Apollo 14

Apollos 11 and 12 landed on the relatively flat—and therefore relatively safe—mare regions of the Moon. These are the darker parts of the lunar surface composed of geologically young material created by volcanic activity. Apollo 14 targeted the bright highlands region of Fra Mauro, the same destination as Apollo 13. More of the Moon’s surface is highlands than maria, and to only return samples from maria would be to ignore a major aspect of lunar geology. Scientists also believed that the highlands regions were much older than the maria, which, while making them scientifically more interesting, meant they were more cratered and uneven. Safe landing areas were more difficult to find.

It turned out that landing would be the easy part. After separating from the command module but prior to their lunar descent phase, Al Shepard and Ed Mitchell found that the LM’s computer was errantly entering a mission abort mode. If the spacecraft had been in its descent phase, this would have caused the computer to fire the main engine and abort their one opportunity to land, a dangerous maneuver under any situation.

The astronauts found that tapping on the console near the switch would temporarily reset the abort reading, suggesting that a loose piece of solder or metal was shorting a circuit within the system. But this temporary solution was not enough to ensure a safe landing.

To solve this problem NASA summoned, Don Eyles, a 27-year-old computer engineer from MIT who had worked on the lunar landing program. In less than 2 hours, he wrote a system hot patch that the astronauts manually entered into the LM’s computer which told it to ignore the abort reading during descent. The fix worked.

Shepard landed the lunar module Antares nearer to his target landing site than any other Apollo mission. But due to the uneven terrain of the lunar highlands, Antares stood angled at nearly 7 degrees. This made it difficult for the astronauts to sleep comfortably, at times Shepard and Mitchell had to look out the window to make sure the LM wasn’t tipping over.

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