Collision dynamics of a visual target marker for small-body exploration

摘要

MUSES-C mission is the world first sample and return attempt to or from a near-Earth asteroid. In deep space, it is hard to navigate, guide and control a spacecraft on a real-time basis remotely from the earth, mainly due to the communication delay. Thus, autonomy and robotics technologies are required for final approach and landing to an unknown body. In the final descent phase, cancellation of the horizontal speed relative to the surface of the landing site is essential. During the touchdown and sampling phase, the spacecraft will be navigated relative to the asteroid surface using an optical target marker (TM) placed on the asteroid surface. By using the TM as a reference point, navigation during the landing phase will be much more reliable and precise. Thus, it is important to design a TM with as small a coefficient of restitution as possible to reduce the settling time. To develop a small coefficient of restitution of less than 0.1 in vertical direction, the authors propose a novel TM, which is constructed out of a shell with beads stored internally. To better predict the performance of such a TM, analytical and numerical investigations are performed. The validity and the effectiveness of the proposed method are confirmed and evaluated by numerical simulations and flight results.