Space Telemetry Analysis with PyContract.

PyContract is a Python library for trace analysis, also characterized as an internal DSL (Domain-Specific Language). It combines flavors of state machines and rule-based programming, supporting states that can carry data, thus allowing for monitoring of events that carry data. The fact that it is a Python library offers full expressiveness, and access to a vast amount of libraries, which becomes useful for realistic situations. This is in this paper illustrated by its real life application to data analysis of telemetry logs obtained during testing of NASA’s Europa Clipper flight computer. The mission will place a spacecraft in orbit around Jupiter in order to perform a detailed investigation of its moon Europa. The analysis includes not only verifying functional correctness but also, and especially, performance analysis such as execution times and rates of change. This includes generation of data in table format and visualization as graphs. The important message is that runtime verification and data analysis are closely related topics, which can only be addressed with highly expressive specification languages.