Courageous was a DY-500-class vessel launched from Earth in the early 21st century, prior to the start of World War III. The Courageous suffered a malfunction in its propulsion system when it found itself unable to decelerate or disengage engines. Intended for in-system flight, Courageous instead left the Sol system and was lost, though Earth and Mars continued to receive periodic communication signals from the ship and its recorder markers for years to follow.