How does apollo 11 work?

Apollo 11 lifted off on Saturn V SA-504 from pad 39A at 13:32 UT on 16 July 1969. Two stages placed the stack in parking orbit; there the S-IVB third stage was re-ignited at 16:16:16 UT for a translunar injection burn of 5 minutes, 48 seconds. The command and service module separated from the S-IVB 33 minutes later, turned around and docked at 16:56:03 UT with the lunar module riding behind it, pulling Eagle free before the empty stage was discarded. Every element existed to be thrown away at a planned moment.

The architecture's central idea is that only what must land should land. Lunar orbit insertion came on 19 July at 17:21:50 UT, a retrograde firing of the service module engine for 357.5 seconds. Eagle then descended with two of the three astronauts while Columbia stayed in orbit with the heat shield, the propellant for the trip home and the third. Eagle landed at 20:17:40 UT on 20 July, lifted off at 17:54:01 UT the next day after 21 hours and 36 minutes on the surface, docked with Columbia at 21:34:00 UT and was jettisoned into lunar orbit. Carrying the whole spacecraft down and back would have demanded a far larger rocket.

Transearth injection began at 04:54:42 UT on 22 July with a two-and-a-half-minute firing of the main engine, and from there the spacecraft coasted. Before re-entry the service module was cast off: of a vehicle 11.0 metres long and 3.9 metres across at most, only the conical command module came through the atmosphere, splashing down in the Pacific on 24 July 1969 at 16:50:35 UT. What returned was the cabin and the three men inside it.