LLCD Experimental Line-of-Sight Jitter Testing

Abstract

The LLCD program at MIT Lincoln Laboratory is the first space laser communication system for NASA. The optical communications terminal was carried into lunar orbit by the LADEE spacecraft which launched on September 6, 2013. The primary goal of the LLCD program is to demonstrate optical communication from lunar orbit to the Earth’s surface.

Optical communication systems have many advantages over RF systems which include achieving higher data rates using lower size, weight and power (SWaP). Optical communication systems rely on much narrower beams than RF systems to achieve these advantages; the penalty is that the optical beam must have good stability in order to maintain the communication link between the transmitter and receiver. There are a number of factors that play a role in the stability of the optical beam, but the focus of this talk is on the residual LOS jitter resulting from unrejected spacecraft excitation. Experimentation with physical hardware is a common method for validating mathematical models, including residual LOS jitter models. The LLCD program developed a test bench in order to validate the residual LOS jitter model which provides higher confidence in the computational results.

Statement

This work is sponsored by the National Aeronautics and Space Administration under Air Force Contract #FA8721-05-C-0002. Opinions, interpretations, conclusions and recommendations are those of the author and are not necessarily endorsed by the United States Government.