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Three Axis Control of the Hubble Space Telescope Using Two Reaction Wheels and Magnetic Torquer Bars for Science ObservationsThe Hubble Space Telescope (HST) is renowned for its superb pointing accuracy of less than 10 milli-arcseconds absolute pointing error. To accomplish this, the HST relies on its complement of four reaction wheel assemblies (RWAs) for attitude control and four magnetic torquer bars (MTBs) for momentum management. As with most satellites with reaction wheel control, the fourth RWA provides for fault tolerance to maintain three-axis pointing capability should a failure occur and a wheel is lost from operations. If an additional failure is encountered, the ability to maintain three-axis pointing is jeopardized. In order to prepare for this potential situation, HST Pointing Control Subsystem (PCS) Team developed a Two Reaction Wheel Science (TRS) control mode. This mode utilizes two RWAs and four magnetic torquer bars to achieve three-axis stabilization and pointing accuracy necessary for a continued science observing program. This paper presents the design of the TRS mode and operational considerations necessary to protect the spacecraft while allowing for a substantial science program.
Document ID
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Hur-Diaz, Sun
(Emergent Space Technologies, Inc. Greenbelt, MD, United States)
Wirzburger, John
(Honeywell Technology Solutions, Inc. Columbia, MD, United States)
Smith, Dan
(Lockheed Martin Mission Services Co. Greenbelt, MD, United States)
Date Acquired
August 24, 2013
Publication Date
June 29, 2008
Subject Category
Spacecraft Design, Testing And Performance
Report/Patent Number
Meeting Information
Meeting: F. Landis Markley Astronautics Symposium
Location: Cambridge, MD
Country: United States
Start Date: June 29, 2008
End Date: July 2, 2008
Sponsors: American Astronautical Society, American Inst. of Aeronautics and Astronautics
Funding Number(s)
Distribution Limits
Public Use Permitted.
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