Apollo 14
Apollo 14 was the number eight manned mission in the Apollo program and the third lunar mission. The lunar module touched down on February 5, 1971 on the Fra Mauro formation. This was the original site chosen for the Apollo 13 mission. Over 45.5 kg of moon rock was collected and several surface experiments, including seismic studies, were carried out. Commander Alan Shepard famously hit two golf balls on the lunar surface with a make-shift club he had brought from Earth. Command Module Pilot Stuart Roosa took several hundred seeds on the mission, many of which germinated on return and became known as the Moon trees.
The Apollo 14 crew was the first all rookie crew to leave Earth orbit. Shepard was also the oldest astronaut to go into space. He was a hold over from the Mercury program. He had been grounded for several years because of an inner ear disease which caused him to lose his sense of balance.
There were a few minor problems during the Apollo 14 mission. The most significant was the difficulty that the CSM Kitty Hawk had achieving capture and docking with the LM Antares. Repeated attempts to dock went on for 1 hour and 42 minutes, until it was suggested that pilot Roosa hold Kitty Hawk against Antares using its thrusters, then the docking probe would be retracted out of the way, hopefully triggering the docking latches. This attempt was successful, and no further docking problems were encountered during the mission.
After separating from the command module in lunar orbit, the LM Antares also had two serious problems. First, the LM computer began getting an ABORT signal from a faulty switch. NASA believed that the computer might be getting erroneous readings like this if a tiny ball of soldering material had shaken loose and was floating between the switch and the contact, closing the circuit. The immediate solution was to tap on the panel next to the switch. This did work briefly, but the circuit soon closed again. If the problem occurred after the descent engine fired, the computer would think the signal was real and would initiate an auto-abort, causing the Ascent Stage to separate from the Descent Stage and climb back into orbit. NASA scrambled to find a solution, and determined the fix would involve reprogramming the flight software to ignore the false signal.
Another problem occurred during the powered descent. The LM radar altimeter failed to lock automatically onto the moon's surface, depriving the navigation computer of vital information on the vehicle altitude and groundspeed. This was an unintended consequence of the software patch. After the astronauts cycled the landing radar breaker, the unit successfully acquired a signal near 15,000 m. Just in the nick of time. Shepard then manually landed the LM closer to its intended target than any of the other six moon landing missions.
Despite several harrowing problems, Apollo 14 was a successful mission. Here is an article with some additional information. The crew wanted to hike to the rim of Cone Crater. This article on Universe Today tells you how close they actually came. Astronomy Cast has a great episode about the space capsules used in the early space program.
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