Scientific Method / Science & Exploration



Apollo 11

Launch of Apollo 11. A Prandtl-Glauert singularity can be seen around the main booster. Credit: NASA

On the morning of July 16, 1969, Buzz Aldrin, Neil Armstrong, and Michael Collins sat in the command module, Columbia, atop the Saturn V SA-506. The launch occurred at 9:32AM, and the trio entered orbit a scant 12 minutes later thanks to the power of the five F-1 engines of the first stage and five J-2 engines powering the second stage. After one-and-a-half orbits, the crew fired the final powerful J-2 engine to initiate their translunar injection and began traversing the void between the Earth and the Moon.

Three days later, on July 19, the command module flew behind the moon and entered lunar orbit. After 30 trips around the moon, on July 20, 1969 the lunar module Eagle detached from Columbia and began its 50,000 ft descent onto the surface of the moon. The early parts of the descent were marked by communication outages, and Aldrin and Armstrong noticed that they were seeing landmarks on the lunar surface early in their flight; this suggested that they were landing long, overshooting the planned landing site.

As the descent continued, the navigation and guidance computer began reporting program alarms. The program alarms 1202 and 1201 signified that the computer, which had less power than a modern desktop calculator, could not keep up with the requisite computations—a potentially mission-ending error. Computer analysts, led by Jack Garman, in a back room at NASA's Mission Control determined that as long as the alarms were intermittent, there was no need for abort due to computer problems. It was later learned that the error was the result of the computer processing data from both the landing and rendezvous radar, thus overloading the processor with unnecessary calculations.

With Aldrin acknowledging the intermittent alarms, Armstrong was looking out the window at the surface trying to find an acceptable place to land. It was noted that the landing site the computer had picked out was strewn with boulders between one and two meters across, and was on the edge of what would come to be known as "West crater." Landing here could have severely damaged the LM, or made lunar ascent impossible. Armstrong later said that he felt he could land if he could pilot the LM to come up short of the boulder and rock field, but it soon became obvious that this wouldn't be a possibility.

Unable to land short, Armstrong and Aldrin had to fly over the field, further overshooting their landing target. Since they were traveling longer than they anticipated, the fuel level was reaching the point where an abort decision could need to be called. As they neared 60 feet in altitude, Houston informed them that they had 80 seconds of fuel remaining before a abort decision needed to be made. As they passed 20 feet, there was 50 seconds of fuel left. Touchdown on the lunar surface happened 102 hours, 45 minutes, and 45 seconds after the mission began at 4:17pm EDT July 20, 1969. Thirteen seconds later, Neil Armstrong uttered some of the first words ever spoken on another celestial body, "Houston, Tranquility Base here. The Eagle has landed." They had 25 seconds worth of fuel remaining onboard.

Magnificent desolation

Shortly after landing, while the pair was prepping for the first lunar extravehicular activity, Buzz Aldrin sent the following broadcast, "This is the LM pilot. I'd like to take this opportunity to ask every person listening in, whoever and wherever they may be, to pause for a moment and contemplate the events of the past few hours and to give thanks in his or her own way." Aldrin then privately partook in the sacrament of communion, an event that was not made public until years after the landing. The chalice he used on the moon now resides in Webster Presbyterian Church in Webster, TX where the kit was prepared.

After planning on locations to plant the American flag and Early Apollo Scientific Experiment Package—an instrument kit that had the Laser Ranging Retroreflector and the Passive Seismic Experiment Package—the two began getting ready to take a walk outside. It turned out that getting out of the LM was not as easy as they thought it would be. At some point in the design process, the hatch leading into and out of the LM had been redesigned, but the portable life support systems the astronauts wore had not, resulting in a tighter than ideal fit through the door. After some trouble opening the hatch and some squeezing by Armstrong with Aldrin's help, at 10:56pm EDT on July 20th, 1969 Neil Armstrong became the first man to walk on the surface of the moon, uttering his now famous line, "That's one small step for [a] man, one giant leap for mankind." This event was heard and seen live by over 600 million households around the world.

Buzz Aldrin on the surface of the moon. Credit: NASA

Fifteen minutes later, Buzz Aldrin joined Neil Armstrong on the surface, becoming the second human in history to take such steps. He described the lunar landscape as a "magnificent desolation." The two spent a total of two hours and thirty six minutes on their lunar EVA and collected over 47 pounds of moon rocks. They traveled only about 400 feet from the LM to what is known as "East crater." As each task took longer to accomplish than expected, the pair was not able to complete all their planned tasks in the short time they spent on the moon. In comparison, Apollo 17 astronauts would spend over 22 hours on the lunar surface over the course of three days and three EVAs. Before leaving the lunar surface, Aldrin and Armstrong left a memorial package dedicated to deceased cosmonauts Yuri Gagarin, Vladimir Komarov (the first man to die on a spaceflight), and Apollo 1 astronauts Gus Grissom, Ed White, and Roger Chaffee.

After their EVA, the pair climbed back into the lunar module and began prepping for the trip back to Columbia, where they would rejoin Collins. During this time, they discovered that the switch that controlled the main circuit breaker that armed the ascent stage rocket was broken. In Aldrin's own words, "Houston, Tranquility. Do you have a way of showing the configuration of the engine arm circuit breaker? Over. (Pause) The reason I'm asking is because the end of it appears to be broken off. I think we can push it back in again. I'm not sure we could pull it out if we pushed it in, though. Over." The solution to this was simply to force a felt-tipped pen into the slot.

Returning to Earth

After a few hours of rest, the pair launched from the lunar surface and rejoined Michael Collins aboard Columbia. They brought with them the 47 pounds of moon rocks, and left behind the experiments, the memorial bag, and the descent stage of the LM which had a plaque on it that read:

"Here Men From The Planet Earth First Set
Foot Upon the Moon, July 1969 A.D., We Came in Peace For All Mankind."

It was signed by all three astronauts and President Nixon and contained
images of the Eastern and Western hemisphere of Earth. It was also
noted that during the ascent, the force from the engine knocked the
American flag over, something fixed in future missions by placing it
further from the spacecraft.

Plaque attached to the descent stage of the Eagle lunar lander. Credit: NASA

The night before the scheduled splash-down back on Earth, the crew made a final TV broadcast where each gave a synopsis of their thoughts on the mission. Command Module Pilot Micheal Collins spoke on the efforts to create the machine they traveled in: "...The Saturn V rocket which put us in orbit is an incredibly complicated piece of machinery, every piece of which worked flawlessly... We have always had confidence that this equipment will work properly. All this is possible only through the blood, sweat, and tears of a number of a people... All you see is the three of us, but beneath the surface are thousands and thousands of others, and to all of those, I would like to say, 'Thank you very much.'"



On July 24th, 1969 the mission ended with the command module Columbia splashing down safely in the Pacific ocean. The trio were picked up by rescue teams stationed aboard the USS Hornet, and at that moment, President Kennedy's challenge to the American people earlier in the decade had been fulfilled. After three weeks in quarantine, to ensure they had not brought anything back with them, the three were welcomed back as heroes with awards and accolades heaped on them. As a science fiction fan, I find it interesting (but not especially surprising) that the three were awarded a special Hugo award for "The Best Moon Landing Ever" in 1969.

As Armstrong's team acknowledged before their return to earth, Apollo 11, and project Apollo in general, was not the achievement of three men atop a rocket. It was the work of the employees at NASA; the workers, engineers, and designers at North American, Grumman, Boeing, and Douglas; the people who built the tools that were used to build the spacecraft;  the individuals who picked up the astronauts when they returned from Earth; and the imagination of people the world over throughout time. For a moment in time, the world came together to marvel at the achievement not of a few individuals, not of a single country, but of mankind as a whole.

On the 40th anniversary of this feat, we at Nobel Intent and Ars Technica would like to add our voices to the worldwide chorus congratulating Micheal Collins, Buzz Aldrin, Neil Armstrong, and all those who helped make this momentous achievement possible. Since that monumental day 40 years ago, 10 other men have walked on the surface of the moon, but we have not been back since 1972, when Eugene Cernan took the last step off the moon and onto the Challenger lunar lander for ascent and rendezvous with the command module America. I was not alive yet in 1969 and did not get to witness these events as the transpired; however, I do hope that at some point in my own life the world can come together and witness one of their own stepping foot onto another terra firma within the heavens.

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