After a three-day journey from Earth, Apollo 11 fired its main engine for six minutes to slow itself into lunar orbit at 17:21 UTC. The burn, performed on the far side of the Moon out of contact with Mission Control, was a point of no return — if it failed, the crew would have flown past the Moon and back toward Earth. Its success set up the historic landing attempt scheduled for the next day.
Apollo 11 had launched from Cape Kennedy on July 16, 1969, and by July 19 was closing in on the Moon after a translunar coast of nearly three days. At 17:21 UTC, as the spacecraft swung around the far side of the Moon — cut off from radio contact with Houston — the crew fired the service propulsion system engine for just under six minutes to slow the craft enough for lunar gravity to capture it into orbit.
The maneuver carried enormous risk. A burn that ran too long or too short could have sent the command module Columbia crashing into the lunar surface or flung it into a useless trajectory back toward Earth, with no way for ground controllers to intervene in real time. When the spacecraft emerged from behind the Moon and re-established contact, Mission Control learned the burn had succeeded and Apollo 11 was safely in an elliptical lunar orbit.
Neil Armstrong, Buzz Aldrin, and Michael Collins spent the day preparing for the following day's descent, checking out the lunar module Eagle and photographing potential landing sites in the Sea of Tranquility. Aldrin later described the sight of the Moon filling their windows as unlike anything photographs had prepared them for — closer, harsher, and more three-dimensional than they expected.
Key people: Neil Armstrong, Buzz Aldrin, Michael Collins