Content deleted Content added
|
|
|
A second GATV launch failure occurred on May 17, 1966, as Gemini 9 astronauts [[Thomas Patten Stafford|Tom Stafford]] and [[Eugene Cernan]] sat on their pad awaiting launch. The Atlas-Agena lifted smoothly into a cloudy sky, vanishing from view around T+50 seconds. Shortly before Booster Engine Cutoff (BECO), the guidance control officer announced that he had lost contact with the booster.
Telemetry indicated that vernierAgena andstaging sustainerhad cutofftaken occurredplace on schedule at T+300 seconds and Agena staging had taken place. The Agena continued transmitting signals until T+436 seconds, when all telemetry ceased. HoweverHidden behind clouds, the Atlas's right boosterB-2 engine had gimbaled hard to right starting at around T+120 seconds and remained fixed in that position, flipping the launch vehicle 216° around headed back towards Cape Kennedy. This rotation had made it impossible for ground guidance to lock on. Radar stations in the [[Bahamas]] tracked it heading north and descending. AtlasVehicle enginestability cutoffwas andgradually Agenaregained stagingfollowing occurredBECO, onhowever schedule,it andhad pitched approximately 231° from its intended flight path. both vehicles plunged into the Atlantic Ocean {{convert|107|nmi|km}} downrange. The Agena engine did not activate since the proper altitude and velocity had not been attained, preventing the guidance system from sending the start command. While the exact cause of the engine gimbal control was not found, telemetry indicated that a short-to-ground occurred in the circuit for the servoamplifier output command signal, which may have been caused by cryogenic leakage in the thrust section. Substantiating this theory were abnormally low thrust section temperatures starting at T+65 seconds. The exact source of the cryogenic leakage was not identified. The loss of the lock on the ground prevented normal engine cutoff signals from being transmitted to the Atlas; BECO was generated by the staging backup accelerometer, SECO at T+273 seconds due to LOX depletion, and VECO and Agena staging from a backup command generated by the missile programmer. Aside from the flight control system, all Atlas systems functioned properly.<ref>"Atlas SLV-3 Flight Evaluation Report, Vehicle 5303" Convair June 27, 1966</ref><ref>{{cite web |url=http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=GEM9TA |title=Gemini 9 Target A |publisher=NASA |edition=Version 4.0.25 |date=August 16, 2013 }}</ref>
While Convair accepted responsibility for the launch failure, Lockheed engineers expressed concern about telemetry data that indicated a servo failure in the Agena, leading to doubts as to whether the stage would have still operated properly if the Atlas hadn't malfunctioned. However, the true cause of failure surfaced when the Air Force released film taken by tracking cameras at Melbourne Beach, Florida, which showed the Atlas pitching over and heading downward. It was then determined that the Agena's servo malfunction was caused by passing through the Atlas's ionized exhaust trail.
|
