Autonomous descent and touch-down via optical sensors

This paper presents an autonomous descent and touch-down scheme of the asteroid sample and return spacecraft, MUSES-C. The spacecraft uses some optical sensors, such as a navigation camera (ONC-Wl), a laser altimeter (LIDAR), a short range laser sensor (LRF), and an artificial landmark (TM) which is released at about 100 m altitude. Navigation system contains image processing, integration of visual and range information, and Kalman filtering. To realize "time of arrival" guidance, the descending plan is uploaded to the spacecraft, considering the asteroid motion. Six degree-of-freedom control is performed by RCS and reaction wheels (RW). In this paper, after brief explanation of MUSES-C navigation, guidance, and control (NGC) system and descent and touch-down scenario, the navigation scheme mainly focused on image processing, descent guidance scheme, and six degree, of-freedom thruster control are described. To verify the performance of the proposed scheme, computer simulations including Graphical Asteroid Simulator are performed.