Exoplanet detection yield of a space-based Bracewell interferometer from small to medium satellites

Space-based nulling interferometry is one of the most promising solutions to spectrally characterize the atmosphere of rocky exoplanets in the mid-infrared (3 to 20 mu m). It provides both high angular resolution and starlight mitigation. This observing capability depends on several technologies. A CubeS at (up to 20 kg) or a medium satellite (up to a few hundreds of kg), using a Bracewell architecture on a single spacecraft could be an adequate technological precursor to a larger, flagship mission. Beyond technical challenges, the scientific return of such a small-scale mission needs to be assessed. We explore the exoplanet science cases for various missions (several satellite configurations and sizes). Based on physical parameters (diameter and wavelength) and thanks to a state-of-the-art planet population synthesis tool, the performance and the possible exoplanet detection yield of these configurations are presented. Without considering platform stability constraints, a CubeSat (baseline of b similar or equal to 1 m and pupils diameter of D similar or equal to 0.1 m) could detect similar or equal to 7 Jovian exoplanets, a small satellite (b similar or equal to 5 m/D similar or equal to 0.25 m) similar or equal to 120 exoplanets, whereas a medium satellite (b similar or equal to 12.5 m/D similar or equal to 0.5 m) could detect similar to 250 exoplanets including 51 rocky planets within 20 pc. To complete our study, an analysis of the platform stability constraints (tip/tilt and optical path difference) is performed. Exoplanet studies impose very stringent requirements on both tip/tilt and OPD control. (C) 2020 Society of Photo-Optical Instrumentation Engineers (SPIE)