50 years ago, NASA’s final Apollo mission left the Moon — are we ready to return?

“The craters at about 10 to 15 meters in diameter seem to have somewhat more blocky material in their rims but they're not clear-cut blocky rim craters,” Harrison Schmitt, Apollo 17’s Lunar Module Pilot, reported over the radio.

Schmitt was the first and only scientist — a geologist — to walk on the Moon. He later went on to become a senator in his home state of New Mexico.

“And here's one that's probably 50 meters across that has a fair number of blocks in the bottom,” he continued. “Looks like it might have just about gotten down to where the gabbro starts to be abundant again.”

Schmitt was describing craters he observed on the lunar surface during his second moonwalk. (Nearly the entire Apollo 17 mission can be re-experienced in surprising detail through a multimedia project: Apollo 17 in Real-Time.)

But it was Eugene Cernan, commander of the Apollo 17 mission, who took the final steps on the Moon before their departure 50 years ago today on December 16, 1972. He left behind a plaque that reads, “Here man completed his first exploration of the Moon, December 1972, A.D. May the spirit of peace in which we came be reflected in the lives of all mankind.”

Apollo 17 came just three years after Apollo 11 chauffeured Neil Armstrong, Buzz Aldrin, and Michel Collins from Cape Kennedy to the Moon on July 16, 1969. In the three years in between Apollo 11 and Apollo 17, a total of twelve astronauts walked on the Moon. In the 50 years since, humans haven’t made a single visit.

John Logsdon, Professor Emeritus at George Washington University’s Elliott School of International Affairs and founder and long-time director of the University’s Space Policy Institute who also served on NASA’s Columbia Accident Investigation Board, was present at the Apollo 17 mission launch.

“Apollo 17 almost didn’t happen,” Logsdon tells Inverse. “Richard Nixon wanted to cancel one of the latest — Apollo 16 and 17 missions — because he didn't see any need for them. And he’d been spooked by the Apollo 13 accident. He was wary of another accident happening while he was campaigning for president.”

And when the mission finally was cleared for takeoff, its troubles still weren’t over.

“It was delayed,” Logdson says. “It ended up going off at one in the morning. It was like the Artemis I launch. It really lit up the sky, but it was some small glitch during the countdown they could easily address.”

The mission’s delay on the day of lift-off was not the only delay. The scheduled lift-off was pushed back for political purposes.

“Its launch date was moved so that it was after the 1972 election in December so that there was no chance of an accident interrupting or influencing Nixon's re-election,” Logsdon says. He adds that during a discussion in November of 1971, Nixon refused to speak about Apollo 16 or 17 or any missions until after the election.

By then, political support for the Apollo missions had already dwindled. After the Apollo 13 incident, NASA canceled Apollo 18 and 19. The remaining flight crews were also shuffled around.

“But NASA had recruited in the mid-'60s — scientist astronauts — six of them,” Logsdon says, “and none of them had flown. So, the scientific community put a lot of pressure on NASA to fly at least one trained scientist. That person turned out to be Harrison.”

Cernan and Schmitt roamed about 21 miles on the Moon over a period of three days, from December 11 to December 14, 1972. They surveyed the lunar surface, while Command Module Pilot, Richard Evans, remained alone in lunar orbit to coordinate with the others and conduct photographic and visual observations.

Cernan and Schmitt performed three moonwalks. The first included a lunar seismic profiling experiment, where they detonated explosives and measured the seismic activity, giving scientists data to understand more information about the Moon’s subsurface. The second moonwalk started promptly with a message from Mission Control: Richard Wagner’s Ride of the Valkyries.

Geologically, the mission was interested in looking at ancient crustal rocks for evidence of young volcanic activity. It was hugely successful. They collected some 3.7-3.8 million-year-old basalts that formed at depths of 130 to 220 km. Other experiments were a success as well.

Despite the scientific feats of Apollo 17, humans are just now finding their way back to the Moon. Artemis III is set to land on the lunar surface in 2025.

“We went to the Moon in the ‘60s for a very political reason, that reason being that Soviet Union,” Logsdon says. “There was enough momentum behind that effort to keep it going for a few missions after Apollo 11, but the political rationale had pretty well dissipated after we won the race to the Moon.”

The Artemis program represents what Logsdon describes as “remaining momentum.” The United States has been toying with the idea of sending humans back to the Moon since George H. W. Bush in 1989 and George W. Bush in the early 2000s.

“Since then, we've been arguing how to do it, not whether to do it,” Logsdon says. “This is the end product of 20 years of discussion to send people back to the Moon.”

The program has gained and lost support over the years, but now Artemis has arrived.

Artemis is accelerating space exploration as well. It will lay the groundwork for humans to venture deeper into space than ever before — with features like a base camp and a human landing system.

Back in 2012, Cernan wasn’t hopeful that his footsteps would be superceded when he told NPR, “I'd like to be able to shake the hand of that young man or young woman who replaces me in that category, but unfortunately, the way things have gone and the way things are looking for the future, at least the near-term future, that won't happen in my lifetime."

Cernan passed away in 2017, and his footprints, like each human footprint on the Moon, can still be seen today. Perhaps they’ll be spotted by NASA’s Artemis III crew, or by future humans wandering the lunar surface.