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“Spacecraft Jitter Prediction using 6-DOF Disturbance Measurements”. Bryce Carpenter Oliver Martin Jason Hinkle Sierra Nevada Corporation Space Systems Group IEEE Aerospace Conference March 2009. Problem Statement. Challenges. Demand for Small Satellites. Flexibility Lower Cost
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“Spacecraft Jitter Prediction using 6-DOF Disturbance Measurements” Bryce Carpenter Oliver Martin Jason Hinkle Sierra Nevada Corporation Space Systems Group IEEE Aerospace Conference March 2009
Problem Statement Challenges Demand for Small Satellites • Flexibility • Lower Cost • Rapid Development • Increased Agility • … • Power availability • Smaller aperture • Decreased • pointing stability • … Beijing-1 Launch Oct. 2005 4-meter resolution, 24-kilometer swath agriculture, city planning, hydrology, 2008 Olympics, …
Paper Contribution • Presentation Overview An analytical technique for system-level jitter characterization prior to system integration 1. Hexapod Reaction Balance 3. Structural Response Analysis 2. Frequency Domain Analysis 4. System-Level Jitter Prediction
Historical Background 2005 – 2007 Distributed Sensing Experiment (DSE) Missile Defense Agency (MDA) February 2008 Trailblazer Operationally Responsive Space (ORS) August 2, 2008 Falcon 1, Flight 3 launches from Omelek Island in Kwajalein Atoll SpaceX
Hexapod Reaction Balance • Measurement device for accurately recording a wide range of dynamic force and torque responses Steel Flexures Force Transducers Kinematic Transformation
Frequency Domain Analysis • Convert time-series to frequency domain using Discrete Fourier Transform:
Power Spectral Density • Convert DFT to PSD:
Structural Frequency Response Analysis • Conduct frequency response analysis in NASTRAN to determine camera motion due to RW disturbance Comm Deck Avionics Deck Payload Bay 28,339 Nodes 33,895 Elements
System Jitter Prediction Reaction Wheel Disturbance Predicted Payload Jitter Flexible Body Response
Conclusion • SNC has developed the Hexapod to accurately measure high frequency forces and torques • Analysis of Hexapod data can be combined with a FEM frequency response analysis to determine system pointing stability
Acknowledgments This material is based upon work supported by the U.S. Army Space and Missile Defense Command under Contract No. HQ0006-04-D-0002.”