Rigid-body-control subsystem sizing for an Earth science geostationary platform

摘要

The Mission to Planet Earth Program envisions both low-Earth and geostationary orbiting spacecraft supporting instruments that will measure and monitor land, ocean, and atmospheric variables that are important to understanding Earth's global change mechanisms. In order to minimize the number of spacecraft required in geostationary orbit, large multi-purpose platforms were proposed which will carry many high resolution science instruments and sensors. Several of these instruments are large antennas which tend to accentuate the environmental and spacecraft-induced disturbances, thereby affecting spacecraft controllability. A rigid-body pointing analysis was conducted to determine if the subject spacecraft could maintain pointing to within a very precise 18-arcsec measured at the rigid payload module. Two reaction wheel assemblies, the NASA standard and the Space Telescope, were investigated as attitude control devices. The results indicate that the spacecraft can theoretically be controlled to maintain the 18-arcsec requirement along each axis. Of the two reaction wheel assemblies, the Space Telescope assembly provided the highest degree of pointing accuracy along with a slight increase in mass and power requirements. The reaction wheels investigated are all representatives of what is currently available. A computer-aided engineering system called space systems integrated simulation (SPASIS) was used to support this analysis.