Correlation Between Light Curve Observations and Laboratory Experiments Using a Debris Scale Model in an Optical Simulator

Active debris removal (ADR) is promising methods for ensuring safe space activities, free from the danger of debris. To carry out an ADR mission, the attitude and motion of the target must be determined precisely. Developing methodology to extract these values using only the target’s light curve would be a great step forward. We started the light curve observations of the ADR candidates, H2A rocket bodies (R/Bs), 2nd stages of Japanese H2A rockets using the 60 cm telescope, and the CMOS (complementary metal-oxide semiconductor) sensor. We developed an optical simulator in the laboratory to mimic observed light curves. The simulator can reproduce the exact light curve using a scale model of the H2A R/B. It considers the attitude, motion, and lighting conditions of the H2A R/Bs. On March 19, 2019, two extremely strong peaks were observed in the light curve of one of H2A R/Bs (satellite number: 39771). Simulations showed that the observed light curve is explained by the attitude of the gravity gradient stabilization where the PAF (payload attach fitting) of the H2A R/B was directed toward the earth. We found a few degrees’ tilt of the target causes shifts of the timings of the peaks. This means that the attitude of the target can be ascertained using the peak timing in some cases. Although this is one case out of countless situations, simulating exactly the same light curve is the one step toward total understanding of ADR targets’ attitude and motion from light curve observations. We also developed a light curve simulation tool using the 3-D (three-dimensional) model of H2A R/B that can estimate the overall tendency of the light curve, which will dramatically reduce experimental times for simulating light curve using the optical simulator.