Alan Shepard and Edgar Mitchell land Apollo 14 at Fra Mauro formation on Moon

On February 5, 1971, Lunar Module Antares separated from Command Module Kitty Hawk to execute a landing in the Fra Mauro formation, an elevated highland region formed by ejecta from the impact that created the Imbrium Basin. This scientifically valuable landing site was originally designated for Apollo 13. However, during descent, Commander Alan Shepard and Lunar Module Pilot Edgar Mitchell faced two rapid-fire technical anomalies that threatened an immediate and automatic mission abort.

The first emergency arose when a loose bit of solder floated inside an abort switch, sending an erroneous 'abort' signal to the Primary Guidance, Navigation, and Control System (PGNCS). If undetected when the descent engine ignited, the computer would automatically trigger an emergency separation and return to orbit. Working at top speed, MIT Instrumentation Laboratory software programmer Don Eyles drafted a software patch. Capcom relayed the exact key sequences to Mitchell, who manually entered them into the guidance computer to override the faulty switch just minutes before descent engine ignition.

Shortly after ignition, a second failure occurred when the landing radar failed to lock onto the lunar surface, depriving the guidance computer of altitude and velocity data. After cycling the radar circuit breaker, the radar acquired lock at an altitude of 6,700 feet, narrowly avoiding the mandatory abort altitude threshold of 10,000 feet. Shepard took manual control and guided Antares to a soft touchdown within 87 feet of the targeted landing point—the most precise touchdown of the entire Apollo program to date. Shepard and Mitchell completed two extravehicular activities (EVAs) totaling over nine hours, deploying the ALSEP instrument suite and collecting 94 pounds of geological samples.