SPEAR · Sub-Neptunes as Predecessors for Earth-like planets Atmospheres Research for Habitability with the ELTs

One of the most significant discoveries of the past decades is the realization that there are more planets than stars in our Galaxy, with a planet diversity that has far surpassed our expectations. A major focus of 21st-century astronomy is the characterization of Earth-sized planets in the habitable zones (HZPs) around nearby M dwarfs and the search for possible biomarkers in their atmospheres. This is driving the development of advanced, dedicated space missions and ground-based Extremely Large Telescopes (ELTs). These upcoming ELTs, equipped with instruments like the ANDES high-resolution spectrograph, aim to probe the atmospheres of HZPs in detail, moving beyond basic parameters to explore their atmospheric composition. Current techniques, like transmission spectroscopy, have been successful in characterizing larger planets but will face significant challenges when applied to small, rocky HZPs. Correcting for stellar, planetary, and systematic signals which are undetectable with current instruments will become crucial, as their signatures will be of the same size or larger than the planetary signals we will be looking for. Moreover, the habitability of these planets is under debate due to their susceptibility to atmospheric loss from intense stellar radiation.To address these challenges, the SPEAR project proposes a multi-faceted approach to develop new simulations and data analysis methodologies that can solve or mitigate the key observational limitations of the ELTs. The project will also develop advanced simulation tools, conduct empirical studies on sub-Neptune planets as benchmarks targets for habitability studies, design optimal observational strategies for the ELTs, and create a prioritized list of targets that expand the parameter space to search for habitability and biomarkers. By the time the ELTs become operational, SPEAR will provide the missing essential tools needed to fully exploit these powerful observatories in the search for habitable world