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DAC-3 Pointing Stability Analysis Results for SAGE 3 and Other Users of the International Space Station (ISS) Payload Attachment Sites (PAS)The purpose of this paper is to provide final results of a pointing stability analysis for external payload attachment sites (PAS) on the International Space Station (ISS). As a specific example, the pointing stability requirement of the SAGE III atmospheric science instrument was examined in this paper. The instrument requires 10 arcsec stability over 2 second periods. SAGE 3 will be mounted on the ISS starboard side at the lower, outboard FIAS. In this engineering analysis, an open-loop DAC-3 finite element model of ISS was used by the Microgravity Group at Johnson Space Flight Center to generate transient responses at PAS to a limited number of disturbances. The model included dynamics up to 50 Hz. Disturbance models considered included operation of the solar array rotary joints, thermal radiator rotary joints, and control moment gyros. Responses were filtered to model the anticipated vibration attenuation effects of active control systems on the solar and thermal radiator rotary joints. A pointing stability analysis was conducted by double integrating acceleration transient over a 2 second period. Results of the analysis are tabulated for ISS X, Y, and Z Axis rotations. These results indicate that the largest excursions in rotation during pointing occurred due to rapid slewing of the thermal radiator. Even without attenuation at the rotary joints, the resulting pointing error was limited to less than 1.6 arcsec. With vibration control at the joints, to a maximum 0.5 arcsec over a 2 second period. Based on this current level of model definition, it was concluded that between 0 - 50 Hz, the pointing stability requirement for SAGE 3 will not be exceeded by the disturbances evaluated in this study.
Document ID
19970012916
Acquisition Source
Langley Research Center
Document Type
Technical Memorandum (TM)
Authors
Woods-Vedeler, Jessica A.
(NASA Langley Research Center Hampton, VA United States)
Rombado, Gabriel
(Grumman Technical Services, Inc. Houston, TX United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1997
Subject Category
Structural Mechanics
Report/Patent Number
NASA-TM-110318
NAS 1.15:110318
Accession Number
97N17040
Funding Number(s)
PROJECT: RTOP 632-20-21-11
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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