Abstract:

The lessons learned from investigating the Upper Atmosphere Research Satellite (UARS) in-flight dynamics are summarized. Key to the success of the study was the applicastion of knowledge discovery in database techniques. The isolation of distrubances was critical to identifying the effect of individual disturbances on the spacecraft. Numerous types of data were examined for spatial and frequency correlation as a means of discovering hidden knowledge of the dynamic behavior of the spacecraft and its instruments. Two in-flight dynamics experiments were conducted on UARS to provide the investigation with cases of isolated and combined instrument and environmental disturbances that were not attainable during the normal operation of the spacecraft. Flight data from the experiments were augmented with data collected from the first 737 days after launch. This study identified many disturbances that greatly impacted the spacecraft line-of-siht pointing but were ignored from prelaunch analysis. The spacecraft attitude response was significantly influenced by the thermal elastic bending of the soalr array, the solar array gear drive, orientation of the solar array, and instrument motion. These disturbances can now be included in a knowledge base for future prelaunch analysis.