Amino acids, the building blocks necessary for life, were previously found in samples of 4.6-billion-year-old rocks from an asteroid called Bennu, delivered to Earth in 2023 by NASA's OSIRIS-REx mission. How those amino acids - the molecules that create proteins and peptides in DNA - formed in space was a mystery, but new research led by Penn State scientists shows they could have originated in an icy-cold, radioactive environment at the dawn of Earth's solar system.
According to the researchers, who published new findings today (Feb. 9) in the Proceedings of the National Academy of Sciences, some amino acids in the asteroid Bennu samples likely formed in a different way than was previously thought, in the harsh conditions of the early solar system.
"Our results flip the script on how we have typically thought amino acids formed in asteroids," said Allison Baczynski, assistant research professor of geosciences at Penn State and co-lead author on the paper. "It now looks like there are many conditions where these building blocks of life can form, not just when there's warm liquid water. Our analysis showed that there's much more diversity in the pathways and conditions in which these amino acids can be formed."
Analyzing a precious bit of space dust no bigger than a teaspoon, the team used custom instruments capable of measuring isotopes, slight variations in the mass of atoms. In studying Bennu, the researchers focused on glycine, the simplest amino acid, a tiny two‑carbon molecule that serves as one of life's basic building blocks. Amino acids link together to form proteins, which carry out nearly every biological function - from building cells to catalyzing chemical reactions.
