Apollo 11

• 1. Introduction

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  Apollo 11, launched on the 16th of July 1969, carried three astronauts toward a destination no human being had ever reached. Commander Neil Armstrong, Command Module Pilot Michael Collins, and Lunar Module Pilot Edwin "Buzz" Aldrin lifted off from Kennedy Space Center in Florida at 13:32 UTC atop a Saturn V rocket. Four days later, Armstrong stepped off the Eagle's landing pad and declared: "That's one small step for a man, one giant leap for mankind." An estimated 600 million people, roughly one-fifth of the world's population, watched that moment live.

  How did the United States arrive at the Moon in 1969? What did it cost in lives, in ingenuity, and in risk? And what happened in the tense final minutes before Eagle touched down, when a cascade of computer alarms nearly ended the mission before it had truly begun? Those questions shape the story of Apollo 11.

• 2. Cold War Origins

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  On the 4th of October 1957, the Soviet Union launched Sputnik 1, the first artificial satellite, and the shock rippled through the United States. The feat demonstrated that the USSR could potentially deliver nuclear weapons over intercontinental distances, undermining American claims of technological and military superiority.

  President Dwight D. Eisenhower responded by creating NASA and launching Project Mercury, aimed at putting a man in Earth orbit. The Soviets struck again on the 12th of April 1961, when cosmonaut Yuri Gagarin became the first person in space and the first to orbit the Earth. Nearly a month later, Alan Shepard became the first American in space, but his 15-minute suborbital flight was a modest counterpoint to Gagarin's full orbit.

  President John F. Kennedy, Eisenhower's successor, chose a response that deliberately set a bar neither country could yet clear. On the 25th of May 1961, he stood before Congress and declared that the United States should commit itself to landing a man on the Moon and returning him safely before the end of the decade. Kennedy later proposed making the Moon landing a joint project when he met Soviet Premier Nikita Khrushchev in June 1961, but Khrushchev declined. The idea of cooperation resurfaced in Kennedy's speech to the United Nations General Assembly on the 20th of September 1963, and was abandoned after Kennedy's death. The race would be run separately.

  Not everyone was enthusiastic. Norbert Wiener, a mathematician at the Massachusetts Institute of Technology, dubbed the proposed program a "moondoggle". Nonetheless, the effort already had a name: Project Apollo.

• 3. Building the Machine

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  A critical early decision shaped the entire mission architecture. In July 1962, NASA head James Webb announced that the spacecraft would use lunar orbit rendezvous rather than a direct flight from Earth to the Moon's surface. This meant the craft would have three distinct parts: the command module, housing the astronauts and the only piece returning to Earth; the service module, providing propulsion, power, oxygen, and water; and the lunar module, with a descent stage for landing and a lighter ascent stage to carry two astronauts back to lunar orbit.

  The Apollo Guidance Computer drew on new advances in semiconductor technology, including silicon integrated circuits. Technologies for the broader Apollo program were developed through the preceding Mercury and Gemini programs.

  The project suffered a devastating halt on the 27th of January 1967, when a launchpad fire on Apollo 1 killed astronauts Gus Grissom, Ed White, and Roger B. Chaffee. After the investigation, the program rebuilt. Apollo 7 evaluated the command module in Earth orbit in October 1968. Apollo 8 tested it in lunar orbit in December. Apollo 9 flew the lunar module in Earth orbit in March 1969. Apollo 10 conducted a full dress rehearsal in lunar orbit in May 1969, with its lunar module flying to within 15 km of the intended Apollo 11 landing site and reporting it acceptable.

  While Apollo progressed, the Soviet N1 rocket, which would have been comparable to the Saturn V, repeatedly failed to develop. The Soviets shifted strategy and attempted to beat the United States to a return of lunar material using uncrewed probes. On the 13th of July 1969, three days before Apollo 11's launch, the Soviet Union sent Luna 15 toward the Moon.

• 4. The Crew and Their Tensions

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  Neil Armstrong, Michael Collins, and Buzz Aldrin were all on their second and final spaceflight. Their crew assignment had been officially announced on the 20th of November 1967, though the original plan placed Jim Lovell, not Collins, in the command module pilot seat.

  Collins had been bumped from that role after doctors diagnosed a bony growth between his fifth and sixth vertebrae, requiring surgery. Lovell took his place on Apollo 8, and Collins later recovered to join Armstrong's crew. The crew dynamics that resulted were notably cool. Armstrong was notoriously aloof. Collins, who described himself as a loner, admitted to rebuffing Aldrin's attempts at a closer relationship. Aldrin and Collins would later describe the three as "amiable strangers", a phrase Armstrong himself rejected.

  The question of who would be the first to step onto the Moon generated its own friction. Early checklists had the lunar module pilot exiting first, as commanders had never performed spacewalks on Gemini missions. Associate Administrator George Mueller told reporters Aldrin would go first. When Aldrin learned Armstrong was being considered because Armstrong was a civilian, he was livid and lobbied other lunar module pilots. Flight director Deke Slayton told Aldrin the commander would go first because that was his role.

  Chris Kraft revealed in his 2001 autobiography that a meeting between Gilruth, Slayton, Low, and Kraft settled the matter definitively. They wanted the first person on the Moon to be like Charles Lindbergh: calm and quiet. The announcement came on the 14th of April 1969. Slayton told Armstrong the plan, and Armstrong replied: "Yes, that's the way to do it."

  The mission insignia carried its own story. Collins designed it, choosing the bald eagle at Lovell's suggestion to symbolize a peaceful American landing. A simulator instructor named Tom Wilson proposed the olive branch in the eagle's beak. When NASA's Bob Gilruth found the eagle's talons "too warlike", the olive branch was moved there instead. Armstrong insisted on "Apollo 11" rather than "eleven", so non-English speakers would not be confused, and the crew agreed to leave their own names off the patch so it would represent everyone who had worked toward the landing.

• 5. Alarms During Descent

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  Eagle separated from Columbia at 17:44 UTC on the 20th of July 1969. As Armstrong and Aldrin began their descent, they noticed they were passing surface landmarks two or three seconds early. They were running long, and would land miles west of the planned target point.

  Five minutes into the descent burn, at roughly 6,000 ft above the lunar surface, the guidance computer began issuing 1201 and 1202 program alarms. Inside Mission Control, computer engineer Jack Garman told Guidance Officer Steve Bales it was safe to continue. The alarms indicated that the computer could not complete all its tasks in real time and was dropping lower-priority ones to protect the critical functions. Margaret Hamilton, the Director of Apollo Flight Computer Programming at the MIT Charles Stark Draper Laboratory, later described the computer's behavior as self-correcting: it recognized the problem and took recovery action rather than forcing an abort.

  Software engineer Don Eyles concluded in a 2005 paper that the cause was a hardware design bug previously seen during testing of the first uncrewed lunar module on Apollo 5. The rendezvous radar switch had been left in the wrong position, so the computer was processing data from both the rendezvous radar and the landing radar simultaneously. An electrical phasing mismatch made the stationary antenna appear to the computer as if it were oscillating, generating spurious interrupt cycles and triggering the cascade of alarms.

  As the alarms cleared, Armstrong looked out and saw the computer was targeting a boulder-strewn area just north and east of a 300 ft crater. He took semi-automatic control. Now 107 ft above the surface, with only 90 seconds of propellant remaining, lunar dust kicked up by the engine began obscuring his view. Armstrong focused on protruding rocks to judge the spacecraft's speed. Aldrin called out: "Contact light!" as the probes on Eagle's footpads touched the surface. Eagle landed at 20:17:40 UTC with 216 lb of usable fuel remaining.

• 6. On the Lunar Surface

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  Armstrong and Aldrin did not rest after landing. The mission schedule called for a five-hour sleep period, but they decided to begin preparations for the moonwalk early, believing sleep would be impossible. Preparations took three and a half hours rather than the expected two.

  At 02:56:15 UTC on the 21st of July, six and a half hours after landing, Armstrong stepped off Eagle's landing pad. Before joining him, Aldrin had quietly taken communion, an elder at the Webster Presbyterian Church whose communion kit had been prepared by the church's pastor, Dean Woodruff. The chalice he used is preserved at Webster Presbyterian, which commemorates the event each year on the Sunday closest to the 20th of July.

  Together, Armstrong and Aldrin spent around two and a half hours on the surface. Armstrong collected a contingency soil sample first, tucking it into a pocket on his right thigh to guarantee some lunar material would return to Earth even if the EVA had to be cut short. He later walked 196 ft from the lunar module to photograph the rim of Little West Crater. Aldrin tried driving a tube into the soil for core samples using the geologist's hammer, but could only penetrate 6 inches into the hard surface.

  The two men planted the American flag, struggling to push the pole more than 5 cm into the hard lunar surface. Before Aldrin could photograph Armstrong with the flag, President Richard Nixon spoke to them by telephone-radio transmission. Nixon described it as "the most historic telephone call ever made from the White House." Frank Borman, on site at the White House as a NASA liaison, had persuaded Nixon to keep his remarks brief.

  Three new minerals were identified in the rock samples the astronauts collected: armalcolite, tranquillityite, and pyroxferroite. Armalcolite was named for Armstrong, Aldrin, and Collins. All three have subsequently been found on Earth as well.

• 7. Return and Aftermath

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  Shortly before liftoff from the Moon, Aldrin accidentally broke the circuit breaker that would arm the ascent engine. The nonconductive tip of a Duro felt-tip pen proved sufficient to activate the switch and complete the circuit. Presidential speechwriter William Safire had prepared a contingency address for Nixon to read if the astronauts were stranded, a text that included an allusion to Rupert Brooke's World War I poem "The Soldier" and a protocol under which Mission Control would close communications and a clergyman would "commend their souls to the deepest of the deep". Collins, orbiting above in Columbia, was not mentioned in the speech, since he would have been able to return to Earth alone.

  Eagle's ascent stage lifted off at 17:54 UTC on the 21st of July, roughly two hours after Luna 15 had crashed in Mare Crisium. British astronomers monitoring Luna 15's descent recorded a witness who said: "I say, this has really been drama of the highest order." The Soviet probe had come close. The race ended in the dust of a failed landing.

  The crew splashed down on the 24th of July, landing 24 km from the aircraft carrier Hornet, which had been redirected 215 nmi northeast after a US Air Force captain with access to top-secret spy satellite images spotted a dangerous storm front moving toward the original recovery zone. Columbia landed upside down but was righted within ten minutes by flotation bags. The astronauts then entered 21 days of quarantine against the remote possibility of lunar pathogens.

  The crew were honoured with ticker-tape parades, a world goodwill tour, and the Presidential Medal of Freedom. The command module Columbia is preserved at the National Air and Space Museum in Washington, D.C. The descent stage of Eagle remains on the lunar surface, and as of 2021 some calculations suggest the ascent stage may still be in orbit around the Moon.