EXEP: Observing Earth-like Exoplanets with a Ground-Based Telescope and a Shared Orbiting Starshade

The paper provides the predicted performance of a hybrid space-ground approach that combines a large ground-based telescope such as the Extremely Large Telescope (ELT), the Thirty Meter Telescope (TMT), and the Giant Magellan Telescope (GMT), with a shared orbiting starshade in space. This integration aims to image Earth-like exoplanets around Sun-like stars with deep contrast imaging and an unmatched angular resolution. However, the presence of atmospheric turbulence on Earth plays a key role in making this concept infeasible and requires compensation with adaptive optics. In this paper, we present a detailed analysis of the configuration of ELT with an orbiting 99 m starshade to measure the reflected light spectra of a full solar system orbiting sun-like star, from Venus to Saturn, including the habitable exoplanets. Our analysis utilizes a comprehensive and realistic model of the entire system, incorporating the latest ELT Adaptive Optics (AO) models to mitigate the effects of Earth’s atmospheric turbulence under moderate weather conditions. Our studies show that the ELT AO effectively corrects for these effects, demonstrating minimal impact on sensitivity with different Strehl Ratios (SR). We simulate the reflected light images and spectra through Earth’s atmosphere. We show observation of the major molecular signatures for life, such as oxygen and water on an exo-Earth, leading to a promising avenue for future hybrid space–ground observatories to revolutionize the search for Earth-like planets. Future advancements for the near-term implementation of this concept toward deployment will be discussed.