Requirements of a Long Term Telemetry Data Analysis and Visualization Tool

Over the last years the German Space Operations Center (GSOC) has been operating several satellites, which are based on a similar satellite bus (CHAMP, GRACE, in the future TerraSAR-X). This provides a good opportunity for analysing the satellite bus behavior in response to the different mission profiles. Since the orbit profiles (CHAMP, GRACE1, GRACE2) are nearly the same (polar LEO) it is possible to directly relate subsystem reactions as provided by the H/K data of the spacecraft to mission specific operations requirements. The analysis of spacecraft telemetry can be divided into long-term and short-term analyses. The latter are directly performed during contact to the spacecraft in order to check values and ranges of important telemetry parameters. Simple tools, which are often integrated in the monitoring and control system of the mission control center are used for this purpose. However, to predict trends in the future spacecraft performance, long-term analyses are necessary. Long-term analysis of housekeeping data always involves processing of a huge amount of dumped spacecraft telemetry data, which is usually archived in a compressed format. Once clearly defined, the processing steps and calculation rules for the analysis remain nearly constant except for small changes due to further improvements in the processing. Therefore this represents an ideal case for automatic processing by a software tool. This software has to fulfill certain requirements in order to become a convenient and sophisticated tool for the subsystem engineers who will use it for the prediction of the future spacecraft behavior. The requirements and constraints for such a software have to be analysed and defined in detail to be compliant with the development of a generic software which is able to support not only a single mission, but several missions in parallel in order to reduce the costs for developing and servicing spacecraft specific analysing tools. Important functions for an offline processing software tool like archiving, decompressing, variable data reduction, data reorganizing, calculation and visualization have to be considered and related to the requirements. As a result a generic tool was developed which meets these requirements w.r.t. power and thermal data analysis and processing. The application of this tool has provided an improved understanding of the future behavior of vital spacecraft components such as solar cells and the battery. Thereby adequate measures could be initiated with respect to these components in order to extend the lifetime of the satellite