One of the greatest scientific and technological achievements of the human race reaches a major milestone as the first person to walk on the moon reaches its 50th anniversary on July 20th, 1969. Celebrations this year are taking place across the country.
But did you know that the Apollo 11 mission was the first-time people rode in a vehicle controlled by a computer. And the computer kept crashing at the most critical moment.
Stephen Witt of Wired Magazine has a fascinating write-up on the guidance computer system that controlled the Apollo 11 lunar module. The computer in the lunar module consisted of a keypad and resembled a microwave. Buzz Aldrin controlled the computer by entering two-digit commands he had memorized. The computer would respond with 5-digit codes that he would interpret. How many of you would trust your memory of 2-digit and 5-digit codes to land on the moon for the first time?
During the final phases of the landing sequence the processor on the computer was getting overwhelmed with tasks. It displayed a code that Aldrin had not seen before. When the computer was over taxed, it was designed to remember the highest priority tasks, reboot itself, resume the high priority tasks and forget the lower level items.
The guidance system was using 87% processing power, Aldrin’s commands 3%, and a mystery program another 10%. And when the computer resets itself, the display goes completely blank. And the computer crashed 5 times in 4 minutes. Each time Armstrong and Aldrin wondering if the computer would turn back on.
Once the lunar module was below 1000 feet of the moon’s surface there was no way to abort. It would be too dangerous. But the mission was still a go. Once Neil Armstrong took manual control of the stick, it alleviated some of the processing overload and the errors stopped. If you watch the new CNN documentary, you will see the repeated alarms going off in the final minutes before they land. But he overshot the intended landing spot by several miles due to the distractions.
Once Armstrong and Aldrin were safely landed on the moon, engineers at MIT were scrambling to figure out what caused the computer error. If they didn’t, it may be hard to impossible for the crew to return safely to the command module in lunar orbit with Michael Collins. With less than 3 hours to spare they found the issue. A dial was turned to the wrong setting for the rendezvous radar that allowed tracking of the command module in orbit. Periodically this wrong setting was overloading the processor with unnecessary tasks.
The Apollo crew were instructed to fix the dial setting and the rest will live on in history for all time.
Virginia and D.C. events commemorating the moon landing anniversary:
You can visit the Virginia Air and Space Center in Hampton VA for a virtual interactive experience of the history of lunar exploration as well as future moon missions.
Additional information: https://www.eurekaexhibits.com/our-exhibits/apollo-50th-anniversary/
15 MLB teams, including the Washington Nationals will place replica statues of Neil Armstrong’s spacesuit in their ballparks.
The National Air and Space Museum in Washington D.C, from July 16th-20th will hold a 5-day celebration at the museum and on the National Mall.
The National Gallery of Art in Washington D.C. will host an exhibition of over 50 works that will be on display thru January 5, 2020.
CNN will show their fantastic documentary “Apollo 11” capturing the moments leading up to, during, and the return of the moon landing with previously unseen video and photos, edited together to relieve the drama of the events itself with zero commentary. Saturday July 20th, 9pm and 11pm CNN.