Apollo 11

The Apollo 11 spacecraft comprised three modules: the Command Module (CM-107) Columbia, the Service Module (SM-107), and the Lunar Module (LM-5) Eagle. The crew—Neil Armstrong (commander), Buzz Aldrin (lunar module pilot), and Michael Collins (command module pilot)—were all experienced test pilots and veterans of earlier spaceflights. Armstrong had flown Gemini 8, Aldrin had performed the first spacewalk on Gemini 12, and Collins had piloted Gemini 10.¹

The mission launched atop a Saturn V rocket from Launch Complex 39A at the Kennedy Space Center. After a translunar injection, the spacecraft entered lunar orbit on July 19. The next day, Armstrong and Aldrin separated Eagle from Columbia and descended to the surface, landing with only about 25 seconds of fuel remaining. The landing site, in the southwestern part of the Sea of Tranquility, was chosen for its relatively smooth terrain and scientific interest.²

Armstrong and Aldrin spent 21 hours 36 minutes on the lunar surface, including a 2-hour 31-minute extravehicular activity (EVA). During the EVA, they deployed the Early Apollo Scientific Experiment Package (EASEP), which included a passive seismic experiment, a laser ranging retroreflector, and a solar wind composition experiment. They also collected 21.5 kilograms of lunar material, including basaltic rocks and regolith.³

The astronauts took photographs, set up a US flag, and received a phone call from President Richard Nixon. They left behind a plaque reading "Here men from the planet Earth first set foot upon the Moon, July 1969 A.D. We came in peace for all mankind." The EVA was broadcast live, with Armstrong's famous words "That's one small step for man, one giant leap for mankind" becoming iconic. After re-entering Eagle, they rested before lifting off to rendezvous with Collins in lunar orbit.⁴

After rejoining Columbia, the crew jettisoned Eagle and began the trans-Earth injection. The Service Module's engine performed the critical burn to leave lunar orbit. The Command Module re-entered Earth's atmosphere on July 24, splashing down in the Pacific Ocean about 1,400 kilometers east of Wake Island. The crew was recovered by the USS Hornet and placed in a mobile quarantine facility to prevent potential lunar contamination.

The mission fulfilled Kennedy's 1961 goal of landing a man on the Moon before the decade's end. It marked the culmination of the Apollo program and the Space Race, with the US achieving a decisive victory over the Soviet Union. The lunar samples provided insights into the Moon's origin and geological history, and the mission's success spurred advances in computing, materials science, and public interest in space exploration. Apollo 11 remains a benchmark for human spaceflight and a symbol of technological achievement.

Several details of Apollo 11 are less widely known. The lunar module's computer, the Apollo Guidance Computer, had only 2 kilobytes of RAM and 36 kilobytes of ROM, yet it guided the landing. During descent, the computer issued several alarms (1201 and 1202) caused by an overloaded processor; mission control correctly judged them non-critical.⁵

The crew carried a silicon disc etched with goodwill messages from 73 countries, left on the lunar surface. Armstrong and Aldrin also left behind a memorial to fallen astronauts, including Yuri Gagarin and the Apollo 1 crew. The mission's television camera used a slow-scan format that was converted for broadcast, resulting in the grainy images seen worldwide. After the mission, the crew toured the world, and the Command Module Columbia is now displayed at the Smithsonian National Air and Space Museum. The exact location of the landing site was later photographed by the Lunar Reconnaissance Orbiter, showing the descent stage and footprints still visible.⁶

Lunar Module

The spacecraft that landed on the Moon and returned to lunar orbit.

Command Module

The crew cabin that carried astronauts to and from lunar orbit.

EVA

Extravehicular activity, or spacewalk, outside the spacecraft.

Sea of Tranquility

A lunar mare where Apollo 11 landed.

Saturn V

The heavy-lift rocket used for Apollo missions.