meter telescope — to conduct ultrasensitive, broadband spectral surveys of the G+0.693-0.027 molecular cloud .

Every molecule has a unique rotational signature, a kind of chemical fingerprint that appears as specific spectral lines when viewed through a radio telescope. The researchers matched the faint radio signals coming from the cloud against laboratory-measured spectra of erythrulose, confirming its presence beyond reasonable doubt .

The search was possible because of painstaking laboratory work published years earlier. In 2021, researchers at the University of the Basque Country (UPV/EHU) had already determined the hyper-precise molecular structure of erythrulose, creating the spectroscopic roadmap needed for a definitive space-based detection .

How a Sugar Forms in the Cold of Space

Space between stars is unimaginably cold and mostly empty. So how does a sugar molecule assemble there?

The leading model, supported by quantum chemical simulations, suggests that erythrulose forms on the surface of icy dust grains . Energetic processing — driven by cosmic ray bombardment and ultraviolet radiation — drives chemical reactions between simpler two-carbon aldehydes and alcohols stuck to the grains . Once formed, the molecules are released into the gas phase through sputtering, a process akin to sandblasting caused by shock waves.

The G+0.693-0.027 cloud is particularly good at this. It is a region of ongoing cloud-cloud collision, which generates powerful shocks that knock molecules off grain surfaces and into detectable gas-phase abundances . This same cloud has already yielded more than 20 first-time detections of interstellar molecules .

Why This Matters for the Origin of Life

The discovery has immediate implications for one of biology's deepest mysteries: Where did the first genetic molecules come from?

The most widely accepted hypothesis for the origin of life involves an "RNA World," where ribonucleic acid (RNA) served as both information storage and catalyst before DNA evolved. But RNA itself is extremely complex. Some researchers propose that simpler genetic systems preceded RNA.

Erythrulose fits neatly into this picture. The molecule can undergo chemical conversion to threose, the four-carbon sugar that forms the backbone of threose nucleic acid (TNA) — a potential pre-RNA genetic material . Because erythrulose is detected at such high abundance in the same cloud that has already yielded many other RNA precursors (including hydroxylamine, glycolamide, and carbonic acid), the discovery shows that nature can produce the building blocks for alternative genetic systems without any biological intervention .

Delivering Life's Ingredients to Early Earth

The finding also strengthens a long-debated hypothesis about how Earth got its prebiotic inventory. Complex organic molecules, including sugars needed for genetic precursors, appear to have been already present in the material that formed our Solar System .

During the Late Heavy Bombardment — a period roughly 4.1 to 3.8 billion years ago when comets, asteroids, and meteorites pummeled the inner planets — these molecules could have been delivered intact to the early Earth, providing a ready-made supply of prebiotic ingredients . The detection of a true sugar in interstellar space makes this delivery hypothesis significantly more plausible.

Bottom Line

The detection of erythrulose does not prove that life exists elsewhere in the universe. But it does prove that one of the most important classes of biological molecules — true sugars — can form naturally and abundantly in interstellar space. The same chemistry happening today in the molecular cloud G+0.693-0.027 likely happened 4.6 billion years ago in the cloud that gave birth to our Sun and its planets. The sugars were there from the start.