Apollo 16 - Mission Highlights - Lunar Surface

Lunar Surface

Young, Mattingly and Duke continued preparing for Lunar Module (LM) activation and undocking shortly after waking up to begin flight day five. The boom that extended the mass spectrometer out from the Command/Service Module's Scientific Instruments Bay was stuck in a semi-deployed position. It was decided that Young and Duke would visually inspect the boom after undocking from the CSM in the LM. Young and Duke entered the LM for activation and checkout of the spacecraft's systems. Despite entering the LM forty minutes ahead of schedule, Young and Duke completed preparations only ten minutes early due to numerous delays in the process. With the preparations finished, Young and Duke undocked in the LM Orion from Mattingly in the Command/Service Module Casper 96 hours, 13 minutes, 13 seconds into the mission. For the rest of the two spacecrafts' pass over the near side of the Moon, Mattingly prepared to shift Casper to a circular orbit while Young and Duke prepared Orion for the descent to the lunar surface. At this point, during tests of the CSM's steerable rocket engine in preparation for the burn to modify the craft's orbit, a malfunction occurred in the engine's backup system. According to mission rules, Orion would have then re-docked with Casper, in case mission control decided to abort the landing and use the Lunar Module's engines for the return trip to Earth. After several hours of analysis, however, mission controllers determined that the malfunction could be worked around and Young and Duke could proceed with the landing. As a result of this, powered descent to the lunar surface began about six hours behind schedule. Because of the delay, Young and Duke began their descent to the surface at an altitude higher than that of any previous mission, at 20.1 kilometres (10.9 nmi). At an altitude of about 4,000 m (13,000 ft), Young was able to view the landing site in its entirety. Throttle-down of the LM's landing engine occurred on time and the spacecraft tilted forward to its landing orientation at an altitude of 2,200 m (7,200 ft). The Lunar Module Orion, with Young and Duke inside, landed 270 m (890 ft) north and 60 m (200 ft) west of the planned landing site at 104 hours, 29 minutes, and 35 seconds into the mission, at 2:23:35 UTC on 21 April.

After landing, Young and Duke began powering down some of the LM's systems to conserve battery power. Upon completing their initial adjustments, the pair configured Orion for their three-day stay on the lunar surface, removed their spacesuits and took initial geological observations of the immediate landing site. Young and Duke then settled down for their first meal on the surface. After eating, they configured the cabin for their first sleep period on the Moon. The landing delay caused by the malfunction in the Command/Service Module's main engine necessitated significant modifications to the mission schedule. Apollo 16 would spend one less day in lunar orbit after surface exploration had been completed to afford the crew contingency time to compensate for any further problems and to conserve expendables. In order to improve Young's and Duke's sleep schedule, the third and final moonwalk of the mission was trimmed from seven hours to five.

The next morning, flight day five, Young and Duke ate breakfast and began preparations for the first extra-vehicular activity (EVA), or moonwalk, of the mission. After the pair donned and pressurized their spacesuits and depressurized the Lunar Module cabin, John Young climbed out onto the "porch" of the LM, a small platform above the ladder. Duke handed Young a jettison bag, full of trash, to dispose of on the surface. Young then lowered the equipment transfer bag (ETB), containing equipment for use during the EVA, to the surface. Young descended the ladder and, upon setting foot on the lunar surface, became the ninth human to walk on the Moon. Upon stepping onto the surface, Young expressed his sentiments about being there: "There you are: Mysterious and Unknown Descartes. Highland plains. Apollo 16 is gonna change your image." Charles Duke soon descended the ladder and joined Young on the surface, becoming the tenth and youngest human to walk on the Moon at age 36. After setting foot on the lunar surface, Duke expressed his excitement, commenting: "Fantastic! Oh, that first foot on the lunar surface is super, Tony!" The pair's first task of the moonwalk was to unload the Lunar Roving Vehicle (LRV), along with other equipment, from the Lunar Module. This was done without problems. On first driving the lunar rover, Young discovered that the rear steering was not working. He alerted mission control to the problem before setting up the television camera and planting the flag of the United States with Duke. The day's next task was to deploy the Apollo Lunar Surface Experiments Package (ALSEP); while they were parking the lunar rover, on which the TV camera was mounted, to observe the deployment, the rear steering began functioning without explanation. While deploying a heat-flow experiment that had burned up with the Lunar Module Aquarius on Apollo 13 and had been attempted without success on Apollo 15, a cable was inadvertently snapped after getting caught around Young's foot. After ALSEP deployment, Young and Duke collected samples in the vicinity. About four hours after the beginning of EVA-1, the pair mounted the lunar rover and drove to the first geologic stop, Plum Crater, a 36 m-wide (118 ft) crater on the rim of Flag Crater, a crater 290 m (950 ft) across. There, at a distance of 1.4 km (0.87 mi) from the LM, Young and Duke sampled material from the vicinity of Flag Crater, which scientists believed penetrated through the upper regolith layer to the underlying Cayley Formation. It was there that Young retrieved, at the request of mission control, the largest rock returned by an Apollo mission, a breccia nicknamed Big Muley after mission geology principal investigator Bill Muehlberger. The next stop of the day was Buster Crater, about 1.6 km (0.99 mi) from the LM. There, Duke took pictures of Stone Mountain and South Ray Crater while Young deployed a magnetic field experiment. At that point, scientists began to reconsider their pre-mission hypothesis that Descartes had been the setting of ancient volcanic activity, as the two astronauts had yet to find any volcanic material. Following their stop at Buster, Young did a demonstration drive of the lunar rover while Duke filmed with a 16 mm movie camera. After completing more tasks at the ALSEP, Young and Duke returned to the LM to close out the moonwalk. They reentered the LM 7 hours, 6 minutes, and 56 seconds after the start of the EVA. Once inside, they pressurized the LM cabin, went through a half-hour briefing with scientists in mission control, and configured the cabin for the sleep period.

Shortly after waking up on the morning of flight day six three and a half minutes early, Young and Duke discussed with mission control in Houston the day's timeline of events. The second lunar excursion's primary objective was to visit Stone Mountain to climb up the slope of about 20 degrees to reach a cluster of five craters known as "Cinco Craters". After preparations for the day's moonwalk were completed, the astronauts climbed out of the Lunar Module. After departing the immediate landing site in the lunar rover, Young and Duke arrived at the day's first destination, the Cinco Craters, 3.8 km (2.4 mi) from the LM. At 152 m (499 ft) above the valley floor, the pair were at the highest elevation above the Lunar Module of any other Apollo mission. After marveling at the view from the side of Stone Mountain, which Duke described as "spectacular", the astronauts gathered samples in the vicinity. After spending 54 minutes on the slope, Young and Duke climbed aboard the lunar rover en route to the day's second stop, station five, a crater 20 m (66 ft) across. There, they hoped to find Descartes material that had not been contaminated by ejecta from South Ray Crater, a large crater south of the landing site. The samples they collected there, although their origin is still not certain, are, according to geologist Don Wilhelms, "a reasonable bet to be Descartes." The next stop, station six, 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. Bypassing station seven to save time, Young and Duke arrived at station eight on the lower flank of Stone Mountain, where they sampled material on a ray from South Ray Crater for about an hour. There, they collected black and white breccias and smaller, crystalline rocks rich in plagioclase. At station nine, an area known as the "Vacant Lot", which was believed to be free of ejecta from South Ray, Young and Duke spent about forty minutes gathering samples. Twenty-five minutes after departing station nine, the astronauts arrived at the final stop of the day, located halfway between the ALSEP site and the Lunar Module. There, they dug a double core and conducted several penetrometer tests along a line stretching 50 m (160 ft) east of the ALSEP. At the request of Young and Duke, the moonwalk was extended by ten minutes. After returning to the LM to wrap up the second lunar excursion, the two astronauts climbed back inside the landing craft's cabin, sealing and pressurizing the interior after 7 hours, 23 minutes, and 26 seconds of EVA time, breaking a record that had been set on Apollo 15. After eating a meal and proceeding with a debriefing on the day's activities with mission control, Young and Duke reconfigured the LM cabin and prepared for the sleep period.

Flight day seven was to be Young's and Duke's third and final day on the lunar surface, for they would return to orbit to rejoin Ken Mattingly in the Command/Service Module following the day's moonwalk. During the third and final lunar excursion of the mission, astronauts Young and Duke were to explore North Ray Crater, the largest of any of the craters any Apollo expedition had visited. After exiting Orion, the pair drove the lunar rover 0.8 km (0.50 mi) away from the LM before adjusting their heading to travel 1.4 km (0.87 mi) to North Ray Crater. The drive was smoother than that of the previous day, as the craters were more shallow and boulders were less abundant north of the immediate landing site. Boulders gradually became larger and more abundant as Young and Duke approached North Ray in the lunar rover. Upon arriving at the rim of North Ray Crater, they were 4.4 km (2.7 mi) away from the LM. After their arrival, the duo took photographs of the 1 km (0.62 mi) wide and 230 m (750 ft) deep crater. Young and Duke visited a large boulder, taller than a four-story building, which became known as 'House Rock'. Samples obtained from this boulder delivered the final blow to the pre-mission volcanic hypothesis, proving it incorrect. House Rock had numerous bullet hole-like marks where micrometeroids from space had impacted the rock. About 1 hour and 22 minutes after arriving, the astronauts departed for station thirteen, a large boulder field about 0.5 km (0.31 mi) from North Ray. On the way, they set a lunar speed record, travelling an estimated 17.1 kilometres per hour (10.6 mph) downhill. They arrived at a 3 m (9.8 ft) high boulder, which they called 'Shadow Rock'. Here, they sampled permanently shadowed soil. During this time, Mattingly was preparing the Command/Service Module in anticipation Young's and Duke's return approximately six hours later. After three hours and six minutes, Young and Duke returned to the LM, where they completed several experiments and offloaded the rover. A short distance from the LM, Duke placed a photograph of his family and a United States Air Force commemorative medallion on the surface. Young drove the rover to a point about 90 m (300 ft) east of the Lunar Module, known as the 'VIP site', so its television camera, controlled remotely by mission control, could observe Apollo 16's liftoff from the Moon. Young and Duke then reentered the LM after a five-hour and forty minute final excursion. After pressurizing the LM cabin, the crew began preparing to return to lunar orbit.