The Lunar Laser Communications Demonstration (LLCD)

NASA is presently overseeing a project to create the world's first free-space laser communications system that can be operated over a range ten times larger than the near-earth ranges that have been demonstrated to date. To be flown on the lunar atmosphere and dust environment explorer (LADEE), which is planned for launch by NASA in 2012, it will demonstrate high-rate laser communications from lunar orbit to a transportable ground terminal on the Earth. To support up to 622 Mbps over the approximately 400 thousand kilometer link, the system will make use of a high peak power doped fiber transmitter, a hybrid pointing and tracking system, high efficiency modulation and coding techniques, superconducting photon counting detectors, and a scalable optical collector architecture. It also will support up to 20 Mbps on the optical uplink, plus a highly accurate continuous two-way time of flight measurement capability with the potential to perform ranging with sub-centimeter accuracy to the moving spacecraft. The project is being undertaken by MIT Lincoln Laboratory (MIT/LL) and the NASA Goddard Space Flight Center (GSFC.).