Between May 1961 and December 1972, the United States spent roughly $25.4 billion (about $257 billion in 2020 dollars, per a NASA-commissioned inflation study by Robert L. Harris) to send 27 astronauts around or onto the Moon. Three of them died on the way. The first time any human set foot on another world, the United States was carrying out a program that had not existed eight years earlier.
The Kennedy Commitment
On April 12, 1961, the Soviet Union put Yuri Gagarin in orbit. Six weeks later, on May 25, 1961, Kennedy addressed a joint session of Congress and asked for an additional $531 million in fiscal 1962, with the explicit goal of “landing a man on the Moon and returning him safely to the Earth before this decade is out.” The Special Message to the Congress on Urgent National Needs is the founding document of the Apollo program, and Kennedy’s reasoning is preserved in the record that John Logsdon reconstructed in The Decision to Go to the Moon (1970) and updated in John F. Kennedy and the Race to the Moon (2010).
The stated reasoning was prestige and security. “If we are to win the battle that is now going on around the world between freedom and tyranny,” Kennedy said, the “dramatic achievements in space” of the Soviet Union “have been impressive.” The unstated reasoning was that the Soviets would probably win any other race the United States could pick; the National Security Council had concluded in April 1961 that the lunar goal was the only one the United States could plausibly achieve first.
Kennedy did not live to see Apollo 11. He was assassinated on November 22, 1963, less than three years after his commitment speech. The program continued under Lyndon Johnson and Richard Nixon, with James Webb running NASA from 1961 to 1968.
Building the Hardware
The Saturn V was developed at the Marshall Space Flight Center in Huntsville, Alabama, under Wernher von Braun. The rocket stood 110.6 m tall, weighed 2,950 metric tons fully fueled, and produced 34 meganewtons (7.6 million pounds-force) of liftoff thrust from five F-1 engines, the most powerful single-chamber liquid-fueled engine ever flown. The first successful Saturn V flight was Apollo 4 on November 9, 1967; the rocket flew 13 times between 1967 and 1973 without a failure.
The Apollo spacecraft consisted of three modules. The Command Module, built by North American Aviation, was a conical crew cabin with a 3.9 m base. The Service Module, also built by North American, provided propulsion, electrical power from fuel cells, and consumables for the round trip. The Lunar Module, built by Grumman, was a two-stage vehicle with no aerodynamic surfaces, designed to operate only in vacuum, with a descent stage that became the launch platform for the ascent stage.
Mission Control in Houston (the Manned Spacecraft Center, now the Lyndon B. Johnson Space Center) was built in 1962–63 with the help of an unusual partnership with the U.S. Air Force, which supplied early warning radar and tracking data. The Manned Space Flight Network used 17 ground stations on three continents. The onboard guidance computer, the Apollo Guidance Computer built at MIT’s Instrumentation Laboratory, ran at 0.043 MHz with 2 KB of RAM and 36 KB of ROM. The program was the work of roughly 400,000 people across NASA, the Air Force, and a network of contractors led by North American Aviation, Grumman, and Boeing.
The Path to Apollo 11
Project Mercury (1958–1963) put six Americans in space, beginning with Alan Shepard’s 15-minute suborbital hop on May 5, 1961. Project Gemini (1964–1966) developed the techniques Apollo required: orbital rendezvous, extravehicular activity, and long-duration spaceflight up to nearly 14 days. Gemini also produced the first American spacewalk (Ed White, June 3, 1965) and the first rendezvous of two spacecraft (Gemini 6A and Gemini 7, December 1965).
On January 27, 1967, during a plugs-out test on the launch pad at Cape Kennedy, a fire broke out in the pure-oxygen cabin of the Command Module. Astronauts Gus Grissom, Ed White, and Roger Chaffee died of smoke inhalation; the inward-opening hatch prevented their escape. The Apollo 1 fire set the program back about 20 months and forced a complete redesign of the Command Module — a 60/40 oxygen–nitrogen cabin atmosphere, an outward-opening hatch, fire-resistant materials, and stricter wiring. The benefit was a spacecraft that did not kill its crew in 12 subsequent crewed missions.
Apollo 7, the first redesigned Block II crewed mission, flew in October 1968 with Schirra, Eisele, and Cunningham. Apollo 8, in December 1968 with Borman, Lovell, and Anders, was the first crewed mission to leave Earth orbit and the first to enter lunar orbit. The decision to send Apollo 8 to the Moon was made in August 1968 by George Low and Robert Gilruth in part to catch up to the Soviet Zond program’s circumlunar flights, and in part because the Lunar Module was not ready. The Apollo 8 crew’s Christmas Eve broadcast from lunar orbit was the most-watched television program to that date.
Apollo 9 tested the Lunar Module in Earth orbit in March 1969. Apollo 10, in May 1969, did a full dress rehearsal of the landing, with Tom Stafford and Gene Cernan flying the Lunar Module to within 15.6 km of the lunar surface before separating and returning to John Young in the Command Module.
The Landing
Apollo 11 launched from Pad 39A at the Kennedy Space Center at 13:32 UTC on July 16, 1969. Neil Armstrong, Michael Collins, and Buzz Aldrin entered lunar orbit on July 19. At 17:44 UTC on July 20, the Lunar Module Eagle, with Armstrong and Aldrin aboard, separated from the Command Module Columbia.
The landing was not routine. The automated descent was taking Eagle into a boulder field west of the chosen site in the Sea of Tranquility. At an altitude of about 100 m, Armstrong took manual control and flew the Lunar Module downrange to a smoother area, burning fuel budgeted for the post-landing stay. The Low Fuel Warning light came on at 20:05 UTC, with the engine still running; Eagle touched down at 20:17 UTC on July 20, 1969, with less than 30 seconds of usable fuel remaining. Armstrong’s first words from the surface were, “Houston, Tranquility Base here. The Eagle has landed.”
Armstrong stepped onto the surface at 02:56 UTC on July 21 (10:56 p.m. Eastern Daylight Time on July 20), and the words, “That’s one small step for [a] man, one giant leap for mankind,” were broadcast to an estimated 650 million viewers worldwide. The “a,” which would have changed the meaning, was lost in the radio transmission; Armstrong insisted afterward that he had said it. Aldrin joined him 19 minutes later. The two astronauts spent 2 hours and 31 minutes outside the Lunar Module, deploying a passive seismometer and a laser retroreflector, collecting 21.5 kg of lunar samples, and planting a U.S. flag.
Eagle’s ascent stage lifted off at 17:54 UTC on July 21, and the three astronauts splashed down in the Pacific Ocean at 16:50 UTC on July 24, 1969.
After Apollo 11
Five more Apollo missions landed on the Moon. Apollo 12 (November 1969) made a precision landing near the Surveyor 3 probe, which had been on the surface since April 1967. Apollo 13 (April 1970) was the only crewed mission to fail its primary objective: an oxygen tank explosion in the Service Module forced the crew to use the Lunar Module as a “lifeboat.” The successful return of Lovell, Swigert, and Haise earned the mission the “successful failure” label.
Apollo 14 (January 1971) returned to the Fra Mauro site that Apollo 13 had been targeting, with Alan Shepard as commander. Apollo 15, 16, and 17 (1971–72) were the J-missions, with extended stays, the Lunar Roving Vehicle, and a much heavier emphasis on geological science. Apollo 17 was the last crewed lunar landing; the crew included Harrison Schmitt, the only professional geologist to walk on the Moon.
The program’s end was political, not technical. The Nixon administration canceled Apollos 18, 19, and 20 in September 1970 to keep NASA funding at a level that would not crowd other programs, including the Space Shuttle. The Saturn V production line was shut down; the tooling was destroyed.
Key sources
- John M. Logsdon, The Decision to Go to the Moon: Project Apollo and the National Interest (MIT Press, 1970); updated as John F. Kennedy and the Race to the Moon (Palgrave Macmillan, 2010)
- W. Henry Lambright, Powering Apollo: James E. Webb of NASA (Johns Hopkins, 1995)
- Asif A. Siddiqi, Challenge to Apollo: The Soviet Union and the Space Race, 1945–1974 (NASA SP-2000-4408, 2000) for the Soviet lunar effort
- NASA Mission Reports for Apollo 11 (SP-238), Apollo 13 (SP-400), and the Apollo Program Summary Report (JSC-09423)