Space Weathering-Induced Formation of Hydrogen Sulfide (H₂S) and Hydrogen Disulfide (H₂S₂) in the Murchison Meteorite

Theoretical calculations and experimental simulations indicate that the surprisingly low sulfur abundance on the surfaces of spacecraft visited S-type asteroids 433 Eros and 25143 Itokawa may be due to space weathering. Two current missions, Osiris-Rex and Hayabusa 2, are studing asteroids 101955 Bennu (B-type) and 162173 Ryugu (C-type), respectively. Understanding space weathering effects related to sulfur containing species is only in the beginning stages and has not been studied from the point of view of C-type asteroids. This laboratory study details the formation of hydrogen sulfide (H₂S) and hydrogen disulfide (H₂S₂) from conversion of nonvolatile-sulfuretted species in the Murchison meteorite by exposure to energetic electrons and laser processing, which mimics the synergic effect of secondary electrons generated by galactic cosmic rays and high-energy solar wind particles plus micrometeorite impact on airless bodies. The results indicate that space weathering processes likely induce depletion of sulfur on the surface of C-type and undifferentiated S-type asteroids. For keeping scientific integrity of these fragile species, cold/cryogenic curation of future collected samples from asteroids might be required.