On-orbit jitter measurement and analysis of precision pointing spacecraft and their instruments

This paper presents jitter performance of the first in a series of the new generation of Geostationary Operational Environmental Satellites, GOES-N spacecraft and instruments. Practical techniques are presented to demonstrate the importance of measuring and analyzing the dynamic interaction between the spacecraft and instruments for precise pointing of the spacecraft and its instruments. The discussion presented in this paper includes system requirements, mathematical modeling, 2D, FFT/3D/AFT, FFT image analysis, and instrument system sensitivity to jitter during ground and on-orbit testing. Emphasis is given to the cause and effect of the electromechanical disturbance, beginning with the dynamics of the instruments subsystem and their interaction and sensitivity to external and self-generated disturbances. Flight segment disturbances and impact on unwanted optical motion caused by scanning mirrors, as well as motion of the magnetometer boom, solar array, and attitude control system is presented. Also, presented is the disturbance and jitter on the solar array yoke XRP and its SXI instrument. The reaction wheel assemblies' disturbances are also considered. On-orbit testing, which was tailored to measure the deployment signature of the magnetometer and instrument's cooler doors not only for frequency but also to establish on-orbit damping knowledge is discussed. Methodology, techniques, and sensors used to measure and subsequently optimize and compensate for the flight segment disturbance are also described. Ground optical testing in ambient environment and dynamic interaction testing, which includes detector microphonics in thermal vacuum, are compared with those obtained on-orbit end-to-end. This paper offers a unique opportunity to build a database and utilize lessons learned for dynamic interaction in structures and payload detectors on future space platforms.