In the early 1960s, the US lagged behind the Soviet Union in the “Space Race.” The Soviets had launched the first satellite in 1957, and on April 16, 1961, Yuri Gagarin became the first human in space. In response, in 1961 US President John F. Kennedy publicly committed to landing a man on the moon before the end of the decade. The project was carefully chosen—landing on the moon was so far beyond the capabilities of either protagonist that the Soviets’ early lead might not seem so significant.

Despite the reservations of many at the time regarding a moon landing’s scientific value, especially given the dangers and technical complexities involved, human spaceflight was now the focus of the US space program. NASA managers felt that with enough funding they could put a man on the moon by 1967. NASA administrator James E. Webb suggested another two years be added as a contingency.

In those six years from 1961 to 1967, NASA tripled its workforce, even though most of the planning, designing, and building of the hardware was undertaken by private industry, research institutes, and universities. NASA claimed that only the construction of the Panama Canal and the Manhattan Project to develop the nuclear bomb rivaled the effort and expense of the Apollo program.

“I believe that 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.” John F. Kennedy

Project Mercury astronaut John Glenn enters the Friendship 7 on February 20, 1962. His mission, lasting just under five hours, was the US’s first manned orbital spaceflight.

Which way to the moon?

At the time of Kennedy’s historic announcement, the US boasted a grand total of 15 minutes of human spaceflight. To move from here to a moon landing, many technological hurdles needed to be overcome. One of the first was the method of getting to the moon. Three options, known as mission architectures, were on the table. The direct ascent (DA) profile, or “all-theway,” required an enormous multistage rocket with enough fuel on board to transport the crew back to Earth. This was initially the favored approach. However, it was also the most expensive, and doubts were raised over the feasibility of building such a monster rocket before the 1969 deadline.

In the Earth-orbit rendezvous (EOR) profile, a moon-bound rocket ship would be assembled in space and dock with modules that had already been placed in orbit. Lifting things into space is the most energy-consuming part of any off-Earth mission, but multiple rocket launches would sidestep the need for a single spaceship. This was the safest option, but it would be slow. The real weight-savings came with the lunar-orbit rendezvous (LOR) profile.

Here, a smaller rocket would put a three-part spaceship on course to the moon. At the moon, a command module would remain in orbit with the fuel for the journey home, while a lightweight two-stage lunar lander would be sent to the surface. This quick and comparatively cheap option carried with it the very real risk of leaving a crew stranded in space should anything go wrong. After much debate and lobbying, influential figures, such as Wernher von Braun, director of NASA’s Marshall Space Flight Center, threw their backing behind LOR, and in 1962, LOR was chosen. This was the first of many leaps of faith for Apollo.

Technological hurdles

On February 20, 1962, John Glenn became the first American to orbit Earth, looping three times around the planet in Friendship 7, as part of the US’s first spaceflight program, Project Mercury, which ran from 1958 to 1963. Three more successful Mercury flights followed, but there was a big difference between operations in low Earth orbit and landing on the moon. An entire new fleet of launch vehicles was required. Unlike Mercury spacecraft, which carried a single astronaut, Apollo missions would need a crew of three. In addition, a more reliable power source was needed and much more experience in space. The world’s first fuel cells were built to provide the power.

Project Gemini, NASA’s second human spaceflight program, provided the skills, with endurance spaceflights, orbital maneuvers, and space walks. Scientists also needed to know more about the moon’s surface. A deep layer of dust could swallow up a spacecraft and prevent it from leaving, clog up the thrusters, or cause the electronics to malfunction.

Unmanned fact-finding missions were mounted in parallel with Apollo, but the first wave of robotic explorers dispatched to the moon was an unmitigated failure. Six Ranger landers failed on launch, missed the moon, or crashed on impact, causing the program to be nicknamed “shoot and hope.” Luckily, the final three Rangers were more successful.

Between 1966 and 1967, five Lunar Orbiter satellites were placed in orbit around the moon. They mapped 99 percent of the surface and helped to identify potential Apollo landing sites. NASA’s seven Surveyor spacecraft also demonstrated the feasibility of a soft landing on the lunar soil.

The Saturn V rocket was developed for the Apollo program. Many private corporations were involved in its production, including Boeing, Chrysler, Lockheed, and Douglas.

“From this day forward, Flight Control will be known by two words: “Tough and Competent.”” Gene Kranz

A gamble and a disaster

At 363 ft (110.5 m), Saturn V—the heavy-lift booster that carried the Apollo astronauts out of Earth’s atmosphere—is still the tallest, heaviest, and most powerful rocket ever built. “Man-rating” the rocket (certifying it to carry a human crew) proved particularly troublesome. The mammoth engines generated vibrations that threatened to break the rocket apart. Knowing that the project was behind schedule, NASA’s associate administrator for manned spaceflight, George Mueller, pioneered a daring “all-up” testing regime. Rather than the cautious stage-by-stage approach favored by von Braun, Mueller had the entire Apollo–Saturn systems tested together.

While striving for perfection, the NASA engineers developed a new engineering concept: that of redundancy. Key or critical components were duplicated in order to increase overall reliability. The Mercury and Gemini projects had taught engineers to expect unforeseen risks. A fully assembled Apollo vehicle had 5.6 million parts, and 1.5 million systems, subsystems, and assemblies. Even with 99.9 percent reliability, the engineers could anticipate 5,600 defects. Nevertheless, over its 17 unmanned and 15 manned flights, the Saturn boosters had shown 100 percent reliability. With two partially successful test flights under its belt, Mueller declared that the next launch would carry astronauts.

Until 1967, progress had been smooth, despite the breakneck pace. Then disaster struck. An electrical short-circuit during a launch rehearsal started a fire that incinerated the Apollo 1 crew inside the Command Module. The toxic smoke and intensity of the fire in a pressurized, pure-oxygen atmosphere killed Virgil “Gus” Grissom, Ed White, and Roger Chaffee in less than five minutes. In the wake of this tragedy, the next five Apollo missions were unmanned tests. Modifications were made, resulting in a safer spacecraft with a new gas-operated hatch, a 60–40 oxygen–nitrogen mix in the cockpit, and fireproof wiring throughout.

The Lunar Orbiter satellites took images of potential landing sites. In 1966, Lunar Orbiter 2 sent back this image of Copernicus Crater, one of the first-ever close-up views of the moon.

“Apollo riding his chariot across the sun was appropriate to the grand scale of the proposed program.” Abe Silverstein

Earth’s place in space

Apollo 8 was the first manned spacecraft to leave Earth’s orbit. On Christmas Eve 1968, Frank Borman, James Lovell, and Bill Anders looped around the far side of the moon and witnessed the astounding sight of Earth rising from behind the moon’s surface. For the first time, humans could see their home from space—a startlingly blue world lost in the immensity of the void. As Anders put it: “We came all this way to explore the moon, and the most important thing is that we discovered the Earth.”

The crew was also the first to pass through the Van Allen radiation belts. This zone of charged particles extends up to 15,000 miles (24,000 km) from Earth, and was initially thought to be a serious barrier to human space travel. As it turned out, it resulted in a dosage of radiation only equivalent to a chest X-ray.

Finally, the program was ready for the last step—to take real steps on the moon itself. On July 21, 1969, an estimated global audience of 500 million tuned in to watch Neil Armstrong land the Lunar Module and step out onto the surface of the moon, closely followed by Buzz Aldrin. It was the culmination of nearly a decade of collaborative effort and effectively ended the Space Race.

There were six more missions to the moon following Apollo 11, including the near-disaster of Apollo 13, whose lunar landing in 1970 was aborted after an oxygen tank exploded on board. The crew was returned safely to Earth on the crippled spacecraft in a real-life drama that played out in front of a worldwide television audience.

In 1968, Apollo 8 broadcast live from moon orbit. Images taken from the spacecraft by astronaut Bill Anders included the iconic Earthrise.

Learning about the moon

Before Apollo, much of what was known about the physical nature of Earth’s only natural satellite was speculation but, with the political goals achieved, here was an opportunity to find out about an alien world firsthand. Each of the six landing missions carried a kit of scientific tools—the Apollo Lunar Surface Experiments Package (ASLEP). Apollo’s instruments tested the internal structure of the moon, detecting seismic vibrations that would indicate a “moonquake.” Other experiments measured the moon’s gravitational and magnetic fields, heat flow from its surface, and the composition and pressure of the lunar atmosphere.

Thanks to Apollo, scientists have compelling evidence from analysis of moon rock that the moon was once a part of Earth. Like Earth, the moon also has internal layers and was most likely molten at some point in its early history. Unlike Earth, however, the moon has no liquid water. Since it has no moving geological plates, its surface is not continually repaved, and so the youngest moon rocks are the same age as Earth’s oldest. The moon is not entirely geologically inactive, however, and occasionally has moonquakes that last for hours.

One Apollo 11 experiment remains active and has been returning data since 1969. Reflectors planted on the lunar surface bounce back laser beams fired from Earth, enabling scientists to calculate the distance to the moon to within an accuracy of a couple of millimeters. This gives precise measurements of the moon’s orbit, and the rate at which it is drifting away from Earth (about 1½ in [3.8 cm] per year).

Neil Armstrong took this famous photograph of Buzz Aldrin on the surface of the moon. Armstrong’s reflection, standing next to the lunar module, can be seen in Aldrin’s visor.

Apollo’s legacy

On December 19, 1972, the sonic boom over the South Pacific, as the Apollo 17 capsule thumped into Earth’s atmosphere, sounded the end of the Apollo program. In total, 12 men had walked on the moon. At the time, it was widely assumed that routine flights to Mars would soon be a reality, but in the intervening 40 years, scientific priorities changed, politicians worried about costs, and human space travel has not ventured farther than Earth’s orbit.

For many, the decision to end manned moon missions was a wasted opportunity, caused by a lack of imagination and leadership. However, the end of the acute Cold War competition that gave rise to the Apollo program heralded a new era of international cooperation for NASA, with Skylab, Mir, and the International Space Station.

Gene Cernan, the last man on the moon, predicted that it could be another 100 years before humankind appreciates the true significance of the Apollo missions. One result could be that it may have made the US smarter—the intake for doctoral degrees at American universities tripled during the 1960s, particularly in the field of physics. Apollo contracts also nurtured nascent industries, such as computing and semiconductors. Several employees of the California-based Fairchild Semiconductors went on to found new companies, including Intel, a technology giant. The Santa Clara area where these firms were based has become today’s Silicon Valley. But perhaps Apollo’s real legacy is the idea of Earth as a fragile oasis of life in space. Photos taken from orbit, such as the “Blue Marble” and “Earthrise”, fed into a growing awareness of planet Earth as a single entity, and the need for careful stewardship.

Apollo 11’s command and service module docked with the lunar module in orbit before heading for the moon. Before touchdown, the service module was jettisoned, and only the command module returned to Earth.

“Houston. Tranquility Base here. The Eagle has landed.” Neil Armstrong

On the final three Apollo missions, astronauts explored the surface of the moon on lunar rovers. The rovers were abandoned and can still be seen where they were left behind


Perhaps the embodiment of the NASA spirit is not the heroic astronauts but the legendary Apollo flight director Gene Kranz. Born in 1933, Kranz was fascinated by space from an early age. He served as a pilot with the US Air Force before leaving to pursue rocket research with the McDonnell Aircraft Corporation and then NASA.

Prominent and colorful, with a brutally close-cut flattop hairstyle, Kranz was unmistakable in Mission Control, dressed in his dapper white “mission” vests made by his wife.

Although he never actually spoke the words “Failure is not an option”— they were written for his character in the movie Apollo 13—they sum up his attitude. Kranz’s address to his Flight Control staff after the Apollo 1 disaster has gone down in history as a masterpiece of motivational speaking. In it, he stated the Kranz Dictum—“tough and competent”—that would guide Mission Control. Kranz was awarded the Presidential Medal of Freedom in 1970 for successfully returning Apollo 13 to Earth.

Leave a Comment