Looking back at the Apollo 11 mission 50 years ago, it might be easy to overlook the lasting impact of man’s first steps on the moon. Neil Armstrong, Buzz Aldrin, and Michael Collins captivated not only their fellow Americans, but also the entire world — and they did it with the help of the Apollo Guidance Computer, a 24- by 12.5-inch computer weighing in at just over 70 pounds.
Until the final stage of the spacecraft’s descent, the three men had essentially been passengers, with their spacecraft’s position monitored on the big IBM mainframe back at Mission Control. Once it came time to land the lunar module on the moon, Aldrin and Armstrong were on their own with the Apollo Guidance Computer.
The onboard computer was notable for its lack of vacuum tubes. Instead, it relied on thin slices of silicon — the first “chips.” These chips had been developed by Gordon Moore at Fairchild Semiconductor in Palo Alto, California.
As the lunar module approached the surface of the moon, Aldrin typed memorized codes into the computer to guide it to the lunar floor, just as they had practiced back at NASA. What they hadn’t practiced was Error Code 1202. Aldrin radioed Mission Control to ask what it meant — it meant the computer had crashed. Its system was overloaded.
Thankfully, the team at MIT that had designed the operating system had also anticipated the need for a quick restart in case of a computer crash. The 1202 meant the system had saved its navigation data — which meant the difference between life and death for Aldrin and Armstrong.
You know the story of the #MoonLanding but #DidYouKnow about the Apollo Guidance Computer that saved the Apollo 11 mission from disaster?
The rest, of course, is history. The astronauts took those small steps for man and those giant leaps for mankind and made it home safely. The silicon chips inside the Apollo Guidance Computer made a giant leap as well; Moore left Fairchild to co-found Intel.
Photo: Dima Zel / Shutterstock