Optical architecture and wavefront sensing of the FLUTE-1 technology demonstration mission

Abstract

Building space telescopes with apertures of tens of meters is instrumental for next-generation astrophysics, including direct imaging and characterization of extrasolar planets. Traditional manufacturing and segmentedmirror approaches, such as those used for the JamesWebb Space Telescope, do not scale to these dimensions. The FLUidic TElescope (FLUTE) project offers an alternative path to large-aperture monolithic primary mirrors by exploiting surface tension to shape a thin liquid film into a precise spherical cap in microgravity. The long-term vision is a 50-meter-class observatory; the next step is FLUTE-1, a 1-meter aperture technology demonstration in Low Earth Orbit, maturing through a NASA Innovative Advanced Concepts (NIAC) Phase-II tailored study. This paper presents the architecture of FLUTE-1, focusing on (i) the spherical aberration corrector that converts the spherical fluidic primary into a diffraction-limited imaging system, and (ii) the wavefront-sensing strategy needed to characterize that mirror on orbit. We replace the previously baselined Shack–Hartmann sensor with an Asymmetric Pupil Fourier Wavefront Sensor (APF-WFS) on the science detector, supported by image-based phase retrieval for coarse acquisition so that the multi-wave aberrations expected from an as-deployed fluidic mirror are bridged into the APF-WFS linear regime. FLUTE-1 is a precursor towards deployable, 50-meter-class liquid mirrors in space.