Top left: transit transmission spectrum of TRAPPIST-1b from observations (similar Fig. 11, except for HST-measurement on which an offset has been applied) compared with simulated transit transmission spectra derived by Lincowski et al. (2018) for different terrestrial atmospheres. Each color is associated with a different scenario – gold stands for 10 or 100 bars CO₂ -rich atmospheres, salmon stands for 10 or 100 bars O₂-rich desiccated atmospheres, green stands for 10 or 100 bars O₂-rich outgazing atmospheres, brown stands for 10 or 92 bars Venus-like atmospheres, and blue stands for an aqua planet with either clear or cloudy sky. Top right: similarly but for TRAPPIST-1c. Bottom left: similarly but for TRAPPIST-1e. Bottom right: similarly but for TRAPPIST-1g.