Attitude Guidance for Constraining Star Tracker Elevation Angle During CubeSat-to-Ground Laser Pointing

With the surge in satellite launches in the New Space era, the limitations of radio frequency (RF) communication have led to the development of laser optical communication, which offers high bandwidth and superior data throughput. Since the 1990s, leading space agencies and companies have been actively researching satellite laser communications. However, achieving the high-attitude precision required for laser communication presents challenges, particularly for CubeSats, which are limited by their size, power, and weight. In this study, we propose a guidance algorithm for CubeSats that enables precise pointing and tracking of ground stations (GS) using a single star tracker (ST). This algorithm addresses constraints of CubeSats by ensuring that the ST maintains a certain elevation angle with respect to the local horizontal plane to minimize interference. The proposed algorithm will be applied and validated on CPSat, a 3U CubeSat being developed by Pusan National University and Chosun University, to test laser optical communication. Simulation results demonstrate the effectiveness of the algorithm in achieving the required pointing accuracy and operational performance despite the spatial and performance limitations inherent to CubeSats.