Flight Results on Structural Dynamics from Hermes

Hermes is a geostationary communications satellite equipped with large flexible solar arrays instrumented for experimental purposes. A program for obtaining flight data on structural dynamics was part of the mission, including special in-flight experiments. This paper describes the design of these experiments, the instrumentation, experimental results, and related observations during array deployment and ground tests. Flight results were obtained on natural frequencies, damping factors, and steady-state resonant amplitudes. Finally, comparisons with a theoretical model are given. Generally, excellent agreement was found between measurements and predicted values. However, damping factors measured were higher than expected from ground tests.