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Impact detection onboard satellites using wireless sensor network

: Schäfer, F.; Schimmerohn, M.; Meyer, H.

International Astronautical Federation:
59th International Astronautical Congress, IAC 2008. Vol.9 : Glasgow, Scotland, 29 September - 3 October 2008
Red Hook, NY: Curran, 2009
ISBN: 978-1-61567-160-1
International Astronautical Congress (IAC) <59, 2008, Glasgow>
Fraunhofer EMI ()

A prototype sensor network has been developed that allows the monitoring of hypervelocity impacts from space debris or meteoroids, the detection of low-velocity collisions with satellites, and the determination of the impact location on the satellite surface. The sensors are wideband ultrasonic piezoelectric transducers that detect the acoustic waves that are generated in the satellite structure during an encounter. The sensors are connected through cables to a sampling and data-processing unit that transmits any detected event through a transceiver via a standardized wireless interface to a processing unit of the satellite system. In order to perform localization of the event, at least three sensors are required; in the developed unit, four sensors have been integrated to provide redundancy and the possibility to increase the localization accuracy. Monitoring of encounters is performed on each critical outer surface of the satellite. The most critical is the surface pointing in the ram direction of the satellite, because statistically most of the impacts occur on this surface. In this paper, a description of the sensor network and the data recording-, processing- and wireless transmission technology is given. The location of the impact site is performed by multilateration i.e., through computing the time difference of arrival (TDOA) of the signals propagated from the impact site to three or more of the ultrasonic transducers. The results of a hypervelocity impact test using the wireless sensor network on a typical satellite structure are presented: Two major waveforms propagating in the structure with different wave velocities can be distinguished. The waveforms are longitudinal and bending waves, where bending waves can be detected with better Signal-to-Noise (S/N) ratio. The procedure for computing the wave velocity is described.