Tryptophan Turns Up on Asteroid

Tryptophan, the amino acid often linked to post-turkey-dinner drowsiness, has been discovered on the asteroid Bennu, according to a new study. NASA's OSIRIS-REx mission collected a sample from Bennu in 2020, and it was returned to Earth in 2023 for analysis. The asteroid is of particular interest to scientists because its makeup is thought to reflect the early solar system, offering clues about the origins of life, per CNN. Previous studies of Bennu's material had already identified 33 amino acids, including 14 of the 20 used by life on Earth, plus all five genetic nucleobases, which are "the building blocks of DNA and RNA," per NDTV.

"Finding tryptophan in the Bennu asteroid is a big deal, because tryptophan is one of the more complex amino acids, and until now it had never been seen in any meteorite or space sample," says José Aponte, an astrochemist at NASA's Goddard Space Flight Center and coauthor of the study published Monday in PNAS. The findings support the idea that the ingredients for life may have been present in space and delivered to Earth via asteroids. As Penn State's Kate Freeman, an outside researcher, puts it to CNN, "Asteroids were the early Earth's grocery delivery service." Researchers caution that further testing is needed to confirm the finding, but say the pristine condition of the Bennu sample makes terrestrial contamination unlikely.