Wednesday, March 4, 2020

Apollo 4 - NASAs First All Up Test

Apollo 4 - NASA's First All Up Test On January 27, 1967, tragedy struck on the launch pad during a preflight test for Apollo 1 (also called AS-204), which was scheduled to be the first Apollo manned mission, and would have been launched on February 21, 1967. Astronauts Virgil Grissom, Edward White, and Roger Chaffee lost their lives when a fire swept through the Command Module (CM). The accident was the first major mishap in NASAs short history, and it shocked the nation.   Moving Beyond Tragedy NASA made an exhaustive investigation of the fire (as it does with all space mishaps), which resulted in extensive reworking of the CMs. The agency postponed manned launches until officials cleared the new capsule design for use by human crews. In addition, Saturn 1B schedules were suspended for nearly a year, and the launch vehicle that finally bore the designation AS-204 carried a Lunar Module (LM) as the payload, not the Apollo CM. The missions of AS-201 and AS-202 with Apollo spacecraft aboard had been unofficially known as Apollo 1 and Apollo 2 missions (AS-203 carried only the aerodynamic nose cone). In the spring of 1967, NASAs Associate Administrator for Manned Space Flight, Dr. George E. Mueller, announced that the mission originally scheduled for Grissom, White and Chaffee would be known as Apollo 1, as a way to honor the three astronauts. The first Saturn V launch, scheduled for November 1967, would be known as Apollo 4. No missions or flights were ever designated as Apoll o 2 and Apollo 3.    The delays caused by the fire were bad enough, but NASA also faced budgetary cutbacks as it raced to reach the Moon before the end of the decade. Since the U.S. was in a race to get to the Moon before the Soviets could get there, NASA had no choice to but move ahead with the assets it had. The agency did further tests on the rockets, and eventually scheduled the Apollo 4 mission for an unmanned flight.  It was referred to as  all-up testing. Resuming Space Flight After the complete retooling of the capsule, the mission planners for Apollo 4 had four major goals: Demonstrate structural and thermal integrity and compatibility of launch vehicle and spacecraft; confirm launch loads and dynamic characteristics.Verify operation of command module heatshield (adequacy of Block II design for reentry at lunar return conditions), service propulsion system (SPS; including no ullage start), and selective subsystems.Evaluate performance of emergency detection system in open-loop configuration.Demonstrate mission support facilities and operations needed for launch, mission conduct, and CM recovery. After extensive testing, re-resting, and training,  Apollo 4 launched successfully on November 9, 1967 at 07:00:01 a.m. EST from Launch Complex 39-A at  Cape Canaveral FL. There were no delays in the preflight preparations and with the weather cooperating, there were no delays during countdown. During the third orbit and after SPS engine burn, the spacecraft coasted to a simulated translunar trajectory, reaching an altitude of 18,079 kilometers. The launch marked the initial flight testing of the S-IC and S-II stages. The first stage, S-IC, performed accurately with the center F-1 engine cutting off at 135.5 seconds and the outboard engines cutting off at LOX (liquid oxygen) depletion at 150.8 seconds when the vehicle was traveling at 9660 km/h at an altitude of 61.6 km. Stage separation occurred only 1.2 seconds off the predicted time. Cutoff of the S-II occurred at 519.8 seconds. It was a triumphant, if subdued return to space flight, and moved NASAs goals to reach the Moon farther forward. The spacecraft performance went well, and on the ground, people heaved a huge sigh of relief.   A Pacific Ocean landing occurred on November 9, 1967, 03:37 p.m. EST, just eight hours and thirty-seven minutes and fifty-nine seconds after takeoff. The Apollo 4 Spacecraft 017 splashed down, missing its planned impact point by only 16 kilometers. The Apollo 4 mission was a success, all  objectives were achieved. With the success of this first all up test, the Apollo program resumed manned missions and moving toward the eventual 1969 target for the first human landing on the Moon during the  Apollo 11 mission.  After the loss of the Apollo 1 crew, the Apollo 4 mission benefitted from many tough (and tragic) lessons learned. Edited and updated by Carolyn Collins Petersen.

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