Investigation of Angular Momentum Associated with Hypervelocity Space Debris Impacts in the Low Earth Orbit

Active debris removal (ADR) of large objects, such as rocket bodies, is considered to be one of the best solutions to address the accumulation of space debris. Therefore, a good understanding of the rotational states of rocket bodies is essential for designers of ADR systems. Optical observations of old rocket bodies have shown that some of them are rotating. To assess the possibility that collisions between small pieces of space debris and these objects causes the rotation of them, we conducted hypervelocity impact tests to measure the efficiency of momentum transfer from projectiles to an aluminum target. The aluminum target was vertically hung from the ceiling. After a 1 mm projectile, representing a small piece of space debris, struck the aluminum target, a pendulum motion was initiated. The efficiency of the momentum transfer was calculated using the maximum angle of the pendulum swing. In this study, the efficiencies of the impact speeds ranging from 3 to 7 km/sec were investigated using the two-stage light-gas gun at the Institute of Space and Astronautical Science at Japan Aerospace Exploration Agency. Although much faster speeds are required to determine if the collisions of small space debris cause the rotations of rocket bodies, the results that were obtained could show that the efficiency of momentum transfer increases with impact velocity.