A pristine record of outer Solar System materials from asteroid Ryugu’s returned sample

Abstract Volatile and organic-rich C-type asteroids may have been one of the main sources Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but meteorite record biased: only strongest types survive atmospheric entry are then modified interaction with terrestrial environment. Here we present results a detailed bulk microanalytical study pristine Ryugu particles, brought to Earth Hayabusa2 spacecraft. particles display close compositional match chemically unfractionated, aqueously altered, CI (Ivuna-type) chondrites, which widely used as proxy for Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics phyllosilicates indicates maximum temperatures ~30 °C during aqueous alteration. We find that heavy hydrogen nitrogen abundances consistent outer origin. most uncontaminated unfractionated extraterrestrial materials studied so far, provide available