by Buzz Aldrin
Our space quests continued through all of this. In the Cold War environment, it had to. The Soviets had jump-started the Space Age with the launch of Sputnik in October 1957, and the satellite’s strange new beeping sound startled the western world as it orbited the Earth. On April 12, 1961, the Soviets sent the first human into space, cosmonaut Yuri Gagarin, for one full orbit around the Earth. NASA responded by sending America’s first astronaut, Alan Shepard, for a fifteen-minute suborbital ride, sixty-two miles up to the edge of space, on May 5. Three weeks after Shepard’s fledgling flight, President John F. Kennedy addressed Congress and issued a stunning challenge to the nation to embrace a bold new commitment to land a man on the moon and bring him safely home before the end of the decade. It was May 25, 1961. We didn’t have the know-how, the technology, or the rocketry, but we had the willpower. NASA’s innovative engineers and rocket scientists, including the indomitable Wernher von Braun, along with the aerospace industry, congressional support, and teams of thousands throughout the country, worked together to bring us to this point of being on the verge of realizing Kennedy’s challenge.
We needed this first moon landing to be a success to lift America, and to reaffirm that the American dream was still possible in the midst of turmoil. We needed this mission to succeed after eight years of national effort to get us here. Yes, we were determined to win the space race, to beat the Soviets to the moon. In the broadest sense, we hoped this mission would lift and unite the world, and stand as a symbol of peace for all mankind. That’s why we included an olive branch in the design of our Apollo 11 mission patch, which we wore on all our space-suits. Initially, the design depicted an American bald eagle (the inspiration for the name of our lunar landing craft) with its talons stretched out, about to land on the crater-marked surface of the moon. When we added the olive branch of peace to be carried in the eagle’s talons, that made it all the more significant to me. In addition, we departed from tradition and chose not to include our names on the patch. We felt the mission had a bigger meaning than that of the individuals involved.
On the third day of our journey, Apollo 11 flew into the shadow of the moon. We were more than five-sixths of the way to our destination. But for now we marveled at the unusual view ahead of us of a shadowed lunar sphere eclipsing the sun, lit from the back with a bright halo of refracted light. The soft glow of reflected light from the Earth helped us see ever more vividly the moon’s protruding ridges and the impressions of craters, almost adding a 3-D sensation to our view.
On the morning of day four, it was time to enter the moon’s gravitational influence. We needed two Lunar Orbit Insertion burns to move us into position before the command module could separate from the lunar module so Neil and I could begin our descent to the surface. For the first burn, we strapped ourselves in to swing around the moon’s far side, the rugged, dark side never seen from Earth, bombarded by meteoric activity And for the first time we would lose all communication signals with Mission Control during the forty-eight minutes it would take for us to traverse the far side. The burn had to be precisely orchestrated at exactly the right time for six minutes to slow us down to just over 3,600 miles per hour—the speed at which we would be “captured” by lunar gravity. But we were entirely on our own for this one. This had to go right. Mike punched the PROCEED button to fire the engine, and the timing was perfect—although Mission Control would not receive confirmation for another forty minutes.
Now that we were in lunar orbit, we had two hours to initiate one more burn to transform our wide elliptical orbit into a tighter, more circular one. We carefully aligned our navigation using star sightings. Through a complex series of star positioning checks and alignment of our CM platform, we were ready for our second burn. If we over-burned for as little as two seconds, we would be on a collision course back toward the far side of the moon. Working this time in full coordination with Mission Control, the tricky procedure came off perfectly as we sailed even closer to the moon.
The next morning at 8:50 a.m. (EDT) on Sunday, July 20, 1969, Neil and I floated up through the access tunnel that linked the CM to the LM, the spacecraft in which Neil and I would descend to the lunar surface. We were no longer in flight suits, but fully suited up in our twenty-one-layered extra-vehicular-activity (EVA) spacesuits that we would wear until returning to the CM. We hooked up the hoses from our suits to the oxygen supply on the LM, donned our helmets, and waited while Mike went through his lengthy preparations for separation. Our hearts pounded in anticipation of the “powered descent” to the lunar surface.
As lunar module pilot, I had previously entered the LM on the second day of our journey to check things out and prepare what would now be Neil’s and my home away from home for approximately twenty-four hours. The LM was the epitome of bare-bones construction. A technological wonder, it had to be as light as possible, so it was far from luxurious inside. Everything in the interior of the LM had been sprayed with a dull navy-gray fire-resistant coating. To further reduce weight, nothing was covered unless absolutely necessary; all the wiring bundles and plumbing were completely exposed, and there weren’t even covers on the walls of circuit breakers and switches. There were no seats in the LM, or sleeping couches. We would sleep in makeshift hammocks hung from the walls, and we would fly the lunar lander while standing up, almost shoulder to shoulder, in our pressurized suits and helmets. We would be tethered to the deck of the LM by elastic cords. Two small upside-down triangular windows, one on each side of the control panels, provided our only sight of the surface. It was going to be an interesting ride.
The time seemed interminable as Mike went through his checklist to make sure every item was carefully set up. If he botched the undocking and damaged the tunnel, Neil and I would have no way to rejoin Mike in the CM. At least not the way we planned. If we found that the tunnel was jammed after attempting to re-dock, then Neil and I would have no other option than to exit the LM for an EVA spacewalk, using our emergency oxygen containers, and follow the handrails outside the LM to the top to manually open the CM’s hatch and climb in. As commander of the Gemini 8 mission, Neil had not performed a space-walk, since no commanders participated in EVA prior to Apollo, but he was well trained to perform one if necessary. My five-and-a-half-hour spacewalk on Gemini 12 had been thrilling, and had set a world record for spacewalking in large part thanks to being the first astronaut to train underwater using scuba gear, and the first to use a system of greatly improved fixed hand and foot restraints I had suggested for the exterior of the Gemini spacecraft. But an emergency EVA was a different story. The timing, owing to the limited supply of oxygen in our emergency packs, would be critical. And if for some reason we could not dock at all with the CM, Neil and I would still need to exit the LM for a spacewalk so Mike could gently maneuver the CM in our direction to pick us up. Although far from ideal, an emergency EVA could be our only means of survival. One way or another, we would need to pass through the narrow tunnel connecting the two spacecraft to return home, or we wouldn’t return at all.
On our thirteenth orbit around the moon, we found ourselves on the far side when Mike informed us that we were ready to commence undocking. Until this point, our docked pair of spacecraft had simply been known as Apollo 11. Now, as we rounded the moon back toward Earth’s side and sealed off the hatches to become two separate entities, the CM would take on the name picked by Mike, the Columbia, and the LM became known to Mission Control and the world as the Eagle, the name selected by Neil and me. Houston began monitoring the data that was now streaming between the computers of the two spacecraft. Finally we heard the words from Mission Control: “You are go for separation, Columbia.”
Mike wasted no time. As though he were backing a truck out of a parking space, he pulled the Columbia away from the Eagle, releasing us with a resulting thump. At 1:47 p.m. (EDT), July 20, the Eagle separated from the Columbia. “Okay, Eagle” Mike said. “You guys take care.”
“See you later,” Neil replied, as casually as if
we were back in Houston, heading home from another day of training.
As one last precaution before setting off on his own solo orbits around the moon—the first man in history ever to do so—Mike visually inspected the LM from his perspective in the Columbia, after we had undocked. “I think you’ve got a fine-looking machine there, Eagle, despite the fact that you’re upside down.”
“Somebody’s upside down,” Neil quipped in return.
Standing shoulder to shoulder, now it was our turn to focus on our lengthy checklist as we began flying the LM backwards, continuing in our own orbit around the moon. We flew around the moon once and started around a second time while Mission Control monitored all aspects of our progress. Then, with the friendly twinge of a Texas drawl, the voice of astronaut Charlie Duke, who was now serving as Capcom, parted the static. “Eagle, Houston. You are go for DOI.”
Charlie was telling us that it was showtime. Descent Orbit Insertion (DOI), would take us on an initial coasting descent to within eight miles of the lunar surface, just slightly higher than most commercial aircraft fly over Earth. The DOI burn lasted less than thirty seconds. I looked out the triangular window closest to me and could see the surface of the moon rolling by. The craters were becoming larger and more distinct, their beige color taking on a chalky gray appearance. We continued flying above the terrain until we again heard Charlie Duke. “Eagle, Houston,” Charlie sounded controlled but excited. “If you read, you’re go for powered descent. Over.”
Because of the static in our headsets, Charlie’s words were garbled, but fifty miles above us, Mike Collins heard them clearly and relayed the message: “Eagle, this is Columbia” he said calmly. “They just gave you a go for powered descent.” With no video monitor onboard, Mike could not see the LM or watch the proceedings, but he could listen in on the radio communications. It was a good thing he was paying attention.
Neil nodded as we acknowledged the implications of Charlie’s message. Inside my helmet, I was grinning like we had just won the biggest race of all time. In eleven minutes we were going to set the Eagle down for a landing unlike any other.
NEIL THREW THE switch to ignite the powered descent burn. Oddly, we could barely hear it or feel any sensation when a hot orange plume poured out of the engine into the black space below us. Had we not seen the change on the instrument panel in front of us, we might not have even known that the engine had ignited and was whisking us downward. But downward we were going, and rapidly, too. Through the window on my right, I could see the moonscape seemingly rising toward us.
I turned on the 16-millimeter movie camera that was located in my window to film our descent to the lunar surface. I also switched on my microphone to voice activated mode (VOX). Neil didn’t really care whether or not we were on an open mike as we descended, but I did, so I turned the setting to VOX. There were simply too many things going on to have to worry about a “push to talk” microphone system as we came down. Looking back, I’m glad that I left the mike on. Millions of people on Earth listened in to the static-filled radio transmissions between Mission Control in Houston and us as we descended. Some of our transmissions were barely distinguishable. That was one problem we had not anticipated in our hundreds of hours of working in the simulator back on Earth—it hadn’t really occurred to us that we wouldn’t be able to hear instructions from Mission Control, but we were catching enough to stay focused and keep going.
Five minutes into our powered descent, everything was looking good as we passed through about 35,000 feet on our altitude readout. Suddenly an alarm flashed on the screen in front of me.
Neil saw it as well. “Program alarm!” he said instantly to Houston.
Even with our transmissions traveling at the speed of light, it took one and a half seconds each way between the moon and the Earth, causing a three-second delay in all our communications. This meant that Charlie couldn’t respond immediately, so his response was based on our prior communication. Indeed, he was still quite positive.
“It’s looking good to us. Over.”
“It’s a twelve-oh-two.” Neil’s voice included a hint of urgency. “What is it?” Neil said to me. We had never seen a 1202 alarm in our simulations, and in the middle of our crucial eleven-minute landing maneuver, we weren’t about to take out the thick guidance and navigation dictionary we had brought along. Then to Houston, Neil said, “Give us a reading on the twelve-oh-two Program Alarm.”
“Twelve-oh-two,” I called out, the seriousness of the alarm evident in my voice as the data screen in front of me went blank. We were now at 33,000 feet above the moon, not a time or place to have an alarm go off, and certainly not a time to have our landing data disappear. Neil and I exchanged tense looks. Something was affecting our guidance computer and causing it to have difficulty in handling the gigantic array of information coming into it from the landing radar.
Nevertheless, we weren’t thinking about aborting; we didn’t want to get this close to landing on the moon and have to turn back; we were intent on fulfilling our mission. On the other hand, the alarm was ominous. If the 1202 alarm meant an overflow of data in the computer, we might not be able to rely on the very computer we needed to land on the moon. Either the computer’s programs were incapable of managing all the landing data coming in to it at once, or perhaps there was a hardware problem caused by all the jostling around since wed left Earth four days ago. Maybe something inside the computer had broken, just as might happen to a home computer. In any case, we had no time to fix it. The potential for disaster was twofold: first, maybe the computer could not give us the accurate information we needed to land; or, second, if in fact we succeeded in landing, the computer’s malfunction could prevent us from blasting off the moon and making our rendezvous with Mike the next day. The demands on the computer then would be even greater.
While we grappled silently with these possibilities, we continued descending toward the moon pushing through 27,000 feet. The large red ABORT STAGE button on the panel loomed large in front of us. If either Neil or I hit the button, the Eagle would instantly blast back up toward Columbia, and America’s attempt to land on the moon would be dubbed a failure.
“Roger,” Charlie’s voice broke through the static into our headsets. “We’ve got you … we’re go on that alarm.” Even from 250,000 miles away, I could hear the stress in Charlie’s voice. Yet for some reason the experts at Mission Control judged the computer problem an “acceptable risk,” whatever that meant. There was no time to discuss the situation, or to remedy it; we could only trust that Mission Control had our best interests at heart and would guide us in the right decisions. Of the hundreds and hundreds of people who had helped get us here, nobody wanted to abort the mission. Yet at the same time we knew that Mission Control would not jeopardize our lives unnecessarily. Two nights before we launched, NASA’s top administrator, Tom Paine, had eaten dinner with Neil, Mike, and me in the crew quarters. “If you have to abort,” he said, “I’ll see that you fly the next moon landing flight. Just don’t get killed.”
Just as I was getting over my concern about the first alarm, another 1202 alarm appeared on the display, another computer overload problem. Nearly seven minutes in, we had descended to 20,000 feet. I felt a shot of adrenaline surge through my system. I’d been a fighter pilot during the Korean War and had shot down two Russian-built MiGs that had been gunning for me. I knew instinctively the sense of danger a pilot experiences when he is in serious trouble and knows he needs to head back to his home base. Neil and I were in serious trouble, and we were a long, long way from home.
At Mission Control in Houston, twenty-six-year-old Steve Bales— about the average age of most of the guys in the Mission Operations Control Room—was the expert in the LM guidance systems. When the alarms started flashing in the Eagle, they showed up on Steve’s computer as well. He immediately realized the problem, but determined that it would not jeopardize our landing. He based his decision on the fact that the computer was receiving an overflow of
radar information; it had been programmed to recognize the radar data as being of secondary importance and would ignore it while it did the more important computations necessary for landing—he hoped.
Forty years later, I can now tell you why that computer overloaded, although at the time it never occurred to us. The reason the computer could not handle the data was that Neil and I had purposely left the rendezvous radar in the on position.
At some point after the Eagle had separated from the Columbia, I should have turned off the rendezvous radar, but I’d chosen not to do so. I hadn’t wanted to eliminate an opportunity to check the rendezvous radar before we actually needed it, so I’d simply left it on. I wanted a safety precaution in case we had to make a quick ascent, hightailing it away from the moon’s surface and back into space to catch up with Mike Collins and the Columbia, our ride back home. As it was, we had no idea that the computers couldn’t handle information from the rendezvous radar and the landing radar at the same time, or process the data quickly enough.
About two weeks prior to our launch, the Apollo 12 astronauts had also been training at the same time as the Apollo 11 crew, since the missions were quite similar. They had experienced the computer alarms in simulation, so they’d aborted the mission. The simulation trainers in Houston and Florida said, “You should not have aborted. It was not that serious.”
Flight Director Gene Kranz was irate. “Go back and study this matter,” he told the Apollo 12 crew. “We don’t want any of these kinds of mistakes in the future.”
