Apollo 4

Apollo 4, (also known as Apollo-Saturn 501 and AS-501), was the first test flight for the Saturn V, the launch vehicle which was ultimately used by the U.S. Apollo program to send the first astronauts to the Moon. Apollo 4 flew without a crew, and was an "all-up test", meaning all rocket stages and spacecraft would be fully functional on the initial flight, a first for NASA. It was the first time the S-IC first stage and S-II second stage flew. It also demonstrated the S-IVB third stage's first in-flight restart. The mission used a Block I Command Service Module (CSM) modified to test several key Block II revisions, including its heat shield at simulated lunar-return velocity and angle.

The launch, on November 9, 1967, was the first from the John F. Kennedy Space Center on Merritt Island, Florida. The mission lasted almost nine hours, splashing down in the Pacific Ocean, achieving all mission goals. NASA deemed the mission a complete success, because it proved the Saturn V worked, an important step towards achieving the Apollo program's primary objective: landing astronauts on the Moon, and bringing them back safely before the end of the decade.