How the Apollo Astronauts Guided Their Ships With a Brilliantly Simple Telescope

One of the most impressive aspects of the Apollo space program was how NASA worked around the limitations in computer power. The smartwatch on your wrist eclipses what the Apollo space craft’s computers were capable of, so NASA’s engineers often had to rely on clever ingenuity to solve difficult problems.

As engineerguy Bill Hammack explains, in order to properly align the Lunar Module’s guidance system (before GPS and other electronic aides existed) the Apollo astronauts relied on an Alignment Optical Telescope that used techniques devised by Archimedes to be simple, lightweight, but absolutely essential to getting to the moon and back again.





Fun fact: the Apollo Guidance Computer referred to in the video was on board both the LEM and the Command Module. It provided 2K of RAM and 34K of ROM, and had a 2 MHz clock speed. Its performance was similar to room-filling mainframes of the time, but fit in a small, lightweight box. The ROM was composed of “rope memory”, strands of wire looped through magnetized cores. They were made by hand by female seamstresses; they called it Little Old Lady (LOL) memory.

The Apollo computer was one of the first applications of the newly invented integrated circuit. NASA development money help bring ICs into the manufacturing mainstream.

You can play with a simulated version of the computer here:…

Apollo Guidance Computer and DSKY I/O panel:

Rope memory: