‘TODAY IS OUR DAY’
Reliving the harrowing final descent to the moon’s surface
By all appearances it was just an ordinary day in Houston — hot and sticky from dawn to dusk, made tolerable only by air conditioning and, perhaps, a dip in the pool.
But this was the summer of 1969. There would be few ordinary days in a season that would witness the start of The Troubles, the end of the Beatles, the Stonewall riots, the Manson murders, the Chicago 8, Chappaquiddick, Woodstock, the Miracle Mets.
Now it was Houston’s turn.
The streets were mostly empty as Gene Kranz wheeled
his ’67 Cougar toward NASA’s Manned Spaceflight Center. He had plenty of time to think. This was his day of days, a moment he had anticipated for most of the decade, through mission after mission as he worked his way up to Apollo flight director — all of it toward a singular goal. By nightfall, two Americans would be standing on the moon, circling it in frustration or dead.
Kranz was confident as he opened the heavy steel door to Mission Control. He and his team had done all they could in the time they had. He greeted his controllers, checked the status of the spacecraft, then began to read through the overnight logs. He tried to keep the momentous possibility of the day at arm’s length, though one recurring thought gave him satisfaction: Whatever hap
pened, he would have a front-row seat.
Kranz had slept well, no doubt better than the three men in the Apollo Command/Service Module. The CSM was roomier than space capsules of old, but comfort was not on its list of priorities. Its job was to get them to the moon and back home. Attached to it was an even more cramped vehicle that could barely contain two grown men, and only then if they stood up. If all went well, this awkward looking machine would shuttle Neil Armstrong and Buzz Aldrin to the surface of the moon — meeting the challenge laid down by President John F. Kennedy eight years earlier, and filling with awe billions of people around the world.
Kranz could not help but notice that something was missing as he prepared for the beginning of his shift. Noise. Conversations were steady but quiet. And that was a good thing.
Throughout the night and into the morning, all the data received back home from Columbia and Eagle — as the capsule and lander had been named — was as it should be. There had been no alarms, no significant issues. Kranz could not help but remember the chaotic times during some of the simulation runs, a few of which ended badly. Even many of the previous Apollo missions had their dicey moments. The day ahead
The Apollo 11 crew had been awakened with an odd request. Mission Control relayed an old Chinese story about a lovely young girl who had been banished to the moon about 4,000 years ago. Apparently she had stolen the pill of immortality from her husband. Keeping her company was a large Chinese rabbit, and the two would be found in the shade of a cinnamon tree.
After a typically quirky rundown of the overnight news back on Earth, the crew began to prepare for the day ahead. For Aldrin and Armstrong, that meant donning their EVA spacesuits, a lengthy procedure because of the myriad small components. Command Module pilot Michael Collins also had to suit up in the unlikely event he had to rescue his crewmates if something went wrong.
For hours the crew went through endless preparations before the module’s 13th revolution around the moon. Now it was getting serious. Soon it would be time for the spacecraft to split in two. As all the various controllers watched the telemetry streaming in from Columbia, the chatter back and forth with the spacecraft was steady, technical and crisp, the way Kranz liked it.
“OK, all flight controllers,” Kranz said at last, “go amber and stand by for Go, No Go for undocking.”
It was a quick and unanimous poll. There was no reason not to move forward. Powering up and prepping the lunar lander began before separation and ended with explosive bolts and a small guillotine that cut Eagle’s cord to the CSM. Then Armstrong, Eagle’s pilot, had to gently roll the craft so that Collins could do a quick visual inspection from Columbia.
As the two flew in tandem, Loss Of Signal approached. LOS occurs when a spacecraft is on the back side of the moon. Mission Control gets no data or voice communication. This period — “over the hill,” it’s called — created an opportunity to rush to the bathroom and perhaps to the coffee or soda machine, for the few who weren’t too nervous to eat or drink. But it also was an uncomfortable period. Controllers did not like to be in the dark. The flow of data from its machines 238,000 miles away was the lifeblood of Mission Control.
There was no way to know what exactly was going on, only what was supposed to be happening — a procedure that was relatively straightforward but had been practiced only a couple of times in space. The smallest part failure or mistake could jeopardize the mission. Mission Control waited.
The duration of silence was the same with each orbit, but sometimes it seemed infinitely longer. As the time for signal acquisition arrived, “CapCom” Charlie Duke, an Apollo astronaut who served as the voice of NASA to his brethren far above, began calling out to Eagle. Soon data began streaming through Eagle’s “steerable” antenna. It looked good.
Finally the voice of Armstrong responded.
“How does it look, Neil?” Duke asked in his unmistakable drawl.
“The Eagle has wings,” the astronaut replied.
What sounded like a special code from a World War II movie was actually a simple acknowledgment that the lunar module was performing properly and ready for the next phase. During their upcoming visit over the hill, Eagle was to fire its engines briefly to alter its orbit from circular to elliptical. Once done, that meant that somewhere along the line, for just a few minutes, it would be only 50,000 feet or so above the lunar surface. When it reached that point, Eagle was to begin its powered descent. Like all the other big moments so far, the PDI (Powered Descent Initiation) started on the dark side of the moon.
Kranz polled his flight controllers one more time. Go or No Go for the burn to put the Eagle in position to descend. Again, a unanimous yes. ‘This is our time’
It wasn’t long before the next signal loss arrived. The previous few minutes had been taken up with reviewing telemetry data and going through the next checklist. Clocks were synchronized so that NASA would know precisely when the Eagle’s engines had started their burn. Then another wait.
Kranz took a moment. He was not a sentimental guy, but there was something he wanted to say. He asked his controllers to switch to a private communication link so only they would hear him.
“Today is our day,” Kranz began, “and the hopes and dreams of the entire world are with us. This is our time and our place, and we will remember what we do here always.”
But Kranz wanted to give them more than inspirational thoughts. He chose to emphasize how much they had gone through in recent years, how much they had learned through numerous Apollo missions and countless simulations, and above all how ready they were, whatever the risks involved.
“Whatever happens here today, I will stand behind every decision you will make,” he said. “We came into this room as a team, and we will leave as a team. And from now on, no person will enter or leave this room until either we have landed, we have crashed, or we have aborted.”
Everywhere, in every nation and city and every place with a television — save for those places which for ideological reasons were unwilling to allow constant coverage — people waited for one of those outcomes. Few could understand the technical side of things, how exactly the lunar module worked, or why this feat was so different and so much harder than what actors did in the movies. They listened to one of the three nationwide broadcasts — Walter Cronkite was the big dog — and heard explanation after explanation.
Houston understood better than most because those involved in the space program were neighbors, friends, friends of friends, fellow church members, PTA parents. Oil and space were pretty much it for the city in those days, and the closer you got to Clear Lake, the emerging community NASA called home, the more it seemed like a company town.
Among the waiting were three especially interested wives and mothers, Jan Armstrong, Joan Aldrin, Pat Collins. Their children sprawled over the furniture and the floor, and friends kept them company. They spent the afternoon watching and then not watching the TV broadcast, each hoping to show professional cool to mask their churning insides, wanting it to be over. Joan Aldrin smoked and fretted, leaning against a wall. She and the others had given up so much already. The idea of giving up their husbands permanently was more than they could handle.
“Oh, God,” Collins confided to a friend. “I can’t stand it.” No fairy tale
Whatever the Life magazine stories had presented, their life stories were no red, white and blue fairy tale. (Later, two of the three marriages would end in divorce.) Their husbands were half-strangers to the children, often absent or too tired to engage in anything like a normal life. The last few months of nonstop training especially had been hellacious. Today offered relief, at long last, if just those last 50,000 feet could be managed.
That was the job of the ungainly lunar module, which looked like a mechanical spider, or perhaps a half-finished science project. Apollo astronaut Pete Conrad called it “an ugly and unearthly bug.” Then again, it didn’t have to be sleek like an airplane. Aerodynamics were not an issue in the lunar environment. It only had to work.
In a room not far from Mission Control, engineers whose companies had built the spacecraft or some of its components also were following the constantly downloading data for any sign of trouble. The spotlight was on Tom Kelly of Grumman Aerospace and three key members of his team, each of whom had helped nurse the lunar module through hundreds of tribulations before getting it right. This was their day, too.
Grumman had weathered repeated false starts and fierce criticism from NASA during the long years of development. No contractor envied the task that had been handed to a company mostly known for building airplanes. It was one thing to build a reliable rocket or capable capsule. There was precedent for those. While North American Aviation had fought tooth-and-nail for the whole contract, its interest was a one-piece moonship that would be put together in Earth orbit. To engineer a separate, one-of-akind “dinghy” with impossible
size and weight restrictions that could do the job with negligible chance of failure was an unfathomable challenge that few wanted.
“I thought I would explode from pent-up nervous energy,” Kelly later recalled. “And yet I was fascinated as one after another of the events required in a flight plan flashed by. LM’s rendezvous and landing radars were both on and operating. Everything was looking good.”
Communication issue
And then it wasn’t. Signal acquisition was restored after the brief dark side journey. Eagle was poised for final approach to the Sea of Tranquility. The burn had gone properly, and the lander was traveling at 3,000 mph at 47,000 feet, a bit faster than the flight plan called for, but an issue that could be handled — everyone assumed — so long as the speed did not increase.
Suddenly communication was lost. Getting the antennas aligned for a smooth back-and-forth had been a periodic problem. Now at the most critical moment, Mission Control could not talk directly to Armstrong and Aldrin.
“The communication problem has bit us,” Kranz recalled in his autobiography, “and I am hardpressed to keep my frustration from surfacing in my voice. Every member of the … team is ready for the race. Now we’re dead in the water. I have only five more minutes and then it’s Go or No Go.”
The devout Catholic said a quick prayer: Please God, give us comm. It falls on Duke to try to get the controllers’ instructions and comments relayed through to Collins in Columbia, whose communication link is solid. Kranz polled his team again. All said go despite the radio issues.
Duke reached out: “Eagle, Houston. If you read, you are go for powered descent.” There was no recognition. Collins stepped in: “Eagle, Columbia. They just gave you a go for powered descent. Eagle, do you read, Columbia?
“We read you,” Aldrin replied at last.
“Eagle, Houston,” Duke said. “We read you now. You’re go for PDI.”
“Roger,” Aldrin said. Kranz was beside himself with the in-and-out radio contact.
“Here we were getting ready to go to the moon, and we can’t even talk to the crew,” he recalled.
When the Eagle had dropped to 33,500 feet, alarms started going off. These were not unexpected. They had occurred often during simulations. Still, Aldrin was shocked. Later he said he felt like “somebody was getting in our way” to stop them from completing the task, but he did not want to divert his attention from the task at hand. He asked Mission Control what to do.
Duke heard Armstrong refer to a “12 02 alarm.” The CapCom was not sure what that meant, and he feared the worst.
“Communications dropouts are a nuisance,” Duke said later, “but a computer problem was a showstopper.”
Deal breaker or not?
Or so he thought. But Kranz had experienced something like it before. During one of the last simulations, the testing supervisor had thrown a variety of alarms at the controllers, who ultimately decided to abort even though all of their computer readouts looked good. It turned out that the alarms indicated a backed-up computer announcing that it was trying to catch up. After that drill, Kranz made it a point to determine which alarm codes were deal breakers and which could be ignored.
Armstrong was getting increasingly worried about the master caution that was being triggered by the alarms and asked for help. Kranz had pushed for a change in the flight rules governing the descent, allowing for a later final call on whether to go or abort. He was now glad he did, and he told him to press on, that none of the data coming back indicated a problem. That satisfied Eagle’s pilot.
“My own feeling,” Armstrong later recalled, “was that as long as everything was going well and looked right, the engine was operating right, I had control, and we weren’t getting any unusual attitudes, or things that looked like they were way out of place, I would be in favor of continuing, no matter what the computer was complaining about.”
And so they went, dropping steadily while also moving horizontally over the lunar landscape. When the Eagle reached 4,000 feet, Kranz called for one final vote. All his controllers said go. Duke passed it along. Aldrin acknowledged it, and as soon as he did another computer alarm went off. It was the same as an earlier one triggered by a computer essentially announcing that it was trying to catch up with more input than it can handle.
Armstrong’s task of finding the designated landing spot was proving impossible. The faster speed from the moment of separation from Columbia meant the original flight plan was not going to work. The Eagle was off course, and the closer it got to the ground, the more unfamiliar the terrain looked.
Still it kept dropping. Mission Control was receiving data in fits and starts. Other than being offcourse and overshooting its intended landing site, the Eagle’s numbers looked good, at least when controllers could see them. Kranz repeatedly queried his team for any reason to stop the descent. They were fast approaching the point where abort would be increasingly problematic. But as the controllers continued through their checklists, there was no compelling reason. So long as the alarms were accounted for and the computer didn’t back up so severely that it decided to abort the mission on its own, Eagle would keep heading down.
Running short on fuel
But as the controllers monitored their data, a new issue became significant. Because of the severe weight restrictions on the lunar module, there was only so much fuel allotted to the descent engines. And it was fast running out. It reached the point where it could no longer be measured because the remaining fuel, sloshing around, was below the level of the sensor. At that point, controllers began a mental countdown clock to estimate the time remaining until the tanks were drained.
They suddenly became very concerned. They did not understand what Eagle was doing. It was getting lower, yes, but moving much faster horizontally.
“I see the vehicle going across the surface of the moon like I have never seen it do in simulations,” remembered Steve Bales, the controller in charge of guidance. “I say, ‘What has gone wrong? What is going on?’ It’s going five times as fast horizontally. It’s not supposed to do that, it’s supposed to just gently hover down.”
Concern was rampant, not just in Mission Control but in all the nearby support rooms. Engineers and scientists did not grasp the reason Eagle would not slow down and drop to the surface, and the balky communications link had not allowed the folks in Houston to appreciate the challenge Armstrong was facing, or why he assumed control of the craft so early.
Armstrong, of course, was looking in vain for a place to land. The potential targets became no good as he got closer. They were strewn with boulders, some bigger than automobiles. If the lander failed to hit flat ground, the risk of tipping over was great. Even if the crew survived the landing, the likelihood of the Eagle remaining intact was almost nil.
The controllers grew silent. It was vital not to distract Eagle’s pilot. Kranz knew where he was heading, having studied the maps himself. He was aware that the terrain was not ideal. It was up to Armstrong to find enough square feet of level ground.
“I was tempted to land (earlier),” Armstrong said later, “but my better judgment took over. We pitched over to a level attitude which would allow us to maintain our horizontal velocity and just skim over the top of the boulder field. … I was quite concerned about the fuel level. … We had to get on the surface very soon or fire the ascent engine and abort.”
‘60 seconds’
As the descent rate monitor grew closer to zero, there was little commentary or call-outs. The Eagle had pitched up vertically and was all but hovering as Armstrong surveyed the surface. Aldrin reported 100 feet, then 75. He didn’t want to say anything and make his pilot more anxious, so he stayed silent as Armstrong headed for the other side of a crater.
“Sixty seconds,” suddenly was heard. It was the voice of controller Bob Carlton, who oversaw the LM’s propulsion and guidance systems, estimating the time left before fuel ran out.
As Kranz later recalled, there was no response from the crew. They were too busy. Besides, they understood what they had to do, the limits they might be called on to push. This is what they had trained for.
“I get the feeling they are going for broke,” Kranz remembered feeling. “I have had this feeling since they took over manual control. They are the right ones for the job. I cross myself and say, ‘Please, God.’ ”
Again came the fuel time: “Stand by for 30 seconds, 30 seconds.” Duke repeated the time to make sure the crew got the word. And then came an agonizing silence. Not a word. Not a cough or cleared throat.
Suddenly a report from the crew, relayed through Carlton: “Forty feet, picking up some dust, 30 feet, seeing a shadow. Fifteen sec—.” Everyone in Mission Control is now standing, even if there’s nothing to look at. What’s happened?
From Eagle: “Contact light … engine stop … ACA out of detent.”
In other words, Eagle is on terra firma, albeit of the lunar variety. The descent engine had been turned off. The manual controller remains in an out-of-center position.
“Flight, we’ve had shutdown,” Carlton said.
“We copy you down, Eagle,” Duke said.
Words from above
Outside the sealed Mission Control office, spectators and other employees were screaming and stomping their feet. The promise had been fulfilled. The only thing missing was a word from the crew. At last, having finished the brief post-landing checklist, Neil Armstrong pops up.
“Houston, Tranquility Base here,” he said. “The Eagle has landed.”
At 3:17 that Sunday afternoon, Kranz felt a chill overwhelm him like none in his life. Professionals aren’t supposed to get carried away. He was shocked by the sudden emotions, so many years building, then tried to bring himself around by slamming his forearm against his console. His pen flew through the air.
In a halting voice, Kranz addressed his controllers. There was more business to conduct.
“Everybody stand by for Stay, No Stay,” he said. “Stand by for T-1.”
While the watching world lost itself in a stunning and unbelievable moment, Aldrin and Armstrong calmly settled into a quick assessment of the lunar module. While their wives smiled and cried and accepted the hugs of those around them, the two men now on the moon knew there was a slight possibility that they might suddenly have to take off again. The controllers efficiently began to handle their chores, moving from T-1 to T-2 and finally T-3.
A few seconds later, Kelly and his Grumman associates, themselves crying and celebrating, got a call from another engineer monitoring the spacecraft. Almost at the same time, the Mission Control propulsion flight controller noticed the same thing. There was a problem, potentially a serious one. The celebrations ended and they had to determine how real was the chance that Eagle might soon blow up.
“The pressure and temperature were rising in a section of fuel line between the helium heat exchanger and the fuel control valve on the descent rocket engine,” Kelly recalled later.
The fuel remaining in the heat exchanger after engine shutdown was frozen by the cold helium. That meant there was a bit of liquid fuel trapped in the fuel line between the valve and the frozen “slug.” Heat from the engine
“I get the feeling they are going for broke. I have had this feeling since they took over manual control. They are the right ones for the job. I cross myself and say, ‘Please, God.’ ”
— Apollo 11 flight director Gene Kranz
parts was slowly increasing the pressure and temperature of the trapped fuel.
What did that mean? No one knew exactly. The problem had never come up before. What they did know was that if the temperature exceeded 400 degrees, the fuel would become unstable. An explosion was possible.
The issue was serious enough that within minutes Kranz and George Low, head of Apollo’s spacecraft program manager, had joined Kelly and his team in the Spacecraft Analysis room. A solution had to be found. The temperature was rising fast. It had just reached 350 degrees. Engineers had at most 10 minutes to fix the problem.
The only thing that came to mind was to “burp” the line: Open and shut the fuel valve for just an instant by pushing the button to start the engine. After asking a slew of questions, Kranz concurred, as did Low. The crew was not yet aware of the problem, so Kranz returned to Mission Control to speak with Duke, who would tell them what to do.
The quick double-push of the start button was not without risk. One of them was the possibility of destabilizing the lunar module and causing it to tip over. But with the temperature now above 350, it was likely the only obvious option.
Fortunately, nature intervened. As Kranz was about to speak with Duke, the very heat that was raising the fuel to a dangerous temperature managed to melt the frozen slug that had trapped it. The temperature and pressure quickly dropped within the normal range.
“We looked at the screen in amazement for a few seconds, then broke into smiles and cheers of relief,” Kelly later wrote in his account of how the lunar module came to be. “I collapsed back into my chair and realized that I was drenched in sweat. To this day, when asked about how I felt after the first LM landed on the moon, I say that for 10 minutes following touchdown, I was too busy and worried to even know they were there.”
Reality sinks in
And so it was for many at Mission Control. Then came the full impact of what had happened that day, the goal that Gus Grissom, Ed White and Roger Chaffee had given their lives to help achieve. The hard work that President Kennedy never got to appreciate, and which tore so many Apollo families apart even as it brought a nation together.
Kranz and his team worked through the Stay, No Stay procedures to make sure there was no reason for Eagle to leave the moon before its scheduled departure time. Then he headed over to the press conference to deal with the endless questions from the assembled media, many from
distant nations.
“While walking … I finally have time to absorb the full reality of it, in a moment of silence when there is no busy chatter on comm loops,” he remembered. “In a way, I feel cheated that I didn’t have the chance to savor those seconds as deeply as those who watched. More than ever, I appreciate the great training, the unrelenting pressure put on us in getting ready for Apollo 11.”
Later that evening, as reporters kept talking into cameras and pounding on typewriters, a lashing rainstorm hit parts of Houston. Hard summer rains are common to America’s home of human space operations. But on that evening, as much as any before, they seemed especially welcome — as if the constantly building tension of what might be, what could be, was finally and fully released.
And when the clouds cleared, people looked up at the moon in a new way.