A retired software engineer named Martin C. Martin made a discovery recently. He found a bug, in the physics code of the Lunar Lander computer game that had been hidden for 55 years. The game, created by high school student Jim Storer in 1969 was a text based simulation where players had to land a lunar module on the Moons surface while managing fuel consumption.
Martin came across this bug while trying to figure out the strategies for landing the module with fuel efficiency in the Lunar Lander game. Despite using techniques like the “suicide burn” and careful landing approaches he noticed that sometimes the game would mistakenly indicate that the lander missed landing on the Moon altogether. Curious about this issue he decided to dig into the games source code, for investigation.
A Missing Division
After reviewing the code, for the Lunar Lander Martin found that the landing algorithm was based on physics principles, such as the Tsiolkovsky rocket equation and a Taylor series expansion. However he also spotted a mistake—a missing division by two in the calculation formula for determining the landers path. This minor error had repercussions leading to inaccuracies in predicting when the lander would reach its lowest point and ultimately impacting its landing.
Despite this flaw Martin admired the math concepts incorporated into the Lunar Lander game by Storer, a school senior at that time. Storer shared that his physicist father had helped him derive the equations used in the games simulation. The bug persisting for over 55 years underscores that realism isn’t always paramount, for a gaming experience. Fortunately actual Apollo lunar missions didn’t face an issue.