Apollo The First Visit by Humans to Another World

The Apollo 11 mission achieved the national goal set by President Kennedy in 1961—namely landing human beings on the surface of the Moon and returning them safely to Earth within the decade of the 1960s. On July 20, 1969, astronauts Neil Armstrong (commander) and Edwin (Buzz) Aldrin (lunar module pilot) flew the lunar module (called Eagle) to the surface of the Moon, touching down safely in the Sea of Tranquility. While Armstrong and then Aldrin became the first two persons to walk on another world, their fellow astronaut Michael Collins (the CM pilot) orbited above in the Columbia command and service module (CSM).

On July 16, 1969, a gigantic Saturn V rocket flawlessly lifted off its pad at Complex 39-A of the Kennedy Space Center and started the most profound journey of exploration in human history. The Apollo 11 spacecraft (CSM-LM combined) followed a similar mission profile to the Moon, as had its immediate predecessor, the Apollo 10 spacecraft. Following launch, Apollo 11 entered orbit around Earth. After completing one and one-half orbits of Earth, the third stage of the Saturn V (the S-IVB upper stage) reignited for an approximately six-minute-duration translunar injection burn that placed the spacecraft on a course for the Moon. Thirty-three minutes later, the Apollo 11 astronauts separated the Columbia CSM from the S-IVB stage, turned the spacecraft around, and docked with the Eagle LM. About 75 minutes later, they released the S-IVB and injected this spent rocket stage into heliocentric orbit. While the docked CSM-LM spacecraft configuration coasted through cislunar space for its rendezvous with history, the Apollo 11 astronauts made a live, color, television broadcast back to Earth.

On July 19, the astronauts performed a 358-second, retrograde firing of the CSM's service propulsion system (SPS) to achieve insertion into lunar orbit. This orbit insertion burn was accomplished while the spacecraft was behind the Moon and out of contact with Earth. A second, much shorter duration (17-second) SPS burn circularized the spacecraft's orbit around the Moon.

The next day (July 20), Armstrong and Aldrin entered the Eagle to perform a final checkout before traveling in the LM down to the lunar surface. As the LM and CSM separated, Collins made a visual inspection of the Eagle from the Columbia (CSM). Armstrong and Aldrin then fired the LM's descent engine for 30 seconds. Their actions put the Eagle in a descent orbit, which had a closest approach to the Moon's surface of nine miles (14.5 km). The two astronauts fired the LM descent engine once again, this time for 756 seconds, and they began the final phase of their historic descent to the Moon's surface. Although Armstrong piloted the LM to a safe touchdown on the lunar surface, when he finished he had less than 30 seconds of propellant supply remaining. The problem that the astronauts encountered was finding a suitable landing site. Despite all the previous photographic reconnaissance that was performed during the site-selection process, the original landing site chosen in Mare Tranquilitatis (the Sea of Tranquility) was actually populated with a large number of small craters and rocks—landing incorrectly near any one of which could have spelled disaster for the mission. Searching for a suitable landing spot as the fuel supply for the Eagle's descent engine approached exhaustion, Armstrong finally spotted a relatively smooth place and quickly set the spidery-looking spacecraft down at 4:17 p.m. (EDT) on July 20, 1969.

Throughout this harrowing search for a safe lunar landing spot, personnel at NASA's mission controller center in Houston, Texas, were very anxiously monitoring the depletion of the Eagle's propellant supply. As soon as signals from the LM indicated that some type of contact had been made with the surface, mission control sent the following short message: "We copy you down, Eagle." The modest time delay (a little more than two seconds) for radio signals to go back and forth between Earth and the Moon seemed like an eternity to everyone in the room that day. Then back came Armstrong's famous reply: "Houston, Tranquility Base here. The Eagle has landed!" The response from Houston at this historic moment proved equally memorable: "Roger, Tranquility. We copy you on the ground. You've got a bunch of guys here about to turn blue. We're breathing again. Thanks a lot." This simple dialogue marked the start of one of the greatest moments in exploration.

Six hours later, Armstrong opened the ingress-egress hatch on the LM and cautiously descended the ladder. As his left foot made contact with the lunar soil, he reported back to Houston: "That's one small step for (a) man . . . one giant leap for mankind." About 19 minutes later, Aldrin followed and became the second human being to walk on the Moon. As he looked out at the lunar landscape and noticed the starkness of the shadows and the barren, almost desertlike characteristics of the Moon's surface, Aldrin remarked: "Beautiful, beautiful. Magnificent desolation."

The important deed was done. Intelligent life had successfully traveled from the surface of one world in this solar system to the surface of another. Consciousness was physically starting to spread beyond the boundaries of Earth. Now the human race faced a very interesting societal decision: Will it be the galaxy or nothing (self-annihilation)?

Like tourists everywhere, Armstrong and Aldrin began their visit to the Moon by snapping pictures, lots of pictures. They also collected souvenirs, some 47.7 pounds (21.7 kg) of soil and rock samples for the planetary scientists back home on Earth. Once their initial euphoria subsided a bit, they began to deploy instruments, such as the Early Apollo Surface Experiments Package (EASEP) near the lunar module. In a very busy few hours, they traversed a total of about 820 feet (250 meters) across the Moon's surface, gathered rock specimens, inspected the LM, positioned science instruments, and planted an American flag—not as a symbol of territorial claim (an act prohibited by international treaty) but rather as a permanent symbol of the nation that accomplished the first human landing. They also removed the protective, thin metal plate that was covering the Apollo 11 plaque mounted on the LM's ladder.

At the conclusion of their extravehicular activity (EVA), the astronauts returned to the LM and closed the hatch. They were supposed to sleep for a few hours before attempting to blast off from the lunar surface and rejoin Michael Collins, who was orbiting above in the Columbia CSM. Clearly, there was far too much to do and see and so little time. The best "rest" Aldrin managed to accomplish on the floor of the cramped lunar module was (in his own words) a "couple of hours of mentally fitful drowsing." Armstrong simply stayed awake inside the tiny crew cabin that was filled with noisy pumps and bright warning lights.

On July 21, after spending 21 hours and 36 minutes on the lunar surface, the astronauts fired the LM's ascent engine and lifted off from the Moon's surface. As the upper half of the Eagle arose into lunar orbit, the lower half remained behind on the surface in the Sea of Tranquility at 0.67 degrees N latitude, 23.5 degrees E longitude (lunar coordinates). The Eagle (as well as the other abandoned lunar-module descent stages from Apollo 12, 14, 15, 16, and 17) now serves as a permanent memorial to humans' conquest of space. Armstrong and Aldrin then docked with Columbia and transferred the collection of lunar rocks and some equipment into the command module.

On July 22, in preparation for the journey back to Earth, the astronauts jettisoned the ascent stage of the lunar module into orbit around the Moon. The precise fate of the upper half of the Eagle LM is not known, but NASA mission managers assumed that it crashed into the Moon's surface within a month to four months after being abandoned in orbit. After completing 31 revolutions of the Moon, the Columbia prepared to return home to Earth. A two-and-one-half-minute firing of the CSM's main rocket engine began the all-important transearth injection process.

On the morning of July 24, the command module made its programmed separation from service module (SM) and its three occupants prepared for reentry. After a mission elapsed time of 195 hours, 18 minutes, and 35 seconds, Armstrong, Aldrin, and Collins splashed down in the middle of the Pacific Ocean about 15 miles (24 km) away from the recovery ship, USS Hornet. U.S. Navy recovery crews arrived quickly by helicopter and tossed biological isolation garments into the spacecraft. After the suitably "cocooned" astronauts emerged from the Columbia command module, the team of recovery swimmers swabbed the spacecraft's hatch down with an organic iodine solution. Then the astronauts and recovery team personnel decontaminated each other's protective garments with a solution of sodium hypochlorite. The three astronauts were then plucked from the ocean's surface, transported by helicopter to the USS Hornet, and placed immediately in a special lunar quarantine trailer facility on the deck of the aircraft carrier. After a quick change of clothing inside the quarantine facility, the astronauts appeared at the window and received personal congratulations from President Richard M. Nixon (who had flown to the USS Hornet).

While confined in their quarantine trailer, Armstrong, Aldrin, and Collins—along with their now biologically isolated command module and its precious cargo of lunar rocks—traveled (primarily by aircraft) to the Lunar Receiving Laboratory in Houston, Texas. There, they remained in quarantine until late in the evening on August 10. From a medical perspective, this period of quarantine proved totally uneventful for the astronauts. Showing no signs of any ill effects from exposure to lunar dust or to any "postulated" extraterrestrial microorganism that might have hitchhiked back to Earth on their spacesuits or equipment, NASA's biomedical experts decided to release the three astronauts from quarantine. They went home to their families and, after a much-deserved period of privacy, embarked on a triumphant tour around the world.

To demonstrate that NASA scientists harbor no lingering concerns about back contamination from the Moon, there is a publicly accessible lunar rock sample and the Apollo 11 command module (Columbia) on

Though separated by the window of the Mobile Quarantine facility (located on the deck of the USS Hornet), President Richard M. Nixon was still able to share a humorous moment with Apollo 11 astronauts (left to right) Neil A. Armstrong, Michael Collins, and Edwin (Buzz) Aldrin shortly after they splashed down in the Pacific Ocean on July 24, 1969. Uncertain about the issue of back contamination, NASA managers quarantined the crews of the first three successful lunar landing missions (Apollo 11, 12, and 14). When no harmful effects appeared, NASA abandoned these quarantine procedures for the crews of the remaining lunar landing missions (Apollo 15, 16, and 17). (NASA)

exhibit at the National Air and Space Museum in Washington, D.C. Almost all the lunar rocks brought back by the Apollo astronauts are now kept under strictly controlled environmental conditions to preserve their scientific research value.

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