Communications challenges for the exploration of nearby star systems with low mass probes Author: Philip Mauskopf, PhD Physics, Professor, Arizona State University Description: Typically, in the field of interstellar exploration most attention is paid to propulsion schemes, but developing the technology to send information back to Earth from a nearby star is a no less daunting undertaking. For the Breakthrough Starshot system – relying as it does on ultra-low-mass probes to approach near-relativistic speeds – this task is all the more challenging. In this paper, we describe the figures of merit and requirements for such a communication system and compare them to the current state-of-the-art in planetary missions such as NASA’s New Horizons spacecraft and the upcoming Psyche mission – which will include NASA’s first deep space optical communications system demonstration. We also identify areas in which we see potential for improvements and investments in deep space communications. Finally, we will introduce and describe a new dedicated research effort in this area by the Breakthrough Initiatives, focused on meeting the size, mass, power and cost requirements of the Starshot system.