SOUL · Sulfur’s Origins for Uncovering Life (SOUL): Laboratory spectroscopy and astrochemical study

Unraveling the full interstellar sulfur (S) chemical inventory, alongside the “missing sulfur” problem, represents a key challenge in current astrochemistry. Despite recent advances in sensitivity, bandwidth, and spatial resolution at existing observational facilities, along with the launch of new space telescopes like JWST, a major knowledge gap persists between laboratory and observational data.The proposed scientific project, Sulfur’s Origins for Uncovering Life (SOUL): Laboratory spectroscopy and astrochemical study, aims to investigate whether S exists in the form of relevant, yet undiscovered S-bearing species in the interstellar medium. SOUL will conduct pioneering laboratory studies and sensitive interstellar searches of new S-bearing species, from small refractory molecules that may impact the total S budget to much more complex organosulfur compounds, potentially linked to prebiotic chemistry and life's origin, striving for their first detections in space. To achieve this goal, SOUL will adopt a multidisciplinary approach, combining laboratory, observational, and modeling efforts. In the laboratory, high-resolution rotational spectroscopy, coupled with advanced quantum-chemical computations, will be used to unravel the spectra of the target species and provide the needed spectroscopic data. Then, SOUL will use ultra-deep radioastronomical surveys to search for S-bearing molecules in chemically rich shock-dominated interstellar sources, offering a unique complement to recent data from JWST and space missions such as Rosetta. These observational results will be supplemented with new gas-grain chemical models to provide a solid basis for elucidating their chemistry, yet not fully determined. This will be key to shed light on the life cycle of sulfur, linking our Solar System (e.g., meteorites, asteroids and planets) to the beginning of star and planet formation, and to disclose the onset of the prebiotic raw material that possibly triggered life on Earth.