The Habitable Worlds Observatory will revolutionize our understanding of the universe by directly detecting biosignatures on extrasolar planets and allow us to answer the question if we are alone in the universe. To accomplish the tight science goals associated with this mission, the development of an ultrastable observatory with a coronagraphic instrument is necessary. The observatory itself may need to stay stable on the order of 10 picometers over a wavefront control cycle, orders of magnitude more stable than what is required on current space missions. The metrology to verify stability requirements must be roughly a factor of ten more stable. The ultrastable laboratory at NASA’s Goddard Space Flight Center has further stabilized its testbed to allow for dynamic measurements on diffuse and specular objects on the order of single picometers, and we are currently measuring drifts on the orders of tens of picometers over different temporal bands. This paper will discuss the mechanical updates to the testbed setup, the analysis performed on several test articles, and the path forward on the road to measuring achieving the required stability for Habitable Worlds Observatory.
NASA’s Habitable Worlds Observatory will consist of a segmented telescope and high contrast coronagraph to characterize exoplanets for habitability. Achieving this objective requires an ultra-stable telescope with wavefront stability of picometers in certain critical modes. The NASA funded Ultra-Stable Large Telescope Research and Analysis – Technology Maturation program has matured key component-level technologies in 10 areas spanning an “ultra-stable” architecture, including active components like segment edge sensors, actuators and thermal hardware, passive components like low distortion mirrors and stable structures, and supporting capabilities like precision metrology. This paper will summarize the final results from the four-year ULTRA-TM program, including advancements in performance and/or path-to-flight readiness, TRL/MRL maturation, and recommendations for future work.
The James Webb Space Telescope (JWST) launched on December 25, 2021, and its optical performance in orbit has been even better than predicted pre-flight. The static wavefront error (WFE) is less than half the value specified for the requirement of having diffraction-limited image quality at 2 microns in the NIRCam shortwave channel, enabling the observatory to deliver both sharper images and higher sensitivity than anticipated. In addition to the excellent image quality, the optical stability has also exceeded expectations, both in terms of high-frequency dynamic contributions (which would be perceived as part of “static WFE”) and in terms of drifts over minutes, hours, and days. Stability over long timescales is critical for several important science cases, including exoplanet transit spectroscopy and coronagraphy. JWST’s stability success was achieved through detailed design and testing, with several important lessons learned for future observatories, especially the Habitable Worlds Observatory that is expected to need even higher levels of stability. We review the stability architecture, how it was technologically demonstrated, the ground test results and improvements, the on-orbit results, and the lessons learned.
NASA’s Habitable Worlds Observatory will consist of a segmented telescope and high contrast coronagraph to characterize exoplanets for habitability. Achieving this objective requires an ultra-stable telescope with wavefront stability of picometers in certain critical modes. The NASA funded Ultra-Stable Large Telescope Research and Analysis – Technology Maturation program continues to mature key component-level technologies for this new regime of “ultra-stable optical systems,” including active components like segment edge sensors, actuators and thermal hardware, passive components like low distortion mirrors and stable structures, and supporting capabilities like precision metrology. This paper will present an update to the latest results from hardware testbeds and simulations in the areas listed above. It will also contain a correction to previously published results of Ball’s Integrated Demo, which consists of a capacitive sensor and three actuators operating in closed loop.
The recently released Astro2020 Decadal Survey recommends a large IR/O/UV space telescope that can observe potentially habitable exoplanets. Achieving this goal requires a telescope with wavefront stability on the order of picometers in some modes. The Ultra-Stable Large Telescope Research and Analysis – Technology Maturation (ULTRATM) program has matured key component-level technologies for this new regime of “ultra-stable optical systems,” including active components like segment edge sensors, actuators and thermal sensing and control hardware, as well as passive components like low distortion mirror mounts and stable composites for structures. Hardware testbeds have demonstrated component performance in the desired regime and with path-to-flight properties and simulations have applied those results to the flight system. These component level demonstrations are a critical step to enable subsequent subsystem and system level demonstrations of an ultra-stable telescope.
KEYWORDS: James Webb Space Telescope, Control systems, Calibration, Mirrors, Telescopes, Temperature metrology, Space telescopes, Interferometers, Metrology, Data modeling
The Astro 2020 Decadal Survey has recommended technology and pre-formulation efforts for a 6-meter class Ultraviolet Optical Infrared telescope which is stable for high contrast observations of Exoplanets and general astrophysics. Here we report on progress on an ultra-stable test system and a series of picometer scale metrology demonstrations using High Speed Interferometry to achieve new levels of thermal control and new methods of calibration along with small scale demonstrations of mirror and structure components. Here we review the history of these efforts and recent ultra-stable measurements of a glass test article including thermal control and optical stability. We will summarize the challenge and progress of making drift measurements and report on recent progress in thermal control and glass ultrastability control that could have implications for future systems. We will close with a discussion of implications of these results to future efforts.
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