Choosing objectives for the final mission
Apollo 17, flown in December 1972, was the Apollo programme's sixth and final crewed lunar landing. Its purpose went beyond landing once more: it sought to investigate geological relationships between lunar highland and mare material, collect rocks and soil, deploy long-term experiments, and conduct orbital photography and remote sensing. Greater surface-stay capability, a lunar rover and scientific instruments made this a mission focused on exploration range and sample context.
The Taurus–Littrow landing valley lay on the southeastern edge of Mare Serenitatis. Scientists hoped to find ancient material in the adjacent massifs and evidence of younger volcanic activity in the valley's dark mantle. On 11 February 1972, the site-selection committee recommended it after comparison with candidates including Gassendi and Alphonsus. Scientific value was assessed alongside terrain, the landing ellipse and the crew's ability to walk back in an emergency. “Young volcanic material” was still a hypothesis, not an established conclusion.
Crew and ground cooperation
The crew comprised Commander Eugene Cernan, Command Module Pilot Ronald Evans and Lunar Module Pilot Harrison Schmitt. Schmitt was a geologist, and his flight reflected scientists' demand to bring professional observational skills to the Moon; Cernan also completed extensive field training. William Muehlberger, Lee Silver and others helped train them. Exercises in 1972 included volcanic areas in Hawaii, Montana's Stillwater complex and a simulated crater in Arizona, developing the crew's description, interpretation and sampling skills.
Engineering and operations also had a defined organization. Rocco Petrone directed the Apollo Program, Richard Smith led the Saturn programme at Marshall Space Flight Center, Owen Morris headed the spacecraft programme at the Manned Spacecraft Center, and Kennedy Space Center handled launch operations. The mission equipment included a Saturn V rocket, command and service modules CM/SM-114, lunar module LM-12 and the third lunar rover. Geological traverses had to fit their capabilities and the limits of communications and life support.
Launch, lunar orbit and landing
At 05:33 on 7 December 1972, the rocket lifted off from Pad 39A at Kennedy Space Center, Florida; all times here are Greenwich Mean Time. A fault in the automatic sequence late in the countdown caused a delay of two hours and forty minutes, with launch proceeding only after ground personnel investigated and resolved it. The flight plan shortened the translunar transfer to compensate for the delayed departure, illustrating why scheduled times cannot replace actual operational records.
The spacecraft entered lunar orbit on 10 December. At 19:54 on 11 December, Cernan and Schmitt landed the lunar module at Taurus–Littrow, less than 200 meters from the preferred point, while Evans remained in orbit making observations. The nearly 75 hours after landing included rest, preparation inside the module and surface work, not continuous extravehicular activity. The three surface excursions totaled about 22 hours and four minutes.
From geological traverses to laboratory samples
Along rover traverses, the crew investigated the valley floor, boulders at the bases of the South and North Massifs and contacts between different landforms, returning about 110 kilograms of samples. On the second excursion, they discovered orange soil at Shorty crater, collected surface material and obtained a double-tube core. The third excursion examined boulders, their downhill tracks and surrounding soils at the foot of the North Massif. Photographs, descriptions and sample locations made the rocks more than objects detached from their settings.
The preliminary science report recorded that, after return, surface dust was first removed from rock samples with nitrogen, followed by examination under a low-power binocular microscope. Thin sections were prepared from 35 rocks for petrographic study. The preliminary-examination team included petrographic and analytical groups, with members from Johnson Space Center, the U.S. Geological Survey, universities and laboratories. Different specialists thus carried field sampling forward into classification and chemical analysis on Earth.
What the instruments gained and lost
The surface experiment package was deployed about 185 meters west-northwest of the lunar module, including heat-flow, seismic-profiling and atmospheric-composition equipment. The rover also supported gravity measurements along its route. In orbit, an ultraviolet spectrometer, infrared scanning radiometer and radar sounder examined the lunar environment and subsurface structure from different perspectives. The preliminary report recorded that the infrared instrument operated in orbit for about 100 hours and made 108 measurements, covering about one-third of the lunar surface.
Successful deployment did not mean every experiment achieved its planned performance. The fixed Lunar Surface Gravimeter could not balance properly. The mission report traced the problem to an error in mass conversion: its sensor balance mass was about two percent too light, outside the approximately ±1.5 percent adjustment range. Ground commands achieved limited balance but substantially reduced sensitivity. This instrument must be assessed separately from the rover-carried Traverse Gravimeter, which did obtain measurements along the route.
Return and preliminary conclusions
On 14 December, the lunar module's ascent stage lifted off and rendezvoused with the command module, after which samples and equipment were transferred. During the return journey, Evans performed an EVA to retrieve film cassettes from the service module. The crew splashed down in the Pacific on 19 December, ending a flight of about 12.6 days. Interpretation of samples and instrument data continued after the mission ended.
The orange soil illustrates that interpretive process. The 1973 science report identified it as glass particles and, using preliminary dating, placed the material at about 3.7 billion years old; the later impact forming Shorty crater had excavated it. It could not establish recent volcanic eruptions at the landing site. Apollo 17's important results included not only quantities of samples and remote-sensing data but also the use of actual material to revise site-selection hypotheses. The ages and origin interpretations in the preliminary report should retain their status as findings from that stage of research.