Origin and Evolution of Extraterrestrial Ozone in the JWST, JUICE, and Europa Clipper Era: A Laboratory Investigation

Ozone (O3) is considered among the most promising biosignatures to look for inside and outside the solar system, i.e., in planetary atmospheres and surfaces as well as in the atmosphere of exoplanets. Recent studies show that the O3 detection in exoplanetary atmospheres is already achievable with the James Webb Space Telescope (JWST) and also the search for O3 ice on the surface of several icy worlds will be soon possible thanks to the JUpiter ICy moons Explorer (JUICE) and Europa Clipper space missions (in addition to JWST). In this context, we noticed that there is a lack of insight when considering the possible radiolytic production of O3 within ices of different oxygen-bearing species which may be found on icy extraterrestrial surfaces (and consequently also released to enrich their atmospheres). We report here a comparative laboratory study on the production of O3 from several ion irradiated ices and icy mixtures: CO, CO:N2, CO:SO2, CO2, H2O:CO2, N2O, NO2:N2O4, and pure O2. The samples were processed with 200 keV protons (unless otherwise specified) and analyzed by Fourier Transform Infrared (FTIR) spectroscopy at 16 K. Our aim is to contribute to the understanding of how much O3 could be produced by energetic charged particles irradiating different oxygen-bearing ice species and compare these results to the case of O2 ice. We believe that the results presented in the current study may have a great scientific impact, especially in view of the future exploration of the icy worlds of the solar system and the current and future exploration of exoplanets by the ongoing and the upcoming space missions.