Two-sensor ultrasonic spacecraft leak detection using structure-borne noise

Micrometeorite hits can create air leaks in manned spacecraft. Leak-generated-guided ultrasonic waves can be monitored within the platelike spacecraft skin to detect and locate leaks. Cross-correlation techniques allow measurement of the deterministic behavior of the leak-generated noise. Measured leak-into-vacuum cross-correlations of noise signals from two adjacent transducers are recorded as the transducer pair is rotated to determine the relative phase delay as a function of rotation angle. The direction to the leak is found from the variation of phase with angle or from synthetic aperture analysis. The leak is then located through triangulation from two or more sensor-pair locations