All Five Nucleobases Confirmed in Ryugu Samples via Hayabusa2 Return

The team extracted organics from 5.4 grams of Ryugu material using water and hydrochloric acid under ultra-clean conditions, then identified all five nucleobases at comparable abundances. This extends the 2023 detection of uracil alone and aligns with Bennu findings reported in 2025, while differing from the purine-heavy Murchison meteorite. The balance of purines versus pyrimidines appears tied to local ammonia concentrations during aqueous alteration on the parent body roughly 4.5 billion years ago.

Ryugu's carbon-rich composition and lack of terrestrial contamination provide stronger evidence than meteorites that these molecules formed in space before delivery to early Earth. The data connect to broader patterns seen in Orgueil and Murchison, where similar prebiotic inventories vary by parent-body chemistry, supporting the view that asteroids seeded a common inventory of genetic precursors across the inner Solar System.

Next steps include targeted searches for nucleobase derivatives and sugar phosphates in additional Ryugu and Bennu aliquots, plus laboratory simulations of ammonia-driven synthesis to test whether the observed ratios match predicted formation pathways under early Solar System conditions.