Pointing control for the SPIDER balloon-borne telescope

J. A. Shariff, P. A.R. Ade, M. Amiri, S. J. Benton, J. J. Bock, J. R. Bond, S. A. Bryan, H. C. Chiang, C. R. Contaldi, B. P. Crill, O. P. Doré, M. Farhang, J. P. Filippini, L. M. Fissel, A. A. Fraisse, A. E. Gambrel, N. N. Gandilo, S. R. Golwala, J. E. Gudmundsson, M. HalpernM. Hasselfield, G. C. Hilton, W. A. Holmes, V. V. Hristov, K. D. Irwin, W. C. Jones, Z. D. Kermish, C. L. Kuo, C. J. MacTavish, P. V. Mason, K. G. Megerian, L. Moncelsi, T. A. Morford, J. M. Nagy, C. B. Netterfield, R. O'Brient, A. S. Rahlin, C. D. Reintsema, J. E. Ruhl, M. C. Runyan, J. D. Soler, A. Trangsrud, C. E. Tucker, R. S. Tucker, A. D. Turner, A. C. Weber, D. V. Wiebe, E. Y. Young

Research output: Chapter in Book/Report/Conference proceedingConference contribution

8 Scopus citations

Abstract

We present the technology and control methods developed for the pointing system of the Spider experiment. Spider is a balloon-borne polarimeter designed to detect the imprint of primordial gravitational waves in the polarization of the Cosmic Microwave Background radiation. We describe the two main components of the telescope's azimuth drive: the reaction wheel and the motorized pivot. A 13 kHz PI control loop runs on a digital signal processor, with feedback from fibre optic rate gyroscopes. This system can control azimuthal speed with < 0.02 deg/s RMS error. To control elevation, Spider uses stepper-motor-driven linear actuators to rotate the cryostat, which houses the optical instruments, relative to the outer frame. With the velocity in each axis controlled in this way, higher-level control loops on the onboard flight computers can implement the pointing and scanning observation modes required for the experiment. We have accomplished the non-trivial task of scanning a 5000 lb payload sinusoidally in azimuth at a peak acceleration of 0.8 deg/s2, and a peak speed of 6 deg/s. We can do so while reliably achieving sub-arcminute pointing control accuracy.

Original languageEnglish (US)
Title of host publicationGround-Based and Airborne Telescopes V
EditorsHelen J. Hall, Larry M. Stepp, Roberto Gilmozzi
PublisherSPIE
ISBN (Electronic)9780819496133
DOIs
StatePublished - 2014
EventGround-Based and Airborne Telescopes V - Montreal, Canada
Duration: Jun 22 2014Jun 27 2014

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9145
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Other

OtherGround-Based and Airborne Telescopes V
CountryCanada
CityMontreal
Period6/22/146/27/14

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Keywords

  • Spider
  • actuation
  • balloon-borne telescopes
  • control systems
  • cosmic microwave background

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