Space is a vast and important territory that has been studied and explored by humans for centuries.Since the first man-made satellite was launched in 1957,thousands of projects involving space probes and their utilization have been implemented.Many kinds of satellites are currently used for communication,broadcasting,earth observation,navigation,and deep-space exploration,etc.Because of their unique features referred to as "stay high and cover wide",satellites are considered to be irreplaceable because of the functions that they perform,and spacecraft require various kinds of communications.Over the past few decades,there have been various efforts to build a space Internet for deep space exploration purposes.We have therefore established this special issue,and to date,we have received a total of 52 manuscripts from authors worldwide.