Evidence of both molecular cloud and fluid chemistry in Ryugu regolithOPEN ACCESS
Maitrayee Bose, Robert A. Root, Yunbin Guan, Jacob Eaton, Axel Wittmann, Thomas Skrmetti, Steven J. Desch
Science Advances
24 Jul 2024
Vol 10, Issue 30
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“The sulfur chemistry of (162173) Ryugu particles can be a powerful tracer of molecular cloud chemistry and small body processes, but it has not been well explored. We report identification of organosulfurs and a sulfate grain in two Ryugu particles, A0070 and A0093. The sulfate grain shows oxygen isotope ratios (δ17O = −11.0 ± 4.3 per mil, δ18O = −7.8 ± 2.3 per mil) that are akin to silicates in Ryugu but exhibit mass-independent sulfur isotopic fractionation (Δ33S = +5 ± 2 per mil). A methionine-like coating on the sulfate grain is isotopically anomalous (δ15N = +62 ± 2 per mil). Both the sulfate and organosulfurs can simultaneously form and survive during aqueous alteration within Ryugu’s parent body, under reduced conditions, low temperature, and a pH >7 in the presence of N-rich organic molecules. This work extends the heliocentric zone where anomalous sulfur, formed by selective photodissociation of H2S gas in the molecular cloud, is found.”
