CubeSat-Scale High-Speed Laser Downlinks

Abstract

The recent surge in the development of new commercial services hosted by satellites in low Earth orbit will lead to rapid increases in the demand for data downlinking, presenting a challenge for conventional radio-frequency communication systems. Optical communication systems offer a significant but so far unrealized potential for ultrahigh- volume downlinking. A number of demonstration laser communication missions have flown in space, but no optical systems are in routine operational use. Existing optical communication systems are typically too large for use in next-generation small commercial satellite systems.

The Optical Communication and Sensor Demonstration (OCSD) is a three-spacecraft program that will provide a technology demonstration of the first laser communication system designed for use in CubeSats. Simplicity and low mass is achieved by dispensing with the gimbal system and using the spacecraft ACS to point the laser beam. The engineering model of the OCSD, launched in October 2015, was intended for risk-reduction for the two flight units to follow in spring 2016. A software anomaly cut short the testing of the ACS, but the spacecraft will still be used to test many other new flight systems. The anomaly will not delay the launch of the two flight units, which are expected to achieve downlink rates of up to 622 Mb/s. The OCSD mission demonstrates the approach to satellite development using the CubeSat paradigm, making use of frequent and inexpensive access to space to shorten development cycles, accept higher risks, and test by flying.