Hardware demonstrations of component-level technologies for ultra-stable optical systems

Abstract

Two of the large mission concepts developed for the 2020 Astronomy and Astrophysics Decadal Survey - the Large UV/Optical/Infrared (LUVOIR) Surveyor and the Habitable Exoplanet (HabEx) Observatory - aim to perform direct imaging and spectroscopy of exo-Earth candidates with high-contrast coronagraphs. Meeting this ambitious science goal will require architectures with large-area primary mirrors to achieve the high resolution and greater photon flux needed to detect faint objects, as well as instrumentation to suppress light from a host star ~10 billion times brighter than the exoplanet of interest. Achieving contrast of 10−10 at visible wavelengths using a coronagraph ushers in a new regime where the corresponding wavefront stability is expressed in units of picometers rather than nanometers. The NASA-funded “Ultra-Stable Large Telescope Research and Analysis - Technology Maturation” (ULTRA-TM) program is working to mature critical technologies for ultra-stable optical systems to support these mission concepts and enable ground-breaking science. This paper describes the progress towards demonstrating performance of enabling technologies through component-level hardware testbeds - specifically for picometer-capable edge sensors and actuators with flight-like properties, which are needed for active sensing and control of large, segmented primary mirrors like LUVOIR. Key performance requirements include resolution, range, and operational bandwidth, which are derived from wavefront stability budgets traceable to the top-level coronagraph performance and science goals driving the ultra-stability need. Raising the TRL of these technologies will address some of the most difficult parts of the stability problem with the tightest requirements and longest lead times, as well as provide significant risk reduction for their inclusion in future mission concepts.