Design of a laboratory testbed for external occulters at flight Fresnel numbers

The Advanced Technology Large Aperture Space Telescope (ATLAST) team identified five key technology areas to enable candidate architectures for a future large-aperture ultraviolet/optical/ infrared (LUVOIR) space observatory envisioned by the NASA Astrophysics 30-year roadmap, "Enduring Quests, Daring Visions." The science goals of ATLAST address a broad range of astrophysical questions from early galaxy and star formation to the processes that contributed to the formation of life on Earth, combining general astrophysics with direct-imaging and spectroscopy of habitable exoplanets. The key technology areas are internal coronagraphs, starshades (or external occulters), ultra-stable large-aperture telescope systems, detectors, and mirror coatings. For each technology area, we define best estimates of required capabilities, current state-of-the-art performance, and current technology readiness level (TRL), thus identifying the current technology gap. We also report on current, planned, or recommended efforts to develop each technology to TRL 5.

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“…Additional efforts are underway to improve laboratory and field demonstrations to more closely match flight-like configurations. 37…”

Section: Contrast Performance Demonstration and Validationmentioning

confidence: 99%

Technology gap assessment for a future large-aperture ultraviolet-optical-infrared space telescope

Bolcar

Balasubramanian

Crooke

et al. 2016

J. Astron. Telesc. Instrum. Syst

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“…Mounting them with "struts" will cause unacceptable diffraction unless the struts themselves are apodized similarly to the petal edges; this is the approach taken by the experiments at science contrast levels. 21 In our case, the starshade was manufactured 5 by depositing chrome on an optical reference flat.…”

Section: Optical Considerationsmentioning

confidence: 99%

Starshade formation flying I: optical sensing

Bottom

Martin

Cady

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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A key challenge for starshades is formation flying. To successfully image exoplanets, the telescope boresight and starshade must be aligned to approximately one meter at separations of tens of thousands of kilometers. This challenge has two parts: first, the relative position of the starshade with respect to the telescope must be sensed; second, sensor measurements must be combined with a control law to keep the two spacecraft aligned in the presence of gravitational and other disturbances. In this work, we present an optical sensing approach using a pupil imaging camera in a 2.4-meter telescope that can measure the relative spacecraft bearing to a few centimeters in one second, much faster than any relevant dynamical disturbances. A companion paper will describe how this sensor can be combined with a control law to keep the two spacecraft aligned with minimal interruptions to science observations.

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