Exo-S is a direct imaging space-based mission to discover and characterize exoplanets. The mission is comprised of two formation-flying spacecraft – a starlight suppressing starshade and a telescope separated by ~30,000 km. To align the starshade between the target star and telescope, one of the two spacecraft must perform a retargeting slew. This drives the need for a sophisticated program to help optimize this path to maximize target yield within mission constraints such as solar and earth avoidance angles, thrust and fuel limitations, and target scheduling for previously-discovered known giant planets. The Design Reference Mission (DRM) describes the sequence of observations to be performed and estimates the number of planets that will be detected and characterized. It is executed with a Matlab-based tool developed for the Exo-S Study. Here we analyze four case studies:
• Case 1: Starshade with a 1.1m dedicated telescope prioritizing the search for earths in the Habitable Zone (HZ).
• Case 2: Starshade with a 1.1m dedicated telescope focused on maximizing planet harvest return and characterization.
• Case 3: Starshade that rendezvous with a 2.4 m shared telescope prioritizing the search for earths in the HZ.
• Case 4: A Rendezvous Earth Finder mission based on a 40-m diameter starshade with a 2.4 m telescope, operating for 4 years, and focused exclusively on detecting Earths in the HZ
Previous starshade DRM tools have been reported in the literature, all of them focused on detection and/or characterization of Earth-twins in the habitable zone. This study has taken then next step and focused on total planet harvest including known Gas Giants, Earths in the Habitable Zone and elsewhere, super-earths, sub-Neptunes, and Jupiters. The DRM employs a hierarchical approach: an observation schedule of known radial velocity gas giants, whose availabilities for observation are known form their orbital parameters, forms a "framework" of observation that have a high probability of success. Between these observations, the next highest priority stars are scheduled and these in turn form the framework for the next observational tier. We report the expected observational completeness, planet yields, and planet characterizations for the three case studies.
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