Apollo 16

Apollo 16, the tenth manned mission in American Apollo space program, was the fifth mission to land on the Moon and the first to land in a highlands area. Launched on April 16, 1972, it was a J-class mission, featuring the program's second Lunar Roving Vehicle; and brought back 94.7 kg of lunar samples.
It included three lunar EVAs: 7.2 hours, 7.4 hours, 5.7 hours and one trans-earth EVA of 1.4 hours. Despite a malfunction in the Command Module which almost aborted the lunar landing, Apollo 16's lunar module landed successfully in the Descartes Highlands on April 21. Commander John W. Young and Lunar Module Pilot Charles Duke spent nearly three days on the lunar surface while Command Module Pilot Ken Mattingly orbited the Moon.
A subsatellite was released from the Service Module while in lunar orbit to carry out experiments on magnetic fields and solar particles (the first subsatellite had been released from Apollo 15).
The crew splashed down in the Pacific Ocean on April 27.

The original launch date in March 1971 was scrubbed well in advance due to an issue with a fuel tank supplying the RCS on the command module. The location of the problem forced a rolback to the VAB on January 27, 1971. The stack was returned after repairs well before the final countdown had initiated.[3]
A malfunction in a backup yaw gimbal servo loop in the main propulsion system of the CSM Casper caused concerns about firing the engine to adjust the CSM's lunar orbit, and nearly caused the Moon landing to be aborted. After a delayed first landing attempt, it was determined that the malfunction presented relatively little risk, and Young and Duke (who were already undocked, and flying LM Orion when the problem occurred) were permitted to land on the Moon.

Young and Duke spent three days exploring the Descartes highland region, while Mattingly circled overhead in Casper. This was the only one of the six Apollo landings to target the lunar highlands. On the first day of lunar surface operations, news was relayed to them that the House of Representatives had approved the Space Shuttle program. Young stated that it was needed.[4]
The astronauts discovered that what was thought to have been a region of volcanism was actually a region full of impact-formed rocks (breccias). Their collection of returned specimens included a 25-pound (11 kg) chunk that was the largest single rock returned by the Apollo astronauts[5] (nicknamed "Big Muley" after Bill Muehlberger, principal investigator for the mission's geology activities[6]). The scientific results of Apollo 16 caused planetary geologists to revise previous interpretations of the lunar highlands, concluding that meteorite impacts were the dominant agent in shaping the Moon's ancient surfaces.

Young and Duke set up their Apollo Lunar Surface Experiments Package (ALSEP), which included an experiment to measure heat flow between two probes they were to insert into holes drilled in the surface. Young, however, accidentally got one foot tangled up in the cable to one of the probes, detaching it and rendering the experiment useless.
The astronauts also conducted performance tests with the lunar rover, Young at one time getting up to a top speed of 11 miles per hour (18 kilometers per hour), which still stands as the record speed for any wheeled vehicle on the Moon (listed as such in the Guinness Book of Records).
Apollo 16 was originally scheduled for splashdown at 3:30 pm EST on April 28. The mission was shortened by a day (reducing the time in orbit around the Moon after the LM left the Moon and docked with the CSM) because of the problems with the command module prior to landing. As Duke described on the Apollo Lunar Surface Journal website: "The more you waited up there - if you did have a problem - the less time you had to think of something brilliant to fix it. They got a little nervous and brought us home a day early, I think, just to make sure we could have some ample time to fix any problems."[7] There were no problems encountered during the return flight.
The aircraft carrier USS Ticonderoga delivered the Apollo 16 command module to the North Island Naval Air Station, near San Diego, California on Friday, May 5, 1972. On Monday, May 8, 1972, ground service equipment being used to empty the residual toxic RCS fuel in the command module tanks, exploded in a Naval Air Station hanger. A total of 46 people were sent to the hospital for 24 to 48 hours observation, most suffering from inhalation of toxic fumes. Most seriously injured was a technician who suffered a fractured kneecap when the GSE cart overturned on him. A hole was blown in the NAS hangar roof 250 feet above, and about 40 windows in the hanger were shattered. The command module suffered a three-inch gash in one panel.[8][9][10]

Apollo 14

Apollo 14 was the eighth manned mission in the American Apollo program, and the third to land on the Moon. It was the last of the "H missions", targeted landings with two-day stays on the Moon with two lunar EVAs, or moonwalks.
Commander Alan Shepard, Command Module Pilot Stuart Roosa, and Lunar Module Pilot Edgar Mitchell launched on their nine-day mission on January 31, 1971 at 4:04:02 pm local time after a 40 minute, 2 second delay due to launch site weather restrictions, the first such delay in the Apollo program.[2] Shepard and Mitchell made their lunar landing on February 5 in the Fra Mauro formation; this had originally been the target of the aborted Apollo 13 mission. During the two lunar EVAs, 42 kilograms (93 lb) of Moon rocks were collected and several surface experiments, including seismic studies, were performed. Shepard famously hit two golf balls on the lunar surface with a make-shift club he had brought from Earth. Shepard and Mitchell spent about 33 hours on the Moon, with about 9½ hours on EVA.
While Shepard and Mitchell were on the surface, Roosa remained in lunar orbit aboard the Command/Service Module, performing scientific experiments and photographing the Moon. He took several hundred seeds on the mission, many of which were germinated on return resulting in the so-called Moon trees. Shepard, Roosa, and Mitchell landed in the Pacific Ocean on February 9.

Apollo 15

Apollo 15 was the ninth manned mission in the American Apollo space program, the fourth to land on the Moon and the eighth successful manned mission. It was the first of what were termed "J missions", long duration stays on the Moon with a greater focus on science than had been possible on previous missions. It was also the first mission where the Lunar Roving Vehicle was used.
The mission began on July 26, 1971, and concluded on August 7. At the time, NASA called it the most successful manned flight ever achieved.[2]
Commander David Scott and Lunar Module Pilot James Irwin spent three days on the Moon and a total of 18½ hours outside the spacecraft on lunar extra-vehicular activity. The mission was the first not to land in a lunar mare, instead landing near Hadley rille in an area of the Mare Imbrium called Palus Putredinus (Marsh of Decay). The crew explored the area using the first Lunar Rover, allowing them to travel much farther from the Lunar Module lander than had previously been possible. They collected a total of 77 kg (170 lbs) of lunar surface material. At the same time, Command Module Pilot Alfred Worden orbited the Moon, using a Scientific Instrument Module (SIM) in the Service Module to study the lunar surface and environment in great detail with a panoramic camera, gamma ray spectrometer, mapping camera, laser altimeter, mass spectrometer, and lunar sub-satellite deployed at the end of Apollo 15's stay in lunar orbit (an Apollo program first).
Although the mission accomplished its objectives, their success was somewhat overshadowed by bad publicity that accompanied public awareness of the unauthorized souvenirs carried aboard by the astronauts, who had made plans to sell those souvenirs upon their return.

Apollo 13

Apollo 13 was the seventh manned mission in the American Apollo space program and the third intended to land on the Moon. The craft was launched on April 11, 1970, at 13:13 CST. The landing was aborted after an oxygen tank exploded two days later, crippling the service module upon which the Command Module depended. Despite great hardship caused by limited power, loss of cabin heat, shortage of potable water and the critical need to jury-rig the carbon dioxide removal system, the crew returned safely to Earth on April 17.
The flight was commanded by James A. Lovell with John L. "Jack" Swigert as Command Module pilot and Fred W. Haise as Lunar Module pilot. Swigert was a late replacement for the original CM pilot Ken Mattingly, who was grounded by the flight surgeon after exposure to German measles.

Objective
The Apollo 13 mission was to explore the Fra Mauro formation, or Fra Mauro highlands, named after the 80-kilometer-diameter Fra Mauro crater located within it. It is a widespread, hilly geological (or selenological) area thought to be composed of ejecta from the impact that formed Mare Imbrium.
The next Apollo mission, Apollo 14, eventually made a successful flight to Fra Mauro.

Oxygen tank incident

Explosion

"Houston, we've had a problem."

Swigert and Lovell reporting the incident on April 14, 1970
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En route to the Moon, approximately 200,000 miles (320,000 km) from Earth, Mission Control asked the crew to turn on the hydrogen and oxygen tank stirring fans, which were designed to destratify the cryogenic contents and increase the accuracy of their quantity readings. Approximately 93 seconds later the astronauts heard a loud "bang", accompanied by fluctuations in electrical power and firing of the attitude control thrusters.[6] The crew initially thought that a meteoroid might have struck the Lunar Module (LM).
In fact, the number 2 oxygen tank, one of two in the Service Module (SM), had exploded.[10] Damaged Teflon insulation on the wires to the stirring fan inside oxygen tank 2 allowed the wires to short-circuit and ignite this insulation. The resulting fire rapidly increased pressure beyond its 1,000 pounds per square inch (6.9 MPa) limit and the tank dome failed, filling the fuel cell bay (Sector 4) with rapidly expanding gaseous oxygen and combustion products. It is also possible some combustion occurred of the Mylar/Kapton thermal insulation material used to line the oxygen shelf compartment in this bay.[11]


Apollo 13's damaged Service Module, as photographed from the Command Module after being jettisoned
The resulting pressure inside the compartment popped the bolts attaching the Sector 4 outer aluminum skin panel, which as it blew off probably caused minor damage to the nearby high-gain S-band antenna used for translunar communications. Communications and telemetry to Earth were lost for 1.8 seconds, until the system automatically corrected by switching the antenna from narrow-band to wide-band mode.
Mechanical shock forced the oxygen valves closed on the number 1 and number 3 fuel cells, which left them operating for only about three minutes on the oxygen in the feed lines. The shock also either partially ruptured a line from the number 1 oxygen tank, or caused its check or relief valve to leak, causing its contents to leak out into space over the next 130 minutes, entirely depleting the SM's oxygen supply.[11]
Because the fuel cells combined hydrogen and oxygen to generate electricity and water, the remaining fuel cell number 2 finally shut down and left the Command Module (CM) on limited-duration battery power. The crew was forced to shut down the CM completely and to use the LM as a "lifeboat".[12] This had been suggested during an earlier training simulation but had not been considered a likely scenario.[13] Without the LM, the accident would certainly have been fatal [14].

Apollo 11

Apollo 11 was the spaceflight which landed the first humans, Neil Armstrong and Edwin "Buzz" Aldrin, Jr, on Earth's Moon on July 20, 1969, at 20:17:39 UTC. The United States mission is considered the major accomplishment in the history of space exploration.
Launched from the Kennedy Space Center Launch Complex 39 in Merritt Island, Florida on July 16, Apollo 11 was the fifth manned mission, and the third lunar mission, of NASA's Apollo program. The crew consisted of Armstrong as Commander and Aldrin as Lunar Module Pilot, with Command Module Pilot Michael Collins. Armstrong and Aldrin landed in the Sea of Tranquillity and became the first humans to walk on the Moon on July 21. Their Lunar Module, Eagle, spent 21 hours 31 minutes on the lunar surface, while Collins remained in orbit in the Command/Service Module, Columbia.[2] The three astronauts returned to Earth on July 24, landing in the Pacific Ocean. They brought back 47.5 pounds (21.5 kg) of lunar rocks.
Apollo 11 fulfilled U.S. President John F. Kennedy's goal of reaching the Moon before the Soviet Union by the end of the 1960s, which he had expressed during a 1961 mission statement before the United States Congress: "I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth."[3]
Five additional Apollo missions landed on the Moon between 1969 and 1972.