Apollo 17

The Apollo 15 prime crew received the backup assignment since this was to be the last lunar mission and the backup crew would not rotate to another mission. However, when the Apollo 15 postage stamp incident became public in early 1972, the crew was reprimanded by NASA and the United States Air Force (they were active duty officers). Director of Flight Crew Operations Deke Slayton removed them from flight status and replaced them with Young and Duke from the Apollo 16 prime crew and Roosa from the Apollo 14 prime and Apollo 16 backup crews.[14][16]

• Robert F. Overmyer[17]
• Robert A. Parker[18]
• C. Gordon Fullerton[19]

Apollo 17 space-flown silver Robbins medallion

The insignia's most prominent feature is an image of the Greek sun god Apollo backdropped by a rendering of an American eagle, the red bars on the eagle mirroring those on the flag of the United States. Three white stars above the red bars represent the three crewmen of the mission. The background includes the Moon, the planet Saturn, and a galaxy or nebula. The wing of the eagle partially overlays the Moon, suggesting man's established presence there. The gaze of Apollo and the direction of the eagle's motion embody man's intention to explore further destinations in space.[20]

The patch includes, along with the colors of the U.S. flag (red, white, and blue), the color gold, representative of a "golden age" of spaceflight that was to begin with Apollo 17. The image of Apollo in the mission insignia is a rendering of the Apollo Belvedere sculpture. The insignia was designed by Robert McCall, with input from the crew.[20]

Apollo 17 launches on December 7, 1972

Apollo 17 was the last crewed Saturn V launch and the only night launch. The launch was delayed by two hours and forty minutes due to an automatic cutoff in the launch sequencer at the T-30 second mark in the countdown. The issue was quickly determined to be a minor technical error. The clock was reset and held at the T-22 minute mark while technicians worked around the malfunction in order to continue with the launch. This pause was the only launch delay in the Apollo program caused by this type of hardware failure. The countdown then resumed, and the liftoff occurred at 12:33 am EST.[3][22]

Approximately 500,000 people were estimated to have observed the launch in the immediate vicinity of Kennedy Space Center, despite the early morning hour. The launch was visible as far away as 800 km (500 mi); observers in Miami, Florida, saw a "red streak" crossing the northern sky.[22]

At 3:46 am EST, the S-IVB third stage was re-ignited to propel the spacecraft towards the Moon.[3]

At approximately 2:47 pm EST on December 10, the service propulsion system engine on the CSM ignited to slow down the CSM/LM stack into lunar orbit. Following orbit insertion and orbital stabilization, the crew began preparations for landing in the Taurus-Littrow valley.[3]

After separating from the CSM, the LM Challenger and its crew of two, Eugene Cernan and Harrison Schmitt, adjusted their orbit and began preparations for the descent to Taurus-Littrow. While Cernan and Schmitt prepared for landing, Command Module Pilot Ron Evans remained in orbit to take observations, perform experiments and await the return of his crew-mates a few days later.[3][23]

Soon after completing their preparations for landing, Cernan and Schmitt began their descent to the Taurus-Littrow valley on the lunar surface. Several minutes after the descent phase was initiated, the LM pitched over, giving the crew their first look at the landing site during the descent phase and allowing Cernan to guide the spacecraft to a desirable landing target while Schmitt provided data from the flight computer essential for landing. The LM touched down on the lunar surface at 2:55 pm EST on December 11. Shortly thereafter, the two astronauts began re-configuring the LM for their stay on the surface and began preparations for the first moonwalk of the mission, or EVA-1.[3][23]

Eugene Cernan on the lunar surface, December 13, 1972

During their stay on the lunar surface, Cernan and Schmitt performed three moonwalks (EVAs). The astronauts deployed the LRV, the Apollo Lunar Surface Experiments Package (ALSEP) and seismic explosive charges. They drove the rover to nine planned geological survey stations to collect samples and make observations. Additionally, twelve short sampling stops were made at Schmitt's discretion while riding the rover, during which the astronauts rapidly collected lunar material without dismounting.[24] During lunar surface operations, Commander Cernan always drove the rover, while Lunar Module Pilot Schmitt was a passenger who assisted with navigation. This division of responsibilities between the two crew positions was used consistently throughout Apollo's J-missions.[25][26][27]

The first lunar excursion began four hours after landing, at 6:54 p.m. EST on December 11. The first task was to offload the rover and other equipment from the LM. While working near the rover, Cernan caught his hammer under the right-rear fender extension, accidentally breaking it off. A similar incident occurred on Apollo 16 as John Young maneuvered around the rover. Although this was not a mission-critical issue, the loss of the part caused Cernan and Schmitt to be covered with dust thrown up when the rover was in motion.[28] The crew attempted a short-lived fix using duct tape, attaching a map to the damaged fender. However, lunar dust stuck to the tape's surface, preventing it from adhering properly. The crew deployed the ALSEP just west of the landing site. This task done, they departed for the first geological survey station: Steno crater to the south of the landing site. The astronauts gathered 14 kilograms (31 lb) of samples, took seven gravimeter measurements, and deployed two explosive packages. The latter were detonated remotely to test geophones placed by the astronauts, and also seismometers left during previous missions.[29] The EVA ended after seven hours and twelve minutes.[3][30]

Apollo 17 landing site, photographed in 2011 by Lunar Reconnaissance Orbiter

Lunar Regolith collected during Apollo 17

On December 12, awakened by "Ride of the Valkyries",[31] Cernan and Schmitt began their second lunar excursion. First, the rover's fender needed a better fix. Overnight, the flight controllers devised a procedure communicated by John Young: taping four cronopaque maps together and clamping the "replacement fender extension" onto the fender.[32]^:977 The astronauts carried out the new fix which did its job, lasting the remainder of the exploration.[28][33][34] Cernan and Schmitt then departed for station 2—Nansen Crater, at the foot of the South Massif. Upon arrival, Cernan reported their range as 7.6 km[32]^:1144 (4.7 mi, 25,029 ft[35]) away from the lunar module; it was the furthest distance traveled away from a spacecraft during the Apollo program. The astronauts were at the extremity of their "walkback limit", a safety constraint meant to ensure that they could walk back to the LM if for whatever reason the rover failed. They began a return trip, traveling northeast. Stopping at station 4—Shorty crater—the astronauts discovered orange soil, which proved to be very small beads of volcanic glass formed over 3.5 billion years ago.[36] The final stop before returning to the LM was Camelot crater; throughout the sojourn, the astronauts collected 34 kilograms (75 lb) of samples, took another seven gravimeter measurements, and deployed three more explosive packages.[3] Concluding the EVA at seven hours and thirty-seven minutes, Cernan and Schmitt had completed the longest-duration EVA in history to-date, traveling further away from a spacecraft and covering more ground on a planetary body during a single EVA than any other spacefarers.[35] Once the LM was repressurized, CAPCOM Bob Parker was particularly impressed, saying: "Absolutely outstanding. I can't say more than that. And I mean it from the bottom of my heart or the bottom of my soul or something, my conscience."[32]^:1363

The third moonwalk, the last of the Apollo program, began at 5:25 pm EST on December 13. Cernan and Schmitt rode the rover northeast of the landing site, exploring the base of the North Massif and the Sculptured Hills. Stopping at station 6, they examined a house-sized split boulder dubbed Tracy's Rock (or Split Rock), after Cernan's daughter. The ninth and final planned station was conducted at Van Serg crater. The crew collected 66 kilograms (146 lb) of lunar samples and took another nine gravimeter measurements. Before concluding the moonwalk, the crew collected a breccia rock, dedicating it to the nations of Earth, several of which were represented in Mission Control Center in Houston, Texas, at the time. A plaque located on the LM, commemorating the achievements made during the Apollo program, was then unveiled. Before reentering the LM for the final time, Gene Cernan expressed his thoughts:[3]

... I'm on the surface; and, as I take man's last step from the surface, back home for some time to come - but we believe not too long into the future - I'd like to just [say] what I believe history will record. That America's challenge of today has forged man's destiny of tomorrow. And, as we leave the Moon at Taurus-Littrow, we leave as we came and, God willing, as we shall return, with peace and hope for all mankind. "Godspeed the crew of Apollo 17."[37]

Cernan then followed Schmitt into the LM; the final lunar excursion had a duration of seven hours and fifteen minutes.[3]

Apollo 17 post-splashdown recovery operations

Apollo 17 command module America after splashdown, with USS Ticonderoga in background

Eugene Cernan and Harrison Schmitt successfully lifted off from the lunar surface in the ascent stage of the LM on December 14, at 5:55 pm EST. After a successful rendezvous and docking with Ron Evans in the CSM in orbit, the crew transferred equipment and lunar samples between the LM and the CSM for return to Earth. Following this, the LM ascent stage was sealed off and jettisoned at 1:31 am on December 15. The ascent stage was then deliberately crashed into the Moon in a collision recorded by seismometers deployed on Apollo 17 and previous Apollo expeditions.[3][38]

During the return to Earth, Evans performed a 65-minute EVA to retrieve film cassettes from the service module's scientific instrument module (SIM) bay, with assistance from Schmitt who remained at the command module's hatch.[39][3] At approximately 160,000 nautical miles[40]^:1730 (184,000 mi; 296,000 km) from Earth, it was the third "deep space" EVA in history, performed at great distance from any planetary body. As of 2021, it remains one of only three such EVAs, all performed during Apollo's J-missions under similar circumstances. It was the last EVA of the Apollo program.

On December 19, the crew jettisoned the no-longer-needed SM, leaving only the CM for return to Earth. The Apollo 17 spacecraft reentered Earth's atmosphere and landed safely in the Pacific Ocean at 2:25 p.m., 6.4 kilometers (4.0 mi) from the recovery ship, USS Ticonderoga. Cernan, Evans, and Schmitt were then retrieved by a recovery helicopter and were safely aboard the recovery ship 52 minutes after landing.[3][38]

Apollo 17 Lunar Roving Vehicle as it was finally left parked on the Moon. The surface electrical properties (SEP) receiver is the antenna on the right-rear of the vehicle

Apollo 17 was the third mission (the others being Apollo 15 and Apollo 16) to make use of a Lunar Roving Vehicle. The LRV, in addition to being used by the astronauts for transport from station to station on the mission's three moonwalks, was used to transport the astronauts' tools, communications equipment, and samples.[41] The Apollo 17 LRV was also used to carry experiments unique to the mission, such as the Traverse Gravimeter and Surface Electrical Properties experiment.[42][43] The Apollo 17 LRV traveled a cumulative distance of approximately 35.9 km (22.3 mi) in a total drive time of about four hours and twenty-six minutes; the greatest distance Eugene Cernan and Harrison Schmitt traveled from the lunar module was about 7.6 km (4.7 mi).[44]

Apollo 17 included a biological cosmic ray experiment (BIOCORE), carrying five mice that had been implanted with radiation monitors to see whether they suffered damage from cosmic rays.[45]

The five pocket mice (Perognathus longimembris) were implanted with radiation monitors under their scalps and flown on the mission. The species was chosen because it was well-documented, small, easy to maintain in an isolated state (not requiring drinking water for the duration of the mission and with highly concentrated waste), and for its ability to withstand environmental stress. Four of the five mice survived the flight; the cause of death of the fifth mouse was not determined.[45]

The study found lesions in the scalp itself and liver. The scalp lesions and liver lesions appeared to be unrelated to one another, and were not thought to be the result of cosmic rays. No damage was found in the mice's retinas or viscera.[45] At the time of the publication of the Apollo 17 Preliminary Science Report, the mouse brains had not yet been examined.[45] However, subsequent studies showed no significant effect on the brains.[46]

Officially, the mice—four male and one female—were assigned the identification numbers A3326, A3400, A3305, A3356 and A3352. Unofficially, according to Cernan, the Apollo 17 crew dubbed them Fe, Fi, Fo, Fum, and Phooey.[47]

Apollo 17 SIM bay on the service module America, seen from the Lunar Module Challenger in orbit around the Moon

Sector one of the Apollo 17 SM contained the scientific instrument module (SIM) bay. The SIM bay housed three experiments for use in lunar orbit: a lunar sounder, an infrared scanning radiometer, and a far-ultraviolet spectrometer. A mapping camera, panoramic camera, and a laser altimeter were also included in the SIM bay.[41]

The lunar sounder beamed electromagnetic impulses toward the lunar surface, which were designed with the objective of obtaining data to assist in developing a geological model of the interior of the Moon to an approximate depth of 1.3 km (0.81 mi).[41]

The infrared scanning radiometer was designed with the objective of generating a temperature map of the lunar surface to aid in locating surface features such as rock fields, structural differences in the lunar crust, and volcanic activity.[41]

The far-ultraviolet spectrometer was to be used to obtain data pertaining to the composition, density, and constituency of the lunar atmosphere. The spectrometer was also designed to detect far-UV radiation emitted by the Sun that has been reflected off the lunar surface.[41]

The laser altimeter was designed with the intention of measuring the altitude of the spacecraft above the lunar surface within approximately two meters (6.6 feet), and providing altitude information to the panoramic and mapping cameras.[41]

Throughout the Apollo lunar missions, the crew members observed light flashes that penetrated closed eyelids. These flashes, described as "streaks" or "specks" of light, were usually observed by astronauts while the spacecraft was darkened during a sleep period. These flashes, while not observed on the lunar surface, would average about two per minute and were observed by the crew members during the trip out to the Moon, back to Earth, and in lunar orbit.[41]

The Apollo 17 crew conducted an experiment, also conducted on Apollo 16, with the objective of linking these light flashes with cosmic rays. As part of an experiment conducted by NASA and the University of Houston, one astronaut wore a device that recorded the time, strength, and path of high-energy atomic particles that penetrated the device. Evidence supports the hypothesis that these flashes occur when charged particles travel through the retina in the eye.[41][48]

Apollo 17 was the only Apollo lunar landing mission to carry the Traverse Gravimeter Experiment (TGE), built by Draper Laboratory at the Massachusetts Institute of Technology. As gravimeters had proven to be useful in the geologic investigation of the Earth, the objective of this experiment was to determine the feasibility of using the same techniques on the Moon to learn about its internal structure. The gravimeter was used to obtain relative gravity measurements at the landing site in the immediate vicinity of the lunar module, as well as various locations on the mission's traverse routes. Scientists would then use this data to help determine the geological substructure of the landing site and the surrounding vicinity.[42]

The TGE was carried on the Lunar Roving Vehicle; measurements were taken by the astronauts while the LRV was not in motion or after the gravimeter was placed on the surface.[41] A total of twenty-six measurements were taken with the TGE during the mission's three moonwalks, with productive results. As part of the Apollo Lunar Surface Experiments Package (ALSEP), the astronauts also deployed the Lunar Surface Gravimeter, a similar experiment, which ultimately failed to function properly.[42]

Apollo 17 was the only lunar surface expedition to include the surface electrical properties (SEP) experiment. The experiment included two major components: a transmitting antenna deployed near the lunar module and a receiving antenna located on the Lunar Roving Vehicle. At different stops during the mission's traverses, electrical signals traveled from the transmitting device, through the ground, and were received at the LRV. The electrical properties of the lunar soil could be determined by comparison of the transmitted and received electrical signals. The results of this experiment, which are consistent with lunar rock composition, show that the top 2 km (1.2 mi) of the Moon are extremely dry.[43]