Laser Ultrasonic Testing for In-Space Welding Environments

NASA has expressed a key need for the development and hardening of in-situ instrumentation to support ground-based thermal vacuum chamber testing in which the effectiveness of welds may be studied in a space analog environment, in preparation for inspection during space-capable laser beam welding. In-situ laser ultrasonic inspection has not previously been used to meet this need. This alternative technology has a long history of successes in demonstrating its capability to identify and characterize welding flaws and defects with submillimeter dimensions in-situ, but only in terrestrial environments. Current imaging technologies are limited to flaws and defects apparent at the surface, while current ultrasonic and X-ray technologies are generally not practical in space environments. We propose to adapt a terrestrial laser ultrasonic inspection system for in-situ use in space analog environments. In Phase I we will perform laser ultrasonic inspections of relevant weld samples in our laboratory, and study space analog environments, to arrive at inspection system adaptations that will meet this need. We anticipate demonstrating flaw detection in our laboratory, developing initial designs and test plans for a suitable prototype system to test in space analog environments in Phase II, and developing an initial design for an in-space laser ultrasonic system for detection of critical flaws in welds.