Apollo 11: Lunar orbit insertion ignition, 19 July 1969 12:21 PM CDT
This is the sixth of eleven geocaches being placed in commemoration of the 50th Anniversary of Apollo 11. These caches are being scheduled to publish at 50 years after the event each one represents. The city where they are placed has the distinction of sharing its name with the Apollo 11 Command Module, Columbia.
Many things have already occurred in the flight to reach the point of entering lunar orbit. Let’s recap the flight profile thus far:
Apollo 11 was launched by a Saturn V rocket, a three-stage liquid-propellant super heavy-lift launch vehicle. Used by NASA from 1967 to 1973, the Saturn V was developed specifically to support the Apollo program for human exploration of the Moon and was later used to launch Skylab, the first American space station. Saturn V rockets were launched 13 times from Kennedy Space Center without experiencing a single loss of crew or payload.
About 3 minutes into the flight, the first stage was shut down and ejected, followed by ignition of the second stage. Then at about 9 minutes the second stage was shut down an ejected, followed by ignition of the third and final stage. Earth orbit was achieved at about 12 minutes into the flight and the third stage was shut down. The spacecraft then orbited the earth one and a half times before reigniting the third stage engines for translunar injection at 2 hours 45 minutes into the mission, setting the craft on its trajectory to the moon.
About 3 hours 15 minutes into the flight, it was time for a critical maneuver: transposition, docking, and extraction. Under the control of Command Module Pilot Michael Collins, the command module “Columbia” was separated from the third stage of the Saturn V, turned around 180 degrees, and docked with the lunar module “Eagle” stored in the first payload compartment above the rocket. Collins then extracted the LM from storage. The combined Columbia-Eagle spacecraft then continued to the moon while the final stage of the rocket ended up in a trajectory past the moon and into orbit around the Sun. Separation was at 4 hours 40 minutes into the flight.
The rest of the flight was mostly filled with sleep, meals, navigational checks, and television broadcasts. There was also a brief firing of the Command Service Module engine for course correction based on the navigational checks and an inspection of the lunar module to ensure everything was ready for the landing attempt upon reaching the moon.
Approaching the moon on the fourth day of flight, Apollo 11 was on a “free return” trajectory. That means they were on a course that would pass by the moon without entering orbit and then return directly to earth. The service module engine would have to be fired in order to inject the spacecraft into lunar orbit. (Later Apollo missions, including the ill-fated Apollo 13, did not utilize a free return trajectory and so did not have an option to do nothing and end up back at earth.) On 19 July 1969 at 12:21 PM CDT the engine was fired for 6 minutes to change course into lunar orbit. A second burn was later carried out to circularize the orbit. The Command Module, Columbia, would complete 30 orbits of the moon before returning toward earth.
Apollo 11 has reached the moon. Now to descend to and land on the surface.
This geocache has been placed in accordance with the published guidelines of Columbia Parks & Recreation Department, Lida M. Gochenour, Administrative Supervisor.