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Apollo program insignia
Apollo 17 astronaut Harrison Schmitt standing next to a boulder at Taurus-Littrow on the Moon in December 1972.

The Apollo program was a NASA spaceflight endeavor that landed the first humans on Earth's moon. Conceived during the presidency of Dwight D. Eisenhower, Apollo began in earnest after US President John F. Kennedy announced his support for a manned moon landing on May 25, 1961, as part of a special address to a joint session of Congress declaring a national goal of "landing a man on the Moon" by the end of the decade.[1][2]

Kennedy's goal was accomplished during the Apollo 11 mission on July 20, 1969 with the landing of astronauts Neil Armstrong and Buzz Aldrin, while Michael Collins remained in lunar orbit. Five subsequent Apollo missions also landed astronauts on the Moon, the last in December 1972. In these six Apollo spaceflights twelve men walked on the Moon. These are the only times humans have landed on another celestial body.[3]

The Apollo Program ran from 1961 until 1975, and was the US civilian space agency's third human spaceflight program (following Mercury and Gemini). Apollo used Apollo spacecraft and Saturn launch vehicles, which were later used for the Skylab program and the joint American-Soviet Apollo-Soyuz Test Project. These later programs are thus often considered to be part of the overall Apollo program.

The program was accomplished with only two major setbacks. The first was the Apollo 1 launchpad fire that resulted in the deaths of astronauts Gus Grissom, Ed White and Roger Chaffee. The second was an explosion on Apollo 13 during the moonward leg of its journey, which badly damaged the spacecraft. The three astronauts aboard narrowly escaped with their lives, thanks to the efforts of flight controllers, project engineers, backup crew members and the skills of the astronauts themselves.

Apollo set major milestones in human spaceflight. It stands alone in sending manned missions beyond low Earth orbit; Apollo 8 was the first manned spacecraft to orbit another celestial body, while Apollo 17 marked the last moonwalk and the last manned mission beyond low Earth orbit. The program spurred advances in many areas of technology peripheral to rocketry and manned spaceflight, including avionics, telecommunications, and computers. Apollo sparked interest in many fields of engineering and left many physical facilities and machines developed for the program as landmarks. Many objects and artifacts from the program are on display at various locations throughout the world, notably at the Smithsonian's Air and Space Museums.

Contents

Background

The Apollo program was conceived early in 1960, during the Eisenhower administration, as a follow-up to America's Mercury program. While the Mercury capsule could only support one astronaut on a limited earth orbital mission, the Apollo spacecraft was to be able to carry three astronauts on a circumlunar flight and perhaps even on a lunar landing. The program was named after the Greek god of light and music by NASA manager Abe Silverstein, who later said that "I was naming the spacecraft like I'd name my baby."[4] While NASA went ahead with planning for Apollo, funding for the program was far from certain, particularly given Eisenhower's equivocal attitude to manned spaceflight.[5]

May 25, 1961: President John F. Kennedy addresses a Joint Session of Congress and lays out his plan to put a man on the moon and return him safely to Earth.

In November 1960, John F. Kennedy was elected President after a campaign that promised American superiority over the Soviet Union in the fields of space exploration and missile defense. Using space exploration as a symbol of national prestige, he warned of a "missile gap" between the two nations, pledging to make the U.S. not "first but, first and, first if, but first period."[6] Despite Kennedy's rhetoric, he did not immediately come to a decision on the status of the Apollo program once he was elected President. He knew little about the technical details of the space program, and was put off by the massive financial commitment required by a manned moon landing.[7] When NASA Administrator James Webb requested a thirty percent budget increase for his agency, Kennedy supported an acceleration of NASA's large booster program but deferred a decision on the broader issue.[8]

President John F. Kennedy delivers a speech at Rice University on the subject of the American space program, September 12, 1962.

On April 12, 1961, Soviet cosmonaut Yuri Gagarin became the first person to fly in space, reinforcing American fears about being left behind in a technological competition with the Soviet Union. At a meeting of the U.S. House Committee on Science and Astronautics held only one day after Gagarin's flight, many congressmen pledged their support for a crash program aimed at ensuring that America would catch up.[9] Kennedy, however, was circumspect in his response to the news, refusing to make a commitment on America's response to the Soviets.[10] On April 20 Kennedy sent a memo to Vice President Lyndon B. Johnson, asking Johnson to look into the status of America's space program, and into programs that could offer NASA the opportunity to catch up.[11] Johnson responded on the following day, concluding that "we are neither making maximum effort nor achieving results necessary if this country is to reach a position of leadership."[12] His memo concluded that a manned moon landing was far enough in the future to make it possible that the United States could achieve it first.[12]

On May 25, 1961, Kennedy announced his support for the Apollo program as part of a special address to a joint session of Congress:[1]

I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space project in this period will be more impressive to mankind, or more important in the long-range exploration of space; and none will be so difficult or expensive to accomplish.
John F. Kennedy

At the time of Kennedy's speech, only one American had flown in space — less than a month earlier — and NASA had not yet sent a man into orbit. Even some NASA employees doubted whether Kennedy's ambitious goal could be met.[2]

Answering President Kennedy's challenge and landing men on the moon by the end of 1969 required the most sudden burst of technological creativity, and the largest commitment of resources ($24 billion), ever made by any nation in peacetime. At its peak, the Apollo program employed 400,000 people and required the support of over 20,000 industrial firms and universities.[13]

We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win, and the others, too...Many years ago the great British explorer George Mallory, who was to die on Mount Everest, was asked why did he want to climb it. He said, "Because it is there." Well, space is there, and we're going to climb it, and the moon and the planets are there, and new hopes for knowledge and peace are there. And, therefore, as we set sail we ask God's blessing on the most hazardous and dangerous and greatest adventure on which man has ever embarked.
John F. Kennedy[14]


Choosing a mission mode

Once Kennedy had defined a goal the Apollo mission planners were faced with the challenge of designing a set of flights that could meet this stated goal while minimizing risk to human life, cost, and demands on technology and astronaut skill. Four possible mission modes were considered:

Early Apollo configuration for
Direct Ascent and
Earth Orbit Rendezvous - 1961 (NASA)
  • Direct Ascent: A spacecraft would travel directly to the Moon, landing and returning as a unit. This plan would have required a very powerful booster, the planned Nova rocket.
  • Earth Orbit Rendezvous (EOR): Multiple rockets (up to fifteen in some claims) would be launched, each carrying various parts of a Direct Ascent spacecraft and propulsion units that would have enabled the spacecraft to escape earth orbit. After a docking in earth orbit, the spacecraft would have landed on the Moon as a unit.
  • Lunar Surface Rendezvous: Two spacecraft would be launched in succession. The first, an automated vehicle carrying propellants, would land on the Moon and would be followed some time later by the manned vehicle. Propellant would be transferred from the automated vehicle to the manned vehicle before the manned vehicle could return to Earth.
  • Lunar Orbit Rendezvous (LOR): One Saturn V would launch a spacecraft that was composed of modular parts. A command module would remain in orbit around the moon, while a lunar module would descend to the moon and then return to dock with the command module while still in lunar orbit. In contrast with the other plans, LOR required only a small part of the spacecraft to land on the Moon, thereby minimizing the mass to be launched from the Moon's surface for the return trip.

In early 1961, direct ascent was generally the mission mode in favor at NASA. Many engineers feared that a rendezvous —let alone a docking— neither of which had been attempted even in Earth orbit, would be extremely difficult in lunar orbit. However, dissenters including John Houbolt at Langley Research Center emphasized the important weight reductions that were offered by the LOR approach. Throughout 1960 and 1961, Houbolt campaigned for the recognition of LOR as a valid and practical option. Bypassing the NASA hierarchy, he sent a series of memos and reports on the issue to Associate Administrator Robert Seamans; while acknowledging that he spoke "somewhat as a voice in the wilderness," Houbolt pleaded that LOR should not be discounted in studies of the question.[15]

Seamans' establishment of the Golovin committee in July 1961 represented a turning point in NASA's mission mode decision.[16] While the ad-hoc committee was intended to provide a recommendation on the boosters to be used in the Apollo program, it recognized that the mode decision was an important part of this question. The committee recommended in favor of a hybrid EOR-LOR mode, but its consideration of LOR —as well as Houbolt's ceaseless work— played an important role in publicizing the workability of the approach. In late 1961 and early 1962, members of NASA's Space Task Group at the Manned Spacecraft Center in Houston began to come around to support for LOR.[16] The engineers at Marshall Space Flight Center took longer to become convinced of its merits, but their conversion was announced by Wernher von Braun at a briefing in June 1962. NASA's formal decision in favor of LOR was announced on July 11, 1962. Space historian James Hansen concludes that:

Without NASA's adoption of this stubbornly held minority opinion in 1962, the United States may still have reached the Moon, but almost certainly it would not have been accomplished by the end of the 1960s, President Kennedy's target date.
James Hansen[17]

The selection of LOR was further validated when an explosion on Apollo 13's service module left it without oxygen or electrical power, while on a trajectory to the moon. Without the secondary, independent life support system of the Lunar module, the crew would have perished.

Spacecraft

The decision in favor of lunar orbit rendezvous dictated the basic design of the Apollo spacecraft. It would consist of two main sections: the Command/Service Module (CSM), in which the crew would spend most of the mission, and the Lunar Module (LM), which would descend to and return from the lunar surface.

Command/service module

Apollo CSM in lunar orbit.

The Command module (CM) was conical in shape, and was designed to carry three astronauts from launch into lunar orbit and back from the moon to splashdown. Equipment carried by the command module included reaction control engines, a docking tunnel, guidance and navigation systems and the Apollo Guidance Computer. Attached to the command module was the service module (SM), which housed the service propulsion system and its propellants, the fuel cell power system, four maneuvering thruster quads, the S-band antenna for communication with Mission Control, and storage tanks for water and air. On Apollo 15, 16 and 17 it also carried a scientific instrument package. The two sections of the spacecraft would remain attached until just prior to re-entry, at which point the service module would be discarded. Only the command module was provided with a heat shield that would allow it and its passengers to survive the intense heat of re-entry. After re-entry it would deploy parachutes that would slow its descent through the atmosphere, allowing a smooth splashdown in the ocean.

Under the leadership of Harrison Storms, North American Aviation won the contract to build the CSM for NASA. Relations between North American and NASA were strained during the Apollo program, particularly after the Apollo 1 fire during which three astronauts died. The cause of the accident was determined to be an electrical short in the wiring of the command module; while determination of responsibility for the accident was complex, the review board concluded that "deficiencies existed in Command Module design, workmanship and quality control."[18]

Lunar module

Apollo LM on lunar surface

The Lunar Module (LM) (also originally known as Lunar Excursion Module, or LEM), was designed solely to land on the moon, and to ascend from the lunar surface to the command module. It had a limited heat shield and was of a construction so lightweight that it would not have been able to fly in Earth gravity. It carried two crew members and consisted of two stages, a descent and an ascent stage. The descent stage incorporated compartments in which cargo such as the Apollo Lunar Surface Experiment Package and Lunar Rover could be carried.

The contract for design and construction of the lunar module was awarded to Grumman, and the project was overseen by Tom Kelly. There were also problems with the lunar module; due to delays in the test program, the LM became what was known as a "pacing item," meaning that it was in danger of delaying the schedule of the whole Apollo program.[19] Due to these issues, the Apollo missions were rescheduled so that the first manned mission with the lunar module would be Apollo 9, rather than Apollo 8 as was originally planned.

Boosters

When the team of engineers led by Wernher von Braun began planning for the Apollo program, it was not yet clear what sort of mission their rocket boosters would have to support. Direct ascent would require a booster, the planned Nova rocket, which could lift a very large payload. NASA's decision in favor of lunar orbit rendezvous re-oriented the work of Marshall Space Flight Center towards the development of the Saturn 1B and Saturn V. While these were less powerful than the Nova would have been, the Saturn V was still much more powerful than any booster developed before—or since.

Liquid hydrogen was used as fuel for the J-2 engines on the Saturn V second and third stages, and on the second stage of the Saturn 1B.[20]

Saturn IB

The Saturn IB was an upgraded version of the earlier Saturn I. It consisted of a first stage made up of eight H-1 engines and a second S-IVB stage which was identical to the Saturn V's third stage. The Saturn IB had only 1.6 million pounds of thrust in its first stage—compared to 7.5 million pounds for the Saturn V—but was capable of putting a command and lunar module into earth orbit.[21] It was used in Apollo test missions and in both the Skylab program and the Apollo-Soyuz Test Program. In 1973 a refitted S-IVB stage, launched by a Saturn V, became the Skylab space station.

Saturn V

The Saturn V rocket launched Apollo 11 and her crew on its journey to the Moon, July 16, 1969.
Saturn V diagram from the Apollo 6 press kit

The Saturn V consisted of three stages and an Instrument Unit which contained the booster's guidance system. The first stage, the S-IC, consisted of five F-1 engines arranged in a cross pattern, which produced a total of 7.5 million pounds of thrust. They burned for only 2.5 minutes, accelerating the spacecraft to a speed of approximately 6,000 miles per hour (2.68 km/s).[22] During development, the F-1 engines were plagued by combustion instability—if the combustion of propellants was not uniform across the flame front of an engine, pressure waves could build which would cause the engine to destroy itself. The problem was solved in the end through trial and error, fine-tuning the engines through numerous tests so that even small charges set off inside the engine would not induce instability.[23]

The second stage, the S-II, used five J-2 engines. They burned for approximately six minutes, taking the spacecraft to a speed of 15,300 miles per hour (6.84 km/s) and an altitude of about 115 miles (185 km).[24] At this point the S-IVB third stage took over, putting the spacecraft into orbit. Its one J-2 engine was designed to be restarted in order to make the translunar injection burn.[25]

Missions

Mission types

In September 1967, the Manned Spacecraft Center in Houston, Texas, proposed a series of missions that would lead up to a manned lunar landing. Seven mission types were outlined, each testing a specific set of components and tasks; each previous step needed to be completed successfully before the next mission type could be undertaken. These were:

  • A - Unmanned Command/Service Module (CSM) test
  • B - Unmanned Lunar Module (LM) test
  • C - Manned CSM in low Earth orbit
  • D - Manned CSM and LM in low Earth orbit
  • E - Manned CSM and LM in an elliptical Earth orbit with an apogee of 4600 mi (7400 km)
  • F - Manned CSM and LM in lunar orbit
  • G - Manned lunar landing

Later added to this were H missions, which were short duration stays on the Moon with two lunar EVAs ("moonwalks"). These were followed by the J missions, which were longer three day stays, with three LEVAs, using the lunar rover.[26] Apollo 18 to 20 would have been J missions, as Apollo 15 to 17 were.

Another group of flights — the I missions — were planned, which would have been long duration orbital missions using a Scientific Instrument Module (SIM) which included a panoramic camera, gamma ray spectrometer, mapping camera, laser altimeter, mass spectrometer, and lunar sub-satellite. When it became obvious that later flights were being cancelled, this was incorporated into the J missions and operated by the Command Module Pilot during the lunar surface operations. After trans-earth injection, the CMP had to perform an EVA to retrieve the film.

Unmanned missions

Preparations for the Apollo program began long before the manned Apollo missions were flown. Test flights of the Saturn I booster began in October 1961 and lasted until September 1964. Three further Saturn I launches carried boilerplate models of the Apollo command/service module. Two pad abort tests of the launch escape system took place in 1963 and 1965 at the White Sands Missile Range. Three unmanned tests of Apollo components with the Saturn IB (Apollo-Saturn, or AS) were officially designated AS-201, AS-202, and AS-203.

The only unmanned missions to officially include Apollo as part of their name rather than serial number were Apollo 4, Apollo 5 and Apollo 6.[27] The simple numbering was started at "4" due to the previous 3 Apollo-Saturn flights using the Saturn IB. Apollo 4 was the first test flight of the Saturn V booster. Launched on November 9, 1967, Apollo 4 exemplified George Mueller's strategy of "all up" testing. Rather than being tested stage by stage, as most rockets were, the Saturn V would be flown for the first time as one unit. The mission was a highly successful one. Walter Cronkite covered the launch from a broadcast booth about 4 miles (6 km) from the launch site. The extreme noise and vibrations from the launch nearly shook the broadcast booth apart- ceiling tiles fell and windows shook. At one point, Cronkite was forced to dampen the booth's plate glass window to prevent it from shattering.[28] This launch showed that additional protective measures were necessary to protect structures in the immediate vicinity. Future launches used a damping mechanism directly at the launchpad which proved effective in limiting the generated noise.

Apollo 5 was a Saturn IB flight which tested a legless, windowless version of the lunar module (LM) in Earth orbit (no Command and Service Module (CSM) was included). Apollo 6, a second Saturn V launch with a CSM but no LM, was the last in the series of unmanned Apollo missions. It was launched on April 4, 1968, and landed back on Earth almost ten hours later at 21:57:21 UTC.

Manned missions

Apollo 11 astronaut Buzz Aldrin with the U.S. flag

On each manned mission there were three astronauts: a commander, a command module pilot (CMP), and a lunar module pilot (LMP). In the case of a moon landing the commander and the LMP descended to the Moon, while the CMP remained in lunar orbit.

Apollo 7, launched on October 11, 1968, was the first manned mission in the Apollo program. It was an eleven-day Earth-orbital mission intended to test the redesigned command module. It was the first manned launch of the Saturn IB launch vehicle, and the first three-man American space mission.

A mounted camera captures Neil Armstrong as he becomes the first human to step on the moon.

By the summer of 1968 it became clear to program managers that a fully functional LM would not be available for the Apollo 8 mission. Rather than perform a simple earth orbiting mission, they chose to send Apollo 8 around the moon during Christmas. The original idea for this switch was the brainchild of George Low. Although it has often been claimed that this change was made as a direct response to Soviet attempts to fly a piloted Zond spacecraft around the moon, there is no evidence that this was actually the case. NASA officials were aware of the Soviet Zond flights, but the timing of the Zond missions does not correspond well with the extensive written record from NASA about the Apollo 8 decision. It is relatively certain that the Apollo 8 decision was primarily based upon the LM schedule, rather than fear of the Soviets beating the Americans to the moon.

Between December 21, 1968 and May 18, 1969, NASA launched three Apollo missions (8, 9, and 10) using the Saturn V launch vehicle. Each mission had a crew of three astronauts, and the last two included Lunar Modules, but none of these were intended as Moon landing missions.

That's one small step for [a] man, one giant leap for mankind.

Neil Armstrong[29]

Astronaut Harrison H. Schmitt on December 13, 1972, during the Apollo 17 mission, the last human lunar landing to date.

The next two flights (11 and 12) included successful Moon landings. The Apollo 13 mission was aborted before the landing attempt, but the crew returned safely to Earth. The four subsequent Apollo missions (14 through 17) included successful Moon landings. The last three of these were J-class missions that included the use of Lunar Rovers.

Apollo 17, launched December 7, 1972, was the last Apollo mission to the moon. Mission commander Eugene Cernan was the last person to leave the Moon's surface. The crew returned safely to Earth on December 19, 1972.

Apollo applications program

Following the success of the Apollo program, both NASA and its major contractors investigated several post-lunar applications for the Apollo hardware. The "Apollo Extension Series", later called the "Apollo Applications Program", proposed up to thirty flights to earth orbit. Many of these would use the space that the lunar module took up in the Saturn rocket to carry scientific equipment.

Of all the plans, only two were implemented: the Skylab space station (May 1973 – February 1974), and the Apollo-Soyuz Test Project (July 1975). Skylab's fuselage was constructed from the second stage of a Saturn IB, and the station was equipped with the Apollo Telescope Mount, itself based on a lunar module. The station's three crews were ferried into orbit atop Saturn IBs, riding in CSMs; the station itself had been launched with a modified Saturn V. Skylab's last crew departed the station on February 8, 1974, while the station itself returned prematurely to Earth in 1979, by which time it had become the oldest operational Apollo component.

The Apollo-Soyuz Test Project involved a docking in Earth orbit between a CSM and a Soviet Soyuz spacecraft. The mission lasted from July 15 to July 24, 1975. Although the Soviet Union continued to operate the Soyuz and Salyut space vehicles, NASA's next manned mission would not be until STS-1 on April 12, 1981.

Summary of missions

U.S. Mission Booster Crew Launched Mission Goal Mission Result
AS-201 Saturn 1B Unmanned February 26, 1966 Suborbital Partial Success - Unmanned suborbital flight was the first test flight of Saturn 1B and of the Apollo Command and Service Modules; problems included a fault in the electrical power system and a 30 percent decrease in pressure to the service module engine 80 seconds after firing.
AS-203 Saturn 1B Unmanned July 5, 1966 Earth orbit Success - fuel tank behavior test and booster certification - informally proposed later as Apollo 2, this name was never approved.
AS-202 Saturn 1B Unmanned August 25, 1966 Suborbital Success - command module reentry test successful, even though reentry was very uncontrolled. Informally proposed as Apollo 3, this name was never approved.
AS-204 (Apollo 1) Saturn 1B Virgil I. "Gus" Grissom, Edward White, Roger B. Chaffee (Launch cancelled) Earth orbit Failure - never launched: command module destroyed and three astronauts killed on 27 January 1967 by fire in the module during a test exercise - Retroactively, the mission's name was officially changed to "Apollo 1" after the fire. Despite the fact that it was scheduled to be the fourth Apollo mission (and despite the fact that NASA planned to call the mission AS-204), the flight patch worn by the three astronauts, which was approved by NASA in June 1966, already referred to the mission as "Apollo 1"
Apollo 4 Saturn V Unmanned November 9, 1967 Earth orbit Success - first test of new booster and all elements together (except lunar module), successful reentry of command module
Apollo 5 Saturn 1B Unmanned January 22, 1968 Earth orbit Success - first flight of lunar module (LM); multiple space tests of LM, no command or service module flown; no controlled reentry. Used the Saturn 1B originally slated for the cancelled manned AS-204 ("Apollo 1") mission
Apollo 6 Saturn V Unmanned April 4, 1968 Earth orbit Partial success - severe oscillations during orbital insertion, several engines failing during flight, successful reentry of command module (though mission parameters for a 'worst case' reentry scenario could not be achieved)
Apollo 7 Saturn 1B Walter M. "Wally" Schirra, Donn Eisele, Walter Cunningham October 11, 1968 Earth orbit Success - eleven-day manned Earth orbit, command module testing (no lunar module), some minor crew and illness issues (all three men caught the same head-cold and reported stress).
Apollo 8 Saturn V Frank Borman, Jim Lovell, William A. Anders December 21, 1968 Lunar orbit Success - ambitious mission profile (changed relatively shortly before launch), first human lunar orbit (no lunar module), first earthrise seen by men and major publicity success, some minor sleeping and illness issues
Apollo 9 Saturn V James McDivitt, David Scott, Russell L. "Rusty" Schweickart March 3, 1969 Earth orbit Success - ten-day manned Earth orbit, with EVA and successful manned flight / docking of lunar module
Apollo 10 Saturn V Thomas P. Stafford, John W. Young, Eugene Cernan May 18, 1969 Lunar orbit Success - second manned lunar flight; first test of lunar module in lunar orbit; "dress rehearsal" for first landing, coming to 8.4 nautical miles (15.6 km) to the Moon's surface
Apollo 11 Saturn V Neil Armstrong, Michael Collins, Edwin E. "Buzz" Aldrin July 16, 1969 Lunar landing Success - first manned landing on the Moon (manual landing required), exploration on foot in direct vicinity of landing site; one EVA
Apollo 12 Saturn V Charles "Pete" Conrad, Richard Gordon, Alan Bean November 14, 1969 Lunar landing Success - mission almost aborted after lightning struck at launch with brief loss of fuel cells and telemetry; successful landing within walking distance (less than 200 meters) of the Surveyor 3 probe; two EVAs
Apollo 13 Saturn V Jim Lovell, Jack Swigert, Fred Haise April 11, 1970 Lunar landing Partial Failure [30] - early shutdown of inboard S-II engine; unrelated explosion in service module during Earth-Moon transition caused mission to be aborted - crew took temporary refuge in the lunar module and returned safely to Earth after a single pass around the Moon.
Apollo 14 Saturn V Alan B. Shepard, Stuart Roosa, Edgar Mitchell January 31, 1971 Lunar landing Success - docking problems, abort switch contamination and delayed landing radar acquisition all threatened landing; first color video images from the Moon; first materials science experiments in space; two EVAs
Apollo 15 Saturn V David Scott, Alfred Worden, James Irwin July 26, 1971 Lunar landing Success - first longer (3 days) stay on Moon, first use of lunar rover to travel total of 17.25 miles (27.76 km), more extensive geology investigations; 1 lunar "standup" EVA, 3 lunar surface EVAs plus deep space EVA
Apollo 16 Saturn V John W. Young, Ken Mattingly, Charles Duke April 16, 1972 Lunar landing Success - malfunction in a backup yaw gimbal servo loop almost aborted landing (and reduced stay duration in lunar orbit by one day for safety reasons); only mission to target lunar highlands; malfunction prevented controlled ascent stage impact after jettison; 3 lunar EVAs plus deep space EVA
Apollo 17 Saturn V Eugene Cernan, Ronald Evans, Harrison H. "Jack" Schmitt December 7, 1972 Lunar landing Success - last manned landing on the Moon, only mission with a scientist (geologist) on board; this is also the latest manned moon landing and manned flight beyond low Earth orbit; 3 lunar EVAs plus deep space EVA
Skylab 1 Saturn V Unmanned May 14, 1973 Earth orbit Partial Success - Launch of Skylab space station; micrometeoroid shield and one solar panel lost at launch, second jammed during deployment
Skylab 2 Saturn 1B Charles "Pete" Conrad, Paul Weitz, Joseph Kerwin May 25, 1973 Space station mission Success - Apollo spacecraft takes first US crew to Skylab, the first American space station, for a 28 day stay; freed stuck solar panel and deployed replacement sunshield
Skylab 3 Saturn 1B Alan Bean, Jack Lousma, Owen Garriott July 28, 1973 Space Station mission Success - Apollo spacecraft takes second US crew to the Skylab space station for a 59 day stay
Skylab 4 Saturn 1B Gerald Carr, William Pogue, Edward Gibson November 16, 1973 Space station mission Success - Apollo spacecraft takes third US crew to the Skylab space station for an 84 day stay
ASTP (Apollo 18) Saturn 1B Thomas P. Stafford, Vance D. Brand, Donald K. "Deke" Slayton July 15, 1975 Earth orbit Success - Apollo-Soyuz Test Project, in which an Apollo space craft conducted rendezvous and docking exercises with Soviet Soyuz 19 in space - sometimes referred to as "Apollo 18"
Planned Apollo 18, Apollo 19, and Apollo 20 Moon Missions Saturn V Missions cancelled Never launched Lunar landings Cancelled - Several more missions (with detailed planning for up to Apollo 20) were cancelled

Samples returned

Lunar
Mission
Sample
Returned
Representative
Sample
Apollo 11 22 kg
Apollo 12 34 kg
Apollo 14 43 kg
Apollo 15 77 kg
The most famous of the Moon rocks recovered, the Genesis Rock, was discovered and returned from the Apollo 15 mission.
Apollo 16 95 kg
Ferroan Anorthosite moon rock, collected by Apollo 16. The only sources of moon rocks on Earth are those collected from the Apollo program, the former Soviet Union's Luna missions, and lunar meteorites. Future missions manned or unmanned would provide the opportunity to collect more.
Apollo 17 111 kg

The Apollo program returned 381.7 kg (841.5 lb) of rocks and other material from the Moon, much of which is stored at the Lunar Receiving Laboratory in Houston.

In general the rocks collected from the Moon are extremely old compared to rocks found on Earth, as measured by radiometric dating techniques. They range in age from about 3.2 billion years old for the basaltic samples derived from the lunar mare, to about 4.6 billion years for samples derived from the highlands crust.[31] As such, they represent samples from a very early period in the development of the Solar System that is largely missing from Earth. One important rock found during the Apollo Program was the Genesis Rock, retrieved by astronauts James Irwin and David Scott during the Apollo 15 mission. This rock, called anorthosite, is composed almost exclusively of the calcium-rich feldspar mineral anorthite, and is believed to be representative of the highland crust. A geochemical component called KREEP was discovered that has no known terrestrial counterpart. Together, KREEP and the anorthositic samples have been used to infer that the outer portion of the Moon was once completely molten (see lunar magma ocean).

Almost all of the rocks show evidence for having been affected by impact processes. For instance, many samples appear to be pitted with micrometeoroid impact craters, something which is never seen on earth due to its thick atmosphere. Additionally, many show signs of being subjected to high pressure shock waves that are generated during impact events. Some of the returned samples are of impact melt, referring to materials that are melted in the vicinity of an impact crater. Finally, all samples returned from the Moon are highly brecciated as a result of being subjected to multiple impact events.

Analysis of composition of the lunar samples support the giant impact hypothesis, that the Moon was created through a "giant impact" of a large astronomical body with the Earth.[32]

Program costs and cancellation

In March 1966, NASA told Congress the "run-out cost" of the Apollo program to put men on the moon would be an estimated $22.718 billion for the 13-year program which eventually accomplished six successful missions between July 1969 and December 1972.[citation needed] According to Steve Garber, the NASA History website curator, the final cost of project Apollo was between $20 and $25.4 billion in 1969 dollars[citation needed] (approximately $145 billion in 2008 dollars[citation needed]).

The costs associated with the Apollo spacecraft and Saturn rockets amounted to about $83 billion [Apollo spacecraft: $28 billion (Command/Service Module: $17 billion; Lunar Module: $11-billion), Saturn I, Saturn IB, Saturn V launch vehicles: about $46 billion] in 2005 dollars.[citation needed]

Canceled missions

Originally three additional lunar landing missions had been planned, as Apollo 18 through Apollo 20. In light of the drastically shrinking NASA budget and the decision not to produce a second batch of Saturn Vs, these missions were canceled to make funds available for the development of the Space Shuttle, and to make their Apollo spacecraft and Saturn V launch vehicles available to the Skylab program. Only one of the remaining Saturn Vs was actually used to launch the Skylab orbital laboratory in 1973; the others became museum exhibits at the John F. Kennedy Space Center in Cape Canaveral, Florida, George C. Marshall Space Center in Huntsville, Alabama, Michoud Assembly Facility in New Orleans, Louisiana, and Lyndon B. Johnson Space Center in Houston, Texas.

Scientific and engineering legacy

Unflown command module CM-007 at the Museum of Flight in Seattle

The Apollo program, specifically the lunar landings, has been called the greatest technological achievement in human history.[33][34] The program stimulated many areas of technology. The flight computer design used in both the lunar and command modules was, along with the Minuteman Missile System, the driving force behind early research into integrated circuits. The fuel cell developed for this program was the first practical fuel cell. Computer-controlled machining (CNC) was pioneered in fabricating Apollo structural components.

Influence on future human space exploration

Several nations have planned future human lunar missions, and several space agencies also intend to build lunar bases.

Neil Armstrong, the commander of the first successful landing Apollo 11, is often asked by the press for his views on the future of spaceflight. In 2005, he said that a human voyage to Mars will be easier than the lunar challenge of the 1960s: "I suspect that even though the various questions are difficult and many, they are not as difficult and many as those we faced when we started the Apollo (space program) in 1961."

Constellation program

In a speech on January 14, 2004, President George W. Bush announced a new Vision for Space Exploration, which included plans for the United States to return astronauts to the Moon no later than 2020 (with the first human landing currently targeted for 2019). This mission would be a part of the Constellation program, NASA's program to create a new generation of spacecraft for human spaceflight.

Replacing the Space Shuttle following its retirement in 2010 could be the Orion crew capsule, which closely resembles the Apollo command module in its aerodynamic shape. NASA administrator Michael D. Griffin has described the capsule as "Apollo on steroids," and the New Scientist magazine reports that "some critics... say the whole Orion program is little more than a throwback to Apollo-era technology."[35] In other respects, however—including its cockpit displays and its heatshield—Orion would be employing new technology.[36] More closely based on Apollo designs is the upper stage of the Ares I, the launch vehicle designed to take Orion into orbit. It would be based on a J-2X engine, a redesigned version of the J-2 engine used in the Saturn family of boosters. In working on the J-2X, NASA engineers have visited museums, searched for Apollo-era documentation and consulted with engineers who worked on the Apollo program. "The mechanics of landing on the moon and getting off the moon to a large extent have been solved," said Constellation program manager Jeff Hanley. "That is the legacy that Apollo gave us."[37]

Like Apollo, Orion would fly a lunar orbit rendezvous mission profile, but unlike Apollo, the lander, known as Altair, would be launched separately on the Ares V rocket, a rocket based on both Space Shuttle and Apollo technologies. Orion would be launched separately and would link up with Altair in low earth orbit like that of the Skylab program. Also, Orion, unlike Apollo, would remain unmanned in lunar orbit while the entire crew lands on the lunar surface, with the lunar polar regions in mind instead of the equatorial regions explored by Apollo. Constellation would also employ an Earth orbit rendezvous mission profile, which was dropped in favor of lunar orbit rendezvous in Apollo.

Cultural legacy

A world wide audience

"Everything that I ever knew - my life, my loved ones, the Navy - everything, the whole world was behind my thumb." –James Lovell

The Apollo 8 crew's 1968 Christmas Eve broadcast was the most widely watched television broadcast up until that time. The broadcast's historic significance and worldwide impact is discussed here.

Approximately one fifth of the population of the world watched the live transmission of the first Apollo moonwalk.[38]

Apollo 11 broadcast data restoration project

As part of its 40th anniversary celebrating the Apollo program, NASA has promoted the restoration of data recorded during the televised Apollo 11 moon landing.[39] After a 3 year exhaustive search for missing tapes that contained the original footage of the Apollo 11 moonwalk, NASA concluded the missing data tapes were more than likely destroyed during a period when they were erasing old magnetic tapes and reusing them to record satellite data.[40]

We're all saddened that they're not there. We all wish we had 20-20 hindsight. I don't think anyone in the NASA organization did anything wrong, I think it slipped through the cracks, and nobody's happy about it.
Dick Nafzger, TV Specialist, NASA Goddard Space Flight Center[40]

The moon landing data was recorded by a special lunar camera which recorded in a format that wasn't compatible with the format used for broadcast TV. This resulted in lunar footage that had to be converted for the live television broadcast and stored on magnetic telemetry tapes. During the years that followed the Apollo program, a magnetic tape shortage prompted NASA to remove massive numbers of magnetic tapes from the National Archives and Records Administration to be recorded over with newer satellite data. Stan Lebar, who designed and built the lunar camera at Westinghouse Electric Corporation, also worked with Nafzger to locate the missing tapes. The search concluded that the missing original data lunar tapes were lost.[40]

So I don't believe that the tapes exist today at all. It was a hard thing to accept. But there was just an overwhelming amount of evidence that led us to believe that they just don't exist anymore. And you have to accept reality.
Stan Lebar, Lunar Camera Designer, Westinghouse Electric Corporation[40]

With a budget of $230,000, the surviving original lunar broadcast data from Apollo 11 was compiled by Nafzger and assigned to Lowry Digital for restoration. Due to be complete in September 2009, the video will be processed to carefully remove random noise and camera shake without destroying historical legitimacy.[41]

We've got to be very, very mindful of history. If you want to go to the extreme, you could take these images and completely re-create them. You could create a three-dimensional model of the lunar lander, and you could make it look beautiful. But I don't think that's the point. I think the point is that Apollo 11 was a very, very special historical event.
John Lowry, Founder, Lowry Digital[40]

The images that Lowry Digital is working with have been taken from tapes in Australia, the CBS News archive, and kinescope recordings made at Johnson Space Center. The restored Apollo landing video will remain in black and white, contain conservative digital enhancements and will not include sound quality improvements.[41]

Psychological impact on the astronauts

"We went to explore the Moon, and in fact discovered the Earth." –Eugene Cernan

Many astronauts and cosmonauts have commented on the profound effects that seeing Earth from space has had on them; the twenty-four astronauts who traveled to the Moon are the only humans to have observed Earth from beyond low Earth orbit, and have traveled further from Earth than anyone else to date.

One of the most important legacies of the Apollo program is the now-common view of Earth as a fragile, small planet, captured in the photographs taken by the astronauts during the lunar missions. The most famous of these photographs, taken by the Apollo 17 astronauts, is "The Blue Marble" (see image at right). These photographs have also motivated many people toward environmentalism.[42]

Historical observation

"There the lunar module sits, parked just where it landed 40 years ago, as if it still really were 40 years ago and all the time since merely imaginary." –The New York Times[43]

In 2008, JAXA's SELENE probe observed evidence of the halo surrounding the Apollo 15 lunar module blast crater while orbiting above the lunar surface.[44]

In 2009, NASA's robotic Lunar Reconnaissance Orbiter, while orbiting 50 kilometres (31 mi) above the Moon, photographed the remnants of the Apollo program left on the lunar surface, and photographed each of the sites where manned Apollo flights landed.[45][46]

In a November 16, 2009 editorial, The New York Times opined that:

[T]here’s something terribly wistful about these photographs of the Apollo landing sites. The detail is such that if Neil Armstrong were walking there now, we could make him out, make out his footsteps even, like the astronaut footpath clearly visible in the photos of the Apollo 14 site.

Perhaps the wistfulness is caused by the sense of simple grandeur in those Apollo missions. Perhaps, too, it’s a reminder of the risk we all felt after the Eagle had landed — the possibility that it might be unable to lift off again and the astronauts would be stranded on the Moon. But it may also be that a photograph like this one is as close as we’re able to come to looking directly back into the human past.

New York Times[43]

Proposed future lunar missions, such as the Google Lunar X Prize, intend to land robotic spacecraft on the lunar surface and record close-up videos and photographs of the Apollo Lunar Modules and other artificial objects on the surface.[47]

Documentaries

Numerous documentary films cover the Apollo project and the space race, including:

Robbins Medallion flown on Apollo 14

See also

Notes

  1. ^ a b John F. Kennedy, "Special Message to the Congress on Urgent National Needs", May 25, 1961
  2. ^ a b Murray and Cox, Apollo, pp. 16-17.
  3. ^ 30th Anniversary of Apollo 11, Manned Apollo Missions. NASA, 1999.
  4. ^ Murray and Cox, Apollo, p. 55.
  5. ^ Murray and Cox, Apollo, p. 60.
  6. ^ Beschloss, 'Kennedy and the Decision to Go to the Moon,' in Launius and McCurdy, eds., Spaceflight and the Myth of Presidential Leadership.
  7. ^ Sidey, John F. Kennedy, pp. 117-118.
  8. ^ Beschloss, 'Kennedy and the Decision to Go to the Moon', p. 55.
  9. ^ "Discussion of Soviet Man-in-Space Shot," Hearing before the Committee on Science and Astronautics, U.S. House of Representatives, 87th Congress, First Session, April 13, 1961.
  10. ^ Sidey, John F. Kennedy, p. 114
  11. ^ Kennedy to Johnson, "Memorandum for Vice President," April 20, 1961.
  12. ^ a b Johnson to Kennedy, "Evaluation of Space Program," April 21, 1961.
  13. ^ NASA Langley Research Center's Contributions to the Apollo Program. NASA Langley Research Center.
  14. ^ John F. Kennedy,"Address at Rice University on the Nation's Space Effort"
  15. ^ Brooks, Grimwood and Swenson, Chariots for Apollo, p. 71.
  16. ^ a b Hansen, Enchanted Rendezvous, p 21
  17. ^ Hansen, Enchanted Rendezvous, p. 27.
  18. ^ Report of the Apollo 204 Review Board, Findings and Recommendations
  19. ^ Chariots for Apollo, Ch 7-4
  20. ^ Nasa Facts Online - Propellants
  21. ^ Saturn IB News Reference: Saturn IB Design Features
  22. ^ Saturn V News Reference: First Stage Fact Sheet
  23. ^ Murray and Cox, Apollo, pp. 145-51, 179-81.
  24. ^ Saturn V News Reference: Second Stage Fact Sheet
  25. ^ Saturn V News Reference: Third Stage Fact Sheet
  26. ^ Woods, W. David (2008). How Apollo Flew to the Moon. Springer Science+Business Media, p. 339. ISBN 978-0-387-71675-6.
  27. ^ Murray and Cox, Apollo, p. 238.
  28. ^ Murray and Cox, Apollo, p. 248.
  29. ^ See Neil Armstrong#First_Moon_walk for more information.
  30. ^ Apollo 13 - A Successful Failure
  31. ^ James Papike, Grahm Ryder, and Charles Shearer (1998). "Lunar Samples". Reviews in Mineralogy and Geochemistry 36: 5.1–5.234. 
  32. ^ Burrows, William E. (1999). This New Ocean: The Story of the First Space Age. Modern Library. p. 431. ISBN 0375754857. OCLC 42136309. 
  33. ^ 30th Anniversary of Apollo 11, NASA, 1999.
  34. ^ 30th Anniversary of Apollo 11. BBC, 23 July 1999.
  35. ^ NASA to boldly go... with Lockheed Martin - space - September 1, 2006 - New Scientist Space
  36. ^ Technology Review: Part Apollo, Part Boeing 787
  37. ^ NASA is borrowing ideas from the Apollo - USATODAY.com
  38. ^ Burrows, William E. (1999). This New Ocean: The Story of the First Space Age. Modern Library. p. 429. ISBN 0375754857. OCLC 42136309. 
  39. ^ http://www.nasa.gov/mission_pages/apollo/40th/
  40. ^ a b c d e "Houston, We Erased The Apollo 11 Tapes". National Public Radio, July 16, 2009.
  41. ^ a b Borenstein, Seth for AP. "NASA lost moon footage, but Hollywood restores it". Yahoo news, July 16, 2009.
  42. ^ Al Gore (2007-03-17). "An Inconvenient Truth Transcript". Politics Blog -- a reproduction of the film's transcript. http://forumpolitics.com/blogs/2007/03/17/an-inconvient-truth-transcript/. Retrieved 2007-07-29. 
  43. ^ a b "The Human Moon". The New York Times. 2009-11-16. http://www.nytimes.com/2009/11/17/opinion/17tue4.html. Retrieved 2009-11-19. 
  44. ^ Japan Aerospace Exploration Agency (2008-05-20). "The "halo" area around Apollo 15 landing site observed by Terrain Camera on SELENE(KAGUYA)". Press release. http://www.jaxa.jp/press/2008/05/20080520_kaguya_e.html. Retrieved 2009-11-19. 
  45. ^ "LRO Sees Apollo Landing Sites". NASA. 2009-07-17. http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/apollosites.html. Retrieved 2009-11-19. 
  46. ^ "Apollo Landing Sites Revisited". NASA. http://www.nasa.gov/mission_pages/apollo/revisited/index.html. Retrieved 2009-11-19. 
  47. ^ "Rules & Guidelines". X PRIZE Foundation. 2008-11-20. http://www.googlelunarxprize.org/lunar/about-the-prize/rules-and-guidelines. Retrieved 2009-11-19. 

References

Further reading

External links


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