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Focal plane calibration of the Spitzer space telescope

Bayard, David S. and Kang, Bryan H. and Brugarolas, Paul B. and Boussalis, Dhemetrios (2009) Focal plane calibration of the Spitzer space telescope. IEEE Control Systems Magazine, 29 (6). pp. 47-70. ISSN 0272-1708.

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The Spitzer space telescope (Spitzer) is currently NASA's largest and most sensitive infrared (IR) telescope in space. Spitzer's focal plane carries detectors from three science instruments, namely, the infrared array camera (IRAC), the infrared spectrograph (IRS), and the multiband imaging photometer for Spitzer (MIPS). In this article we discuss the instrument pointing frame (IPF) Kalman filter, which is used to calibrate Spitzer's telescope focal plane. The IPF filter is a high-order square-root iterated linearized Kalman filter that carries 37 states to estimate frame misalignments, while correcting for systematic errors due to optical distortions, scan-mirror errors, thermomechanically induced drift variations, and gyro bias and drift in all axes. The Spitzer application demonstrates that the integrated approach offers significant advantages with respect to optimality, time-efficiency, anomaly detection, and health monitoring compared to existing telescope-calibration approaches, where the parameters are artificially broken into subsets that are estimated by separate teams of analysts. Performance results for the IPF Kalman filter indicate that all Spitzer calibration requirements are satisfied, and are consistent with margins predicted by preflight error analysis. On a final note, after more than five-and-a-half years of probing the cool cosmos, Spitzer entered standby mode on May 15, 2009, as a result of running out of the liquid helium coolant that kept its infrared instruments chilled. This event marks the successful completion of the Spitzer's cold mission as originally commissioned by NASA. However, even though the telescope is warming up, the IRAC arrays continue to operate and provide useful scientific data. A new follow-on warm mission based on the IRAC arrays has been defined and initiated, so that Spitzer will remain in commission for several years to come.

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Additional Information:© 2009 IEEE. This work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. The focalplane survey was a highly collaborative effort, and the authors acknowledge the entire Spitzer project and the close participation of various engineering and science teams, namely Jocelyn Keene, Bill Wheaton, Jane Morrison (MIPS), Peter Eisenhardt, Sean Carey (IRAC), Carl Grillmair, Keven Uchida, Bernhard Brandl (IRS), Elmain Martinez, Myche McAuley (MIPL), Amy Mainzer (PCRS), Dan Swanson, Chris Voth, Dave Eckart, Angus McMechen (OET, Lockheed- Martin), John Gilbert, John Miles (IOC/SV planning), Keyur Patel, Bob Wilson (flight system), Fernando Tolivar, Tooraj Kia, Johnny Kwok, Mike Werner, Charles Lawrence, Nick Gautier, Jeff Van Cleve, and Bill Mahoney (consultations, scientific and technical advice).
Subject Keywords:Kalman filters, aerospace instrumentation, astronomical telescopes, error analysis, focal planes
Issue or Number:6
Record Number:CaltechAUTHORS:20100414-093925084
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17978
Deposited By: Tony Diaz
Deposited On:30 Apr 2010 03:33
Last Modified:03 Oct 2019 01:36

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