Editing Apollo 6 (section)

==Aftermath==
In a post-launch press conference, Apollo Program Director [[Samuel C. Phillips]] said, "there's no question that it's less than a perfect mission", but that the launch vehicle's reaching orbit despite the loss of two engines was "a major unplanned accomplishment".<ref name= "moonport 6a" /> Mueller called Apollo 6 "a good job all around, an excellent launch, and, in balance, a successful mission&nbsp;... and we have learned a great deal", but later stated that Apollo 6 "will have to be defined as a failure".<ref name = "moonport 6a" />

The phenomenon of pogo, experienced during the first stage of the flight, was well known. However, NASA thought that the Saturn V had been "detuned"—that is, prevented from vibrating at its natural frequencies. Soon after the Apollo 6 flight, NASA and its contractors sought to eliminate the problems for future flights, and about 1,000 government and industry engineers worked on the problem. To damp pressure oscillations in the F-1 and J-2 engines, cavities in valves leading to them were filled with [[helium]] gas shortly before takeoff as a shock absorber.<ref name = "moonport 6a" /> 
[[File:Fernbank-07.jpg|thumb|upright|Apollo 6 command module on display at the [[Fernbank Science Center]] in [[Atlanta]], [[Georgia (U.S. state)|Georgia]]]]
The problems with the S-II and the S-IVB were traced to the J-2 engines, present in both stages. Tests showed that the propellant lines leading to the spark igniters could fail in low atmospheric pressure or in vacuum. The propellant lines had [[metal bellows]] to allow for thermal expansion. In ground testing the cold propellants passing through the propellant lines would form a layer of frost on the LOX line and [[liquid air]] on the LH<sub>2</sub> line, damping out any vibrations. In the vacuum of space, there was no such protection: the bellows vibrated rapidly and failed at peak flow, causing a burn-through of the propellant lines. The bellows were replaced with rigid bends and the lines strengthened.{{sfn|Brooks 1979|pp=251–252}} In Apollo 6's wake, NASA engineers debated whether to configure the spacecraft's emergency detection system to automatically abort in the event of excessive pogo; this plan was opposed by Director of Flight Crew Operations [[Deke Slayton]]. Instead, work began on having a "pogo abort sensor" to allow the flight crew to judge whether to abort, but by August 1968, it had become clear that pogo could be dealt with without such a sensor, and work on it was abandoned.{{sfn|Orloff & Harland 2006|p=172}}{{sfn|Brooks 1979|pp=251–252}}

The SLA problem was caused by its honeycomb structure. As the rocket accelerated through the atmosphere, the cells expanded due to trapped air and water, causing the adapter surface to break free. In response, engineers drilled small holes in the surface to allow trapped gases to dissipate, and placed a thin layer of cork on the adapter to help absorb moisture.{{sfn|Orloff & Harland 2006|p=158}}

NASA's efforts were enough to satisfy the [[United States Senate Committee on Aeronautical and Space Sciences|Senate Committee on Aeronautical and Space Sciences]]. In late April, the committee reported that the agency had quickly analyzed and diagnosed the abnormalities of Apollo 6, and had taken corrective action.<ref name = "moonport 6a" /> After detailed analysis of the Saturn V's performance, and of the fixes for future launch vehicles, engineers at the [[Marshall Space Flight Center]] in Alabama concluded that a third uncrewed test flight of the Saturn V was unnecessary. Therefore, the next Saturn V to fly, on [[Apollo 8]], would carry a crew ([[Apollo 7]], the first crewed Apollo mission to fly, would be launched by a [[Saturn IB]]).<ref name = "legacy" />{{sfn|Orloff & Harland 2006|p=572}}

After the mission, CM-020 was transferred to the [[Smithsonian Institution]].<ref name = "end">{{cite web|title=Apollo/Skylab ASTP and Shuttle Orbiter Major End Items|date=March 1978|url=https://s3.documentcloud.org/documents/6473665/Apollo-Skylab-ASTP-and-Shuttle-Orbiter-Major-End.pdf|publisher=[[NASA]]|page=15}}</ref> The Apollo 6 command module is on display at the [[Fernbank Science Center]] in [[Atlanta]], [[Georgia (U.S. state)|Georgia]].<ref>{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/lunar/apolloloc.html |title=Apollo: Where are they now? |last=Williams |first=David R. |work=[[National Space Science Data Center]] |publisher=NASA |access-date=July 7, 2013}}</ref>