On July 20, 1969, humans walked on another world for the first time in history. After a landing that included dodging a lunar crater and boulder field and almost running out of fuel just before touchdown, Neil Armstrong and Buzz Aldrin explored the area around their lunar landing site for 21 hours and 36 minutes while Michael Collins piloted the Command Module around the Moon. They collected soil and rock samples, set up experiments, planted an American flag, and left behind medallions honoring the Apollo 1 crew and a plaque saying, “We came in peace for all mankind.”

The Apollo 11 astronauts (left to right): Neil A. Armstrong, Commander; Michael Collins, Command Module Pilot; Edwin E. “Buzz” Aldrin, Lunar Module Pilot.

At 10:56 pm EDT, Armstrong planted the first human foot on the Moon. With more than half a billion people watching on television, he climbed down the ladder and proclaimed: “That’s one small step for a man, one giant leap for mankind.” An estimated 530 million people around the world watched on television. In the United States, 93 percent of the population’s TVs were tuned to one of the three major networks covering the occasion.

Astronaut Jim Lovell served on the crew of Apollo 8, the first crew to leave Earth orbit and travel to orbit the Moon in December 1968. He saw how Apollo brought people around the world together to celebrate the achievement. “You have to remember what the United States was like in 1968 with the Vietnam War, the murders (of Rev. Martin Luther King Jr. and Sen. Robert Kennedy), and the riots. Apollo 8 was the high point in my space career. NASA put a spacecraft around the Moon on Christmas Eve, and it changed the whole attitude of the country.”

The legacy of Apollo, said Lovell — the first person to fly in space four times — is that “if you set your mind to do something, get everybody together and everybody agrees we should accomplish it, and then we go ahead — it became something we all could be proud of.”

Apollo 11 astronaut Michael Collins explained that with Apollo 11, the crew “had three important things going for us, two of which we don’t have today. The first one was, I wouldn’t say money was no object, but we were getting slightly over three percent of the federal budget. The second one was a deadline — by the end of the decade. You could motivate people… saying, ‘We gotta do this by the end of the decade.’ It was a very powerful tool. The third thing, we still have. We had a lot of smart people, young people, dedicated people who got to work early, stayed at work late. You didn’t have to tell them they were part of a team — they knew they were part of a team.”

The team that would serve as mission control for Apollo 11 was led by Eugene Kranz and three other flight directors. Said Kranz, the team was made up of the finest systems engineers in the world — the average age was 26 (Kranz was 36). When July 20, 1969 came, he told the team, “It’s now time to get down to business. From the day of our birth, we were meant for this time and place, and today we will land an American on the Moon. Whatever happens here today,” said Kranz, “I will stand behind every decision you will make. We came into this room as a team and we will leave as a team.”

Said Buzz Aldrin, “Apollo 11 was about exploration. About taking risks for great rewards in science and engineering. About setting an ambitious goal before the world and then finding the political will and the national means to achieve it. The voyage of Apollo still seems incredible. We are inspired by the magnitude and team efforts of people from all walks of life. From industries big and small that worked in tandem to attain a long-term goal of magnificent achievement.”

The Apollo 11 crew launched on the Saturn V, a 363-foot-tall, 6,400,000-pound rocket. This high-angle view of the launch was provided by a “fisheye” camera mounted on the launch tower. (NASA)

Fifty years later, Apollo 11 remains one of humankind’s greatest achievements and much more than “one small step” — it was a leap that would create the International Space Station, start a commercial launch business, and drive rovers on the surface of Mars.

The First Leap

Before taking that “giant leap” onto the surface of the Moon, NASA had to decide how to get there. At the time, many NASA managers and engineers believed the most feasible method was direct ascent — a spacecraft launched by an enormous rocket traveling directly to the Moon and landing as one unit. After exploring the surface, a portion of the lander would blast off, returning to Earth. Another approach, called Earth Orbit Rendezvous, involved launching several Saturn 1 rockets. A spacecraft, similar to the direct method, would be assembled in space for the lunar mission.

A small group of engineers had an idea called Lunar Orbit Rendevous that proposed two separate vehicles — one to land on the surface while another circled the Moon. The risky part was that the landing craft had to rendezvous with the “mother ship” in lunar orbit so the astronauts could return home. At that time, bringing two spacecraft together in space had never been tried. While initially a skeptic, Dr. Wernher von Braun, director of NASA’s Marshall Space Flight Center in Alabama, agreed that the lunar orbit rendezvous approach would simplify reaching the goal in a timely manner. Von Braun led the team that developed the Saturn V rocket to launch the two spacecraft.

Astronaut Buzz Aldrin walks on the surface of the Moon near the lunar module Eagle during the Apollo 11 mission. Mission commander Neil Armstrong took this photo with a 70-mm lunar surface camera. (NASA)

In 1962, NASA Administrator James Webb announced that by adding one vehicle to those already under development, landing on the Moon could be accomplished in a shorter time span and with less money. Initially called the lunar excursion module, the name was later changed to lunar module (LM), which was designed and built by Grumman Aerospace.

Initial LM designs included large, curved windows and seats, and a redundant forward docking port. Redesigns were required to save weight and enhance safety. The cockpit windows were replaced with smaller triangular versions. A rectangular overhead window was included for use in rendezvous with the command module after leaving the lunar surface. A forward hatch was designed to make it easier to climb out while wearing bulky spacesuits with backpacks.

While there were many key LM systems, nothing was more important than the engines that would allow the spacecraft to land on the Moon and another to return to the command module. At the base of the LM was the descent propulsion system that allowed astronauts to control the final decent from about 50,000 feet, including hovering as the commander picked out the best spot to land.

The Science of Apollo 11

The primary goal of the first Moon landing mission was to demonstrate that the Apollo spacecraft systems could safely land two astronauts on the surface and return them safely to Earth. During the first lunar surface extravehicular activity (EVA), the crew was to spend about two hours outside the LM. In addition to collecting rock and soil samples for return to Earth, the astronauts would also conduct science. In 1968, NASA announced that when Apollo astronauts first landed on the Moon, they would deploy three scientific experiments — a passive seismometer, a laser ranging retroreflect and a solar wind composition experiment.

The seismometer was a 100-pound seismic station to detect moonquakes. The experiment was solar-powered and had its own communications capability to transmit its results back to Earth after the astronauts departed the lunar surface. If the Moon was seismically active, the instrument could provide information about its internal structure and possibly yield clues about its formation.

The laser ranging retroreflector weighed about 70 pounds and consisted of an array of precision optical reflectors to serve as a target for Earth-based lasers. By precisely measuring the time it takes a laser beam to travel from Earth and bounce back from the retro-reflector, scientists calculated the Earth-Moon distance to an accuracy of eight centimeters. Measurements taken over time and from different stations on Earth helped determine fluctuations in Earth’s rotation and recorded continental drift.

During 2½ hours of lunar surface exploration, the Apollo 11 crew set up experiments and collected 47 pounds of lunar surface material. In this photo, Aldrin easily carries scientific equipment that would have been too heavy to carry on Earth. The two packages made up the Early Apollo Scientific Experiment Package (EASEP). On the left is the Passive Seismic Experiment Package (PSEP) and on the right is the Laser Ranging Retroreflector (LRR).

The solar wind composition experiment consisted of a sheet of aluminum to trap particles of the solar wind; in particular, helium, neon, argon, krypton, and xenon. The astronauts unfurled the aluminum foil collector near the beginning of their EVA and then rolled it up and returned it to Earth for laboratory analysis.

During their flight from Earth, the experiments were stowed in the scientific equipment bay of the LM’s descent stage. The crew manually retrieved the packages once on the lunar surface and deployed the experiments. Beginning with the second Moon landing, astronauts deployed more sophisticated experiments as part of the Apollo Lunar Surface Experiments Package (ALSEP) and conducted more extensive geological surveys.

Apollo’s Impact on Future Leaps

Apollo started out as a demonstration of America’s technological, economic, and political superiority. But a portion of Apollo, like the entire space program, was always dedicated to scientific research. Apollo taught us a lot, and not just about the Moon.

Some of the earliest beneficiaries of Apollo research were Earth scientists. The Apollo 7 and 9 missions, which stayed in Earth orbit, took photographs of the Earth in different wavelengths of light, highlighting things that might not be seen on the ground, like diseased trees or crops. This research led directly to NASA’s Landsat Program, which has been studying Earth’s resources from space for more than 45 years.

Apollo hardware was used in building Skylab, America’s first space station. The Skylab craft was an Apollo Saturn IV-B upper stage, and its launch was the last use of the Apollo Saturn V booster. When it came time to build the space shuttle, NASA engineers used what they had learned during Apollo to make the shuttle’s basic structure stronger and safer while reducing weight.

The Apollo astronauts brought back more than 800 pounds of rocks. They included material with a large amount of natural glass, formed when meteorites struck the Moon. Some of the glass was formed more than 4 billion years ago, preserved by the lack of water and atmosphere on the Moon, giving scientists insights into the early days of the solar system.

The discovery of a rock called anorthosite showed that the Moon had once been the site of very complex geological processes, not always the “magnificent desolation” that Buzz Aldrin described.

Perhaps the most important finding came from comparing similarities in the composition of lunar and terrestrial rocks and then noting differences in the amount of specific substances.

The Apollo lunar flights ended in 1972, but Apollo’s legacy goes well beyond science. In 1975, the Apollo-Soyuz Test Project saw the last Apollo spacecraft dock with a Soviet Soyuz, and their two crews conducted joint operations in orbit — a legacy that continues today as the United States, Russia, and 16 other countries work together aboard the International Space Station.



Apollo 11 Introduction 

Seventeen Seconds of Fuel Remained 

One Small Step