VIBRATIONS OF THE LOW-POWER ATMOSPHERIC COMPENSATION EXPERIMENT SATELLITE

The Low Power Atmospheric Compensation (LACE) satellite dynamics exper iment has measured vibrations of an orbiting satellite from a ground s ite and has observed the excitation of satellite vibrations by a seque nce of boom movements. The preprogrammed boom movements were initiated by commands from a ground control site and observed by the Massachuse tts Institute of Technology Lincoln Laboratory Firepond laser radar fa cility located in Westford, Massachusetts. In the tests, a narrow-band heterodyne CO2 laser radar, operating at a wavelength of 10.6 mu m, d etected vibration-induced differential Doppler signatures of the LACE satellite. Augmentation of vibration amplitudes was achieved through t iming of repeated boom movements. Evidence of open loop vibration damp ing by this method of repeated boom movements was also obtained, altho ugh the data were not conclusive since only a single attempt at open-l oop damping was observed. The tests have demonstrated the feasibility and advantages of using relatively low cost ground-based observation t echniques for vibration measurements and health monitoring of orbiting structures and for improving the accuracy of mathematical models for the structural dynamics of light, flexible space structures.