Practical Limits on Nanosatellite Telescope Pointing: The Impact of Disturbances and Photon Noise

Ewan S. Douglas, Kevin Tracy, Zachary Manchester

Research output: Contribution to journalArticlepeer-review

Abstract

Accurate and stable spacecraft pointing is a requirement of many astronomical observations. Pointing particularly challenges nanosatellites because of an unfavorable surface area–to-mass ratio and a proportionally large volume required for even the smallest attitude control systems. This work explores the limitations on astrophysical attitude knowledge and control in a regime unrestricted by actuator precision or actuator-induced disturbances such as jitter. The external disturbances on an archetypal 6U CubeSat are modeled, and the limiting sensing knowledge is calculated from the available stellar flux and grasp of a telescope within the available volume. These inputs are integrated using a model-predictive control scheme. For a simple test case at 1 Hz, with an 85-mm telescope and a single 11th magnitude star, the achievable body pointing is predicted to be 0.39 arcseconds. For a more general limit, integrating available star light, the achievable attitude sensing is approximately 1 milliarcsecond, which leads to a predicted body pointing accuracy of 20 milliarcseconds after application of the control model. These results show significant room for attitude sensing and control systems to improve before astrophysical and environmental limits are reached.

Original languageEnglish (US)
Article number676252
JournalFrontiers in Astronomy and Space Sciences
Volume8
DOIs
StatePublished - Aug 13 2021
Externally publishedYes

Keywords

  • CubeSats
  • astrophysics
  • attitude sensing and control
  • environmental disturbances
  • jitter
  • nanosatellites
  • satellite pointing

ASJC Scopus subject areas

  • Astronomy and Astrophysics

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