NTRS - NASA Technical Reports Server

Back to Results
Polar Spin Axis AnomalyThe Global Geospace Science (GGS) Polar Plasma Laboratory (POLAR) spacecraft was launched on February 24, 1996, by a Delta 2. The spacecraft, a major axis spinner, appeared to function nominally throughout the early mission phase, which included several deployments, and orbit and attitude maneuvers. Of particular interest is the fact that the spacecraft was launched with a deliberate dynamic imbalance. During a segment of early orbit operations, a pair of Lanyard Deployed Booms (LDB) were extended. These booms were not identical; the intent was that the spacecraft would be nearly dynamically balanced after they were deployed. The spacecraft contained two dynamic balance mechanisms intended to fine tune the balance on orbit. However, subsequent images taken by the science instruments on the Despun Platform during the dynamic balancing segment indicated an offset of the principal spin axis from the geometric axis. This offset produced a sinusoidal blurring of the science images sufficiently large to degrade science data below mission requirement specifications. In the end, the imbalance encountered in flight was significantly outside the correction capability of the balances. The purpose of this paper is to examine the flight data during the various deployment and maneuver stages of the early orbit operations coupled with analytical simulations to discuss some of the potential causes of the resultant imbalance.
Document ID
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Crouse, Patrick L.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Flatley, Thomas W.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Morgenstern, Wendy M.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
September 8, 2013
Publication Date
May 1, 1997
Publication Information
Publication: Flight Mechanics Symposium 1997
Subject Category
Spacecraft Design, Testing And Performance
Accession Number
Distribution Limits
Work of the US Gov. Public Use Permitted.
Document Inquiry

Available Downloads

There are no available downloads for this record.
No Preview Available