On May 25, 1961, President John F. Kennedy, addressing a special session of Congress, threw down the gauntlet. He boldly challenged the assembled lawmakers: “I believe 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.” At the time of Kennedy's speech, the United States had accumulated exactly 15 minutes, 22 seconds of human spaceflight experience.

 
The huge, 363-foot-tall Apollo 11 space vehicle is launched from Pad A, Launch Complex 39.  Kennedy Space Centre, at 9:32 a.m. (EDT), July 16, 1969. Onboard the Apollo 11 were astronauts Neil A. Armstrong, commander; Michael Collins, command module pilot; and Edwin E. Aldrin, Jr., lunar module pilot.

Kennedy's proposal was daunting in its technical complexity, but by the late fall of 1961, according to Robert Gilruth, who had led the Apollo program at NASA's Manned Spacecraft Centre near Houston, the team had agreed on a lunar-orbit rendezvous. By the autumn of 1961, contracts had already been awarded to North American Aviation (later Rockwell) for the construction of the 34.5-foot (10.5-meter)-tall Apollo Command and Services Modules (CSM), the spacecraft that would carry three astronauts on their eight-day lunar voyage.

 
Apollo/Saturn 1B.

Rocket engineer Wernher von Braun, already at work since the late 1950s on a powerful new rocket named Saturn, began developing in January 1962 the largest launch vehicle ever to fly successfully, the 363-foot (111-meter)-tall three-stage Saturn 5, its rocket engines capable of producing 7.76 million pounds (34.5 million newtons) of thrust. The Saturn 5 would be preceded by the comparatively smaller Saturn 1 and its larger offspring, the Saturn 1B, standing 224-feet (68-meters) tall and capable of producing 1.64 million pounds (7.3 million Newtons) of thrust, to be used for un-crewed spacecraft testing and the first Earth-orbiting piloted Apollo missions.

The most significant disagreements involved the best method of going to the Moon. The “direct ascent” approach, which was quickly abandoned, involved a single launch of a massive rocket to fly directly to the Moon and land. The Earth-orbit-rendezvous, initially favoured by Von Braun and others at NASA, required launches of dual Saturn 5s that docked together in Earth orbit. Fuel would be pumped from one into the other, and the fully fuelled rocket would ignite on its mission to the Moon.

However, by early 1962, the radical lunar-orbit-rendezvous (LOR), championed by NASA engineer John C. Houbolt, was gaining popularity. LOR would require the launch of one Saturn 5 carrying a CSM and a separate lunar landing craft into Earth orbit. The CSM would dock with the landing craft, extract it from a protected compartment on the upper stage of the Saturn 5, and then fire an onboard engine to propel the combination to the Moon. The landing craft would separate and descend to the lunar surface carrying the astronauts. Following the lunar surface exploration, the upper portion of the lander would launch itself up to the orbiting CSM, dock so the astronauts could return to the CSM, and then be discarded before the CSM's return to Earth. After considerable debate, this approach was officially selected on July 30, 1962.

On November 7, 1962, NASA awarded a contract to Grumman Aircraft for the construction of the 23-foot (7-meter)-tall, spider-legged Lunar Module (LM), capable of carrying two astronauts to the Moon's surface and returning them to lunar orbit.

Project Apollo required construction of facilities to build the Saturn, and for mission control and astronaut training, as well as for design of the spacecraft and rockets. Four years of intensive effort and $800 million were spent to construct the immense Vehicle Assembly Building and Launch Complex 39 on Florida's Merritt Island (adjacent to Cape Canaveral) as well as the mission control and astronaut training facilities at the Manned Spacecraft Center (now the Johnson Space Centre) near Houston, Texas. 

On May 28, 1964, just three years after Kennedy's pledge, a Saturn 1 rocket lifted off from Cape Kennedy carrying the first Apollo into Earth orbit. Four more Saturn 1's were launched in 1964 and 1965 on additional CSM tests and carrying payloads to investigate the effects of micrometeoroids. A Saturn 1B carried the first operational Apollo CSM into orbit on February 26, 1966, followed by the first LM test flight on January 22, 1968.

Apollo's darkest hour occurred on January 27, 1967, during a routine ground test for Apollo 1, the first crewed Apollo mission. Astronauts Vigil “Gus” Grissom, Edward White, and Roger Chaffee were killed when a spark from an exposed wire ignited a firestorm in the pure oxygen atmosphere of the sealed spacecraft, asphyxiating all three astronauts within seconds.

 
Close-up view of the exterior of Apollo 012 Command Module at Pad 34 showing the effects of the intense heat of the flash fire that killed the prime crew of the Apollo/Saturn 204 mission. Astronauts Virgil I. Grissom, Edward H. White II, and Roger B. Chaffee lost their lives in the accidental fire.

After an almost 19-month flight hiatus, on October 11, 1968, a Saturn 1B rocket launched Apollo 7 with astronauts Walter Schirra, Donn Eisele, and Walter Cunningham on a successful test of the redesigned Apollo CSM.

The first crewed Saturn 5 flight lifted off on December 21, 1968, with the Apollo 8 spacecraft carrying astronauts Frank Borman, James Lovell, and William Anders on a three-day journey to the Moon. The three became the first humans to travel beyond the influence of Earth's gravity and view the Moon up close. On Christmas Eve 1968, they read from the book of Genesis while broadcasting live television images of the lunar surface to a worldwide audience.

Apollos 9 and 10 were launched in early 1969 to test equipment and practice procedures for the lunar mission. Apollo 9 astronauts James McDivitt, Russell Schweickart, and David Scott carried out an Earth orbital test of the CSM. Apollo 10 astronauts Thomas Stafford, John Young and Eugene Cernan flew a “dress rehearsal” of the first lunar landing mission, with Stafford and Cernan descending to within 50,000 feet (14,240 meters) of the Moon's surface.

Apollo 11 lifted off on the first expedition to explore another celestial body on July 16, 1969. After a three-day journey, astronauts Neil Armstrong and Edwin “Buzz” Aldrin undocked the Eagle from the CSM Columbia, piloted by Michael Collins, and descended to the lunar surface, softly landing on the Moon's Sea of Tranquility.

 
Astronaut Edwin E. Aldrin, Jr., lunar module pilot of the first lunar landing mission, poses for a photograph beside the deployed United States flag during an Apollo 11 Extravehicular Activity (EVA) on the lunar surface. The Lunar Module is on the left, and the footprints of the astronauts are clearly visible in the soil of the Moon, July 20, 1969.

On July 20, 1969, Armstrong planted the first human footprint on the Moon, declaring for posterity, “That's one small step for (a) man, one giant leap for mankind.” Armstrong and Aldrin spent about 2 hours exploring the lunar surface, deploying experiments, and collecting samples of rocks and soil. The dream had been accomplished, five months before the deadline set by President Kennedy.

Apollo 12 conducted the second human Moon landing in November 1969, as astronauts Charles “Pete” Conrad and Alan Bean landed on the Ocean of Storms, only 600 feet (183 meters) from the un-crewed Surveyor 3 spacecraft that had touched down 31 months earlier. Conrad and Bean conducted two “moonwalks,” or Extra-Vehicular Activities (EVAs), totalling about 7 hours on the lunar surface. Astronaut Richard Gordon piloted Apollo 12's CSM Yankee Clipper. 

Apollo 13 suffered a catastrophic explosion in a Service Module oxygen tank at about the midpoint of its lunar journey on April 13, 1970, but the three astronauts, James Lovell, Fred W. Haise, and John L. Swigert, safely returned to Earth through the heroic efforts of their ground support team in Houston. The lunar module remained attached to the CSM Odyssey and served as a lifeboat as the astronauts used its life support systems and rocket engine to limp back home.

Space pioneer Alan B. Shepard commanded the Apollo 14 mission to the Moon in February 1971. Stuart Roosa piloted the CSM Kitty Hawk. Shepard and Edgar Mitchell landed on the Moon's Fra Mauro region and spent almost ten hours working on the lunar surface during two EVAs.

The first lunar “automobile” was used on Apollo 15, during July-August 1971, as astronauts David Scott and James Irwin drove the battery-powered Lunar Roving Vehicle (or “rover”) during three EVAs along Hadley Rille, at the base of the Moon's Apennine Mountains. Scott and Irwin conducted three EVAs, totalling more than 18 hours on the lunar surface, as Alfred Worden orbited above in the Endeavour.

Apollo 16, in April 1972, made the second use of the lunar rover as astronauts John Young and Charles Duke explored the Moon's Descartes highlands, 18,000 feet (5,486 meters) above lunar “sea level.” Thomas Mattingly piloted the CSM Casper, and Young and Duke spent more than 20 hours exploring the lunar surface after making another pinpoint landing in the LM.

The final lunar expedition, Apollo 17 in December 1972, was also the most ambitious. Astronauts Eugene Cernan and Harrison “Jack” Schmitt, a geologist, landed in the Taurus-Littrow valley of the Moon's Sea of Serenity, only 300 feet from the target zone. Cernan and Schmitt spend about 22 hours on the lunar surface, driving almost 21 miles (34 kilometres) in their “rover” during three EVAs as astronaut Ronald Evans orbited above.

In all, 12 American astronauts left their footprints in the lunar soil during Project Apollo. Three additional lunar landing missions, Apollos 18 through 20, were cancelled after a series of congressional budget cuts even though the required hardware had already been constructed and paid for.

More than 842 pounds (382 kilograms) of lunar rock and soil were collected, sophisticated lunar surface experiment stations were deployed, and thousands of photographs were taken during the six lunar landing missions, yielding a wealth of scientific data that is still being analyzed today. Apollo's total cost (in 1968 dollars): $24 billion.

Apollo Test Flights and missions
Mission		Astronauts	Launch Landing1 Landing2	Highlights
Apollo 7		Walter M. Schirra, Jr. Donn F. Eisele Walter Cunningham	10/11/1968 10/22/1968	First manned Apollo mission to fly. Made 163 orbits of earth.
Apollo 8		Frank Borman James A. Lovell, Jr. William A. Anders	12/21/1968 12/27/1968	First occupied launch of Saturn V. Looped around moon on Christmas Eve.
Apollo 9		James A. McDivitt David R. Scott Russell R. Schweikart	3/03/1969 3/13/1969	First manned test of Lunar Module. Made 151 orbits of Earth.
Apollo 10		Thomas P. Stafford John W. Young Eugene A. Cernan	5/18/1969 5/26/1969	Orbited moon. Lunar Module dropped to within 9 miles of Lunar surface.
Apollo 11		Neil A. Armstrong Michael Collins Edwin E. "Buzz" Aldrin	7/16/1969 7/20/1969 7/24/1969	First Lunar landing. Landed on moon with less than 30 seconds of fuel remaining. Took core samples. Planted American flag.
Apollo 12		Charles "Pete" Conrad Richard F. Gordon, Jr. Alan L. Bean	11/14/1969 11/19/1969 11/24/1969	Struck by lightning during launch. Landed near, and returned parts of, old Surveyor 3 probe.
Apollo 13		James A. Lovell, Jr. Fred W. Haise, Jr. John L. Sweigert. Jr.	4/11/1970 4/17/1970	OK, Houston, we've had a problem here. O2 tank blew up; Used LM as a lifeboat which got them safely around moon and home.
Apollo 14		Alan B. Shepard, Jr. Edgar D. Mitchell Stuart A. Roosa	1/31/1971 2/03/1971 2/09/1971	Extensive scientific experiments. Astronauts almost got lost when lunar landscape became disorienting.
Apollo 15		David R. Scott James B. Irwin Alfred M. Worden	7/26/1971 7/30/1971 8/07/1971	First use of Lunar Rover. Astronauts rode over 27 kilometres. First Apollo space walk.
Apollo 16		John W. Young Thomas K. Mattingly II Charles M. Duke, Jr.	4/16/1972 4/20/1972 4/27/1972	Malfunction almost scrubbed landing. Stayed 3 days, got Lunar Rover up to almost 18 kph.
Apollo 17		Eugene A. Cernan Ronald E. Evans Harrison H. Schmitt	12/07/1972 12/11/1972 12/19/1972	Last men on the moon (so far).
Click on the red flight numbers for a detailed description of the mission