Swarm to earth communication in OLFAR

Abstract

New science drivers have recently emerged in radio astronomy for observation of low-frequency radio waves, below 30 MHz. Exploring this frequency requires a space-based radio telescope with a very large aperture that is impossible to realize in a monolithic fashion. A distributed system consisting of a swarm of 50 or more nano-satellites is used to realize such an instrument. Equipped with low-frequency antennas, the very small spacecraft provide the needed aperture to capture and sample ultra-long electromagnetic waves. The distributed low-frequency telescope has to fulfill multiple tasks in which drawbacks such as the size and the limited power available are overcome by the large number of satellites. Sending the processed data to a base station is one of these aforementioned tasks that is critical for the functionality of the system. In our paper we analyze the challenges of downlinking data from a swarm of nano-satellites to Earth and propose a diversity scheme that helps the system to achieve its mission