by Dan Parry
Mission Control: 'Roger. We copy.'
Aldrin: 'Got the Earth right out our front window.'
Armstrong [to Aldrin]: 'Sure enough.'
While Buzz had set his microphone to 'vox', transmitting everything he said, Neil's was on 'push-to-talk', so that Houston only heard his words when he wanted them to. At one point during training, Neil's reluctance to share everything with the world had led him to mutter a comment to Buzz about 'that damned open mic of yours'.31 Pushing the transmit button on his hand controller, Armstrong asked Houston to assess the difference in their altitude estimates. While managing a stream of data from the rendezvous radar, the computer was now also accepting updates from the landing radar. Neil and Buzz had the option of telling the computer to ignore the rendezvous updates, but they didn't choose to do this following advice received in training. However, the training had been devised for Apollo 10. With no intention of landing, Stafford knew he would rendezvous after a relatively short flight. He had no desire to switch the radar off and never got low enough for the landing radar to pose any problems. Eagle's computer was now receiving data from both radar systems at once. When Buzz gave it the additional task of looking at the difference between the two altitude estimates, it began to perform a combination of tasks that had not been tried before. In checking the spacecraft's current position, firing thrusters and setting the forward trajectory, the computer was running out of spare capacity, and at five minutes into the burn it triggered a yellow warning light along with an intermittent alarm.
Armstrong [to Houston]: 'Program alarm.'
Mission Control: 'It's looking good to us. Over.'
Armstrong [to Houston]: 'It's a 1202.'
Aldrin: '1202.'
Armstrong [to Aldrin]: 'What is it?'
On the ground, Bales – who had been preoccupied with the navigation error – now needed to work out how much trouble the computer was in. He quickly talked over the internal radio loop to Jack Garman, his backroom specialist, who told him that 1202 was a reference to 'executive overflow'. The computer was struggling to complete some of its tasks, just as had happened prior to the 1201 alarm during training. To Neil and Buzz, however, the alarm code was unfamiliar, and Armstrong was forced to break his concentration and pay close attention to the spacecraft's systems. Without knowing what the problem was it was impossible to know how much danger they were in.
This time, unlike the training session, Bales looked at whether there were any actual problems with the guidance and navigation data. The telemetry suggested that everything seemed to be working well. Since the computer hadn't crashed altogether but had simply returned to the top of its list of tasks, Bales decided the alarm could be ignored. The computer could still function – as long as it wasn't pushed any further. If it began to trigger successive alarms he knew they would have to abort. Armstrong didn't know if they were at that point already, and Buzz later said that 'hearts shot up into throats while we waited to learn what would happen'.32
Bales told Kranz that the mission could continue, and Kranz instructed Duke to give the go-ahead to the crew.
Mission Control: 'Roger. We're go on that alarm.'
With Eagle now down to 27,000 feet, less than 30 seconds later the alarm rang out again. This time Buzz realised it sounded whenever he asked the computer how far they were from the landing site.
Aldrin: 'Same alarm, and it appears to come up when we have a 16-68 up.'
Mission Control: 'Roger. Copy.'
Armstrong [to Aldrin]: 'Were we – were – was it [their delta- H] coming down?'
Aldrin: 'Yes, it is coming down beautifully.'
Mission Control: 'Eagle, Houston. We'll monitor your delta-H.'
The spacecraft was flying at 800mph, at an altitude of three and a half miles. Now that Houston was easing its workload, the computer was free to begin the next phase of the landing sequence. At six minutes and 25 seconds into the burn the digital autopilot slowed the engine. Still flying horizontally, feet first, Neil would soon have to slowly pitch up so that Eagle assumed more of an upright position.
At home in Houston, Janet Armstrong and 12-year-old Ricky sat on the floor listening to the television while studying lunar maps and diagrams. Thinking of Neil standing up like a trolleybus driver as he flew towards the surface, Janet excitedly called out, 'Come on, come on, trolley!'33
In Mission Control, Jay Greene – his quickfire Brooklyn accent cutting across the radio loop – told Kranz that the trajectory looked good. At 5,000 feet above the ground Neil got ready to take over from the digital autopilot, and with less than four minutes remaining he briefly tested the hand controller. Satisfied with its response, he focused on the view ahead. The surface was filling more and more of his window as Eagle approached a vertical position, the Sun now directly behind them. At 4,000 feet Kranz polled the controllers ahead of the landing.
Mission Control: 'Eagle, Houston. You're go for landing. Over.'
Aldrin: 'Roger. Understand. Go for landing; 3,000 feet.'
Mission Control: 'Copy.'
Aldrin: 'Program alarm – 1201.'
Alarms sounded a total of five times during the descent. They did not recur frequently enough to prompt an abort but they were a major distraction for Neil. The computer was bringing them down on a specific trajectory and would not swerve from its course despite the fact it couldn't tell whether it was taking them towards rocks or a crater. Neil needed to keep an eye on where they were heading. Yet as much as he wanted to monitor their descent, each time an alarm went off he was forced to look down at the instruments to see if everything was all right. As a result he missed many of the landmarks he had memorised. 'I just didn't get a chance to look out the window,' Armstrong later said.34
Armstrong [to Houston]: '1201.'
Mission Control: 'Roger, 1201 alarm. We're go. Same type. We're go.'
Aldrin: '2,000 feet; 2,000 feet.'
Armstrong [to Aldrin]: 'Give me an LPD.'
After interrogating the computer, Aldrin obtained a landing point designator angle of 47 degrees. By looking at this angle on the scale etched on his window Neil could see where the computer was leading them. As they came down to just a thousand feet above the surface, again there was a program alarm and again Neil was forced to shut it out of his mind as he focused on the landing. With the fuel decreasing all the time he couldn't afford to spend time on a problem that wasn't critical. The computer was bringing them down just short of a crater that was the size of a football field and surrounded by boulders, most of them as big as cars. The LM would survive a landing on sloping ground but rocks could damage its legs or tear open its fragile skin.
At around 600 feet Armstrong activated the hand controller and, following the pilot's maxim of 'when in doubt, land long', cut his rate of descent and tipped Eagle forward slightly. Flying the spacecraft like a helicopter, Neil allowed the main engine to carry them across the dangers below, at a speed of 40mph. Now entering the dead-man's box, if the engine failed there was little he could do about it. Come what may, in less than three minutes the limited amount of fuel would force him down. Yet looking at the ground ahead Neil still didn't like what he saw.
Armstrong [to Aldrin]: 'Pretty rocky area.'
Ignoring the difficulties below, Buzz continued to support Neil with a constant account of their progress, his life now in Armstrong's hands.
Aldrin: '600 feet, down at 19 [feet per second].'
Aldrin: '540 feet, down at 15.'
Aldrin: 'OK, 400 feet, down at 9; 58 [feet per second] forward.'
Armstrong [to Aldrin]: 'No problem.'
Aldrin: '350 feet, down at 4 ... 330, 3½ down. OK, you're pegged on horizontal velocity.'
Uncertain where he was and running low on fuel, Neil finally spotted a suitable area, sandwiched between more craters and another boulder field. By now 'quite concerned' about the fuel level, he still had some distance to cover to reach safety.35 'I was being absolutely adamant,' Armstrong later said, 'about my right to be
wishy-washy about where I was going to land.'36
In Houston, Janet put her arm round Ricky's shoulder as she sat with a hand over her mouth. To most TV viewers there was barely any indication of just how much pressure the men were under.
As he cleared an 80-foot crater, Armstrong was still covering a greater distance horizontally than vertically. At less than 100 feet, with dust being blown aside and obscuring his visibility, he faced a multitude of competing demands. He needed to be edging forward at the moment of landing in order to stay clear of the dust kicked up by the rocket exhaust. The rate of velocity must not be fast enough to risk damaging the legs, and he would have to avoid a slope of more than 15 degrees. He could not land while drifting sideways, and he must avoid craters. At the same time he must remain aware of their abort options, his position relative to the Sun, and the fuel rate called out by Buzz. Above all he had to come down soon.
In Houston, the controllers could see the LM's odd trajectory and could not understand what was happening. Why wasn't he landing? Bob Carlton's figures showed there was just 5 per cent fuel remaining. In his relaxed southern drawl he called 60 seconds, Duke passing on the message. Later, Charlie Duke said the atmosphere was so tense you could have cut a chunk out of it. Anxious to do what he could to help the crew, at one point he was jabbed in the ribs by Deke who muttered, 'Shut up, Charlie, let 'em land!'37
Leaning against a doorframe in her living room, Joan Aldrin dabbed her eyes with a tissue.38 In homes around the world millions of people listened to the sound of one of the spacemen calmly reading out some numbers, everything apparently going smoothly.
Aldrin: '40 feet, down 2½. Picking up some dust.'
There was no mistaking that comment by anybody: the Moon was real, and at last so was the chance of landing on it.
Aldrin: '30 feet, 2½ down. Faint shadow.'
Aldrin: '4 forward, 4 forward. Drifting to the right a little. OK. Down a half.'
Aldrin: '20 feet, down a half; drifting forward just a little bit. Good. OK.'
In Houston, Carlton counted down the seconds as the fuel supply reached a critical level. To Kranz he sounded completely unperturbed, as if 'out picking cotton'.39 Other than Carlton, the MOCR was silent, the rest of the controllers almost not daring to breathe as they helplessly waited for Eagle to land. Carlton reported there were just 45 seconds remaining. No-one reacted. Kranz knew the crew must now either abandon it or come down immediately. He didn't know how high they were when they'd started picking up dust, but since they must be within reach of the surface he had to accept that the final decision was Armstrong's.
Fifteen seconds later, Carlton spoke again, and again Duke passed on the warning.
Mission Control: '30 seconds.'
Armstrong [to Aldrin]: 'Forward drift?'
Armstrong was struggling to see the ground through the clouds of dirt rising up from the surface. He was a little confused, he said later, about Eagle's sideways motion and he tried to focus on anything that appeared to be static. 'I could see rocks and craters through this blowing dust,' he recalled.40
Aldrin: 'OK.'
Suddenly a blue light on Armstrong's instrument panel lit up as one of the six-foot probes beneath Eagle's landing pads made contact.
Aldrin: 'Contact light.'
Armstrong [to Aldrin]: 'Shutdown.'
The right and forward landing pads reached the ground simultaneously as Neil brought Eagle smoothly down to the surface. He had intended to let the LM fall the last three feet but he didn't have time to switch the engine off early, as planned.41 'It just settled down like a helicopter on the ground and landed,' Armstrong later said.42
Aldrin: 'OK. Engine stop. ACA out of detent [the hand controller needed to be put in the correct position].'
Armstrong: 'Out of detent. Auto.'
Aldrin: 'Mode control, both auto. Descent engine command override, off. Engine arm, off; 413 is in [a reference to an AGS program].'
Armstrong [to Aldrin]: 'Engine arm is off.'
Neil, the soft-spoken auditor's son from small-town America, had landed on the Moon. It was later established that he had more fuel than he thought (which wasn't registered due to sloshing in the tanks). Nevertheless Armstrong had enough for only another 25 seconds of flight. Now, his immediate task was to confirm the landing for the benefit of everyone listening in. Reluctant to say 'Houston, Eagle, Eagle has landed', he had decided in advance what he was going to say and had warned Charlie Duke.
Duke: 'We copy you down, Eagle.'
Armstrong: 'Houston, Tranquility Base here. The Eagle has landed.'
Still wearing their helmets and gloves, Armstrong and Aldrin smiled at each other and warmly shook hands. Buzz later said, 'I had known what he was going to say, but he had never told me when he was going to say it.'43
While Buzz's emotional reaction to the landing was 'quickly suppressed', in Joan Aldrin's front room everyone burst into applause – everyone other than Joan, who left them to it and walked into Buzz's study in search of privacy.44 In the Armstrong household, Janet and Ricky hugged each other in delight.45
In New York, an announcement was made at Yankee Stadium, where 16,000 people cheered and sang 'The Star-Spangled Banner'. In Moscow, cosmonauts – including Alexei Leonov, who had performed the world's first EVA – heard the landing on television and applauded their rivals' achievement. In Britain, TV viewers were glued to the country's first all-night broadcast, including coverage of jubilant scenes in Trafalgar Square. In Japan, Emperor Hirohito also followed the landing on television, and later cancelled his plans in order to watch the moonwalk. It was 3.17pm in Houston, where cheering and applause in Mission Control's viewing gallery took the controllers by surprise. 'There's nothing in training that prepares you for that second,' Kranz remembered.46 John Houbolt, hoping the world would freeze at that moment, was congratulated by Wernher von Braun amid a frenzy of flag-waving and back-slapping. The euphoria threatened to catch on in the MOCR, but between them Slayton and Kranz brought the noise back to an acceptable level so that the team could establish whether Eagle was in any immediate danger.
Duke: 'Roger, Tranquility. We copy you on the ground. You got a bunch of guys about to turn blue. We're breathing again. Thanks a lot.'
Duke slumped back in his chair and grinned at Slayton.47
Armstrong: 'Thank you.'
Duke: 'You're looking good here.'
Armstrong [to Aldrin]: 'OK. Let's get on with it. [To Houston] OK. We're going to be busy for a minute.'
They needed to quickly check that the LM was safe. If an emergency rendezvous were needed Eagle would have to launch within the next 12 minutes, before Columbia flew out of reach. Prior to the mission, it had been agreed to make two successive decisions at this point as to whether it was safe to stay. Less than two minutes after the landing, the flight controllers quickly checked the LM's systems before announcing all was well. They confirmed their decision seven minutes later, after a more detailed study of the telemetry. Once Michael passed out of range he would not return for another two hours, so for a little while yet at least Neil and Buzz had the Moon to themselves.
Chapter 13
SNEAKING UP ON THE PAST
For astronomers and geologists, Apollo 11 promised to offer a unique glimpse into the earliest years of the Moon, the Earth and the solar system. Relative to the Earth, the Moon is so big that some astronomers don't regard it as a moon at all but more the smaller partner in a binary planetary system. Many of the features on the near side are big enough to be seen with the naked eye, including mountainous regions rising to thousands of feet. But, since it orbits the Earth primarily (and does not orbit the Sun directly, in the way the Earth does), the Moon is not officially classified as a planet by the International Astronomical Union. It is better described as Earth's only natural satellite.
Information given to the press before the launch offered three competing theories for its origin.1 While some experts believed the Moon evolved separately from (but at the s
ame time as) the Earth, others thought its mass was once part of the Earth itself until driven into space by some cataclysmic impact. A third idea suggested it had wandered through space until captured by the Earth's gravitational field.2 In the search for the truth, the Moon's most alluring feature was the promise it held of an unprecedented look into the long-lost history of the Earth. In the billions of years since our planet was formed, climate conditions and continental drift have erased important clues about the past. Seas have come and gone, coastlines have vanished and mountain ranges have been greatly eroded. The lunar surface, however, undisturbed by the processes alive on Earth, remains suspended in a deathly state of preservation. While the Earth's surface is rarely older than 500 million years, there was hope that an astronaut on a lunar mission might find rocks dating back to more than four billion years. In 1969, scientists imagined the Moon would reveal the dormant secrets of the solar system's formative years.
Quite how well preserved the Moon would prove to be depended partly on its history of seismic and volcanic activity. Geologists had been trying to land a seismometer on the surface since the Ranger 1 mission. It was hoped that the instrument carried by Apollo 11 would finally answer some of their questions about the Moon's internal structure. Whether they could find answers to other questions would depend on the astronauts' ability to find valuable examples of moon rocks and successfully bring them home. To stir things up a bit, Armstrong had considered sneaking a piece of limestone (the sedimentary product of sea creatures) into the LM and placing it into one of the two rock-boxes.3 Samples of material were due to be sent to teams of scientists at 127 laboratories around the world, their research interests ranging from rare gases and metals to the analysis of lunar glass.4 Looking for an exclusive insight into the earliest days of the Moon, they were hoping to be whisked away on a bountiful journey into the distant mists of time. It would all begin the moment someone stepped on to the surface.
For astronauts hoping to walk on the Moon, the most striking features were not the rocks found in a specific area but the life-threatening conditions prevalent across the entire lunar terrain. Unprotected by an atmosphere, during the height of the lunar day the ground soars to a temperature of 243°F. Radiation levels are significantly greater than on Earth, occasionally becoming dangerously high, and micrometeoroids regularly pelt the surface. Armstrong and Aldrin would have to overcome these dangers if they were to leave the relative safety of Eagle. And once outside, there was no certainty they would find what they were looking for. Their landing ground had been chosen largely because of its flat terrain rather than for any geological value. They had received little training specific to the site and they were not expected to retrieve much more than samples of whatever they found lying beside the spacecraft.5 Yet slender as these pickings might be, once brought home to Earth they would be unique. Although the dangers were considerable, so were the potential rewards.