Margaret Hamilton (via Hacker News):
There were two built-in computers – one on the command module, Columbia, and one on the moon module, Eagle. Our task was to develop the software to run on each and every system software they shared. In the beginning, no one thought software was such a big deal. But then they began to realize how much they depended on it. The group grew so there were about 100 software engineers on my team. The astronaut's life was at stake. Our software needed to be ultra-reliable, and it needed to be able to detect an error and recover from it at any time during the mission. And everything had to fit the hardware.[…]
Just as the astronauts were supposed to land, the software's priorities were interrupted by alarms to warn that it was an emergency and that the computer was overloaded. I learned about what happened, standing in the surveillance room at MIT. We crushed afterwards what had happened, which was that a radar switch was in the wrong position, and it took up processing power. It soon became clear that the software not only informed everyone that it was a hardware-related problem, but compensated for it ̵1; restarting and restoring the highest priority tasks. Error warning and recovery mechanisms had come to rescue. It was a total relief when they landed – both the astronauts were safe and the software worked perfectly. […]
In Apollo's early days, the software was not taken as seriously as other technical disciplines. Although we actually had a complex system system, we did not get credit for what was a legitimate field. It was out of desperation I came up with the term, to say, "Hey, we're also engineers." It was an ongoing joke for a long time. So one day in a meeting one of the most respected hardware explained to everyone that he agreed with me. The process of building software should also be considered a technical discipline, just like with hardware.
The whole Apollo 11 data code is available at @github, and it's amazing.
The Apollo 11 mission succeeded in landing on the moon despite two computer-related issues that affected the moon module during the heavy descent. An uncorrected problem in the rendezvous radar interface relies on approximately 13% of the computer's operating cycle, resulting in five program alerts and software re-running. In a lesser known problem, caused by erroneous data, the power of the LM's biasing engine fluctuated wildly, because the gas control algorithm was only marginally stable. The explanation for these issues provides an opportunity to describe the operating system of the Apollo flight computers and the lunar landing guide program.
With the 50th anniversary of the first crew of the Moon, I approach, I thought I would share one of my favorite views on the Moon tour, a map of where Neil Armstrong and Buzz Aldrin went on the moon , placed over a baseball field (larger). The Lunar Module is parked on the pitch and you can see where the two astronauts went, set up cameras, collect samples, and experiment.
50 years ago, Apollo 11 returned to Earth with movie reels containing iconic images: a launch card on the moon, a wrinkled American flag and a portrait of Buzz Aldrin with Neil Armstrong. Today, @nytimes gives a perspective like never before.
Our inspiration came from a map originally created by NASA in 1970 that marks the location and direction of each image taken during this first moon string.
@kartpat, an editor of the Immersive team, wrote a custom program to determine how the moonwalk photographs were oriented in the room. For each image, he calculates the camera's height, direction and tilt and the field of view of the lens.
Result: You can stand where Neil Armstrong and Buzz Aldrin stood when they took these historic photographs. This three-part interactive article uses real-time 3-D graphics and Augmented Reality to bring it all together.
Jeremy Deaton (via Paul Kafasis):
Although almost no one knew it at that time, the mission had almost ended in disaster. It was only saved at the last minute by two canny meteorologists with access to a top secret weather satellite.[…]
The storm, with its high clouds and strong winds, threatened to tear the parachutes at the command module at the descent into the Pacific.
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