New research suggests that amino acids, the fundamental components of life, may have arrived on Earth carried by interstellar dust grains, possibly contributing to the origins of life as we know it.
In a study published in the Monthly Notices of the Royal Astronomical Society, Stephen Thompson, I11’s principal beamline scientist, and Sarah Day, an I11 beamline scientist, investigated whether amino acids such as glycine and alanine could withstand the extreme environment of space and ultimately reach Earth while attached to cosmic dust particles.
Amino acids form the basis of proteins and enzymes that power all biological activity. Scientists have long questioned whether these essential molecules originated on Earth or were delivered from space, and the new findings suggest that cosmic dust may have served as an important transport mechanism.
Testing amino acid survival in space
To test this idea, the researchers created microscopic grains of amorphous magnesium silicate, which is a common constituent of cosmic dust, and placed amino acids glycine, alanine, glutamic acid, and aspartic acid onto their surfaces. The team then used infrared spectroscopy and synchrotron X-ray powder diffraction to observe how the molecules responded when the silicate grains were heated, replicating the gradual warming experienced by dust as it moved through the early solar system.
The experiments showed that only glycine and alanine remained attached to the silicate particles. Both formed crystalline structures, and alanine in particular stayed stable even at temperatures far exceeding its melting point. The researchers also observed differences between the two mirror-image forms of alanine (L- and D-alanine), with L-alanine reacting more strongly to heat than its D-form. Glycine behaved differently, detaching from the silicate surface at temperatures below its normal decomposition threshold, which suggests it separated from the grain rather than chemically breaking down.
To further probe the role of dust surface chemistry, the team produced two sets of amorphous silicate grains and heat-treated one set before adding the amino acids. This process removed hydrogen atoms from the surface, creating silicates with distinct surface properties. These differences were found to affect the temperatures at which the amino acids were released, highlighting how subtle variations in dust composition could influence molecular survival in space.
These subtle differences may have had profound implications for the types of molecules that seeded life on Earth.
Although the study was limited to a single cosmic dust component, the findings could point to the existence of a possible “astromineralogical selection mechanism,” a natural filtering process where the limited range of available dust grain surfaces means that only specific amino acids attach to dust grains. Amino acids are formed within the icy mantles that coat cosmic dust grains, and such a mechanism would come into play as the ice mantles are sublimated away into space, along with the amino acids within them, when the dust grains cross the so-called “snow line” and encounter the warmer, inner regions of the early solar system. This, in turn, could have influenced which molecules were ultimately delivered to Earth, shaping the planet’s early organic inventory.
A cosmic recipe for life
The study supports the idea that amino acids formed in interstellar ice mantles could have transferred to silicate dust grains and survived long enough to be delivered to Earth. This would likely have occurred between 4.4 and 3.4 billion years ago, a period bracketed by the formation of the Earth’s crust and oceans following the end of the so called late heavy bombardment and the appearance in the geological record of the first micro fossils.
Antarctic micrometeorites and samples from comets like Wild 2 and 67P/Churyumov–Gerasimenko have shown high concentrations of organic material, including amino acids. Furthermore, although impacts by comets and asteroids, both of which contain amino acids, would still have occurred at that time the influx of micrometeorites is believed to have been so high that it was likely to have been the dominant source of organic carbon on the early Earth. This showering of the Earth’s surface with space dust rich in life’s precursors, is believed to have potentially compensated for the limited quantities of amino acids produced from terrestrial synthesis alone, allowing life on Earth to begin.
The team’s research adds a vital piece to the puzzle of life’s origins. It shows that interstellar dust grains are not just carriers of molecules – they may actively influence which organics survive and reach planets like Earth. By understanding these processes, scientists can better grasp how life might emerge elsewhere in the universe.
The study also highlights the importance of interdisciplinary science, combining astronomy, chemistry, and geology along with the advanced experimental techniques available at large-scale research facilities like Diamond, to explore one of humanity’s oldest questions about the origins of life.
Reference: “Laboratory study of amino acids on amorphous Mg-silicate using infrared spectroscopy and X-ray diffraction – implications for the survival and delivery of interstellar organics to the solar nebula and early Earth” by Stephen P Thompson and Sarah J Day, 3 September 2025, Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093/mnras/staf1457
This work was supported by Diamond Light Source beamtime award EE11854.
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