{{infobox |above

Apollo Program |image |caption |header1 |label1 Duration |data1 1961-1972 |header2 |label2 Goal |data2 "landing a man on the Moon and returning him safely to the Earth" |header3 |label3 Tasks |data3 Manned landing on the Moon, Scientific studies relating to the Lunar geology |header4 |label4 Losses |data4 * Apollo 1, cabin fire, loss of crew during launch rehearsal Apollo 6 (partial failure), engine cutoffs during ascent kept mission from accomplishing assigned goals Apollo 13 (partial failure), crippled spacecraft unable to land on the Moon as planned |header5 |label5 Organization |data5 NASA |header6 |label6 Spacecraft |data6 * Apollo CSM Lunar Module |header7 |label7 Launcher |data7 * Saturn IB Saturn V |header8 |label8 Legacy |data8 First manned landing on another celestial body |header9 |label9 |data9 |header10 |label10 |data10 }}

The Apollo program was the spaceflight effort carried out by the United States' National Aeronautics and Space Administration (NASA), that landed the first humans on Earth's Moon. Conceived during the Presidency of Dwight D. Eisenhower, Apollo began in earnest after President John F. Kennedy proposed the national goal of "landing a man on the Moon and returning him safely to the Earth" by the end of the 1960s in a May 25, 1961 address to Congress.

Kennedy's goal was accomplished with the Apollo 11 mission when astronauts Neil Armstrong and Buzz Aldrin landed their Lunar Module (LM) on the Moon on July 20, 1969 and walked on its surface while Michael Collins remained in lunar orbit in the command spacecraft, and all three landed safely on Earth on July 24. Five subsequent Apollo missions also landed astronauts on the Moon, the last in December 1972. In these six spaceflights, 12 men walked on the Moon.

Apollo ran from 1961 to 1972, following the Mercury and Gemini programs. It used Saturn family rockets as launch vehicles. Apollo / Saturn vehicles were also used for an Apollo Applications program which consisted of three Skylab space station missions in 1973–74, and a joint U.S.–Soviet mission in 1975.

Apollo was successful despite two major setbacks: the 1967 Apollo 1 cabin fire that killed the entire crew during a pre-launch test; and an in-flight failure on the 1970 Apollo 13 flight which disabled the command spacecraft's propulsion and life support, forcing the crew to use the Lunar Module as a "lifeboat" for these functions until they could return to Earth safely.

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 incidental to rocketry and manned spaceflight, including avionics, telecommunications, and computers. Apollo also sparked interest in many fields of engineering and left many physical facilities and machines developed for the program as landmarks. Its command modules and other objects and artifacts are displayed throughout the world, notably in the Smithsonian's Air and Space Museums in Washington, DC, Kennedy Space Center Visitor's Center in Florida, Space Center Houston in Houston, and the U.S. Space and Rocket Center in Alabama. The Apollo 13 Command Module is housed at the Kansas Cosmosphere and Space Center in Hutchinson, Kansas.

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 eventually to a lunar landing. The program was named after the Greek god of light, music, and the sun by NASA manager Abe Silverstein, who later said that "I was naming the spacecraft like I'd name my baby." Dr. Silverstein recalls he chose the name after perusing a book of mythology at home one evening, early in 1960. He thought that the image of "Apollo riding his chariot across the Sun was appropriate to the grand scale of the proposed program." While NASA went ahead with planning for Apollo, funding for the program was far from certain given Eisenhower's ambivalent attitude to manned spaceflight.

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." Despite Kennedy's rhetoric, he did not immediately come to a decision on the status of the Apollo program once he became 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. When Kennedy's newly appointed NASA Administrator James Webb requested a 30 percent budget increase for his agency, Kennedy supported an acceleration of NASA's large booster program but deferred a decision on the broader issue.

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 one day after Gagarin's flight, many congressmen pledged their support for a crash program aimed at ensuring that America would catch up. Kennedy, however, was circumspect in his response to the news, refusing to make a commitment on America's response to the Soviets.

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. Johnson responded approximately one week later, concluding that "we are neither making maximum effort nor achieving results necessary if this country is to reach a position of leadership." His memo concluded that a manned Moon landing was far enough in the future that it was likely the United States would achieve it first.

On May 25, 1961, Kennedy announced his support for the Apollo program during a special address to a joint session of Congress:

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

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.

It also required the conversion of the Space Task Group, which had been directing the nation's manned space program from NASA's Langley Research Center, into a new NASA center, the Manned Spacecraft Center (MSC), to be housed in a new facility built in Houston, Texas on land donated by Rice University. In September 1962, by which time two Project Mercury astronauts had orbited the Earth, and construction of the MSC facility was under way, Kennedy visited Rice to reiterate his challenge in a famous speech:

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 it while minimizing risk to human life, cost, and demands on technology and astronaut skill. Four possible mission modes were considered:

Direct Ascent: A spacecraft would travel directly to the Moon as a unit, land, and return leaving its landing stage on the Moon. This plan would have required a more powerful launch vehicle, the planned Nova rocket.

Earth Orbit Rendezvous (EOR): Multiple rockets (up to 15 in some plans) 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 excursion module would descend to the Moon and then return to dock with the command ship 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 viable 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.

Seamans' establishment of the Golovin committee in July 1961 represented a turning point in NASA's mission mode decision. 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 Langley Center (which was in process of transitioning to the newly formed Manned Spacecraft Center in Houston), began to come around to support for LOR. 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.''

The LOR method had the advantage of allowing the lander spacecraft to be used as a "life boat" in the event of a failure of the command ship. This happened on Apollo 13 when an oxygen tank failure left the command ship without electrical power. The Lunar Module provided propulsion, electrical power and life support to get the crew home safely.

Spacecraft

Preliminary design studies of Apollo spacecraft began in 1960 as a three-man command module supported by one of several service modules providing propulsion and electrical power, sized for use in various possible missions, such as: shuttle service to a space station, a circumlunar flight, or return to Earth from a lunar landing. Once the Moon landing goal became official, detailed design began of the Command/Service Module (CSM), in which the crew would spend the entire direct-ascent mission and lift off from the lunar surface for the return trip. (An even larger, separate propulsion module would have been required for the lunar descent.)

The final choice of lunar orbit rendezvous changed the CSM's role to a translunar ferry used to take the crew and a new spacecraft, the Lunar Module (LM), which would take two men to the lunar surface and return them to the CSM.

As the program concept evolved, use of the term "module" changed from its true meaning of an interchangeable component of systems with multiple variants, to simply a component of the complete lunar landing system.

Command/Service Module

The Command Module (CM) was the crew cabin, surrounded by a conical re-entry heat shield, designed to carry three astronauts from launch to lunar orbit and back to an Earth ocean splashdown. As such, it was the only component of the Apollo spacecraft to survive without major configuration changes as the program evolved from the early Apollo study designs. 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 cylindrical Service Module (SM), which housed the service propulsion engine and its propellants, the fuel cell power system, four maneuvering thruster quads, a high-gain S-band antenna for communications between the Moon and Earth, and storage tanks for water and oxygen. On the last three lunar missions, it also carried a scientific instrument package. Because its configuration was chosen early before the selection of lunar orbit rendezvous, the service propulsion engine was sized to lift the CSM off of the Moon, and thus oversized to about twice the thrust required for translunar flight.

As used in the actual lunar program, the two modules remained attached throughout most of the flight to make a single ferry craft known as the Command/Service Module (CSM), which carried a separate lunar lander (only half as heavy as the CSM) to the Moon, and the astronauts home to Earth. Just before re-entry, the Service Module was discarded and only the Command Module re-entered the atmosphere, using its heat shield to survive the intense heat caused by air friction. After re-entry it deployed parachutes that slowed its descent, allowing a smooth splashdown in the ocean.

Under the leadership of Harrison Storms, North American Aviation won the contract to build the CSM, and also the second stage of the Saturn V launch vehicle for NASA. Relations between North American and NASA were strained during the winter of 1965-66 by delivery delays, quality shortfalls, and cost overruns in both components. They were strained even more a year later when a cabin fire killed the crew of Apollo 1 during a ground test. The cause was determined to be an electrical short in the wiring of the Command Module; while the determination of responsibility for the accident was complex, the review board concluded that "deficiencies existed in Command Module design, workmanship and quality control." This eventually led to the removal of Storms as Command Module program manager.

Lunar Module

The Lunar Module (LM) (originally known as the Lunar Excursion Module, or LEM), was designed to fly between lunar orbit and the surface, landing two astronauts on the Moon and taking them back to the Command Module. It had no aerodynamic heat shield and was of a construction so lightweight that it would not have been able to fly through the Earth's atmosphere. It consisted of two stages, a descent and an ascent stage. The descent stage contained compartments which carried cargo such as the Apollo Lunar Surface Experiment Package and Lunar Rover.

The contract for design and construction of the Lunar Module was awarded to Grumman Aircraft Engineering Corporation, 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 a "pacing item," meaning that it was in danger of delaying the schedule of the whole Apollo program. The first manned LM was not ready for its planned Earth orbit test in December 1968, but the program was kept on schedule by canceling a second manned Earth orbit LM flight.

Launch vehicles

When the team of engineers led by Wernher von Braun began planning for the Apollo program, it was not yet clear how much payload capacity was required for a manned lunar landing. Sending the three-man Apollo Command Module directly to the lunar surface and back would require an extremely large launch vehicle, the Nova, which could send over to the Moon. NASA's decision to use the Lunar Orbit Rendezvous method eliminated the need for Nova and met the capability of the Saturn rocket family, so the Marshall Space Flight Center proceeded to develop the Saturn I, Saturn IB and Saturn V. While the Saturn V was less powerful than the Nova would have been, it still holds the record for largest payload capacity ( to LEO or ( to the Moon) of any rocket developed as of 2012. The closest comparable launch systems were the Energia ( to LEO) and the unsuccessful N1 ( to LEO), which the Soviet Union developed for manned lunar flight in competition with Apollo.

Saturn IB

The Saturn IB was an upgraded version of the earlier Saturn I rocket. It consisted of: An S-IB first stage powered by eight H-1 engines burning RP-1 with liquid oxygen (LOX) oxidizer, to produce of thrust; An S-IVB-200 second stage, powered by one J-2 engine burning liquid hydrogen fuel with LOX, to produce of thrust; and

An Instrument Unit which contained the rocket's guidance system.

The Saturn IB was capable of putting a partially fueled Command/Service Module, or a Lunar Module, into earth orbit. It was used in five of the Apollo test missions including the first manned mission. It was also used in the manned missions for the Skylab program and the Apollo-Soyuz Test Project.

Saturn V

The Saturn V was a three-stage rocket consisting of: An S-IC first stage, powered by five F-1 engines arranged in a cross pattern, burning RP-1 with LOX oxidizer to produce of thrust. They burned for 2.5 minutes, accelerating the spacecraft to a speed of approximately 6,000 miles per hour (2.68 km/s). An S-II second stage, powered by five of the J-2 engines used in the S-IVB. 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). An S-IVB-500 third stage similar to the Saturn IB's second stage, with capability to restart the J-2 engine. The engine would burn for approximately two and a half minutes and shut down when a low-Earth parking orbit was achieved. After approximately two orbits to confirm the spacecraft was ready to commit to the lunar trip, the engine was restarted to make the translunar injection maneuver taking the spacecraft into an extremely high orbit where it would be captured by the Moon's gravity.

An instrument unit with a guidance system similar to that used on the Saturn IB.

Three Saturn V vehicles launched on Earth orbital flights. Two of the three (Apollo 4 and 6) were unmanned tests of the command and service modules, and the third was a manned flight, Apollo 9, testing the lunar module. Nine Saturn Vs launched manned Apollo missions to the Moon, including Apollo 11. It was also used for the unmanned launch of Skylab.

Missions

Unmanned missions

Apollo required more than six years of spacecraft and launch vehicle development and testing before the first manned missions could be flown. Test flights of the Saturn I launch vehicle began in October 1961 and lasted until September 1964. Three further Saturn I launches carried boilerplate models of the Apollo Command/Service Module (CSM). 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 (in their chronological order of launch) as AS-201, AS-203, and AS-202. According to original plan the first CSM manned orbital mission AS-204, called Apollo 1, should be after two unmanned suborbital flights of CSM (AS-201 and AS-202). Then AS-205 CSM manned orbital and AS-206 LM (the Apollo Lunar Module) unmanned flights followed by dual AS-278 mission of AS-207 CSM and AS-208 LM (started on Saturn IB separately for docking) were scheduled. Later AS-205 mission was canceled, AS-278 dual mission was reassigned as AS-258 and AS-278 CSM+LM common manned mission on Saturn V was planned.

Due to pre-launch fire of Apollo 1 and death of its crew, the manned missions were postponed and more unmanned missions were added for Apollo improvements. The only unmanned missions to be publicly designated as "Apollo" followed by a sequence number were Apollo 4, Apollo 5 and Apollo 6. The simple numbering was started at "4" to follow the three Apollo-Saturn IB flights (AS-201 to AS-202), though all subsequent flights kept the "AS" designations: AS-204 (redesigned from AS-206) and following for Saturn IB flights, and AS-501 and following for Saturn V flights.

File:Apollo-launches.png|500px|thumb|right|alt=Apollo launches, 1-6: unmanned, 7-17: manned|Apollo launches, 1-6: unmanned, 7-17: manned (Click on image to read about mission) rect 0 0 91 494 AS-201 rect 92 0 181 494 AS-203 rect 182 0 270 494 AS-202 rect 271 0 340 494 Apollo 4 rect 341 0 434 494 Apollo 5 rect 435 0 494 494 Apollo 6 rect 495 0 590 494 Apollo 7 rect 591 0 655 494 Apollo 8 rect 656 0 723 494 Apollo 9 rect 724 0 795 494 Apollo 10 rect 796 0 860 494 Apollo 11 rect 861 0 930 494 Apollo 12 rect 931 0 1000 494 Apollo 13 rect 1001 0 1071 494 Apollo 14 rect 1072 0 1130 494 Apollo 15 rect 1131 0 1200 494 Apollo 16 rect 1201 0 1270 494 Apollo 17

Apollo 4 (AS-501) was the first unmanned test flight of the Saturn V launch vehicle, carrying a CSM. 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. 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. 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. The mission was a highly successful one, demonstrating the capability of the Command Module's heat shield to survive a trans-lunar return reentry by using the Service Module engine to ram it into the atmosphere at higher than the usual earth-orbital reentry speed.

Apollo 5 (AS-204) was the first unmanned test flight of LM in Earth orbit, launched on January 22, 1968, by a Saturn IB. The critical LM engines were successfully tested (though a computer programming error cut one test firing short), including an in-flight test of the second stage engine in "abort mode," in which the ascent engine is fired simultaneously with the jettison of the descent stage. This capability was made available, only to be used in the event of a critical problem on the Moon landing, such as running out of descent fuel, but was never needed.

Apollo 6 (AS-502) was the last unmanned Saturn V flight, launched on April 4, 1968. It carried a CSM and a LM Test Article near the mass of the Lunar Module for ballast. It was planned to achieve translunar injection, then after 5 minutes, use the Service Module engine to return the CM to Earth, thus demonstrating the Saturn V's ability to send the Apollo craft to the Moon, and a direct return-to-Earth abort capability. However, "pogo" vibrations caused premature shutdown of two second-stage engines, and failure of the third stage to re-light for the translunar injection. Instead, the Service Module engine was used as in Apollo 4 to raise the craft to a higher Earth orbit, and bring the CM back at a velocity midway between that of low Earth orbit and lunar return velocity. This mission was considered successful enough to launch men on the next Saturn V flight, since fixes for the vibration problem were identified.

Manned missions

The manned missions carried three astronauts, designated as Commander (CDR), Command Module Pilot (CMP), and Lunar Module Pilot (LMP). Besides exercising all crew command decisions, the Commander was the primary pilot of both spacecraft (when present) and was first to exit the LM on the surface of the Moon. The CMP functioned as navigator, usually performed the initial docking with the LM, and remained in the Command/Service Module when his companions flew the LM. The LMP functioned as engineering officer, monitoring the systems of both spacecraft. On a landing mission, he accompanied the Commander on the lunar surface. On the last flight, the LMP was a professional geologist, Dr. Harrison Schmitt.

The first planned manned mission was an Earth orbital test of the Block I CSM launched with a Saturn IB was designated AS-204, or Apollo 1, originally planned for late in 1966, but plagued by delays until February 21, 1967. A second Block I CSM orbital flight, AS-205, was originally planned but canceled in late 1966. The next manned mission was planned as a dual launch of the Block II CSM (originally AS-207, then changed to AS-205) with AS-208 launching an unmanned LM to which the astronauts in the CSM would dock. This mission was first designated AS-258, and later as AS-278. This would be followed by the first manned launch of both spacecraft on a Saturn V in a high Earth orbital test.

These plans had to be revised after the January 27, 1967 fire which killed the Apollo 1 crew in a pre-launch test. Manned flight of the Block I CSM was canceled, and the program concentrated on unmanned testing of the Saturn V and LM while safety improvements were made to the Block II CSM which would be used exclusively in manned flight. The AS-278 mission was revised to use a Saturn V in a single launch instead of two Saturn IBs.

Apollo 7, launched on October 11, 1968, was the first manned mission in the program. It was an 11-day Earth-orbital flight intended to test the CSM as in former planned AS-204 Apollo 1 mission. It was the first manned launch of the Saturn IB launch vehicle and the first three-man American space mission.

Between December 21, 1968 and May 18, 1969, NASA planned to launch three manned test/practice missions using the Saturn V launch vehicle and the complete spacecraft including the LM. But by the summer of 1968 it became clear to program managers that a fully functional LM would not be available for the Apollo 8 launch. Rather than waste the Saturn V on another simple Earth-orbiting mission, they chose to send the crew planned to make the second orbital LM test in Apollo 9, to orbit the Moon in the CSM on Apollo 8 during Christmas. The original idea for this switch was the brainchild of George Low, Manager of the Apollo Spacecraft Program Office. 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 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. The Apollo 8 decision was primarily based upon the LM schedule, not fear of the Soviets beating the Americans to the Moon. Soviets undertook partially successful unmanned Zond 5 and Zond 6 missions and could near December, 8 but have not decided to launch almost ready manned Zond mission before Apollo 8.

This was followed by the first orbital manned LM flight on Apollo 9 (as former planned AS-278 mission and with the original Apollo 8 crew), and the lunar "dress rehearsal" Apollo 10 which took the LM to within of the surface, but did not land. The first landing was achieved on Apollo 11 on July 20, 1969.

Apollo 12 made a precision landing near the Surveyor 3 unmanned lunar probe, which had landed in April 1967. 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.

Astronauts

Forty-one astronauts were assigned to fly Apollo spacecraft; thirty-two of them were part of the Apollo program, with the rest not flying until the subsequent Skylab and Apollo-Soyuz programs. Twenty-four of the Apollo program astronauts left Earth’s orbit and flew around the Moon (Apollo 7 and Apollo 9 did not leave low Earth orbit).

Twelve of these astronauts walked on the Moon’s surface, and six of those drove a lunar rover on the Moon. While three astronauts flew to the Moon twice, none of them landed on the Moon more than once. The nine Apollo missions to the moon occurred between December 1968 and December 1972.

Apart from these twenty-four people who visited the Moon, no human being has gone beyond low Earth orbit. They have, therefore, been farther from the Earth than anyone else. They are also the only people to have directly viewed the far side of the Moon. The twelve who walked on the Moon are the only people ever to have set foot on an astronomical object other than the Earth. Of the twenty-four lunar astronauts taking part in the Moon missions, two went on to command a Skylab mission, one commanded Apollo-Soyuz, one flew as commander for shuttle approach and landing tests and two went on to command orbital shuttle missions. A total of twenty-four Apollo-era astronauts (as well as pre-Apollo astronaut John Glenn) flew the space shuttle.

Capsule Communicator

Mission rules specified that, in most circumstances, only one person in the Mission Control Center would communicate directly with the in-flight crew; this was to be another astronaut, who would be best able to understand the situation in the spacecraft and communicate with the crew in the clearest way. These individuals were designated ''Capsule Communicators'' or CAPCOMs, a term carried over from the Mercury and Gemini programs. They were usually chosen from the backup and support crews, and worked in shifts during long missions. The periodic ''beeps'' heard during communications with the astronauts are known as Quindar tones.

Samples returned

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

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. 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 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 near 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.

Program costs and cancellation

When President Kennedy first chartered the Moon landing program, a preliminary cost estimate of $7 billion was generated, but this proved an extremely unrealistic guess of what could not possibly be determined precisely, and James Webb used his administrator's judgment to change the estimate to $20 billion before giving it to Vice President Johnson.

Webb's estimate shocked many at the time (including the President), but ultimately proved to be reasonably accurate. In January 1969, NASA prepared an itemized estimate of the combined cost of the Mercury, Gemini and Apollo programs. The total for Apollo came to $23.9 billion, itemized as follows:

Apollo spacecraft: $7,945.0 million

Saturn I launch vehicles: $767.1 million

Saturn IB launch vehicles: $1,131.2 million

Saturn V launch vehicles: $6,871.1 million

Launch vehicle engine development: $854.2 million

Mission support: $1,432.3 million

Tracking and data acquisition: $664.1 million

Ground facilities: $1,830.3 million

Operation of installations: $2,420.6 million

The final cost of project Apollo was reported to Congress as $25.4 billion in 1973. It took up the majority of NASA's budget while it was being developed. For example, in 1966 it accounted for about 60 percent of NASA's total $5.2 billion budget.

In 2009, NASA held a symposium on project costs which presented an estimate of the Apollo program costs in 2005 dollars as roughly $170 billion. This included all research and development costs; the procurement of 15 Saturn V rockets, 16 Command/Service Modules, 12 Lunar Modules, plus program support and management costs; construction expenses for facilities and their upgrading, and costs for flight operations. This was based on a Congressional Budget Office report, ''A Budgetary Analysis of NASA’s New Vision for Space'', September 2004. ''The Space Review'' estimated in 2010 the cost of Apollo from 1959 to 1973 as $20.4 billion, or $109 billion in 2010 dollars. Each lunar landing thus cost $18 billion in 2010 dollars.

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 on Merritt Island, 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.

Apollo Applications Program

Following the success of the Apollo program, both NASA and its major contractors investigated several post-lunar applications for Apollo hardware. The Apollo Extension Series, later called the Apollo Applications Program, proposed up to 30 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 and the Apollo–Soyuz Test Project.

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, and the station itself re-entered the atmosphere in 1979, by which time it had become the oldest operational Apollo-Saturn component.

The Apollo-Soyuz Test Project involved a docking in Earth orbit between a CSM and a Soviet Soyuz spacecraft from July 15 to July 24, 1975. NASA's next manned mission would not be until STS-1 in 1981.

Recent observations

In 2008, Japan Aerospace Exploration Agency's SELENE probe observed evidence of the halo surrounding the Apollo 15 lunar module blast crater while orbiting above the lunar surface. In 2009, NASA's robotic Lunar Reconnaissance Orbiter, while orbiting above the moon, photographed the remnants of the Apollo program left on the lunar surface, and photographed each site where manned Apollo flights landed.

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

Proposed future lunar landing missions, such as the Google Lunar X Prize, intended to record close-up images of the Apollo Lunar Modules and other artificial objects on the surface.

Legacy

Science and engineering

The Apollo program, specifically the lunar landings, has been called the greatest technological achievement in human history. 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.

Cultural impact

The crew of Apollo 8, the first manned spacecraft to orbit the Moon, sent televised pictures of the Earth and the Moon back to Earth (left), and read from the creation story in the Biblical book of Genesis, on Christmas Eve, 1968, This was believed to be the most widely watched television broadcast until that time. The mission and Christmas provided an inspiring end to 1968, which had been a bad year for the U.S., marked by Vietnam War protests, race riots, and the assassinations of civil rights leader Martin Luther King and Senator Robert Kennedy.

An estimated one-fifth of the population of the world watched the live transmission of the first Apollo moonwalk.

One legacy of the Apollo program is the now-common view of Earth as a fragile, small planet, captured in photographs taken by the astronauts during the lunar missions. The most famous, taken by the Apollo 17 astronauts, is The Blue Marble (right). These photographs have also motivated some people toward environmentalism.

Many astronauts and cosmonauts have commented on the profound effects that seeing Earth from space has had on them; the 24 astronauts who traveled to the Moon are the only humans to have observed Earth from beyond low Earth orbit, and have traveled farther from Earth than anyone else to date.

The program succeeded in accomplishing one of President Kennedy's goals, which was to take on the Soviet Union in the space race and beat it by accomplishing a singular and significant achievement and thereby showcase the superiority of the capitalistic, free-market system as represented by the US. ''The Economist'' noted, however, the irony that in order to achieve the goal the Apollo program was successful by organizing tremendous public resources within a vast, centralized bureaucracy under government direction.

Apollo 11 broadcast data restoration project

As part of Apollo 11's 40th anniversary in 2009, NASA spearheaded an effort to digitally restore the existing videotapes of the mission's live televised moonwalk. After an exhaustive three-year search for missing tapes of the original video of the Apollo 11 moonwalk, NASA concluded the data tapes had more than likely been accidentally erased.

The Moon landing data was recorded by a special Apollo TV camera which recorded in a format incompatible with 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 following years, 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 try to locate the missing tapes.

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. The video was processed to remove random noise and camera shake without destroying historical legitimacy. The images were from tapes in Australia, the CBS News archive, and kinescope recordings made at Johnson Space Center. The restored video, remaining in black and white, contains conservative digital enhancements and did not include sound quality improvements.

Documentaries

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

''Moonwalk One'' (1970)

''For All Mankind'' (1989)

''Moon Shot'' (documentary commemorating 25 years since the landings) (1994)

''From the Earth to the Moon (TV miniseries)'' (1998)

''Moon'' from the BBC miniseries ''The Planets'' (1999)

''Magnificent Desolation: Walking on the Moon 3D (2005)

''In the Shadow of the Moon'' (2007)

''When We Left Earth: The NASA Missions (miniseries) (2008)

''James May on the Moon (documentary commemorating 40 years since the landings) (2009)

''NASA's Story''

See also

Apollo 1 - unflown mission

Apollo 11 flight to the Moon

Apollo 18, Apollo 19, Apollo 20 - canceled missions

Apollo TV camera

AS-201, AS-202, AS-203, Apollo 4, Apollo 5, Apollo 6 - unmanned missions

List of man-made objects on the Moon

List of megaprojects

Lockheed Propulsion Company

Pad Abort Tests

Soviet manned lunar programs

Splashdown (spacecraft landing)

Notes

References

"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.

Further reading

Chaikin, Andrew. ''A Man on the Moon''. ISBN 0-14-027201-1. Chaikin interviewed all the surviving astronauts and others who worked with the program.

Collins, Michael. ''Carrying the Fire; an Astronaut's journeys''. Astronaut Mike Collins autobiography of his experiences as an astronaut, including his flight aboard Apollo 11

Cooper, Henry S. F. Jr. ''Thirteen: The Flight That Failed''. ISBN 0-8018-5097-5. Although this book focuses on Apollo 13, it provides a wealth of background information on Apollo technology and procedures.

French, Francis and Burgess, Colin, ''In the Shadow of the Moon: A Challenging Journey to Tranquility, 1965-1969.'' ISBN 978-0-8032-1128-5. History of the Apollo program from Apollo 1-11, including many interviews with the Apollo astronauts.

Kranz, Gene, ''Failure is Not an Option''. Factual, from the standpoint of a flight controller during the Mercury, Gemini, and Apollo space programs. ISBN 0-7432-0079-9.

Lovell, Jim; Kluger, Jeffrey. ''Lost Moon: The perilous voyage of Apollo 13'' aka ''Apollo 13: Lost Moon''. ISBN 0-618-05665-3. Details the flight of Apollo 13.

Orloff, Richard W. SP-4029 ''Apollo by the Numbers: A Statistical Reference''

Pellegrino, Charles R.; Stoff, Joshua. ''Chariots for Apollo: The Untold Story Behind the Race to the Moon''. ISBN 0-380-80261-9. Tells Grumman's story of building the Lunar Modules.

Scott, David, and Alexei Leonov. ''Two Sides of the Moon: The Story of the Cold War Space Race''. New York: St. Martin's, 2006. (ISBN 0312308663)

Robert C. Seamans, Jr. ''Project Apollo: The Tough Decisions''. ISBN 0-1607-4954-9. History of the manned space program from September 1, 1960 to January 5, 1968.

Slayton, Donald K.; Cassutt, Michael. ''Deke! An Autobiography''. ISBN 0-312-85918-X. Account of Deke Slayton's life as an astronaut and of his work as chief of the astronaut office, including selection of Apollo crews.

From origin to November 7, 1962 November 8, 1962 - September 30, 1964 October 1, 1964 - January 20, 1966 January 21, 1966 - July 13, 1974

Wilhelms, Don E. ''To a Rocky Moon''. ISBN 0-8165-1065-2. The history of lunar exploration from a geologist's point of view.

External links

Official Apollo program web page

Apollo photo gallery at NASA Human Spaceflight page (includes videos/animations)

Audio recording and transcript of President John F. Kennedy, NASA administrator James Webb ''et al.'' discussing the Apollo agenda (White House Cabinet Room, November 21, 1962)

U.S. Spaceflight History- Apollo Program

Apollo Image Atlas almost 25,000 lunar images, Lunar and Planetary Institute

Project Apollo at NASA History Division

The Apollo Lunar Surface Journal

How Apollo Has Influenced Society

The Apollo Flight Journal

Project Apollo Drawings and Technical Diagrams

Apollo Program Summary Report (Technical)

The Apollo Program (National Air and Space Museum)

Apollo 35th Anniversary Interactive Feature (in Flash)

Exploring the Moon: Apollo Missions

Apollo Archive - large repository of information about the Apollo program.

Apollo Flight Film Archive - repository of scanned Apollo flight film (in high resolution).

NASA History Series Publications (many of which are on-line)

Apollo's Contributions to Society

Category:Human spaceflight programmes Category:Apollo program Category:Exploration of the Moon Category:Engineering projects Category:1960s in the United States Category:1970s in the United States

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Name	Harold Chestnut
Birth date	November 25, 1917
Birth place	Albany, New York
Death date	August 29, 2001
Death place	Schenectady, New York
Residence	United States
Citizenship	American
Fields	Control theory
Awards	Richard E. Bellman Control Heritage Award
Footnotes	}}

Harold (Hal) Chestnut (25 November 1917 – 29 August 2001) was an American electrical engineer, who contributed to the development of the fields of control theory and systems engineering.

Biography

Harold Chestnut was born in 1917 in Albany, New York. He studied electrical engineering at MIT and received a B.S. degree in 1939 and a M.S. degree in 1940. In that same year he began a life-long career with the General Electric Company, which would last until his retirement in 1983. He married his wife Erma Ruth Callaway Chestnut in 1944 and they had three sons.

During the Second World War Chestnut was both a student and an instructor in General Electric's well-known Advanced Engineering Program. He worked on the design of the central fire-control system and remotely controlled gunturrets used on the B-29 aircraft. Later he worked in the Aeronautics and Ordnance Department and the Systems Engineering and Analysis branch of the Advanced Technology Laboratory, where he served as manager from 1956 to 1972. Here he worked on a wide variety of technical problems including reliability issues in rapid transit and the Apollo mission to the moon. Later in his career he returned to the field of electric power. This time the focus was power systems automation.

From 1957 to 1959 he was the first president of the International Federation of Automatic Control (IFAC). After his term as president he chaired the technical board, from 1961 to 1966 and the Systems Engineering technical committee for another three years. He served as honorary editor from 1969 to 1972 and was the first advisor appointed for life in 1984. Chestnut was also involved in the IEEE since its establishment in 1963 and served as president in 1973. He was active in the formation of the IEEE History Center and the International Federation of Automatic Control.

In 1961 Chestnut edited Automatica: The International Journal on Automatic Control and Automation. He also became editor of a John Wiley book series on systems engineering and analysis. In this series Chestnut published his own books.

In the 1980s and 1990s after retirement he created the "Supplemental Ways of Improving International Stability (SWIIS) Foundation" to identify and implement "supplemental ways to improve international stability". He devoted those years to this effort in which he applied principles from the control field, such as stability and feedback, to international political realities.

Harold Chestnut received many awards: In 1966 he received an Honorary Doctorate in engineering from Case Western Reserve University and in 1972 from Villanova University. In 1984 he won the IEEE Centennial Medal and in 1985 the AACC Bellman Heritage Award. Chestnut further in 1981 received the prestigious Honda Prize for ecotechnology, with it a substantial financial award from the Japan’s Honda Foundation. He was further a Fellow of the AIEE, ISA, and AAAS. He was elected to the US National Academy of Engineering in 1974 and selected as a Case Centennial Scholar in 1980.

In 1998 Harold Chestnut and the Chestnut Family provided a gift to IFAC for the IFAC Textbook Prize. The income from this generous gift is used to fund the award for an outstanding textbook author recognized at each IFAC Congress.

Chestnut died in 2001 in Schenectady, New York, aged 83.

Work

Harold Chestnut worked in the fields of control, control theory and systems engineering.

Publications

Harold Chestnut published several articles and books, including:

1951. ''Servomechanisms and Regulating Systems Design''. Vol. 1, with R.W. Mayer, Wiley.

1955. ''Servomechanisms and Regulating Systems Design''. Vol. 2, with R.W. Mayer, Wiley.

1965. ''Systems Engineering Tools''. Wiley.

1967. ''Systems Engineering Methods''. Wiley.

Articles:

1970. "Information requirements for systems understanding". In: ''IEEE Trans. Syst. Sci. Cybern.''. Vol. SSC-6. pp. 3–12, Jan. 1970.

See also

Automatic control

Systems engineering

References

Further reading

Stephen Kahne (2002). "Harold Chestnut, First IFAC President", in ''Automatica'', June 2002, Volume 38, No. 6

U. Luoto et al. (1978). "20 Years Old; 20 years Young", in ''AUTOMATICA'', Vol. 14, pp 49–75, 1978

''In memoriam - Harold Chestnut (1918-2001)'', in: ''Control Systems Magazine, IEEE'', Volume 22, Issue 2, Apr 2002 pp 87–87

"In memoriam—Harold Chestnut". In: ''IEEE the current source'', Vol 28, no 1, April 2002

External links

IFAC homepage

Harold Chestnut Control Engineering Textbook Prize

Category:American electrical engineers Category:Control theorists Category:Systems engineers Category:Richard E. Bellman Control Heritage Award recipients Category:IEEE Centennial Medal laureates Category:Massachusetts Institute of Technology alumni Category:1917 births Category:2001 deaths

nl:Harold Chestnut