Apollo 6

**Apollo 6** was a space flight launched on April 4, 1968. It was the second mission of the United States Apollo program and last unmanned test flight of its Saturn V launch vehicle. It was also the last unmanned Apollo flight. It was an A-Type mission.

It was to show that the Saturn V could carry the weight of the Apollo fast enough and far enough into space to make a flight to the Moon possible. It was also designed to show that the Apollo Command Module's heat shield could survive the high speed re-entry into the Earth's atmosphere. The project was designed to fly into space at the necessary speeds, turn around, and return in about 10 hours.

However problems in the fuel lines of several Saturn V second and third stage engines stopped it from reaching the speeds Apollo would need to reach the Moon. It was able to test the return speeds by using the Apollo spacecraft's engine. This had been done with Apollo 4, the first Saturn V test. Despite the engine failures, the flight gave NASA enough confidence in the Saturn V to use it for manned launches. Since Apollo 4 had also tested the heat shield at a full speed re-entry, a third unmanned flight was cancelled.

## Objectives
Apollo 6 would test the Saturn V launch vehicle's ability to send the entire Apollo craft to the Moon. It would also test the stress a launch would put on the Lunar Module. It would also measure how much vibration there would be with a Saturn V with an almost full load. The Lunar Module was a test vehicle and only weighed , about 80% of the proper Lunar Module of (). Also, the CSM was only fueled to a weight of  instead of the lunar mission weight of .

It was the first mission to use High Bay 3 in the Vertical Assembly Building (VAB), Mobile Launcher 2, and Firing Room 2.

## Vehicle assembly
The first stage of the Saturn V, S-IC, the third stage, S-IVB, and the Instrument Unit computer, arrived by boat on March 13, 1967. The first stage was put together in the Vehicle Assembly Building (VAB) four days later. The S-II second stage was delivered two months later. Scientist used a dumbbell-shaped spacer so testing could proceed. This had the same height and mass as the S-II along with all the electrical connections. The S-II arrived May 24. It was put into the rocket on July 7.

Testing was slow as they were still getting the Saturn V ready for Apollo 4. While the building could hold four Saturn V rockets, there were not enough people or equipment to work on more than one at a time.

The Command and Service Module, a Block I model, as flown on three other unmanned tests, arrived September 29 and was added on December 10. It was made from two existing spacecraft, the CM-020 and SM-014. CM-020 had been damaged in an explosion. CM-014 had been taken apart as part of the investigation into the Apollo 1 fire. After two months of testing and repairs, the rocket was moved to the pad on February 6, 1968.

## Flight
### Launch
While Apollo 4 had a perfect flight, Apollo 6 had problems right from the start. Two minutes into the flight, the rocket experienced severe Pogo oscillations for about 30 seconds. Various parts of the rocket began to vibrate like a tuning fork. This included the fuel pipes. These vibrations caused damage to the part that joined the Command Module and Lunar Module to the Saturn V. Several pieces fell off during the launch.

After the first stage was finished, the S-II second stage began to have its own problems. Engine number two (of five) had problems 225 seconds after liftoff. It got worse at 319 seconds, and then at 412 seconds the engine shut down. Two seconds later Engine Number Three shut down as well. The onboard computer was able to make changes and the other engines burned for 58 seconds longer than normal. The S-IVB third stage also had to burn for 29 seconds longer than usual. The S-IVB also did not work properly.

Another launch shot often said to be Apollo 11 was shot on this day. It shows the rocket lifting up, positioned relatively close up and dead center. The shot can be identified as Apollo 6 as it had a white Apollo module; all the others were silver.

## Public impact
There was little press coverage of the Apollo 6 mission. On the same day as the launch, Martin Luther King, Jr. was shot and killed in Memphis, Tennessee, and President Johnson had announced he would not seek re-election only four days before.

## Capsule location
The Apollo 6 Command Module is on display at the Fernbank Science Center, in Atlanta, Georgia.

## References
## Other websites
* Apollo 6 Press Kit (PDF)
* Apollo 6  at the NASA NSSDC database
* Moonport: A History of Apollo Launch Facilities and Operations 
* Chariots for Apollo: A History of Manned Lunar Spacecraft 
* Fernbank Science Center
* Apollo 6 16mm on-board film. Part 1, Part 2, Part 3, Part 4, Part 5 raw footage taken during the Apollo 6 mission.