Hypervelocity Impact Tests on Ejecta and its International Stabdarization

Although a large spacecraft such as the International Space Station and other artificial satellites arelaunched in the earth orbit thanks to the remarkable progress in the space development, their collisions with orbital debris are an increasing concern. To examine the impact protection performance of spacecraft against orbital debris, hypervelocity impact experiments using a two-stage light gas gun and so on are necessary. There has been an active facility cross calibration program between space agencies, where tests were performed using identical targets and test conditions for each pair of tests, to assure that the results were comparable. Six distinct facility cross calibration testing campaigns have been performed between NASA and gun ranges in Germany, Russia, Japan, France, China and Canada. The test conditions for individual campaigns were negotiated at different times, so the target configuration varied between different campaigns. Projectiles with a diameter of 1 mm were used to simulate orbital debris impacting a target at velocity of 5 km/s. Copper witness plates were used as witness plates to catch the secondary debris, namely ejecta, generated due to hypervelocity impacts. The size distributions of diameter of craters made by ejecta were measured on the witness plates, and they are compared one another among a solar array coupon, CFRP honeycomb and Aluminum honeycomb in this study.