The Apollo Program sent six manned flights to the Moon, and five of those landed on the surface of the Moon. Before the end of the program, a total of 12 men had set foot on the Moon. After Apollo 17, the Apollo Program was canceled because the running cost was too high. Since then, nobody has gone back to the surface of the Moon. There have been regular trips to space, and we have thousands of satellites and space stations that need to be repaired or replaced from time to time.