Minimum Power Slews and the James Webb Space Telescope
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Authors
Karpenko, Mark
Dennehy, Cornelius J.
Marsh, Harleigh C.
Gong, Qi
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Advisors
Date of Issue
2017
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Publisher
American Astronautical Society (AAS)
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Abstract
Power is a precious commodity in space flight. Reducing the power demands of reaction wheels during spacecraft attitude slews can have multiple benefits both in the up-front spacecraft design phase as well as during in-flight operations. In an effort to reduce power requirements of momentum control systems, many authors have contemplated the use of proxies for reaction wheel power to design minimal effort slews. Proxies for power are used because the power input equation is non-smooth leading to a seemingly unsolvable problem in optimal control. In this paper we show, through the application of various transformations and the introduction of appropriate functional constraints, that a smooth cost functional for reaction wheel input power can indeed be built. Standard techniques can then be used to solve and analyze the power optimal slew problem. The concept is applied to reduce the power requirements for a typical largeangle slew of the James Webb Space Telescope. The energy reduction(~ 20%) is obtained by finding a minimum power momentum distribution that achieves the necessary control effort while simultaneously reducing power input to the individual wheels.
Type
Conference Paper
Description
Spaceflight Mechanics 2017
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Format
20 p.
Citation
Karpenko, M., Dennehy, C.J., Marsh, H.C.and Qi Gong. "Minimum Power Slews and the James Webb Space Telescope", 27th AAS/A/AA Space Flight Mechanics Meeting, Volume 160, Advances in the Astronautical Sciences, 2017.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, it may not be copyrighted.