11 April 2020 Starshade formation flying II: formation control
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Abstract

Several starshade concepts for imaging exo-Earths would operate at the second Earth–Sun Lagrange point (L2) and consist of a starshade flying in formation tens to hundreds of thousands of kilometers from a telescope. The starshade would need to maintain meter-level lateral alignment with the line of sight from telescope to target star. A companion paper describes an optical sensing scheme using a pupil imaging camera in the telescope that can sense the relative lateral position to a few centimeters. A full flight-traceable formation flying framework that leverages this sensor is presented. In particular, a two-dimensional “disk deadbanding” algorithm is introduced for lateral control. The framework also maximizes the drift time between thruster burns to reduce interruption to scientific observations. The main sources of uncertainty affecting the control performance are compared, and it is found that spacecraft mass uncertainty is a driving factor. The formation flying environment is also analyzed to identify conditions that lead to worst-case differential gravity and solar radiation pressure disturbances. Finally, for a representative observation scenario with the Wide Field Infrared Space Telescope, this control system is tested through Monte Carlo simulations. The results show robust meter-level control with essentially optimal drift time between thruster burns.

© 2020 Society of Photo-Optical Instrumentation Engineers (SPIE) 2329-4124/2020/$28.00 © 2020 SPIE
Thibault L. B. Flinois, Daniel P. Scharf, Carl R. Seubert, Michael Bottom, and Stefan R. Martin "Starshade formation flying II: formation control," Journal of Astronomical Telescopes, Instruments, and Systems 6(2), 029001 (11 April 2020). https://doi.org/10.1117/1.JATIS.6.2.029001
Received: 21 January 2020; Accepted: 20 March 2020; Published: 11 April 2020
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CITATIONS
Cited by 11 scholarly publications.
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KEYWORDS
Telescopes

Error analysis

Sensors

Space operations

Monte Carlo methods

Sun

Control systems

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