Exoplanet Transit Spectroscopy with a Future Large UV to IR Flagship Observatory

One of the top recommendations of the Astro2020 decadal was a future large flagship mission spanning the far UV to near IR. Although primarily designed to enable direct imaging of potentially habitable exoplanets and general astrophysics, such a flagship will also have revolutionary capabilities to build on the legacy of HST for exoplanet transit spectroscopy. Based on the work of the LUVOIR and HabEx studies, we will review the transformative capabilities this future observatory to build to detect transiting exospheres, probe the physics of atmospheric escape, constrain cloud properties, and measure abundances for a wide range of atomic and molecular species.