1969年3月，阿波罗9号成功完成了在地球轨道上测试登月舱的任务，美国宇航局对约翰·f·肯尼迪(John F. Kennedy)总统提出的在十年内让宇航员登陆月球并安全返回地球的目标更有信心。阿波罗10号将在5月进行着陆彩排，希望阿波罗11号能在7月完成实际着陆。然而，在这之前还有许多工作要做。
With the successful completion in March 1969 of the Apollo 9 mission, which tested the Lunar Module in Earth orbit, NASA’s confidence rose that President John F. Kennedy’s goal of landing a crew on the Moon and returning them safely to Earth before the end of the decade was achievable. Apollo 10 would carry out a dress rehearsal of the landing in May and it was hoped that Apollo 11 would complete the actual landing in July. However, much work remained before that could be accomplished.
In this image, Apollo 11 backup crew members Fred Haise (left) and Jim Lovell prepare to enter the Lunar Module for an altitude test.