Laser beacon tracking for free-space optical communication on small-satellite platforms in low-earth orbit

[摘要] Free-space optical (FSO) communication, or laser communication, is capable of providing high-rate communication links, meeting the growing downlink demand of space missions, including those on small-satellite platforms. FSO communication takes advantage of the high-gain nature of narrow laser beams to achieve higher link efficiency than traditional radio-frequency systems. In order for a FSO link to be established and maintained, the spacecraft;;s attitude determination and control system needs to provide accurate pointing at the optical ground station. However, small satellites, such as CubeSats, have limited ground-tracking capabilities with existing attitude sensors. Miniaturized laser beacon tracking system, on the other hand, has the potential to provide precise ground-based attitude knowledge, enabling laser communication to be accomplished on small-satellite platforms. This thesis details the development of a CubeSat-sized laser beacon camera capable of achieving a sub-milliradian attitude knowledge accuracy with low fade probability during various sky conditions, sufficient to support a high-rate FSO communication link on a CubeSat platform on low-Earth orbit. The high-level Nanosatellite Optical Downlink Experiment (NODE) system architecture, the beacon camera conceptual design as well as prototype development are presented in detail. An end-to-end beacon simulation was constructed to validate the attitude sensing performance of the module under expected atmospheric turbulence and sky brightness conditions. The simulation results show a high-accuracy attitude sensing performance and low fade probability, capable of supporting NODE;;s laser links.

[发布机构] Massachusetts Institute of Technology