Ground-based testing and demonstrations of starshades

摘要

The direct detection and characterization of an Earth-like exoplanet is of the highest scientific priority and a leading technology that will enable such discovery is the starshade external occulter. We report on the latest results in ground-based efforts for demonstrating and advancing the technology of starshades. Using the McMath-Pierce Solar Telescope at the Kitt Peak National Observatory, we are able to track stars as they move across the night sky and stabilize a beam of starlight behind a starshade. This has allowed us to conduct the first astronomical observations achieving high-contrast with starshades. In our latest efforts, we have extended the separation between the starshade and telescope to reach an inner working angle of 10 arcseconds at a flight-like Fresnel number and resolution. In this report, we detail the development of a closed-loop feedback system to further stabilize the beam at the extended baseline and provide results on the contrast achieved. We conclude by laying out future work to design a dedicated siderostat-starshade facility for future testing of and observations with starshades. Our main result: we achieved a broadband contrast ratio of 3.2 × 10~(-5) at 15 arcseconds IWA, while at a flight-like Fresnel number and resolution.