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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Saturn V | 2/10 | https://en.wikipedia.org/wiki/Saturn_V | reference | science, encyclopedia | 2026-05-05T13:12:08.190587+00:00 | kb-cron |
Early in the planning process, NASA considered three methods for the Moon mission: Earth orbit rendezvous (EOR), direct ascent, and lunar orbit rendezvous (LOR). A direct ascent configuration would require an extremely large rocket to send a three-man spacecraft to land directly on the lunar surface with enough fuel to fly back to Earth. NASA proposed the Nova for this method. An EOR would launch the direct-landing spacecraft in two smaller parts which would combine in Earth orbit. A LOR mission would involve a single rocket launching two spacecraft: a mother ship, and a smaller, two-man landing module which would rendezvous back with the main spacecraft in lunar orbit. The lander would be discarded and the mother ship would return home.
Originally, in the early 1960s, when the Saturn project was transferred to NASA from the U.S Army, direct ascent was the preferred method. At the same time, the Air Force had been developing of a lunar mission named Lunex, which would use the direct ascent method. The Space Systems Division estimated that a mission to the Moon using direct ascent could be done by 1967 at an estimated cost of $7.5 billion (equivalent to $60.1 billion in 2024). NASA dismissed both of the rendezvous methods as "dangerous and impractical." Von Braun's team had shown an interest in using the EOR method as early as 1958, arguing that smaller vehicles could be used. Around the same time, Thomas Dolan and his team from the Vought Astronautics Division became the first to study the LOR method. Although his team presented their ideas to NASA, nothing came from his proposal.
In 1960, several NASA officials, including Langley Research Center engineer John Houbolt, argued that a lunar orbit rendezvous provided the simplest landing on the Moon with the most cost–efficient launch vehicle, and the best chance to accomplish the lunar landing within the decade. Throughout 1961, Houbolt and his team went around convincing other research teams to pursue LOR, catching the attention of the chief of the Engineering Division, James Chamberlin. Although in charge of what would later become Project Gemini, he proposed using a two-man spacecraft using LOR to send a one-man lunar lander to the surface of the Moon. Although Chamberlin's plan stalled, it did mark a shift towards LOR. Houbolt also managed to convince NASA official George Low. In June 1962, von Braun announced LOR would be MSFC's choice. As more NASA officials became convinced, LOR was officially selected and announced as the mission configuration for the Apollo program on November 7, 1962 by NASA administrator James E. Webb.
=== Development ===
A boilerplate Apollo spacecraft, BP-027 was used for all configurations of dynamic testing. The boilerplate took the place of actual flight hardware. Boilerplate size, shape, mass, and center of gravity were the same, but it was not necessary for the entire Apollo spacecraft to be completed to commence dynamic testing. The boilerplate was outfitted with instrumentation to record data for engineering study and evaluation. BP-27 was accepted at the Marshall Space Flight Center in late September 1964. The third stage, the S-IVB-D arrived at MSFC before any other Saturn V stage because it was first needed for dynamic testing of the Saturn IB rocket. The third stage arrived on January 4, 1965. Next, the instrument unit, S-IU-200D/500D, was built. Unlike the other major components of the rocket, the instrument unit was built in Huntsville, Alabama, where the MSFC is located. The ring was completed in January 1965 and electronic components from IBM installed by February 1. Like the third stage, it arrived before the other stages because it was needed for dynamic testing in the Saturn IB first. The first stage of the Saturn V rocket, S-IC-D, set out on the maiden voyage of NASA barge Poseidon to Marshall Space Flight Center on October 6, 1965, and arrived on October 13. While the first stage was on its way, dynamic testing for the Saturn V program using the test rocket SA-500D began on October 8. The first stage was lifted into place in the dynamic test stand January 13, 1966. The second stage of the SA-500D had a complex history. Originally, NASA wanted to use the S-II-D stage for its dynamic testing. However, in the spring of 1965, NASA canceled the production of the S-II-D stage and instead opted to use the S-II-S stage for its dynamic tests. The S-II-S stage, which North American Aviation's Space and Information Systems Division (S&ID) at Seal Beach had completed by January 31, 1965, was re-designated as S-II-S/D to be used for dynamic testing. The S-II-S/D would rupture and be destroyed during a test on September 29, 1965 at Seal Beach. It was discovered that the test was exercising a considerable margin above the structural limits required for flight, approximately 144 percent of its designed load limit. Because of this, NASA was forced to substitute the S-II-T stage for testing. In early 1966, the S-II-T was re-designated S-II-T/D, so it could be used for dynamic testing as well as engine firing. On May 28, 1966, S-II-T/D was undergoing a pressure test to find a hydrogen leak, but the hydrogen pressure sensors and switches had been disconnected unbeknownst to the second-shift crew. As a result, the crew, believing that a valve was leaking liquid hydrogen, began closing valves. This caused the liquid hydrogen tank to over pressurize and explode, injuring five men and hospitalizing two others. After the S-II-T/D was destroyed, the S-II-F stage was assigned to dynamic test duties. The S-II-F stage was at the Kennedy Space Center being used as a non-flight version of the stage. Being shipped from Seal Beach, California, to Kennedy Space Center where it arrived March 4. The S-II-F, now designated S-II-F/D, arrived at the MSFC on November 10, 1966.
=== Testing ===