Apollo Program Summary

  • Last updated on November 10, 2022

American project to land humans on the Moon.

The Program’s Beginnings

In 1960, planners at the National Aeronautics and Space Administration (NASA) selected a crewed lunar landing as the follow-up to the Mercury effort to place a man in Earth orbit. In December, 1960, just before leaving office, President Dwight D. Eisenhower advised NASA officials that he would not approve the lunar landing project. However, after the Soviets sent Yuri A. Gagarin into Earth orbit in April, 1961, the new U.S. president, John F. Kennedy, announced on May 25, 1961, the plan “before this decade is out, of landing a man on the Moon and returning him safely to the earth.” The project to accomplish Kennedy’s objective was named Apollo.

The Apollo Spacecraft

To launch Apollo, NASA designed and built a huge, three-stage rocket, the Saturn V, which stood 363 feet tall and developed 7.5 million pounds of thrust at liftoff. In order to minimize the weight of the spacecraft, the Apollo engineers planned a lunar orbit rendezvous technique, requiring the Apollo spacecraft to have a modular design, consisting of three separate units, the Command Module, the Service Module, and the Lunar Module.

The Command Module, built by North American Rockwell, served as the control center for the spacecraft and provided 210 cubic feet of living and working space for the astronauts. It was designed to carry three astronauts from the earth to an orbit around the Moon and back. It was shaped like a cone, with a height of 10 feet 7 inches, a maximum diameter of 12 feet and 10 inches, and an approximate weight of 13,000 pounds. The Command Module was pressurized, so the astronauts could live and work without wearing spacesuits. The wide end of the cone was a blunt heatshield, covered with layers of special ablative material designed to burn away during reentry, dissipating the extreme heat caused by atmospheric friction.

The cylindrical Service Module, built by North American Rockwell, had a diameter of 12 feet and 10 inches and a length of 22 feet and 7 inches. It carried the electrical power systems, most of the electronics, and the life support gases. It also carried the computer system for guidance and navigation, the communications transmitters and receivers, and the oxygen and hydrogen used by the life-support and energy-generation systems. The Service Module’s rocket engine produced 22,000 pounds of thrust. This rocket engine was used to slow the spacecraft to enter lunar orbit and then to speed it up for the return to Earth. Fully fueled, the Service Module weighed about 53,000 pounds.

The Lunar Module, built by the Grumman Aircraft Engineering Corporation, was designed to detach from the Command and Service Modules while they orbited the Moon and to carry two astronauts down to the lunar surface. The Lunar Module was a two-stage rocket, with each stage carrying its own fuel supply. The lower stage carried a 9,700-pound-thrust rocket engine to slow down the Lunar Module for a gentle touchdown on the lunar surface. Four landing legs, each with a landing pad to distribute the weight of the spacecraft over a larger area of the lunar soil, were attached to the Lunar Module descent stage. One of the landing legs was equipped with a ladder to allow the astronauts to climb down to the lunar surface. The upper stage of the Lunar Module consisted of a pressurized compartment providing life support for the two-man crew and an ascent engine to return the crew compartment to lunar orbit. The lower stage of the Lunar Module served as a launching pad for the upper stage. With the landing legs extended, the Lunar Module was 22 feet and 11 inches tall and weighed about 32,000 pounds.

The Apollo Flights

On January 27, 1967, during a preflight test, a fire swept rapidly through the Apollo Command Module. The three astronauts participating in the test, Roger Chaffee, Virgil “Gus” Grissom, and Edward White, were killed in the fire. After the fire, NASA officials designated the test as Apollo 1, honoring the crew. An extensive investigation of the fire showed numerous design flaws in the Apollo Command Module, and crewed launchings were postponed for more than a year while an extensive redesign was conducted.

Apollo 7, the first manned test of the Command and Service Modules, was launched from Cape Kennedy, Florida, on October 11, 1968, on a Saturn IB rocket. Apollo 7 was the only crewed Apollo mission launched on a Saturn IB rocket, which was powerful enough to carry the Command Module and the Service Module into Earth orbit, but could not lift the full Apollo assembly, including the Lunar Module. The spacecraft crew consisted of commander Walter M. Schirra, Jr., Donn F. Eisele, and Walter Cunningham, who held the title of Lunar Module pilot despite the lack of a Lunar Module on the Apollo 7 mission. The crew orbited the earth 163 times and spent almost eleven days in space, demonstrating the reliability of the Command and Service Modules for a time comparable to that of a round trip to the Moon.

Apollo 8, launched on December 21, 1968, was the first crewed mission using the Saturn V rocket, and the first mission to take humans to the Moon and back. The three-person crew consisted of Frank Borman, the commander; James A. Lovell, Jr., the Command Module pilot; and William A. Anders, the Lunar Module pilot. Apollo 8 tested the flight path and operations for the trip to the Moon and back and demonstrated that the Apollo Command Module could successfully reenter the earth’s atmosphere at the high speed of a return from the Moon.

The Apollo 9 mission, launched on March 3, 1969, was the first crewed flight employing all three components of the Apollo spacecraft. The crew, consisting of astronauts James A. McDivitt, the commander; David R. Scott, the Command Module pilot; and Russell L. Schweickart, the Lunar Module pilot, made 152 orbits of the earth. They demonstrated the crew transfer procedures and the rendezvous and docking procedures between the Command Module and the Lunar Module.

The final test of the Apollo spacecraft came with Apollo 10, launched on May 18, 1969. Apollo 10 was a complete Apollo lunar landing mission without an actual landing on the Moon. On the fifth day of the mission, astronauts Thomas Stafford, the commander, and Eugene Cernan, the Lunar Module pilot, descended inside the Lunar Module to within 14 kilometers of the lunar surface, while John W. Young remained in lunar orbit in the Command Module.

The Saturn V rocket carrying Apollo 11 lifted off from the NASA John F. Kennedy Space Center in Florida on July 16, 1969. The Command Module, named Columbia, carried astronauts Neil Armstrong, the commander; Edwin “Buzz” Aldrin, the Lunar Module pilot; and Michael Collins, the Command Module pilot, to the Moon and back. Astronauts Armstrong and Aldrin landed on the Moon in the Lunar Module, named Eagle, on July 20, 1969. Michael Collins remained alone in the Columbia, orbiting the Moon. Columbia served as a communications link between the astronauts on the Moon and mission control in Houston, Texas. After 28 hours on the Moon, the upper stage of the Lunar Module carried Armstrong and Aldrin back into orbit around the Moon, where they rendezvoused and docked with the Columbia. Columbia, the only part of the spacecraft to return to Earth, landed in the Pacific Ocean on July 24, 1969.

Apollo 12, launched on November 14, 1969, carried astronauts Charles Conrad, Jr., the commander; Richard F. Gordon, the Command Module pilot; and Alan L. Bean, the Lunar Module pilot. Astronauts Conrad and Bean landed on the Moon in the Sea of Storms, less than 600 feet from the site where the Surveyor 3 spacecraft had landed on April 20, 1967. The astronauts recovered pieces from the Surveyor 3 to allow scientists to assess the effects of the craft’s two-year exposure to the lunar environment. They also collected 75 pounds of rocks and soil for return to Earth and deployed the Apollo Lunar Surface Experiment Package to perform scientific experiments on the Moon.

Apollo 13, carrying astronauts James A. Lovell, Jr., the commander; John L. Swigert, Jr., the Command Module pilot; and Fred W. Haise, Jr., the Lunar Module pilot, lifted off on April 11, 1970. About 56 hours into the flight, an explosion in one of the oxygen tanks in the Service Module crippled the spacecraft. The crew was forced to orbit the Moon and return to the Earth without landing. The astronauts spent much of the flight in the Lunar Module, using its oxygen and electrical supplies, because of the damage to the Service Module. The astronauts landed safely on Earth on April 17, 1970.

Apollo 14, carrying astronauts Alan B. Shepard, the commander; Stuart A. Roosa, the Command Module pilot; and Edgar D. Mitchell, the Lunar Module pilot, was launched on January 31, 1971. Astronauts Shepard and Mitchell landed on February 5, 1971, within 160 feet of the target point, in the Fra Mauro region of the Moon, the intended landing site of the Apollo 13 mission. During a 4-hour, 20-minute period of extravehicular activity, Shepard and Mitchell climbed up the side of Cone Crater, providing the first experience of climbing and working in hilly terrain in the bulky spacesuits. The astronauts collected 94 pounds of lunar soil and rocks. The upper stage of the Lunar Module lifted off from the lunar surface on February 6, 1971, after 33.5 hours on the Moon. After the crew transferred to the Command Module, the Lunar Module ascent stage was guided to impact on the lunar surface, producing a seismic signal that was recorded by instruments deployed on the lunar surface by Apollo 12 and Apollo 14. The Command Module landed in the Pacific Ocean on February 9, 1971.

By 1970, public interest in lunar exploration had waned and federal budget cuts forced NASA to sacrifice current projects in order to support future ones. Apollo 15, 16, and 17 would be equipped to travel farther, stay longer, and perform more experiments than had previous missions.

Apollo 15, carrying astronauts David R. Scott, the commander; Alfred J. Worden, the Command Module pilot; and James B. Irwin, the Lunar Module pilot, was launched on July 26, 1971. Apollo 15 was the first in a series of advanced missions, carrying the Lunar Rover (LRV), which astronauts Scott and Irwin used to explore the Hadley Rille region of the Moon. The LRV allowed astronauts to travel tens of kilometers from the Lunar Module, in contrast to the hundreds of meters traveled in previous missions. The astronauts collected 173 pounds of samples from the low lunar plains, the Apennine Mountains, and the Hadley Rille, a long, narrow, winding valley. Although Apollo 15’s atmospheric entry was normal, one of the three parachutes that slowed the Command Module’s descent collapsed before landing. Nonetheless, the Command Module landed safely on August 7, 1971.

Apollo 16, carrying astronauts John W. Young, the commander; Thomas K. Mattingly II, the Command Module pilot; and Charles M. Duke, Jr., the Lunar Module pilot, was launched on April 16, 1972. This mission landed in the Descartes region, where astronauts Young and Duke collected 209 pounds of soil and rocks and used an ultraviolet camera and spectrograph to perform the first astronomical measurements from the surface of the Moon. The Apollo 16 crew returned to Earth on April 27, 1972.

Apollo 17, carrying astronauts Eugene A. Cernan, the commander; Ronald E. Evans, the Command Module pilot; and Harrison H. Schmitt, the Lunar Module pilot and, as a trained geologist, only scientist to visit the Moon, was launched on December 7, 1972. On this mission, astronauts Cernan and Schmitt conducted the longest LRV traverse on a single extravehicular activity, a trip of about 100 kilometers. They collected the largest amount of lunar soil and rock ever returned to Earth. Apollo 17’s return to Earth on December 19, 1972, marked the end of U.S. efforts to send humans to the Moon.

Results of the Apollo Program

The major objective of the Apollo Program was accomplished with the landing of twelve American astronauts on the Moon and their safe return to Earth. These landings demonstrated the capability of American engineering, restoring American prestige by finally beating the Soviet Union in the space race. Scientists studying lunar rock samples were finally able to determine the age and origin of the Moon, finding that the Moon formed about 4,560,000,000 years ago, probably from the debris ejected when an asteroid struck Earth.

Bibliography
  • Brooks, Courtney G., James M. Grimwood, and Lloyd S. Swenson. Chariots for Apollo: A History of Manned Lunar Spacecraft. Washington, D.C.: National Aeronautics and Space Administration, 1979. NASA’s official history of the Apollo Program, focusing on the design, construction, and flight of the Apollo spacecraft.
  • Chaikin, Andrew L. A Man on the Moon: The Voyages of the Apollo Astronauts. New York: Viking Press, 1994. An extensive historical account of the Apollo Program, beginning with the Apollo 1 fire and continuing through the successful Moon landing.
  • Logsdon, John W. The Decision to Go to the Moon. Cambridge, Mass.: MIT Press, 1970. An extensive history of the Apollo Program, focusing on the decisions faced by political, industrial, and NASA officials that shaped the Apollo spacecraft and the lunar landing program. Includes a comprehensive bibliography.

The Apollo Programhad to devise spacecraft that not only would take humans out of Earth’s atmosphere, but also land them on the Moon. The Lunar Module transported astronauts from their primary craft to the Moon’s surface.

(NASA CORE/Lorain Valley JVS)
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