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Apollo 11

Updated on May 6, 2010

"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 earth."

The First Men on the Moon

On May 25, 1961, President John F, Kennedy addressed the the U.S. Congress and the American people. The Soviet Union had already sent a man into orbit around the earth, and the United States had launched a manned suborbital flight. The time seemed to have arrived for translating into reality an age-old dream of mankind, to have men leave their planetary cradle and stride on alien worlds.

On July 20, 1969, the flight of Apollo 11 achieved this dream. Two astronauts took the first steps on an alien world. Men had walked on the moon.

The mission of Apollo 11 was a triumph for American science and technology. Beyond that, it was a triumph for a centuries-long chain of scientists and inventors, whose work and dreams had made the flight possible. The roster of their names extends back from rocket engineers of the recent past, such as Konstarttin Tsiolkovsky and Robert H. Goddard, to ancient astronomers, such as Aris-tarchus, who first began to discover the true nature of the universe. The following feature pages describe Apollo 11's historic flight.

It will be the task of future historians to assess the Impact on man's history of the first lunar landing.

Even from this short range of time, however, it can be asserted with good reason that man has reached another crossroads in his quest for knowledge, and that his thinking about himself and his world can never again be quite the same. What man can achieve some day among the stars may indeed be limited only by his own self-knowledge, or lack of it, and by the energy with which he pursues new goats in the exploration of space. As Robert H. Goddard wrote in 1932: "There can be no thought of finishing, for aiming at the stars, both literally and figuratively, is the work of generations, but no matter how much progress one makes there is always the thrill of just beginning."

The Crew of Apollo 11

The three astronauts who made up the crew of Apollo 11 were Neil A. Armstrong, a civilian, and Edwin E. Aldrin, Jr., and Michael Collins, both Air Force officers. Each of the men had made one previous flight into space and was a veteran pilot with several years of training. Aldrin was also a graduate of the Massachusetts Institute of Technology with the degree of doctor of science in astronautics. On the Apollo 11 flight Armstrong was the mission commander, Aldrin served as the commander of the lunar module (code-named Eagle for the flight), and Collins was the pilot of the space-craft's command module (code-named Columbia). Armstrong and Aldrin were the men who would descend to the surface of the moon.

Heading Toward The Moon

The mission of Apollo 11 got under way at 9:32 A. M. Eastern Daylight Time (EDT) on July 16, 1969. Approximately one million spectators in the Cape Kennedy. Fla.. area and hundreds of millions of television viewers around the world watched the Saturn 5 rocket rise slowly from Launch Complex 39 with its manned Apollo payload.

The astronauts entered a temporary "parking" orbit about 115 miles (185 km) above the earth, where the guidance system of the instrumentation unit computed the exact moment for the S-4B stage of the rocket to reignite in order to insert the spacecraft into its translunar path. This path was calculated so that, should the engine of the servic'e module fail to place the Apollo 11 in lunar orbit, the spacecraft would swing around the moon and return to earth along a "free return" trajectory—the same flight path used on Apollos 8 and 10.

The firing of the S-4B stage took place on schedule, speeding the spacecraft to an initial velocity of nearly 24,300 miles (39,100 km) per hour. So accurate was the firing that three of four planned midcourse corrections were subsequently canceled. The long journey to the moon had begun.

Early in the translunar coasting period, several necessary maneuvers were carried out to reorient the spacecraft. The linked command and service modules were turned about so as to dock with the lunar module, after which Eagle's four connections to its adapter and the S-4B stage were severed with spring thrusters and explosive bolts. Later, about 34 hours into the flight, the astronauts relayed their first scheduled color television broadcast to the world. They reported being deeply impressed by the image of the receding earth, with Aldrin adding the perhaps unnecessary comment that "The view is out of this world."

The Soviet Union placed an unmanned probe, Luna 15, into orbit around the moon while Apollo 11 was still en route, and the astronauts were kept informed of its progress. The purpose of the probe was never made clear by the Soviet Union, but one common theory was that it had been meant to follow the progress of the Apollo mission. Another theory held that Luna 15 was an unsuccessful attempt to collect a sample of lunar soil and return it to earth—as Luna 16 managed to do in 1970— before the Apollo mission was concluded. The probe eventually crashed into the moon.

As Apollo 11 neared the lunar surface, the time came to fire the service module's propulsion system. The engine burn reduced the spacecraft's velocity from approximately 6,500 to 3,700 miles (10,460 to 5,960 km) per hour and placed the astronauts in an elliptical orbit around the moon. Apollo 11 had traveled 244.930 miles (394,337 km). The time was 1:22 P. M. (EDT), July 19.

In Lunar Orbit

After completing two circuits of the moon, the astronauts reignited the propulsion system to bring their craft into a roughly circular orbit, between 62 and 75 miles (100 and 121 km) above the lunar surface. Gazing down at the cratered land below, Armstrong described the first view of the area where he and Aldrin planned to touch down a few hours later. "It looks very much like the pictures but like the difference between watching a real football game and one on TV. There's no substitute for actually being here."

The orbital flight continued as on-board systems were checked out thoroughly. This completed, flight commander Armstrong and the controllers in Houston agreed that it was time for the descent maneuver to begin. The first step was to undock Eagle from Columbia. This took place while Apollo 11 was passing above the far side of the moon. Armstrong and Aldrin pressurized the tunnel between the two modules and opened the connective hatches to crawl into Eagle, where they made extensive reviews of all systems and subsystems before undock-ing. Collins remained aboard Columbia.

As the modules returned to the near side of the moon, Armstrong reported to Houston, "The Eagle has wings." The lunar module was ready, and men were about to descend to the moon's surface.

Descending to the Moon

Tension now rose aboard Eagle and Columbia, at mission control in Houston, and in front of television receivers in homes and public places all around the world. (It is estimated that about 500 million persons listened in as the landing took place.) Eagle's descent-stage engine was fired, first at 10% throttle and then at 40%. The lunar module's orbital path became highly elliptical, with a perilune of about 50,000 feet (17,250 meters) above the surface. This was the maneuver to insert the craft into descent orbit.

When the landing approach "corridor" had been identified, the engine was again fired, near the perilune point, to permit the craft to sink downward to the moon. Everything proceeded under the automatic control of the on-board computer until Eag/e was about 7,600 feet (2,320 meters) above the surface and 26,000 feet (7,930 meters) uprange Jrom the planned touchdown site in the Sea of Tran-quility, northwest of Crater Moltke. The craft was further braked at this point, and dropped to about 500 feet (150 meters) as the crew received visual cues from the landscape and assessed the terrain below for the best place to land.

At an altitude of about 450 feet (137 meters), Armstrong and Aldrin took over the controls, having decided against an automatic landing sequence In favor of a semiautomatic procedure. Because of a program alarm that indicated the on-board computer was being overworked, the astronauts and Houston brought Eag/e down through a verbal exchange of instrument data and visual observations. The last few moments were extremely tense ones for everyone involved, for in addition to the program alert, the lunar module's guidance and navigation system was heading the astronauts toward a very rocky crater. Armstrong had to burn the engines for another 70 seconds in order to reach a smoother landing site about 4 miles (6.4 km) away.

The final moments came as Aldrin reported, "Forward, forward, good. Forty feet. Picking up some dust... Drifting to the right... Contact light. OK. Engine stop!" The engine was to be stopped almost immediately after devices dangling below Eagle's footpads contacted the surface and caused a light to shine on the instrument panel. Armstrong delayed for one second; then, looking down onto a sheet of lunar soil blown radially away in all directions by the rocket exhaust, he shut off the engine. "Tranquility Base here. The Eag/e has landed," said Armstrong. The time was 4:17:41 P. M. (EDT), July 20. Men were on the moon.

On the Lunar Surface

Up until this moment of the flight, the millions of television viewers could only listen to words being passed between Apollo 11 and ground control. Soon they would be able to watch events on the moon as well. Ironically, one man who could not see what was happening on the lunar surface until after the mission was completed was Michael Collins, who had to be content with listening to the voices of his crewmates as he circled the moon. Originally the mission plan had scheduled about eight hours for checking out systems, eating, and resting, before the astronauts would actually leave their lunar module. However, after assuring themselves that Eagle was in good shape, Armstrong and Aldrin requested permission to cancel or at least postpone a 4-hour rest period. They wanted to go out on the lunar surface as soon as they could get ready. Houston agreed; it seemed unlikely that the two men would do much sleeping at this stage of their momentous journey.

Nevertheless, more than three hours were needed to get suited up for the extravehicular activities. The donning of portable life-support-system backpacks proved particularly time-consuming in the cramped quarters of Eagle. In their suits at last, the astronauts depressurized their cabin—which proved to be another tedious process—and opened the hatch. It was six and a half hours since the lunar module had landed.

Armstrong slowly descended the 9-rung ladder leading down from the "porch" of the lunar module to the moon's surface. At the second rung he released a fold-down equipment compartment on the side of the module, releasing a television camera that would then record the first steps taken by a man on the moon. Soon the silhouetted figure of Armstrong could be seen, as he continued his descent of the ladder. When he took his first cautious step onto the lunar soil, at 10:56:20 P. M. (EDT), he paused to say the now-familiar words: "That's one small step for a man, one giant leap for mankind."

Soon Armstrong began to give verbal descriptions of the material on which he walked. "The surface appears to be very, very fine grain, like a powder.... I can kick it loosely with my toes. Like powdered charcoal. I can see footprints of my boots in the small, fine particles. ... No trouble to walk around." Meanwhile Aldrin remained in the lunar module, monitoring the television camera and observing his companion's movements outside. Finally he asked, "Is it OK for me to come out?" A few minutes later he stood on the moon.

Like tourists visiting a spectacular vacation area, the astronauts took dozens of photographs, exclaiming "Beautiful view!" and "Magnificent desolation!" They showed television viewers the plaque on Eagle's descent stage, which read:

JULY 1969, A. D.

The plaque was signed by the astronauts and President Richard M. Nixon, who later made a telephone call from the White House, through Houston facilities. Nixon observed, "Because of what you have done, the heavens have become a part of man's world." In the early minutes of their extravehicular activities Armstrong and Aldrin also erected a metallic U. S. flag near the landing craft, before returning to their busy schedule.

Working on the Moon

The surface activities involved three principal goals. First, the astronauts checked and photographed Eagle from all angles, to determine if any flight or landing damage had occurred. They also studied the depressions—only 1 to 2 inches (about 2.5 to 5 cm) deep—made by Eagle's footpads, to gain information on the moon's surface properties. Second, the astronauts had to familarize themselves with the environment by walking and running; their evaluations of clothing and equipment would be invaluable in making plans for later landing missions. Third, they collected as much operational and scientific information as possible during their short period of extravehicular activity.

Armstrong gathered about 45 pounds (20 kg) of rock and soil samples; the samples were placed in sealed bags that were then inserted in two aluminum boxes. The astronauts also set up three instrument systems for obtaining scientific data: a solar wind composition detector, a seismic detector, and a laser reflector from which scientists back on earth later "bounced" laser beams for a more accurate determination of the landing site and of the motions of the earth and the moon and the distance between them.

The solar wind device consisted simply of a very thin aluminum foil deployed so that the foil would be exposed directly to the sun's rays. In effect, it was a trap for the inert-gas constituents of the stream of particles constantly flowing outward from the sun. (The lunar soil itself was later found to be rich in solar wind particles.) Near the end of the stay on the moon, the solar wind device was folded and placed in one of the sample containers.

The seismic detector was deployed to monitor possible "moonquakes," meteoroid impacts, free oscillations of the moon, and general signs of internal activity. The instrument was powered by a radioisotopic heater developed by the Atomic Energy Commission. Almost immediately after its deployment, the station went into operation; it has since provided scientists back on earth with much valuable data about events on the moon.

Armstrong also attempted to take two core samples of subsurface materials. He described the difficulty he encountered in this task. "I could get [the first coring device] down about the first two inches without much of a problem and then I would pound it in about as hard as I could do it. The second one took two hands on the hammer, and I was putting pretty good dents in the top of the extension rod. And it just wouldn't go much more than—I think the total depth might have been about 8 or 9 inches. But even there, it... didn't seem to want to stand up straight, and it would dig some sort of a hole but it wouldn't just penetrate in a way that would support it... If that makes any sense at all. It didn't really to me."

The astronauts also provided interesting verbal descriptions of their lunar environment. Aldrin reported "literally thousands" of craters about 1 to 2 feet (0.3 to 0.6 meter) in diameter in the area. There were also boulders of all shapes, up to 2 feet across, and some even larger. Many of them were above the ground, while others were partially or almost completely buried. The footprints left by the astronauts were about an eighth of an inch (0.3 cm) deep.

Armstrong and Aldrin found mobility was no problem, although both men described the ground as "slippery" (possibly as a result of the many tiny glass spherules later found in the samples of lunar soil). They quickly became accustomed to the low gravity, but found it best to anticipate their motions three or four steps in advance as they worked (in order to compensate for the reduced length of time that the foot remains on the ground during a stride on the moon).

The period of extravehicular activity came to an end when the astronauts had to begin their return to the landing craft, after about two and a half hours of work on the surface. They stowed the solar wind experiment, dusted off their extravehicular mobility units, kicked their boots clean against the footpad of the lunar module, ascended the platform, swung open the hatch, disconnected the equipment conveyor, and jettisoned equipment and items no longer needed. Among the litter that Eagle jettisoned were cameras, the television unit, hand-tools, core bits, the environmental control system cannister and bracket, some used urine bags, and the two portable life support systems. Armstrong and Aldrin took a well-earned rest before their return the next day to Columbia.

In a news conference held after the astronauts had returned from their Apollo mission, Armstrong and Aldrin were asked about the time spent outside the landing craft: "Was there ever a moment on the moon when either one of you were just a little bit spellbound by what was going on?" Armstrong replied, "About two and a half hours."

Returning to Earth

Lift-off from the lunar surface took place at 1:55 P.M. (EDT) on July 21. Despite their strenuous hours of activity on the moon, the two Eagle crewmen actually slept very little before the time of launch. When the ascent engine was fired, the stage soared rapidly upward in what Armstrong described as a very smooth and quiet ride. Left behind was the descent stage of Eagle, along with the instruments and debris of man's first stay on the moon.

The ascent engine had to burn for more than seven minutes in order to produce a final velocity of 4,128 miles (6,646 km) per hour. The first phase of the ascent involved a vertical rise, so that the craft might clear any possible lunar terrain features. The craft was then tipped over by 52° for insertion into lunar orbit. Thereafter, maneuvers brought the two ships within rendezvous distance of each other, and Eagle and Columbia began to dock. The ships suddenly gyrated, to the surprise of the astronauts, but docking was accomplished thereafter without mishap and only three minutes behind schedule. Aldrin and Armstrong crawled back into Columbia to rejoin Collins, the hatches were closed, and Eagle was jettisoned. Columbia was Apollo 11 once again, minus its lunar module.

The journey homeward was essentially a repetition of the events in the missions of Apollo 8 and Apollo 10. The three astronauts functioned much as they had on the moonward journey, making navigational checks, rolling the spacecraft, and so forth. The return trip took about 60 hours, during which the astronauts again transmitted a television program to earth. During this program each of them, In turn, reflected on the meaning of their flight. Aldrin said, "This has been far more than three men on a voyage to the moon; more, even, than the efforts of one nation. We feel that this stands as a symbol of the insatiable curiosity of all mankind to explore the unknown."

Some three and a half hours before the Apollo began to reenter the atmosphere, the astronauts turned the command module away from the sun to permit it to cool to the maximum possible extent. The service module was then separated from the command module.

At about 400.000 feet (125,000 meters) above the earth, the command module began to heat up. As the module penetrated deeper into the atmosphere, the temperature of the heat shield rose to approximately 5,000° F (2,760° C), and the astronauts experienced a deceleration force of more than six g's (six earth gravities). At an altitude of about 24,000 feet (73.000 meters) the heat shield was jettisoned, and the drogue parachutes were deployed.

Five minutes later, with the drogue parachutes severed and the main parachutes of Apollo 11 spread out above their spacecraft, the astronauts splashed down in the Pacific Ocean southwest of Hawaii, within sight of the recovery ship USS Hornet. The time was 12:40 P.M. (EDT), July 24. The historic mission was at an end.

The astronauts landed about 2 miles (3.2 km) away from their intended target and 13 miles (20 km) from the waiting recovery ship, the USS Hornet. The three men and their capsule were quickly retrieved by Navy frogmen and helicopters. Before they left their capsule, Armstrong, Aldrin, and Collins were handed three biological isolation garments with plastic-visored face masks. This was the first of several steps taken back on earth to reduce to an absolute minimum any danger of contamination from lunar materials. During their return flight, the astronauts also had followed precautionary procedures, such as vacuuming their equipment and filtering the cabin atmosphere to remove stray particles of lunar dust.

As soon as they emerged in their germ-proof garments and entered the waiting life rafts, the astronauts were thoroughly washed with a decontaminant, after which they in turn washed the frogman who performed this chore, in case he should have become contaminated in the process. The hatch of the Apollo spacecraft was also scrubbed. These safety measures had been developed by an in-teragency committee prior to the flight, although most scientists felt that the possibility was remote that any microorganisms of any sort existed on the moon, whether dangerous or benign.

Upon being delivered to the Hornet, where President Nixon waited to greet them, the astronauts were immediately transferred to a quarantine van called the Mobile Quarantine Facility. The president spoke to the three men through a window of this facility, congratulating them on their epic flight. The astronauts, still inside their quarantine van, were then taken to Hawaii and flown back to the Manned Spacecraft Center at Houston. There they and their precious cargo of lunar rocks and soil were transferred to a Lunar Receiving Laboratory, where they remained under observation for 18 more days. Having shown no sign of ill effects from having come in contact with the moon, Armstrong, Aldrin, and Collins were permitted to emerge from isolation on August 11. Now truly returned to the world of men, the astronauts had to prepare for another arduous mission: the days and weeks of strenuous parades, interviews, and acclamation that were to follow. For a while, the first men on the moon became the first citizens of earth.


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