[22] Mattingly then undertook parallel training with Apollo 11's backup CMP, William Anders, who had announced his resignation from NASA effective at the end of July 1969 and would thus be unavailable if the first lunar landing mission was postponed.

[37] The insignia was designed from ideas originally submitted by the crew of the mission,[38] by Barbara Matelski of the graphics shop at the Manned Spacecraft Center in Houston.

[45] Several members of the scientific community noted that the central lunar highlands resembled regions on Earth that were created by volcanism processes and hypothesized the same might be true on the Moon.

[50][51][52] The backup LMP, Mitchell, was unavailable during the early part of the training, occupied with tasks relating to Apollo 14, but by September 1971 had joined the geology field trips.

Before that, Tony England (a member of the support crew and the lunar EVA CAPCOM) or one of the geologist trainers would train alongside Haise on geology field trips.

[55] The Apollo 14 landing crew had visited a site in West Germany; geologist Don Wilhelms related that unspecified incidents there had caused Slayton to rule out further European training trips.

During the training exercises the astronauts did not wear space suits, but carried radio equipment to converse with each other and England, practicing procedures they would use on the lunar surface.

This training helped Young and Duke, while on the Moon, quickly realize that the expected volcanic rocks were not there, even though the geologists in Mission Control initially did not believe them.

[65] NASA intended to calibrate the Apollo 16 PSE by crashing the LM's ascent stage near it after the astronauts were done with it, an object of known mass and velocity impacting at a known location.

[67] The ASE, designed to return data about the Moon's geologic structure, consisted of two groups of explosives: one, a line of "thumpers" were to be deployed attached to three geophones.

The Apollo 16 attempt would fail after Duke had successfully emplaced the first probe; Young, unable to see his feet in the bulky spacesuit, pulled out and severed the cable after it wrapped around his leg.

[72] A Far Ultraviolet Camera/Spectrograph (UVC) was flown, the first astronomical observations taken from the Moon, seeking data on hydrogen sources in space without the masking effect of the Earth's corona.

After reaching orbit, the crew spent time adapting to the zero-gravity environment and preparing the spacecraft for trans-lunar injection (TLI), the burn of the third-stage rocket that would propel them to the Moon.

[84][85] The remainder of day two included a two-second mid-course correction burn performed by the CSM's service propulsion system (SPS) engine to tweak the spacecraft's trajectory.

[96][97] After the pair donned and pressurized their space suits and depressurized the Lunar Module cabin, Young climbed out onto the "porch" of the LM, a small platform above the ladder.

There, at a distance of 1.4 km (0.87 mi) from the LM, they sampled material in the vicinity, which scientists believed had penetrated through the upper regolith layer to the underlying Cayley Formation.

[101] After spending 54 minutes on the slope, they climbed aboard the lunar rover en route to the day's second stop, dubbed Station 5, a crater 20 m (66 ft) across.

[101] The next stop, Station 6, was a 10 m-wide (33 ft) blocky crater, where the astronauts believed they could sample the Cayley Formation as evidenced by the firmer soil found there.

[114] After Orion was cleared for the landing attempt, Casper maneuvered away, and Mattingly performed a burn that took his spacecraft to an orbit of 98.3 by 125.6 kilometers; 61.1 by 78.0 miles (53.1 by 67.8 nmi) in preparation for his scientific work.

[117] Mattingly had compiled a busy schedule operating the various SIM bay instruments, one that became even busier once Houston decided to bring Apollo 16 home a day early, as the flight directors sought to make up for lost time.

[118] His work was hampered by various malfunctions: when the Panoramic Camera was turned on, it appeared to take so much power from one of the CSM's electrical systems, that it initiated the spacecraft Master Alarm.

Just under five hours after the subsatellite release, on the CSM's 65th orbit around the Moon, its service propulsion system main engine was reignited to propel the craft on a trajectory that would return it to Earth.

[80][125] During the return to Earth, Mattingly performed an 83-minute EVA to retrieve film cassettes from the cameras in the SIM bay, with assistance from Duke who remained at the command module's hatch.

[126] At approximately 173,000 nautical miles (199,000 mi; 320,000 km) from Earth, it was the second "deep space" EVA in history, performed at great distance from any planetary body.

During the press conference, the astronauts answered questions pertaining to several technical and non-technical aspects of the mission prepared and listed by priority at the Manned Spacecraft Center in Houston by journalists covering the flight.

[129][130] When the wake-up call was issued to the crew for their final day in space by CAPCOM England, the CSM was about 45,000 nautical miles (83,000 km) from Earth, traveling just over 2.7 km/s (9,000 ft/s).

On Monday, May 8, ground service equipment being used to empty the residual toxic reaction control system fuel in the command module tanks exploded in a Naval Air Station hangar.

[136][137] The Apollo 16 command module Casper is on display at the U.S. Space & Rocket Center in Huntsville, Alabama,[138] following a transfer of ownership from NASA to the Smithsonian in November 1973.

However, due to a communication failure before impact the exact location was unknown until January 2016, when it was discovered within Mare Insularum by the Lunar Reconnaissance Orbiter, approximately 260 km (160 mi) southwest of Copernicus Crater.

[143] In 2006, shortly after Hurricane Ernesto affected Bath, North Carolina, eleven-year-old Kevin Schanze discovered a piece of metal debris on the ground near his beach home.