Apollo 17 (1972): The Last Crewed Moon Landing

Apollo 17 was the last crewed Moon landing. Launched from Florida on 7 December 1972, it carried Eugene Cernan and Harrison Schmitt to the Taurus-Littrow valley, where they spent about three days exploring, while Ronald Evans orbited overhead. Schmitt was the first professional scientist to walk on the Moon, and on the way out the crew took the Blue Marble, one of the most reproduced photographs ever made.

Background: the end of Apollo

After Apollo 11 landed in July 1969, NASA planned up to ten more landings. Budgets were shrinking and public attention was turning elsewhere, and the near-disaster of Apollo 13 in April 1970 increased the sense of risk. In 1970 NASA cancelled Apollo 18, 19 and 20, which made Apollo 17 the final mission.

Apollo 17 was one of three “J missions”, which carried a lunar roving vehicle and allowed longer stays and more ambitious science. Scientists had long argued that a trained geologist should go to the Moon. When the later flights were cancelled, Schmitt, a geologist with a doctorate from Harvard, replaced the astronaut Joe Engle on the crew.

The crew and the site

Eugene Cernan, the commander, was a US Navy officer who had flown on Gemini 9A and Apollo 10. Ronald Evans, a Navy pilot, flew the command module America. Schmitt piloted the lunar module Challenger.

The landing site, the Taurus-Littrow valley on the south-eastern edge of the Sea of Serenity, was chosen to sample both very old highland rocks and possible younger volcanic material. The valley is walled by massifs, large blocks of mountain, rising more than 2 kilometres above its floor.

The flight

Apollo 17 lifted off at 12:33 a.m. Eastern time on 7 December 1972, after a countdown fault caused a delay of about two hours and forty minutes. It was the first night launch of a Saturn V, and the glow was seen across much of the south-eastern United States.

About five hours later, as the spacecraft headed for the Moon, the crew photographed the whole sunlit Earth, with Africa, Arabia and the Antarctic ice cap clearly visible. The picture became known as the Blue Marble.

Challenger landed in the valley on 11 December 1972. Evans remained in lunar orbit aboard America, conducting mapping and remote-sensing experiments.

Three days in Taurus-Littrow

Cernan and Schmitt made three moonwalks totalling about 22 hours, using the rover to travel roughly 35 kilometres in all. They set up the Apollo Lunar Surface Experiments Package, a set of instruments that sent data back to Earth for years, and collected rocks and soil at a series of planned stations.

On the first moonwalk a rover fender was accidentally broken, and the vehicle sprayed the astronauts with dust. Overnight, engineers on Earth devised a repair, and Cernan built a replacement fender from laminated maps, tape and clamps.

On the second moonwalk, at Shorty crater, Schmitt noticed orange soil. Analysis on Earth showed it consisted of tiny glass beads formed in volcanic fire-fountain eruptions about 3.6 billion years ago. On the third moonwalk the pair sampled a large split boulder at the foot of the North Massif, later known as Tracy’s Rock after Cernan’s daughter.

Before leaving, the crew unveiled a plaque on the lunar module’s landing stage marking the end of the first human exploration of the Moon. Cernan was the last to climb back aboard, on 14 December 1972, speaking of the hope that people would return in peace.

Return to Earth

Challenger lifted off from the Moon later on 14 December and docked with America. On the way home, Evans made a spacewalk of about an hour to retrieve film from cameras mounted on the service module.

The command module splashed down in the Pacific Ocean on 19 December 1972 and was recovered by the aircraft carrier USS Ticonderoga. The mission lasted about 12 and a half days.

By the numbers

All of these were records for the Apollo programme. Figures vary slightly between sources depending on how time and distance are measured, so they are given here as approximate values.

What the mission found

Apollo 17 was designed to answer questions about the Moon’s early history. The rocks from the massifs included pieces of the ancient highland crust broken and mixed by the huge impact that formed the Serenitatis basin. Dating these samples helped scientists estimate when the great lunar basins formed, roughly 3.8 to 3.9 billion years ago, although the exact timing is still debated.

The valley floor, by contrast, was covered by dark basalt lava flows that filled the valley after the basin formed. The orange and black glass beads found at Shorty crater showed that some eruptions had been explosive fire fountains, driven by gases escaping from deep inside the Moon.

The surface experiments measured heat flowing out of the lunar interior, recorded tiny moonquakes and analysed the Moon’s thin atmosphere. A traverse gravimeter and an electrical properties experiment probed the rocks beneath the valley. Meanwhile, Evans’s instruments in orbit mapped the surface with cameras and radar, extending the science far beyond the landing site.

Legacy

Apollo 17’s samples, the largest collected on any mission, are still studied, and some kept sealed since 1972 were opened only from 2019 onwards using modern techniques. The orange glass helped scientists understand the Moon’s volcanic history and the water locked inside its interior.

The Blue Marble became a symbol of the environmental movement and of Earth as a single, fragile home. Earlier missions such as Apollo 8 had photographed Earth from lunar distance, but the Blue Marble was the first clear picture of the fully lit globe taken by people, and it has been reproduced countless times.

Schmitt later served one term as a US senator from New Mexico. Cernan remained a public advocate for returning to the Moon until his death in 2017, and for decades he was known as “the last man on the Moon”.

No one has returned to the Moon since. Robotic missions, including China’s Chang’e 4 landing on the far side in 2019, have continued exploration, and new crewed programmes aim to send astronauts back.

Timeline

• 1970, September: NASA cancels Apollo 18 and 19, after Apollo 20 had been dropped earlier that year.
• 1972, 7 December: Apollo 17 launches at night from Kennedy Space Center; the crew photographs the Blue Marble.
• 1972, 11 December: Cernan and Schmitt land in the Taurus-Littrow valley and begin their first moonwalk.
• 1972, 12 December: The second moonwalk reaches Shorty crater, where the orange soil is found.
• 1972, 13 December: The third moonwalk visits the split boulder at the North Massif.
• 1972, 14 December: Cernan leaves the lunar surface; Challenger lifts off to rejoin America.
• 1972, 17 December: Evans makes a spacewalk on the way home to retrieve camera film.
• 1972, 19 December: The crew splashes down in the Pacific Ocean.

Why it matters

Apollo 17 closed the first age of human exploration of the Moon with its most scientifically productive mission. Its samples and its image of the whole Earth continue to influence science and how people see their planet.