Figure. Composite image from the Galactic Center. Green and yellow: 8 µm and 24 µm emission observed with Spitzer (Churchwell et al. 2009; Carey et al. 2009). Red: 20 cm emission imaged with MeerKAT (Heywood et al. 2019, 2022) and the Green Bank Telescope (GBT; Law et al. 2008). Image adapted from Henshaw et al. (2023; doi: 10.48550/arXiv.2203.11223) and Longmore et al. (2026; 10.48550/arXiv.2602.20340).
Credit
Credits: Ashley Barnes/Izaskun Jiménez-Serra/Juan García de la Concepción
An international team of scientists has directly detected a sugar in interstellar space for the very first time
Published in the journal Nature Astronomy, the peer-reviewed study reveals the presence of a complex four-carbon sugar in a molecular cloud near the centre of the Milky Way, supporting the theory that the essential building blocks for life may have been delivered to Earth from space.
The research was led by Dr Izaskun Jiménez-Serra, a researcher at the Centro de Astrobiología (CAB), a joint centre of the Spanish National Research Council (CSIC) and the National Institute for Aerospace Technology (INTA).
Solving a prebiotic paradox
Sugars are fundamental to terrestrial life, serving as the backbone for DNA and RNA and powering metabolic processes. However, a major paradox in origin-of-life research is that while sugars are crucial for synthesising the first nucleic acids, laboratory experiments show they do not form in sufficient quantities under early Earth’s prebiotic conditions.
While sugars like ribose and glucose have previously been recovered from meteorites and asteroid samples, they had never been observed directly in deep space.
The CAB-led team changed this by pointing highly sensitive telescopes at G+0.693−0.027, a dense molecular cloud located near the galactic centre. Using ultra-sensitive, broadband spectroscopic surveys from the Yebes 40-meter radio telescope in Spain and the IRAM 30-meter telescope in France, the team identified erythrulose, the only possible four-carbon ketose sugar, which on Earth is found in raspberries and sunless tanning products.
Overturning astrochemistry assumptions
The researchers confirmed the discovery by matching 12 distinct spectral lines of radio emission from the molecular cloud to laboratory measurements of erythrulose recorded at the University of the Basque Country.
Beyond merely identifying the sugar, the team’s findings challenged standard chemical models:
Abundances:
Erythrulose is at least eight times more abundant in the cloud than similar three-carbon sugars, none of which were even detected in the region.
The growth model:
Astrochemists generally believed that interstellar molecules grow sequentially by adding one carbon atom at a time (from one-carbon to two-carbon, to three-carbon, and so on).
The new pathway:
In collaboration with chemists from the University of Extremadura and Radboud University in the Netherlands, the team discovered that erythrulose forms within interstellar ices when simpler two-carbon alcohols and aldehydes bond directly, skipping the three-carbon stage entirely.
Millions of tonnes of space sugar: Interstellar space
By calculating the concentration of erythrulose within the G+0.693−0.027 molecular cloud, the researchers estimated that between 0.5 and 50 million tonnes of this sugar could have rained down on Earth during the Late Heavy Bombardment, a period of intense asteroid impacts that occurred roughly 4.1 to 3.8 billion years ago.
This celestial delivery would have provided the early Earth with an abundant, ready-made supply of sugars to kickstart the planet’s first metabolic and genetic replication processes.
“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 co-author Carlos Briones.