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Problems Encountered During the Recertification of the GLORY Solar Array Dual Axis Gimbal Drive ActuatorsThe Glory observatory is the current incarnation of the Vegetation Canopy Lidar (VCL) mission spacecraft bus. The VCL spacecraft bus, having been cancelled for programmatic reasons in 2000, was nearly integrated when it was put into storage for possible future use. The Glory mission was a suitable candidate for using this spacecraft and in 2006 an effort to recertify the two axis solar array gimbal drive after its extended storage was begun. What was expected to be a simple performance validation of the two dual axis gimbal stepper motors became a serious test, diagnosis and repair task once questions arose on the flight worthiness of the hardware. A significant test program logic flow was developed which identified decisions that could be made based on the results of individual recertification tests. Without disassembling the bi-axial gimbals, beginning with stepper motor threshold voltage measurements and relating these to powered drive torque measurements, both performed at the spacecraft integrator s facility, a confusing picture of the health of the actuators came to light. Tests at the gimbal assembly level and tests of the disassembled actuators were performed by the manufacturer to validate our results and torque discrepancies were noted. Further disassembly to the component level of the actuator revealed the source of the torque loss.
Document ID
20090033100
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Saltzman, Marc (Sterling Dynamics, LLC Sterling, VA, United States)
Schepis, Jospeh P. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Bruckner, Michael J. (Stinger Ghaffarin Technologies, Inc. Greenbelt, MD, United States)
Date Acquired
August 24, 2013
Publication Date
September 23, 2009
Subject Category
Spacecraft Design, Testing And Performance
Meeting Information
Meeting: 13th European Space Mechanisms and Tribology Symposium/European Space Agency
Location: Vienna
Country: Austria
Start Date: September 23, 2009
End Date: September 25, 2009
Distribution Limits
Public
Copyright
Public Use Permitted.

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