Smart apollo

We often hear that the on-board Apollo guidance computer (AGC) had less power than a modern digital watch; but it all depends on what we mean by 'power'. In its way, it was one of the most capable computers ever invented. It absorbed data from a complex gyroscopic inertial navigation system, allied to an optical star telescope and two radar range finders. It also mediated between the astronauts and the thrusters and rocket engines that drove the ship through space. Apollo's command module (Columbia) and Lunar module (Eagle) had an AGC each, but it's the latter's that has attracted the most attention over the 40 years since it took Neil Armstrong and Buzz Aldrin from lunar orbit to their landing on the Moon's surface.