Interplanetary laser communications and precision ranging

Future interplanetary missions, including robotic probes and human travel, will require significantly enhanced communications bandwidth that will be difficult to realize with current radio/microwave frequency links. Besides satisfying this requirement, optical (laser) communications has the potential for substantially lowering mass, power, and volume burden on the host spacecraft; is free from spectrum allocation issues; and can potentially support tracking functions resulting in improved spacecraft navigation. Primary challenges of optical communications include precision laser beam pointing over the huge planetary range, inefficiency of laser transmitters, quantum noise limited detection, especially in presence of additive background during periods of near Sun pointing, atmospheric degradation due to attenuation and turbulence and weather outages. This paper will briefly review the status of technologies that have been devised to meet these challenges and system‐level developments for bi‐directional telecommunications and ranging to distant probes.