Saturn V - Apollo
The Saturn V is a three stage launch vehicle. Thirteen of these rockets had been launched with a successrate of 100%. Alle vehicle configurations, except for the last one (SA-513), were more or less identical: a Saturn V launch vehicle with an Apollo spacecraft on top. The whole stack stood 111 meters tall.
The launch weight of a Saturn V – Apollo came to 2900 Tons.
Without fuel its weight was 230 Tons.
The five first stage F-1 engines delivered a total thrust of about 3700 Tons.
The total weight of the Apollo spacecraft (orbiter + moon lander) came to 45 Tons.
Apollo 4: maiden flight for all stages, all at once
The first flight qualification test, known as the Apollo 4 mission, had been conducted on vehicle SA-501 on 9 November 1967. Despite the fact that the three stages had never flown before, results of static qualification tests on each stage had made NASA confident about the succes of an all-up test in which all components would be flight tested for the first time at once. At that time the whole Apollo program had suffered a lot of delays which had made the launch schedule very tight if NASA wanted to have a moon landing before 1970. The flight of the SA-501 was in that sense of paramount importance. This flight was meant to prove that America could fly to the moon with this rocket. It was a tremendous great relief that the mission was very succesful, all the mission objectives were met. It gave NASA confidence, not only in the design of the Saturn V, but also in the whole process from construction , test, launch preparation up to mission management.
Apollo 6: the second unmanned all-up flight
The flight of the also unmanned SA-502 (Apollo 6) was less succesful. The Saturn V suffered from heavy longitudinal vibrations during the first minutes of the flight. And two of the five second stage J-2 engines failed in mid flight. During the boost phase, the launch vehicle was able to compensate for the second stage engine failures by adjusting the burn times of the three remaining second stage engines and the single J-2 engine of the third stage. The desired parking orbit could be obtained. But unfortunately another malfunction showed up: the third stage engine failed to restart. Because of that, the orbit could not be altered. This capability of a J-2 restart was essential for a translunar flight and was one of the most important mission objectives. Without a restart it was not possible to inject a spacecraft from a parking orbit into a translunar trajectory. Thanks to the sophisticated telemetry in which hundreds of parameters could be monitored remotely, all these problems could be analyzed and became well understood. Solutions could be implemented with relatively ease. So the Apollo 6 mission didn't raise any doubts or second thoughts about the design and the construction of the Saturn V.
The Space Race
The Apollo Program was America's answer in the Cold War related space race between the USA and the Soviet Union. Winning this race would show the ability of a country to mobilize all endavour necessary to achieve technological superiority. Such an achievement would reflect on its global political and military power which lean heavily on technology. The Soviet Union had already achieved a couple of firsts: First man in space, first woman in space, first spacewalk, first rendez-vous in space between two spacecrafts. There were two firsts left: first manned circumlunar flight and first manned moonlanding. A first moonlanding would undoubtedly be of great historical importance and would have a huge impact on national prestige.
Apollo 8: a bold mission
In autumn 1968 intelligence reports gave reasons to suspect that the Soviet Union was about to make a manned circumlunar flight with its brand-new N-1 superbooster, which had a payload capacity comparable with that of a Saturn V. It has pushed NASA to make the bold decision to declare the Saturn V launch vehicle and the Apollo Command & Service Modules qualified for manned circumlunar flights. Nevertheless the Saturn V had only flown twice. Almost prematurely, the third Saturn V (SA-503) became selected for the first manned circumlunar flight in December 1968, mission name "Apollo 8". Although the Apollo 6 mission didn't go without flaws, the mission experiences with the recent Saturn V flights had given NASA enough confidence that the risks involved were managable.
The Apollo spacecraft also imposed a considerable risk, it had only be used once in a manned mission, on an orbital flight around Earth (Apollo 7). Therefore it was decided to meticulously monitor the condition of this not yet fully matured Apollo spacecraft during the Apollo 8 mission, to be able to take immediate appropriate action if necessary.
This breath taking mission was very succesful. For the first time humans were orbiting the Moon and could see her farside with their own eyes. At the farside radio contact was lost with Mission Control for about an half hour on each pass. The first pass at the farside were tense moments.
For reasons of safety, the translunar trajectory, was a socalled free return trajectory, in which the spacecraft automatically would return to Earth after one pass around the moon if no trajectory corrections would be made. Therefore a rather critical burn with the large Service Propulsion engine was needed, to slow the spacecraft down to bring it into a parking orbit around the Moon. This manoeuvre however, had to be made at the farside of the Moon during which no contact with Earth was possible. So after the burn the crew of Apollo 8 and Mission Control had to wait about 20 minutes before Apollo 8 reappeared from behind the Moon and contact with Mission Control could be re-established for also 20 minutes. Only during that period of contact, the obtained flight path could be determined with the desired accuracy by using Radar techniques from Earthbased Radar stations. If the obtained flight path would deviate too much from the required one, additional orbital manoeuvres had to be made or worse: Apollo 8 could have been on a collision course with the Moon. The burn however was succesful and the Spacecraft had obtained just the right orbit as has been calculated by Mission Control. A major milestone had been achieved and it gave NASA much confidence in the way flight trajectory was managed. Ten orbits were made with the Apollo 8 spacecraft. After these ten orbits, a similair delicate manoeuvre was needed to leave the parking orbit around the Moon and bring the three men back to Earth. This burn was also a critical and tense moment in the mission, if the engine would fail, there were no options left to bring the men back to Earth safely, the engine had to ignite. The service propulsion engine appeared to operate flawlessly during the whole mission and the Apollo command module with the three astronauts inside, made a water landing in the Atlantic Ocean on 27. This 4 meter high conical shaped module was the only piece of hardware which remained from the 112 meter high, 2800 metric Tons heavy, Saturn V - Apollo stack. December 1968 after a 6 days mission. Both the Saturn V and the Apollo spacecraft had performed flawlessly, it gave NASA a lot of confidence to push forward and to excecute the plans for a manned moonlanding.
Apollo 9: qualifying the rendez-vous technique
The fourth (SA-504) Saturn V has been used to bring the CSM and the lunar module into space for the first time. The primary objective of this mission was to vindicate the rendez-vous technique in which two spacecrafts could be physically linked up by its pilots anywhere in space. This technique was of paramount importantce for a succesful moonlanding
Apollo 10: the dress rehearsal for the moonlanding mission
The fifth Saturn V (SA-505) has been used for the final moonlanding qualification test. All procedures and flight manoeuvres were tested, up to final descent.
Apollo 11: the moonlanding mission
The sixth Saturn V (SA-506) has been used for the first moonlanding mission (Landing on 20 July 1969).
Both the CSM and the LM had proven to be fit for this mission. All parts of this mission had been done in previous missions except for the final descent and the lift-off sequence from the lunar surface. There were contigency plans and mission rules to minimize risk. But the landing was a totally new flight experience and the this phase of the mission was certainly not without risk. The landing had to be done manually to avoid for instance boulders in the landing zone. And there was a risk that during the landing the craft could still crash or topple over.
If you are interested in my personal view on the Apollo moonlanding missions: Contemplation
Apollo 12: the accurate moonlanding
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Apollo 13: the succesful failure
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Apollo 14: back on track
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Apollo 15: Science on the Moon
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Apollo 16: More science on the Moon
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Apollo 17: the last moonlanding
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