Review of Deep Space Optical Communications

ABSTRACT Amidst the next industrial revolution, advanced spaceborne optical communication technologies that offer terabit per second throughput enable seamless exploration, communication, and efficient information capacity allocation. The current paper aims to provide profound insight into the major developments of laser communication activities in deep space. To achieve this objective, a comprehensive review and comparison of the most prominent ESA‐supported (European Space Agency) initiatives, including the Lunar Optical Communication Link (LOCL) and the Deep Space Optical Communications (DSOC) demonstrations, among other activities, are provided. While ESA has gained sophisticated heritage by means of manufacturing and testing a number of cutting‐edge optical communication technologies within LOCL activity, it also intends to demonstrate an augmented ground infrastructure for establishing an end‐to‐end High Photon Efficiency (HPE) optical communication link between Earth and DSOC payload of NASA's (National Aeronautics and Space Administration) Psyche Spacecraft. To this end, critical and leading system designs including specific issues that are required for the realization of next‐generation systems, along with examples of high‐level architectures, are provided in the current work. Considering the enhanced technical expertise, the paper further addresses the technological prospects and envisaged deep‐space optical data‐return channels for future missions, encompassing the giant planets and beyond at distances larger than 4.2 Astronomical Units (AU), as part of the forthcoming planning cycle, Voyage 2050, of ESA's Space Science Programme. All those prominent goals are addressed and evaluated in terms of fundamental limitations that apply to the information capacity of the HPE optical communication system, which is then compared with a radio frequency (RF) Ka‐band link. The demonstrated capabilities to extend the range over 100 AU of optical communication links, while supporting capacity characterized by a high signal‐to‐noise regime, have the potential to revolutionize planetary exploration.