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MODAL TESTING OF THE CASSINI SATELLITE
The mission of the Cassini satellite is to venture out to the outer solar system to study the rich diversity of the Saturn system. Including the planet's rings and satellites, the surface and atmosphere of its principle moon Titan and the nature of fields and particles in Saturn's magnetosphere.
Arrival of Cassini to the Saturn system will occur nine years after the scheduled launch in 1997.
The modal analysis (testing of a structures reaction to an applied force) is being conducted at NASA's Jet Propulsion Lab in Pasadena, California. The force applied to Cassini is by way of an electrodynamic vibration shaker, or sometimes called a modal thruster in this application. The modal thrusters vibration frequency and force are computer controlled and the resultant reaction of the force applied is monitored by accelerometers (a device that converts motion to an electrical output.)
Four 100 force pound shakers were used to excite Cassini and a total of 256 accelerometers were used to collect the data. The shakers were mounted in various locations to determine resonant frequencies and bending modes of the satellite. The shakers and accelerometers could be easily moved to excite the structure from different angles or locations.
The data collected is analyzed by engineers to determine the ability of the structure to withstand the calculated forces that will be applied during launch and service. Any deficiencies can be addressed before final construction and launch. B&W is proud to have contributed to this important project.
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