Piercing through the Haze: Characterizing Titan-like terrestrial exoplanets with JWST

As we enter a new era of using JWST to characterize exoplanet atmospheres, a top priority is defining observational needs and parameters in the search for life on an exoplanet. Although some studies have begun to consider Titan-like exoplanet atmospheres, more work is needed to prepare for the potential discovery and characterization of Titan analogues with JWST and future missions. We explore the effectiveness of exoplanet atmospheric retrieval methodologies on the Cassini/VIMS-IR spectrum of Titan assuming agnostic haze properties and tholin hazes, as well as a self-consistent photochemical model. We compare our retrieved chemical abundances and haze profiles against fiducial values and Cassini/ISS-NAC UV observations and the forward modeled truths. We generalize these findings to a Titan-like exoplanet in the TRAPPIST-1 system and find that JWST-like observations have limited potential to identify features beyond methane in a Titan-like atmosphere, but may be able to identify the presence of the haze to a few hundred kilometers. The diagnostic features which would differentiate between different haze model (scattering) properties are shortward of 1, and further demonstrate the important role of nUV -- optical observatories in constraining the properties of exoplanet atmospheres. We also find that agnostic priors for the bulk atmosphere can lead to a degeneracy in which a spectrally active gas (CH 4) is erroneously favored as the dominant atmospheric constituent over a spectrally inactive molecule (N 2).