A ground-based NASA communicator who maintains contact with astronauts during space missions. There were four capsule communicators for the Apollo 11 mission that landed on the Moon in 1969: the landing CapCom, the post-landing and goodnight Capcom, the EVA CapCom (for extravehicular activity), and the lunar module launch CapCom. The abbreviated form is now generally considered to stand for ‘spacecraft communicator’.