Charles Duke

On September 10, 1965, NASA announced that it was recruiting a fifth group of astronauts.[24] Duke spotted a front-page article in the Los Angeles Times, and realized that he met all the requirements. He went to see Yeager and the deputy commandant, Colonel Robert Buchanan, who informed him that there were two astronaut selections in progress: one for NASA, and one for the USAF's Manned Orbiting Laboratory (MOL) program.[25] Nominations to NASA had to come through Air Force channels, so it got to pre-screen them. Buchanan told Duke that he could apply for both programs, but if he did, MOL would take him. Duke applied only to NASA, as did Roosa and Worden;[26] Hartsfield applied for both and was taken by MOL.[27]

Astronaut geology training. Duke (center) talks to geologist David Wones (second left)

Duke made the list of 44 finalists selected to undergo medical examinations at Brooks Air Force Base at San Antonio, Texas. He arrived there on January 26, 1966, along with two fellow aviators from Edwards, Joe Engle and Bill Pogue.[26] Psychological tests included Rorschach tests; physical ones included encephalograms, and sessions on treadmills and in a human centrifuge.[28] The eye problem that the Naval Academy had reported was not found.[29]

The final stage of the selection process was an interview by the seven-member selection panel. This was chaired by Deke Slayton, with the other members being astronauts Alan Shepard, John Young, Michael Collins and C.C. Williams, NASA test pilot Warren North, and spacecraft designer Max Faget. These were conducted over a week at the Rice Hotel in Houston.[28][30] In April 1966, a phone call from Slayton informed Duke that he had been selected.[29] NASA officially announced the names of the 19 men selected on April 4, 1966.[31] Young named the group the "Original Nineteen" in a parody of the original Mercury Seven astronauts.[32]

Duke and his family moved to an apartment in League City, Texas, but when Dotty became pregnant again, they bought a vacant lot in El Lago, Texas, next door to astronaut Bill Anders. They met and befriended a young couple, Glenn and Suzanne House. Glenn was an architect, and he agreed to design them a house for $300.[33] Ground was broken in February 1967, but the house was not completed before a second son, Thomas, was born in May.[34]

Astronaut training included four months of studies covering subjects such as astronomy, orbital mechanics and spacecraft systems.[33] Some 30 hours of briefings were conducted on the Apollo command and service module, and twelve on the Apollo lunar module.[35] An important feature was training in geology, so that astronauts on the Moon would know what rocks to look out for. This training in geology included field trips to the Grand Canyon and the Meteor Crater in Arizona, Philmont Scout Ranch in New Mexico, Horse Lava Tube System in Bend, Oregon, and the ash flow in the Marathon Uplift in Texas, and other locations, including Alaska and Hawaii.[36] There was also jungle survival training in Panama, and desert survival training around Reno, Nevada. Water survival training was conducted at Naval Air Station Pensacola using the Dilbert Dunker.[37]

Once their initial training was complete, Duke and Roosa were assigned to oversee the development of the Saturn V launch vehicle, as part of the Booster Branch of the Astronaut Office, headed by Frank Borman and C.C. Williams.[38] He was part of the Mission Control team at the Kennedy Space Center that monitored the launch of Gemini 11 on September 12, 1966, and Gemini 12 on November 11, 1966. His personal responsibility was the Titan II booster.[39][40] They frequently traveled to Marshall Space Flight Center in Huntsville, Alabama, to confer with its director, Wernher von Braun.[41] NASA provided T-38 Talon aircraft for the astronauts' use, and like most astronauts, Duke flew at every opportunity.[34]

Young, right, and Duke maneuver a training version of the Lunar Roving Vehicle in a field at the Kennedy Space Center built to resemble the lunar surface.

The Nineteen were divided into command and service module (CSM) and Lunar Module (LM) specialists. Slayton asked each of them which specialty he preferred, but made the final decision himself. Once again, Duke received his choice, and became a lunar module specialist.[42] He oversaw the development of the lunar module propulsion systems. A major concern was the ascent propulsion system, which was a critical component of the mission that had to work for the astronauts to survive.[43] Testing at the White Sands Missile Range in 1966 indicated combustion instability.[44] George Low, the Apollo Spacecraft Program manager, convened a committee to review the situation, and Duke became the Astronaut Office representative on it.[43] Although Bell was confident that it could resolve the problems, NASA hired Rocketdyne to develop an alternative engine just in case. The committee ultimately decided to use Rocketdyne's injector system with Bell's engine.[45]

In 1969, Duke became a member of the support crew for Apollo 10, along with Joe Engle and Jim Irwin.[46] During Projects Mercury and Gemini, each mission had a prime and a backup crew. For Apollo, a third crew of astronauts was added, known as the support crew. The support crew maintained the flight plan, checklists and mission ground rules, and ensured the prime and backup crews were apprised of changes. They developed procedures, especially those for emergency situations, so these were ready for when the prime and backup crews came to train in the simulators, allowing them to concentrate on practicing and mastering them.[47] The mission commander, Tom Stafford, selected Duke for his familiarity with the LM, especially its propulsion systems.[41] For this reason, Duke served as CAPCOM for the LM orbit, activation, checkout, and rendezvous on Apollo 10.[43][48]

It was unusual for someone to serve as CAPCOM on back-to-back missions, but for the same reason—familiarity with the LM—Neil Armstrong, the commander of Apollo 11, asked Duke to reprise his role on that mission, which included the first crewed landing on the Moon. Duke told Armstrong that he would be honored to do so.[43] Duke's distinctive Southern drawl became familiar to audiences around the world, as the voice of a Mission Control made nervous by a long landing that almost expended all of the Lunar Module Eagle's fuel. Duke's first words to the Apollo 11 crew on the surface of the Moon were flustered, "Roger, Twank...Tranquility, we copy you on the ground. You got a bunch of guys about to turn blue. We're breathing again. Thanks a lot!"[43]

The Apollo 16 crew: Duke (left), John Young (center), and Ken Mattingly (right)

The next rung on the ladder after serving on a support crew was to serve on a backup crew. The pace of the early Apollo missions meant that multiple crews had to be training at the same time. Slayton developed a rotation scheme whereby the backup crew for one mission would become the prime crew for one three missions later, and then the backup for the one three missions after that. If the commander (CDR) declined the offer of another mission, the command module pilot (CMP), as the next most senior astronaut, would become the commander (CDR). Thus, the Apollo 10 crew became the backup crew for Apollo 13. Tom Stafford accepted the position of acting Chief of the Astronaut Office, so the CMP, John Young, stepped up to replace him as CDR; Gene Cernan remained lunar module pilot (LMP), and Jack Swigert, a command module specialist from the Nineteen, was designated the CMP. The intention was that this crew would eventually become the prime crew for Apollo 16, but Cernan disagreed with this; he wanted to command his own mission. Slayton therefore assigned Duke, who was well known to Young from Apollo 10, in Cernan's place. After Michael Collins, the CMP of Apollo 11, declined the offer of command of the backup crew of Apollo 14, Slayton gave this command to Cernan.[49][50][51]

Full-time training for Apollo 13 commenced in July 1969,[52] although the selection of the Apollo 13 and 14 crews was not officially announced until August 7.[53] The prime crew for Apollo 13 consisted of Jim Lovell (CDR), Fred Haise (LMP) and Ken Mattingly (CMP). The mission was originally scheduled to be flown in late 1969, but in view of the successful outcome of Apollo 11, it was postponed until March and then April 1970.[52] Two or three weeks before the launch date, Duke contracted rubella (German measles) from Paul House, the son of Glenn and Suzanne House. The disease is highly contagious, so the NASA doctors checked the prime crew. It was found that Lovell and Haise were immune to the disease, but Mattingly was not. The decision was taken to remove Mattingly and replace him with Swigert.[43]

The subsequent explosion on Apollo 13 greatly affected the backup crew, especially Mattingly, who felt that he should have been on board. Young, Mattingly and Duke worked in the simulators to develop emergency procedures for the crew, who were ultimately returned safely to Earth. Haise and Swigert teased Duke, calling him "Typhoid Mary". The measles incident resulted in procedures being changed; starting with Apollo 14, the crew would be quarantined for three weeks before the flight as well as afterward. In the event, only the Apollo 14 crew had to endure two periods of quarantine; with no signs of life on the Moon, the post-mission quarantine was discontinued in April 1971.[54][55][56]

Young, Mattingly and Duke were officially named as the crew of Apollo 16, the fifth lunar landing mission, on March 3, 1971.[58] The Descartes Highlands were chosen as the landing site on June 3, 1971. This was the highest region on the near side of the Moon. It was believed to be volcanic in origin and mainly composed of basalt, based upon the tones of gray observed from Earth. It was hoped that rock samples retrieved by Apollo 16 would provide clues about the processes that formed the highlands, and perhaps even show that such processes were still active.[59][60]

Training was conducted in the lunar module simulator, which used a TV camera and a scale model of the landing area. Other activities included driving a training version of the Lunar Roving Vehicle (LRV), and collecting geological samples. A final geological field trip was made to the big island of Hawaii in December 1971. On the second day of the trip, Duke caught the flu. By New Year's Day he was so ill that he was unable to get out of bed, and asked the Astronaut Office to send someone to take him to the doctor at the Kennedy Space Center. The doctor took an X-ray that revealed pneumonia in both lungs and called an ambulance to take Duke to the Patrick Air Force Base hospital.[61][62]

Duke feared that he might not recover in time for the launch, which was scheduled for March 17, 1972.[62] The spacecraft and Saturn V launch vehicle had already been rolled out to Launch Pad 39A on December 13.[63] Luck was with Duke: Grumman engineers wanted more time to test the increased capacity of the LM's batteries; a fault was found with the explosive cords that separate the LM from the CSM that warranted their replacement; and a failure of a clamp in Duke's spacesuit during training required the modification of all three astronauts' suits. This caused the launch date to be postponed to the next launch window, on April 16.[64][65] This proved fortunate when an error by launch pad technicians caused one of the CM's Teflon fuel tank bladders to rupture, and the entire space vehicle had to be returned to the Vehicle Assembly Building.[66][67] Slayton noted that "there wasn't even any discussion of replacing him; that was one of the lessons we'd learned on 13."[68]

The astronauts went into quarantine and were allowed out only to fly T-38s for an hour a day. The day before liftoff, the Apollo Program director, Rocco Petrone saw someone he believed to be Duke around the pool at the Holiday Inn. A furious Petrone called the crew quarters demanding to know why Duke had broken quarantine. The staff's protestations that Duke was still there and had not left did not placate Petrone, and they had to track down Duke in training, who suggested that Petrone might have seen his brother Bill.[69] When Apollo 16 was launched at 12:54 Eastern Standard Time (17:54 UTC) on April 16, 1972,[70] Duke became the first twin to fly in space.[71]

Duke on lunar EVA during Apollo 16, April 1972

The launch was normal; the crew experienced vibration similar to that of previous crews. The first and second stages of the Saturn V performed flawlessly, and the spacecraft entered low Earth orbit just under 12 minutes after liftoff. In Earth orbit, the crew faced minor technical issues, including a potential problem with the environmental control system and the S-IVB third stage's attitude control system, but these were resolved or compensated for. After 1.5 orbits, it reignited for just over five minutes, propelling the craft towards the Moon at 35,000 km/h (22,000 mph).[70][72]

In lunar orbit, the crew faced a series of problems. Duke was unable to get the S-band steerable antenna on the LM Orion to move in the yaw axis, and therefore could not align it correctly. This resulted in poor communications with the ground stations, and consequently a loss of the computer uplink. This meant that Duke had to copy down 35 five-digit numbers and enter them into the computer. Correcting any mistake was a complicated procedure. Fortunately, the astronauts could still hear Mission Control clearly, although the reverse was not the case.[73][74]

When Young went to activate the reaction control system, they suffered a double failure on the pressurization system.[73] Young described this as "the worst jam I was ever in".[75] A long debate between the astronauts and with Mission Control followed. It was the only time during the flight that Duke could recall arguing with Young.[73] Although they could not fix the problem, they were able to work around it by shifting propellant into the ascent storage tank. None was lost; it was just moved into another tank.[75]

The Apollo 16 Command and Service Module (CSM), as seen from the Lunar Module (LM, out of view) above terrain on the lunar farside.

With the preparations finished, Young and Duke undocked Orion from Mattingly in the CSM Casper. 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, causing such severe oscillations that Casper seemed to be shaking itself to pieces. According to mission rules, Orion should have then re-docked with Casper in case Mission Control decided to abort the landing and use Orion's engines for the return trip to Earth. This was not done, and the two spacecraft flew on in formation.[72][76] A decision to land had to be made within five orbits (about ten hours), after which the spacecraft would have drifted too far to reach the landing site.[77]

After four hours and three orbits, Mission Control determined that the malfunction could be worked around and told Young and Duke to proceed with the landing.[76][78] As a result of the delay, powered descent to the lunar surface began about six hours behind schedule, and Young and Duke began their descent to the surface at an altitude 5,000 m (16,000 ft) higher than normal. At an altitude of about 4,000 m (13,000 ft), Young was able to view the landing site in its entirety.[78] Orion landed on the Cayley Plains, 270 m (886 ft) northwest of the planned landing site, at 02:23:35 UTC on April 21.[79]

Duke became the tenth person to walk upon the surface of the Moon,[80] following Young, who became the ninth. Apollo 16 was the first scientific expedition to inspect, survey, and sample materials and surface features in the rugged lunar highlands. In a stay of 71 hours and 14 minutes, Duke and Young conducted three excursions onto the lunar surface, during which Duke logged 20 hours and 15 minutes in extravehicular activities. These included the emplacement and activation of scientific equipment and experiments, the collection of nearly 97 kilograms (213 lb) of rock and soil samples, and the evaluation and use of the LRV over the roughest surface yet encountered on the Moon.[81][82]

During their final few minutes on the surface, Duke attempted to set a lunar high jump record. He jumped about 2 feet 8 inches (0.81 m), but overbalanced, and fell over backwards on his primary life support system (PLSS). It could have been a fatal accident; had his suit ruptured or PLSS broken, he might have died.[83] "That ain't very smart", Young noted.[84]

Family picture Duke left on the Moon

On the way back to Earth, Duke assisted in a deep-space EVA that lasted 1 hour and 23 minutes, when Mattingly climbed out of the Casper spacecraft and retrieved film cassettes from the service module. After a journey during which Casper had traveled 2,238,598 kilometers (1,208,746 nmi), the Apollo 16 mission concluded with a splashdown in the Pacific Ocean at 19:45:05 UTC on April 27, and recovery by the aircraft carrier USS Ticonderoga.[85]

Duke left two items on the Moon, both of which he photographed. The most famous is a plastic-encased photo portrait of his family taken by NASA photographer Ludy Benjamin. The reverse of the photo was signed and thumb printed by Duke's family and bore this message: "This is the family of Astronaut Duke from Planet Earth, who landed on the Moon on the twentieth of April 1972."[86]

The other item was a commemorative medal issued by the Air Force, which was celebrating its 25th anniversary in 1972. Duke was the only Air Force officer to visit the Moon that year. With the approval of the Chief of Staff of the United States Air Force, General John D. Ryan, and the Secretary of the Air Force, Robert Seamans, Duke took two silver medallions commemorating the anniversary. He left one on the Moon and donated the other to the Air Force.[86] Today it is on display at the National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio, along with a Moon rock from the Apollo 16 mission.[87]

In the wake of the Apollo 15 postal covers scandal, Slayton replaced the Apollo 15 crew as the backup for the Apollo 17 mission with the Apollo 16 one.[88] Duke became the backup LMP, Young the backup commander, and Roosa the backup CMP. They went into training again in June 1972, just two months after Duke and Young had returned from the Moon. There was only a slim chance that they would be called upon to fly the mission, and in the event were not. Duke never flew in space again.[89] He retired from NASA on January 1, 1976. He had spent 265 hours and 51 minutes in space.[81]