It was not long before the first landing on the moon would end in disaster
At the control center in Houston, it was 15:17 in the afternoon on July 20, 69, when Apollo 11 commander, Neil Armstrong,
He finally uttered the words the world was waiting for: "Here is the foundation of peace. The Eagle Has Landed".
Radio and television reporters from 50 countries and more listened to NASA's call, and seconds later billions of people around the world rejoiced at the news. Everyone longed to hear the astronauts from Apollo, and almost no one paid attention to the fascinating answer of Charlie Duke, from the control center: "We got it, Shlava, we hear you here on Earth. You made some guys here turn blue. We are back to breathing. Thank you".
Why were the control center people so worried?
What is not known to the general public is that the Apollo 11 lander was very close to a possible disaster. The first sign of danger was discovered when the lander was at a height of only 1,828 meters above its base, as it plunged towards the moon for the final landing. Suddenly a yellow warning light started flashing on the computer display in the astronauts' cabin. "A software alarm," Armstrong said.
Bez Aldrin, sitting next to him, pressed a key on the display panel. 1202 report to the control center. He was calm but slightly confused. What the hell is code 1202? He couldn't remember encountering this code during training on the simulators.
In the control center, 26-year-old Steve Balls sat in front of the "guidance" computer terminal, through which he supervised the computer systems of the landing vehicle itself and its navigation systems. The voice of the senior flight controller, Gene Kranz, is heard on the loudspeaker, demanding to know "What is a code.? 1202 Suddenly all attention was directed at Balls. The lander was speeding towards the moon and the computer signaled that something was wrong. He needed a few seconds to think. Above all he had to stay calm. "Go on standby" he answered, trying to gain time. Aldrin wanted an answer right away. "Give us the interpretation of the warning" 1202 he said, in effect asking if they should cancel the landing.
Bales had no time to think. The spacecraft plunged into an area that people at NASA called the "death zone". From the moment the landing vehicle separated from the command vehicle, which continued to move on its course and went on its separate journey, it was possible for the crew unit of the landing vehicle, which entered the launch phase, to interrupt the final landing phase at any given moment, if something went wrong. In the guidance computer of the landing vehicle, special software was installed whose role was to deal with emergencies of the type with a second's warning, even if the other software of the main computer is not functioning. In an emergency the launch stage's separate engine could launch the astronauts back into orbit where they would be reunited with the command unit.
The same goes for the lunar soil. As long as the launch was timed to coincide with the next orbit of the mother spacecraft above it, the top of the lander could leave the moon quite sharply. But the death zone was a brief period of uncertainty. Within the last three minutes of the approach to landing, there was a period of ten seconds, in which the space vehicle was moving downward at such a speed that if the launch engine had activated itself as an emergency "return to orbit" step, the entire fuel reserve would have been wasted due to the resistance to the downward swing. The upper part would not have been able to rise back up and connect to the mother spacecraft, which is orbiting at an altitude of 100 km above it. Instead he would crash on the moon.
The death zone was only 20 seconds away when computer alarm number 1202 sounded. If Balls was going to recommend abandonment, he should have done so at that moment.
According to the rules, the warning code 1202 means that the computer in the landing vehicle could fall at any moment. Making the most courageous and perhaps even the most irresponsible decision of his life, Balls spoke through the communication system to Kranz and the other inspectors: "We are 'going' on the alert," he said.
This was the signal for the other astronauts to ignore the warning and continue disconnecting, much to the relief of astronaut Mike Collins, who reviewed his notes and discovered that warning 1202 meant "executive data load", meaning that the computer was required to do too many operations at once and had to pause some of them. Kranz was surprised, but trusted the inspectors completely. He let the decision be made, and the lander plunged into the death zone.
A few minutes later Aldrin was on the line again with another computer alert. "We have a twelve-twelve warning. .” 1201 "It's the same kind of warning," Balls said. "You are still 'going' for the landing." He relied on his instincts. On July 5, he and his colleagues encountered unexpected alerts 1201 and 1202 during the last training of the control center, before the launch of Apollo 11. At the time, while Krentz was studying it intently, Balls decided to abandon the simulated landing. None of the computer experts in Houston could figure out why the alerts started going off. There was a small glitch in the software, without any precise explanation, they assumed.
So why didn't Balls order an abandonment now, when the astronauts' lives were really in danger?
To tell the truth, he should have canceled the landing, but he didn't believe the warning* 12. What's more, even when warning lights were flashing on the computer, the data he entered into the astronauts' control panels regarding speed and altitude were correct, and the disengagement proceeded more or less as planned...maybe the warning was in vain Just a random glitch in the system.
Twenty years later, Balls still wasn't sure about the decision he made in that terrifying moment. "No one really knew what caused the problem and I would not have been able to know XNUMX percent that the judgment I used was correct. It was based more on instincts than on the facts themselves," he repeated.
He had to rely on his gut feelings. And Kranz had to trust him. Fortunately, they were both right. Balls decided that as long as the computer worked, everything should go well.
The landing vehicle safely dived and cleared the death zone, and when the landing engine began to slow the vehicle down for final contact with the ground and abandonment was possible again, the computer seemed to be functioning (although now the alerts sounded once every few seconds), and Blass was saved. But Armstrong and Aldrin have not yet reached safe shore. Just as Bales began to recover from the panic of the *1202, Charlie Duke from the control center began to broadcast a succinct warning to the entire Apollo 11 crew: "Sixty seconds."
From listening to the original tapes of the dialogue at NASA, it is not possible to discern that anything was wrong; But in technical brevity, what Duke said to Armstrong was actually: "Your disengagement engine has sixty seconds of fuel left."
In all the simulation flights in which Armstrong "flew", he managed to land on the ground with plenty of excess fuel. So what was the problem this time?
Duke broadcast another warning: "Thirty seconds." The senior astronaut, Deke Slayton, who was standing behind Duke, told him quietly: "Shut up Charlie and let them land."
At any given second the engine of the landing unit was supposed to shut down. And as soon as that happened, the upper part would separate automatically and start an emergency return to orbit. Launching the top under these chaotic circumstances was no guarantee of safety, even outside the death zone, but it was better than crashing the entire vehicle on the moon. Kranz and his team then saw something amazing on their telemetry screens. When the vehicle had less than* 30 meters left to land, it began to be thrown forward and leaped over the surface of the moon at a speed of 55 km/h. Did NASA's two best pilots lose control of the spacecraft?
Another ten seconds crept up on them. Aldrin finally broadcast: “Contact lights. Switch mode to 'Automatic'.
Turn off the engine."
These were the first words ever uttered by a person from another world. Unfortunately for Aldrin, Armstrong took credit when he broadcast a minute later in terms that were more accessible to the public: “Here is a peace_base. The Eagle Has Landed".
In the control center, shouts of joy erupted, and Duke's radiophonic response; "There are some guys here who almost turned blue", she almost got lost in the shouts of joy and happiness.
There were tears in Krantz's eyes, but he forced himself to maintain restraint. They still had a lot of work ahead of them. Armstrong and Aldrin were now on the moon, and their first task was to prepare to leave in a hurry. "Everyone calm down" Kranz shouted instructions to the noisy young inspectors around him. It was still not possible to assume with confidence that the astronauts could stay on the moon. What if the landing craft is damaged during landing? What if the ground on the moon held unpleasant surprises and their fragile vehicle sank into soft ground or overturned on the slope of some hidden crater? What if one of the four legs of the landing vehicle rested on a rock and suddenly slipped?
Armstrong and Aldrin immediately set the switches for emergency liftoff. The small spacecraft rested on the ground for a full two minutes when Kranz finally decided that, in his opinion, the "Eagle" had indeed landed. When he finally lifted his arm from the control panel table he found that it was almost stuck in place due to the sweat dripping from it.
Armstrong sounded almost apologetic when contacted and explained what happened at the last minute of the landing. "Houston, it may have seemed like an extremely long final stage, but the guidance computer led us straight into a crater with a large number of rocks and stones, and we were required to manually fly over a rock field to find an acceptable area to land."
Armstrong needed precious extra seconds to hover a few meters above the surface, pushing the vehicle forward several hundred meters in order to find a safe place to land. The dust blown up by the engine significantly detracted from the astronauts' ability to calculate their height in the final stages as well as their speed above the lunar surface. The fact that the overloaded computer navigated the lander about 5 kilometers away from the planned landing site did not help either. Houston didn't need an apology from Armstrong. "Keep calm, there are a lot of smiling faces in this room, and everyone in the world" replied Duke.
"Even up here there are two smiling faces," Aldrin said. "And don't forget that there is one in the command unit," said Collins, sitting alone in the mothership sailing on its course.
While Armstrong and Aldrin were preparing to walk on the moon, Steve Balls and a host of computer experts were trying to figure out what triggered the 1202 alert. No one wanted the guidance computer to startle them again on the way back.
As often happens in technology-intensive projects, it turned out that the problem was due to simple human error. A last minute decision was made before the launch of Apollo 11 to activate two radars for landing. One of them was supposed to oversee the remaining height; The other will transmit in the opposite direction and track the Apollo command vehicle in case the lander's takeoff stage suddenly needs to quickly return. The computer software was originally programmed to deal with only one radar at any given moment, but the experts thought it could run both during landing. As it turned out, they were almost wrong. Alert 1202 was a warning that the computer is close to overload.
Close, but not.
When it came time for the takeoff phase from the moon, the computer had only one task to perform: locate the command unit. At this point the computer alerts disappeared. When Aldrin and Armstrong returned to the command unit, Mike Collins discovered how close Armstrong was to running out of fuel. "Do you really have enough fuel left for only 20 seconds?" Ask. "That's a lot of time," replied Armstrong.
And as for Steve Balls, he received a certificate of merit from NASA and a medal from President Nixon for "saving" the Apollo mission. 11 He often wondered what they might have given him, if he had been wrong.
