Published: December 1969

First Explorers on the Moon

camel contest

The Flight of Apollo 11

“One giant leap for mankind”

By Kenneth F. Weaver
Ektachrome by NASA

This article was originally published in the December 1969 issue of the magazine.

Two thousand feet above the Sea of Tranquillity, the little silver, black, and gold space bug named Eagle braked itself with a tail of flame as it plunged toward the face of the moon. The two men inside standing like the motorman in a 19th-century trolley car-strained to see their goal. Guided by numbers from their computer, they sighted through a grid on one triangular window.

Suddenly they spotted the onrushing target. What they saw set the adrenalin pumping and the blood racing. Instead of the level, obstacle-free plain called for in the Apollo 11 flight plan, they were aimed for a sharply etched crater, 600 feet across and surrounded by heavy boulders.

For Astronaut Neil Armstrong, at the controls of the frail, spidery craft, a crisis in flight was nothing new. In 1966 he had subdued the wildly gyrating Gemini 8 when one of its thrusters stuck. More recently, he had ejected safely from the “flying bedstead,” a 752 jet-powered lunar-landing training vehicle, just before it crashed. Now he would need all the coolness and skill acquired during 500 earthbound hours in simulators and during years test-flying the X-15 and other experimental aircraft for the National Aeronautics and Space Administration.

The problem was not completely unexpected. Shortly after Armstrong and his companion, Edwin (Buzz) Aldrin, had begun their powered dive for the lunar surface ten minutes earlier, they had checked against landmarks such as crater Maskelyne and discovered that they were going to land some distance beyond their intended target.

And there were other complications. Communications with earth had been blacking out at intervals. These failures had heightened an already palpable tension in the control room in Houston. This unprecedented landing was the trickiest, most dangerous part of the flight. Without information and help from the ground, Eagle might have to abandon its attempt.

Moreover, the spacecraft’s all-important computer had repeatedly flashed the danger signals “1201” and “1202,” warning of an overload. If continued, it would interfere with the computer’s job of calculating altitude and speed, and neither autopilot nor astronaut could guide Eagle to a safe landing.

Eagle’s Descent Fuel Runs Low

Armstrong revealed nothing to the ground controllers about the crater ahead. Indeed, he said nothing at all; he was much too busy. The men back on earth, a quarter of a million miles away, heard only the clipped, deadpan voice of Aldrin, reading off the instruments.

“Hang tight; we’re go. 2,000 feet.”

Telemetry on the ground showed the altitude dropping ... 1,600 feet ... 1,400 ... 1,000. The beleaguered computer flashed another warning. The two men far away said nothing.

Not till Eagle reached 750 feet did Aldrin speak again. And now it was a terse litany: “750 [altitude], coming down at 23 [feet per second, or about 16 miles an hour] ... 600 feet, down at 19 ... 540 feet, down at 15 ... 400 feet, down at 9 ... 8 [feet per second] forward ... 330, 3½ down.” Eagle was braking its fall, as it should, and nosing slowly forward.

But now the men in the control room in Houston realized that something was wrong. Eagle had almost stopped dropping, but suddenly—between 300 and 200 feet altitude—its forward speed shot up to 80 feet a second—about 55 miles an hour! This was strictly not according to plan.

At last forward speed slackened again and downward velocity picked up slightly.

“Down at 2½ [feet per second], 19 forward ... 3½ down, 220 feet [altitude] ... 11 forward, coming down nicely, 200 feet, 4½ down ... 160, 6½ down ... 9 forward ... 100 feet.”

And then, abruptly, a red light flashed on Eagle’s instrument panel, and a warning came on in Mission Control. To the worried flight controllers the meaning was clear. Only 5 percent of Eagle’s descent fuel remained. By mission rules, Eagle must be on the surface within 94 seconds or the crew must abort (give up) the attempt to land on the moon. They would have to fire the descent engine full throttle and then ignite the ascent engine to get back into lunar orbit for a rendezvous with Columbia, the mother ship.

When only 60 seconds remained, the countdown began. The quivering second hands on stopwatches began the single sweep that would spell success or failure.

“Sixty seconds,” called Astronaut Charles Duke, the capsule communicator (CapCom) in Houston. Sixty seconds to go. Every man in the control center held his breath.

Failure would be especially hard to take now. Some four days and six hours before, the world had watched a perfect, spectacularly beautiful launch at Kennedy Space Center, Florida. Apollo 11 had flown flawlessly, uneventfully, almost to the moon. Now it could all be lost for lack of a few seconds of fuel.

“Light’s on.” Aldrin confirmed that the astronauts had seen the fuel warning light.

“Down 2½ [feet per second],” Aldrin continued. “Forward, forward. Good. 40 feet [altitude], down 2½. Picking up some dust. 30 feet. 2½ down. Faint shadow.”

He had seen the shadow of one of the 68-inch probes extending from Eagle’s footpads.

“Four forward ... 4 forward, drifting to the right a little.”

“Thirty seconds,” announced CapCom. Thirty seconds to failure. In the control center, George Hage, Mission Director for Apollo 11, was pleading silently: “Get it down, Neil! Get it down!”

The seconds ticked away.

“Forward, drifting right,” Aldrin said.

And then, with less than 20 seconds left, came the magic words: “Contact light!”

The spacecraft probes had touched the surface. A second or two later Aldrin announced, “O.K., engine stop.”

Still later, the now-famous words from Neil Armstrong: “Tranquillity Base here. The Eagle has landed.”

And, with joy in his voice, CapCom replied: “Roger, Tranquillity, we copy you on the ground. You got a bunch of guys about to turn blue. We’re breathing again. Thanks a lot.”

It was 4:17:43 p.m., Eastern Daylight Time, Sunday, July 20, 1969.

Feat Watched by the World

Man’s dream of going to the moon was fulfilled. The most exciting adventure in human memory now neared its climax as the two men prepared to step out on the lunar surface, while their fellow crew member, Mike Collins, kept vigil in his orbiting command module, Columbia, 70 miles above.

To me, it is impossible to compare this exploit with the epic feats of the great 15th- and 16th-century navigators, of the 20th-century polar explorers, or of Lindbergh in 1927. The differences are too profound, and one of the most important of those differences is that the whole world was watching.

According to estimates, one out of every four persons on the face of the earth watched or heard the astronauts by television or radio as they ventured to the moon. Nearly 850 foreign journalists, representing 55 countries and speaking 33 languages, reported the story from Cape Kennedy and Houston.

Americans abroad were thrilled by the impact of the flight on foreign peoples. Dr. Louis B. Wright, former Director of the Folger Shakespeare Library and a National Geographic Society Trustee, observed the effect firsthand in Italy. With 25,000 other people he was attending a performance of Aida in the Roman Arena at Verona on that Sunday night.

“At the first intermission,” Dr. Wright recalls, “an announcement was made in four languages: ‘The Americans have just landed on the moon at 10:17.’ My watch said 10:28.

“The crowd applauded wildly. Here and there spectators pulled little United States flags from their pockets and waved them. And for days afterward, when Italians met me on the street, they all had one word for the flight—‘Fantastico!’”

And so it was—with different inflections—in Buenos Aires and Sydney, Tokyo and Delhi, Dublin, and Madrid.

The thrill of a race had added to the excitement. Since 1961, when President John F. Kennedy had announced the goal “before this decade is out, of landing a man on the moon and returning him safely to the earth,” many people had firmly believed that the Soviet Union was racing to put a Russian on the moon first.

In the past year or so, Soviet chances had seemed to dim, but as Apollo 11 approached the moon, the news that Luna 15 was already in lunar orbit lent color to the suspicion that the Soviets hoped to land an unmanned craft, scoop up some lunar soil, and rush back to earth before the American moon samples could get home. Only when Luna 15 crashed in Mare Crisium—the Sea of Crises—some 500 miles from Tranquillity Base, was the way clear for the U. S. triumph.

That triumph was an especially heady one for those who argued the advantages of manned space flight. Without a man at the controls, they pointed out, Eagle would almost certainly have crashed into an unforgiving field of boulders.

The full story became known only after the astronauts returned to earth. When Neil Armstrong first spotted the landing site through the grid on his window, he did not really know where he was. Actually the crater toward which he was heading—later identified as "West Crater" (an unofficial name) was just within the southwest edge of the planned landing ellipse, a bull’s-eye 7.4 miles long and 3.2 miles wide. But most of the landmarks the astronauts had memorized so carefully before the flight were several miles behind them, and were of no help now.

Armstrong had no doubts, however, about what to do; he had faced problems like this many times before in the simulators.

Taking over partial control from Eagle’s autopilot, he ordered the computer to keep the craft at a steady altitude and gave Eagle its head, reducing the braking effect of the descent engine and letting the craft surge forward at high speed.

Only when he had shot over West Crater and its frightful rocks (“as big as Volkswagens”), and had cleared a second, smaller crater 100 feet in diameter, did he bring the descent engine's braking power into full play again and drop to a level, relatively clear spot.

During the last forty feet or so of descent, the rocket-engine exhaust sent the dust of the moon flying. Not billows of dust; instead, the disturbed particles flew out at low angles and high velocity, like rays of light, with no atmosphere to buoy them or impede them. Armstrong later described it as “much like landing through light ground fog.” The moment the engine shut off, however, the view out the window was completely clear again.

Armstrong’s maneuver took him more than 1,000 feet beyond where the autopilot would have set him down, cost an extra 40 seconds, and left only about 2 percent of usable fuel—about 400 pounds—for the descent engine.

But it meant a safe landing, and a gentle one—so gentle that the two men hardly felt it. Armstrong says that their downward speed was probably no more than one foot a second. And the footpads of the eight-ton craft (it weighed only a sixth of that on the moon) settled just an inch or two into the surface.

Space Suits Balk Lunar Hazards

Inside the spacecraft, Armstrong and Aldrin set calmly about making sure they could get home again. They carefully worked through their check lists to assure that all the systems were working, that the supplies of oxygen and fuel were satisfactory, and that the ascent engine would be ready when needed.

Then history’s first lunar explorers completed the laborious task of suiting up for their excursion onto the moon’s surface. To their many-layered space suits, marvels of engineering that work like Thermos bottles and that can stop micro-meteoroids traveling at 64,000 miles an hour—30 times the speed of a military rifle bullet—they added other ingenious protections against the hazards of the moon’s environment: heavily corrugated plastic overboots that can resist temperatures from 250 degrees above zero F. to 250 degrees below; gloves covered with fine metal mesh (a special alloy of chromium and nickel)—worth $1,000 a yard—to protect the glass-fiber and Teflon material from abrasion; hoods for their transparent bubble helmets, with double visors (both of them coated with gold) to block the sun’s intense glare, heat, and ultraviolet radiation.

Finally each donned a remarkable backpack known as the PLSS (portable life support system) to provide cooling water, electric power, communications, and oxygen enough to last four hours outside the lunar module without replenishing. The men had become, in effect, independent spacecraft.

All this added nearly 190 pounds to each man’s earthly weight. Although that means only about 32 pounds on the moon, it alters the center of gravity and hampers activity. The suit, when pressurized, becomes so hard that hitting it with the fist would be like striking a football. Bending over to the ground is extremely difficult.

I have some idea of how all this paraphernalia must feel: I once tried on Astronaut Gene Cernan’s suit and helmet. Under earthly conditions, I found them heavy, cumbersome, and slightly claustrophobic. But no astronaut complains. Should his space suit lose pressure, he would keep useful consciousness, as pilots say, for only 8 to 12 seconds.

First Step Beamed to a Waiting World

About six and a half hours after Eagle landed, its hatch opened and the Apollo 11 commander backed slowly out to its little porch. On the ladder he paused, pulled a lanyard, and thus deployed the MESA, or modularized equipment stowage assembly, just to the left of the ladder. As the MESA lowered into position with its load of equipment for lunar prospecting, a seven-pound Westinghouse TV camera mounted atop the load began shooting black-and-white pictures. Fuzzy and scored with lines, the pictures nonetheless held earthlings spellbound.

No one who sat that July night welded to his TV screen will ever forget the sight of that ghostly foot groping slowly past the ladder to Eagle’s footpad, and then stepping tentatively onto the virgin soil. Man had made his first footprint on the moon.

Neil Armstrong spoke into his microphone. And in less than two seconds the message that will live in the annals of exploration flew with the wings of radio to the huge telescope dish at Honeysuckle Creek, near Canberra, Australia, thence to the Comsat satellite over the Pacific, then to the switching center at the Goddard Space Flight Center outside Washington, D. C., and finally to Houston and the rest of the world: ”That’s one small step for a man, one giant leap for mankind.”

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