Optical Performance of Hybrid Observatory for Earth-like Exoplanets

The Hybrid Observatory for Earth-like Exoplanets (HOEE) was uniquely proposed to search for the extremely faint Earth-like-exoplanets orbiting Sun-like-stars with unprecedented sensitivity and exceptional angular resolution. This concept integrates an orbiting starshade with existing ground-based telescopes for the first time. This paper addresses the major optical challenges crucial for the success of HOEE. The paper introduces the HOEE optical model of an orbiting 99 m diameter starshade with the 39 m European Extremely Large Telescope (E-ELT), including the forecast sensitivity analysis. The paper examines the optical tolerance for the starshade’s design, manufacture, deployment, and performance. The analysis includes several perturbations related to precise petal position, petal shape, petal clocking, segment position, formation flying alignment requirements, and proportional petal errors in width and length. We present a stability performance comparison with the 60 m starshade of the Habitable Worlds Observatory (HWO). We also explore influence of the bright noise sources, including solar-glint and Earthshine that could potentially affect the detection of these faint habitable exoplanets. We finally discuss the effect of the Earth’s atmospheric turbulence and demonstrate the E-ELT Adaptive Optics system in mitigating these effects. The analysis suggests insignificant changes on sensitivities with the presence of the medium weather conditions. These findings are leading to the innovation of the HOEE concept and establishing it as a pioneering model for opening a new window of future hybrid space-ground observatory missions.