High Precision Orbit Determination Method Based on GPS Flight Data for ALE-1

抄録

ALE-1 is a 68 kg microsatellite with the mission to generate artificial meteors. This satellite was developed by Tohoku University in collaboration with ALE Co., Ltd. It was launched into orbit by the 4th Epsilon rocket on January 18, 2019. In the artificial meteors mission, a pellet is released from the satellite as a meteor source. The source emits plasma when it reenters the atmosphere, so that it can be observed as an artificial meteor from the ground. Highly accurate orbit prediction at the time of the pellet release is required to achieve this mission. For orbit prediction, initial orbit state and orbit propagation are needed. Currently, highly precise orbit propagator exists. Therefore, the focus of this research is on a method to determine accurate initial state. In particular, online processing is noted because it is suitable for real-time mission. To obtain initial state in online processing, Kalman-Filter-based orbit determination (OD) methods are often used. However, they have the problems of vulnerability to outliers and insufficient accuracy. In this study, to solve these problems, two methodologies were proposed. The first methodology is to realize filter robustness against outliers by combining data from multiple Global Positioning System Receivers (GPSR). The second is to selectively adopt plausible orbit state by sequentially estimating the increase rate of propagation. As a result of applying the proposed methodology, highly accurate and reliable OD was realized and the orbit prediction accuracy satisfied the mission requirements.