Moonlighter is the world’s first and only hacking sandbox in space. Currently orbiting the earth near the International Space Station, the satellite is the playground for this year’s Hack-A-Sat 4 competition at DEF CON 31. Mike Walker, from Cromulence, discusses the difference between hacking a live satellite in orbit vs the previous Hack-A-Sat CTFs which only simulated the experience. We discuss limited contact windows, latency, and other aspects of orbital mechanics which will surely influence how Hack-a-Sat 4 will be played.