from Apollo 11 to Apollo 17, there were six manned landings on the moon (the flight plans of Apollo 18, 19 and 2 were cancelled due to financial problems), five of which were successful (Apollo 13 could only fly around the moon due to technical problems), and 12 astronauts were sent to the moon (see "Baidu Encyclopedia-Apollo Plan" for details). At 4: 17: 4 pm EST on July 21st, 1969 (9: 17 pm GMT, 5: 17 am Beijing time GMT), Armstrong said a famous saying that shocked the world on the northwest of the Moon's "Jinghai Base": "This is only a small step for me, but it is a great leap for mankind".