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74: Apollo Guidance Computer Memory (ROM), in kilobytes
Computer technology has been one of Apollo's greatest and long-standing achievements. From the solid-state microcomputer installed on the lunar lander to the powerful IBM mainframes, with their flashing lights and their tape banks.
To navigate the Apollo spacecraft about half a million kilometers from the moon, then descend to a specific spot on the surface, the astronauts used the Apollo guidance computer (AGC).
Housed in a box the size of a small suitcase, with a separate screen and an input panel attached to the main console of the spacecraft, it was a masterpiece of miniaturization.
Developed by the Massachusetts Institute of Technology (MIT), the AGC was filled with thousands of integrated circuits, or silicon chips. The commissioning of this new technology by NASA led to the rapid expansion of Silicon Valley and accelerated the development of today's computers.
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Although the AGC's 74 KB memory and 4 KB RAM are ridiculous today – the equivalent of a 1980s personal computer such as the Sinclair ZX Spectrum or Commodore 64 – it was impressive machine. Designed for the rigors of spaceflight, its software has been wired in coils and, crucially, it has been configured so that it can not fail.
Meanwhile, at NASA's Manned Spacecraft Center, NASA has purchased five of the latest IBM 360 computers to analyze in real time all aspects of the speed, trajectory and health of the spacecraft. . The system provided a backup computer in case of failure of any of them at a crucial time.
Despite the great computing power behind Apollo, some technologies would have been familiar to 19th century explorers. In the days before the pocket calculators, the astronauts performed simple calculations using slide rules and for ease of navigation they took star gazing with sextant.
1202: computer alarms
Just five minutes after Neil Armstrong started the descent engine on the lunar lander, the first of several 1202 and 1201 alarms sounded in his atrium.
"The alarm program … it's a 1202," said Armstrong.
Neither he nor Capcom Charlie Duke knew what the alarm meant. The tension in their voices betrayed the fear that this could lead to the cancellation of the first landing of the moon.
But in Houston, the mission controllers had seen a similar warning a few days earlier during simulations.
"We were on the surface of the moon and the computer was very busy," said Gerry Griffin, director of Apollo flights. "The alarms said," Hey guys, I'm a little overworked. "
Quote: The Apollo guidance computer was not the only miracle of the miniaturization of the Apollo spacecraft
Looking calmly at the data on his console, the guidance officer Steve Bales agreed to continue.
"I later learned that they had actually planned that these alarms would become a priority. Therefore, if the computer got really busy, it would start by setting aside tasks that it was not necessary to calculate, Griffin says. "The alarm reads," Hey, I'm too busy and I just started stuff, "so they continued down."
"There were people on the ground, not only in mission control but also online, the MIT people were listening to the same conversations as us. We could not have done it only with about twenty guys in the control room and three astronauts – we had a lot of help, it was a big team effort. "
9: Number of cassette players used
The Apollo guidance computer was not the only miracle of miniaturization of the Apollo spacecraft. The teams also won the first versions of portable tape recorders Sony Walkman.
Originally intended for astronauts to record their personal observations, they were also able to create their own music mixing tapes.
While youth in mission control may have listened to the latest Beatles title, most astronauts – who were 10 years older – tended to prefer easy listening and selection of countries. The commander of Apollo 17, Gene Cernan, for example, chose the music of Frank Sinatra and Glenn Campbell.
Apollo 9 by Rusty Schweickart was the first to carry cassettes. His teammates chose a selection of countries, but he preferred classical plays that he had listened to at home.
Quote: It was amazing, the music started and she was so powerful that she got me out of this spaceship orbiting the Earth – Rusty Schweickart
"Every Sunday night, after putting the children to bed, I sat in the living room with a desk lamp, creating a circle of light around me on the floor and playing music on the stereo. through a series of writings and quotes that I took back with me, "Schweickart told the BBC World Service program, 10,9,8,7.
But once in orbit, the cassette of the astronaut was not found.
"Dave Scott miraculously found the ninth day of our ten-day mission:" Oh, Rusty, is that what you're looking for? Schweickart explains, "I gave them the bird frankly, put my tape in the Walkman and said that I'm just going to enjoy my music while you're flying, hell.
"It was amazing, the music started and she was so powerful that she got me out of this spaceship orbiting the Earth, to return to those very very quiet evenings at home." me in Houston. It was so powerful, I literally turned off the music, it was an incredibly powerful emotional experience. "
(You can find out more about the music of the space here)
36: Weight of the satellite launched by Apollo, in kilograms
If having two spacecraft in orbit around the moon – the control module and the lander – was not enough, with Apollo 15, NASA planned to add another. Apollo 15 was the first of the class J missions of the agency. In addition to the first lunar rover, it included a reinforced control module with an equipment bay on the side. This has been packed with experiments to study the moon from a lunar orbit.
One of the latest experiments to have been deployed was another spacecraft: a 36-kilogram hexagonal satellite (79 lb.). Designed to stay in orbit around the moon for a year, it would return data on gravity, charged particles, and measurements of the Earth's magnetic field.
Just before returning home, on the 74th orbit of the Moon, the Apollo 15 crew was preparing to release the spacecraft.
Quote: The satellite sent data back to Earth for about six months before failing
In keeping with NASA tradition, Dave Scott armed the mechanism by counting down before operating a switch to send the rotating satellite out of the equipment bay.
"Tally ho!" Scott said as the satellite exited the service module.
"A very nice satellite there."
The satellite returned data to Earth for about six months before failing. It was replaced by an almost identical satellite, launched by the Apollo 16 crew in April 1972. Unfortunately, because it had been launched into a low orbit, the second satellite did not have the same satellite. lasted only six weeks before striking the lunar surface.
22: Diameter of the Saturn V computer, in feet
If the Apollo guidance computer was impressive by its miniaturization, then the computer controlling the Saturn V Moon rocket must rank as the largest ever launched.
Installed in a ring above the top (third) of the rocket, the instrumental unit of Saturn V was massive. In addition to digital and analog computers, the unit contained all the electronics to control and monitor the rocket that would lead humans to the moon.
Designed by Wernher von Braun's rocket team in Huntsville, Alabama, the computer was built by IBM. It practically meant sending a central computer into space and then giving it up.
Although equipped with the latest silicon semiconductor chip technology, the instrument's gyroscopic guidance system, designed to keep the rocket on a stable trajectory, was based on von Braun's technology. had developed for its V2 missile during the Second World War.
When Apollo 12 was struck by lightning at launch, the control module was neutralized, the mission controllers believe that the circular design of the rocket computer saved it from surge.
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