Editing Atlas-Centaur (section)

=== First flight ===
[[File:Atlas 104D Technicians Readying Booster 104D for Erection; AMR Complex 36. Date- 10-31-1961 (21061503084) (2).jpg|thumb|Technicians readying booster 104D for erection]]
[[File:Atlas-LV3C Centaur-A (AC-1).jpg|thumb|Atlas-LV3C Centaur-A (AC-1)]]
In October 1961, the first Atlas-Centaur (Vehicle Flight-1: Atlas 104D and Centaur F-1) arrived at [[Cape Canaveral Space Force Station|Cape Canaveral]] and was erected at the newly completed and specifically built LC-36A. Technical problems caused the vehicle to sit on the launch pad for seven months, the most serious being leakage of liquid hydrogen through the intermediate bulkhead separating the propellant tanks combined with numerous lesser maladies with the guidance and propulsion systems.

==== Failure ====
[[File:Atlas-Centaur launch.jpg|thumb|Unsuccessful maiden flight of the Atlas-Centaur AC-1]]
The vehicle was launched at 2:49 PM EST (18:49 [[Greenwich Mean Time|GMT]]) on 8 May 1962, with the intention of performing a single burn with a partially fueled Centaur. Slightly under a minute into the launch, the Centaur stage ruptured and disintegrated, taking the Atlas with it in a matter of seconds. It was unclear what had caused the failure at first, as tracking camera footage merely showed a large white cloud enveloping the booster followed by the explosion of the entire launch vehicle. Initial assumptions were that Atlas had suffered a LOX tank failure, either from a pressurization problem, rupture of the tank from flying debris, or structural bending/aerodynamic issues caused by the unproven Atlas-Centaur combination, and indeed there had been several previous occurrences of these failure modes on Atlas launches. [[Scott Carpenter]]'s [[Aurora 7|Mercury flight]] was only days away, and if the failure were caused by the Atlas, it could mean significant delays for that mission, which used a similar [[SM-65D Atlas|Atlas D]] derived [[Atlas LV-3B]] booster. However, analysis of telemetry data and closer examination of the launch films quickly confirmed the Centaur as the source of trouble.

The failure was determined to be caused by an insulation panel that ripped off the Centaur during ascent, resulting in a surge in tank pressure when the LH2 overheated. Beginning at T+44 seconds, the pneumatic system responded by venting propellant to reduce pressure levels, but eventually, they exceeded the LH2 tank's structural strength. At T+54 seconds, the Centaur experienced total structural breakup and loss of telemetry, the LOX tank rupturing and producing an explosion as it mixed with the hydrogen cloud. Two seconds later, flying debris ruptured the Atlas's LOX tank followed by complete destruction of the launch vehicle. The panel had been meant to jettison at 49 miles (80&nbsp;km) up when the air was thinner, but the mechanism holding it in place was designed inadequately, leading to premature separation. The insulation panels had already been suspected during Centaur development of being a potential problem area, and the possibility of an LH2 tank rupture was considered as a failure scenario. Testing was suspended while efforts were made to correct the Centaur's design flaws.

==== Investigation ====
A Congressional investigation in June 1962 called the overall management of the Centaur program "weak", and [[Wernher von Braun]] recommended that it be cancelled in favor of a [[Saturn I]] with an [[RM-81 Agena|Agena upper stage]] for planetary missions. 

In addition, the production Centaur stage had less lift capacity than originally planned, leading to [[DARPA|ARPA]] cancelling Project ADVENT. NASA transferred Centaur development from MSFC to the [[Glenn Research Center|Lewis Research Center]] in [[Ohio]] where a team headed by [[Abe Silverstein]] worked to correct the insulation panel problems and various other design flaws.<ref name=":0">{{cite web |url=http://www.spacelaunchreport.com/aclv3cb.html|title=Atlas Centaur LV-3C Development|last=Kyle|first=Ed|date=May 28, 2005|website=spacelaunchreport.com|publisher=Space Launch Report|access-date=April 15, 2016 | archive-url = https://web.archive.org/web/20100821064737/http://www.spacelaunchreport.com/aclv3cb.html | archive-date= August 21, 2010 |url-status = usurped}}</ref>

In November 1962, [[John F. Kennedy|President Kennedy]] suggested cancelling Centaur entirely, but was talked out of it on the grounds that the experience gained with liquid hydrogen rocket engines was vital to the success of the [[Apollo program]]. In addition, von Braun now proposed the Saturn-Agena be ruled out for cost reasons – Saturn was too expensive to justify as a launch vehicle for small uncrewed probes, and Agena was causing concerns to both the Air Force and NASA about its reliability.{{citation_needed|date=July 2019}}

Eight Atlas-Centaur test missions were scheduled to be completed by the end of 1964, followed by the first [[Surveyor program]] launch. Centaur was upgraded to a high priority project because of this direct relation to Apollo.<ref>{{cite web|title=An Historical Meeting on Spaceflight: Background and Analysis|url=https://history.nasa.gov/JFK-Webbconv/pages/backgnd.html
|quote=Although Centaur was intended to launch robotic probes to the Moon and outer planets, Webb argued that NASA would also gain vital experience with liquid hydrogen by building Centaur and would be able to apply this experience toward Apollo.
|publisher=NASA|access-date=February 25, 2023}}</ref>

Meanwhile, the [[Department of Defence|Department of Defense]] (DoD) had settled on the [[Titan (rocket family)|Titan]] family for its heavy-lift launching needs and so the Atlas-Centaur would remain a civilian launch vehicle used by NASA to fly scientific and commercial payloads. A conflict between the Air Force, who had primary oversight of the Atlas, and NASA also existed as the Centaur stage required various modifications to the basic Atlas. By 1962, the Air Force had considered the Atlas fully developed and operational and was against any further significant changes to it which might potentially jeopardize the ICBM program. The dispute was ultimately resolved by NASA agreeing to purchase standard [[Atlas D]] vehicles which could be custom-modified for Centaur launches. However, when the Atlas ICBM program ended in 1965, Convair replaced all of the earlier variants with a standardized booster for all space launches.{{citation_needed|date=July 2019}}