Formation of Alkylsulfonic Acids in Interstellar Analog Ices

By Keith Cowing
Status Report
May 27, 2024
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Formation of Alkylsulfonic Acids in Interstellar Analog Ices
Each spectrum was taken after an irradiation dose of A 100 nA, B 1000 nA, and C 5000 nA current. The original spectrum (gray) is deconvoluted showing functional groups associated with reagents (green), alkylsulfonic acids (orange), and irradiation products (blue). The red line represents the sum. The spectral region (2000–500 cm−1) to the right of the dashed vertical line indicates the region has been magnified by 5 or 10 times for clarity. The inset depicts the ice sample prior to the irradiation (dark yellow) and after 4 min radiation exposure (purple). — Nature

For the last century, the source of sulfur in Earth’s very first organisms has remained a fundamental, unsolved enigma.

While sulfates and their organic derivatives with sulfur in the S(+VI) oxidation state represent core nutrients in contemporary biochemistry, the limited bioavailability of sulfates during Earth’s early Archean period proposed that more soluble S(+IV) compounds served as the initial source of sulfur for the first terrestrial microorganisms.

Here, we reveal via laboratory simulation experiments that the three simplest alkylsulfonic acids—water soluble organic S(+IV) compounds—can be efficiently produced in interstellar, sulfur-doped ices through interaction with galactic cosmic rays.

This discovery opens a previously elusive path into the synthesis of vital astrobiological significance and untangles fundamental mechanisms of a facile preparation of sulfur-containing, biorelevant organics in extraterrestrial ices; these molecules can be eventually incorporated into comets and asteroids before their delivery and detection on Earth such as in the Murchison, Tagish Lake, and Allende meteorites along with the carbonaceous asteroid Ryugu.

Abiotic formation of alkylsulfonic acids in interstellar analog ices and implications for their detection on Ryugu, Nature (open access)

Astrobiology, Astrochemistry

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻