Artemis 2 Begins Its Return To Earth After Exploring Previously Unseen Areas Of The Far Side Of The Moon

Just as NASA had anticipated, the Orion spacecraft lost contact with Earth on Tuesday at 12:44 a.m. CET, at the start of the sixth day of its mission. “We love you, from the Moon,” said astronaut Victor Glover, minutes before the radio signal was lost. “We’ll see you on the other side,” the mission control center in Houston replied. At 1:25 a.m., the signal was restored, and the live video showed the unprecedented view of a tiny Earth emerging from behind a large Moon, on the opposite side from where it had disappeared a short while earlier. Both resembled crescent moons.

Artemis 2’s journey home began amid that 41-minute period of silence, during which the four astronauts saw parts of the far side of the Moon that no one had ever seen before. Furthermore, at 1:00 a.m., they reached the closest point to the Moon of their entire journey, and two minutes later, they set a new record for the greatest distance from Earth ever achieved by a human at 406,771 kilometers (252,755 miles). Hours earlier, they had already broken the previous record for distance from Earth, which had been held since 1970 by the Apollo 13 astronauts.

Far from being an isolated incident, this period of radio silence is an inevitable consequence of traveling to the Moon. Visiting the Moon requires circling it. And, therefore, venturing to its far side to such an extent that the Earth ends up hidden behind the Moon, making telecommunications impossible. That had happened on all previous lunar missions, but never before had it been accompanied by the scientific milestones now achieved by Artemis 2.

A total eclipse for four

In addition to being able to photograph unexplored areas in detail, the astronauts witnessed a total solar eclipse from space, approximately one hour after regaining communication with Earth. At 2:35 a.m., the Sun began to set behind the Moon, and the astronauts had to put on eclipse glasses, just like anyone else during the partial phase of any solar eclipse. However, this 57-minute total eclipse — much longer than any on Earth — was a very exclusive experience. Only the four members of the Artemis 2 crew were able to see it, thanks to Orion’s specific position as it began its return home. And after a full day dedicated to observing the lunar surface, the spacecraft’s pilot, Victor Glover, remarked during the eclipse: “It’s the strangest and most surreal sight we’ve had today, with the Earth’s glow illuminating almost the entire Moon.”

Although this return of astronauts to the Moon did not involve a lunar landing, it is a mission marked by numerous firsts and records. Its four crew members — Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen — by venturing fully into the far side of the Moon, have become the first people to have a complete view of that lunar hemisphere, although they will only be able to observe 21% of its surface, which is the portion currently illuminated. Due to failures during pre-launch tests, the mission had to be delayed, and launch windows in March — which would have offered much greater visibility of the far side — were missed.

Despite this setback — resulting from the mission finally launching on the afternoon of April 1 — the four astronauts have been the first to set eyes on many sites of scientific interest on the far side. “It’s a 3D view combined with personal experience, which will give us a much better understanding than many images obtained by robotic probes [which have already photographed all those areas of the moon],” said Lori Glaze, NASA’s associate administrator, during the agency’s final daily briefing before the lunar flyby.

This highlight of the mission, during which the Orion spacecraft orbited the Moon, began on Monday at 8:45 p.m. CET and lasted 6 hours and 35 minutes. Since they are on a free-return trajectory, which requires no maneuvers to turn around and return to Earth, the astronauts were able to devote all that time to observing and photographing the lunar surface, focusing on a total of 35 lunar sites selected by the mission’s science team, with whom they were in real-time contact. They worked in pairs, taking turns: while one was photographing and the other observing and describing what they saw, the rest of the crew prepared the next section and communicated with NASA’s mission control center in Houston, Texas.

The colors of the Moon

Seeing the colors — greens and browns, beyond the gray we see from Earth — shadows, and textures of the lunar surface in person moved all four astronauts. Mission specialist Christina Koch explained it this way: “I just had an overwhelming sense of being moved by looking at the Moon; it lasted just a second or two, and I actually couldn’t even make it happen again. But something just drew me in suddenly to the lunar landscape, and it became real. The truth is, the Moon really is its own body in the universe — it’s not just a poster in the sky. It is a real place,” Koch said after finishing an observation session dedicated to the Mare Orientale.

That was one of the mission’s major scientific objectives: a lunar mare with a gigantic impact crater at its center. On the Moon, Orientale looks like a bull’s-eye; because it lies between the near side and the far side, no human had ever been able to observe it in its entirety — and directly. The astronauts on the Apollo missions flew so low while orbiting the Moon — at an altitude of just 110 kilometers (68 miles) — that when they crossed over to the far side, they could only see small portions of its surface; and, furthermore, as they were traveling to the visible side, at that time the far side was almost entirely in darkness.

During the middle part of the flyby — those 41 minutes without communication — the spacecraft faced only the Moon’s far side. Then, at a minimum altitude of 6,545 kilometers (4,067 miles) above the Moon’s surface, the astronauts looked out through the windows of the Orion and saw the Moon as large as a basketball held at arm’s length. They were seeing it in three dimensions — with all its relief and shadows — and over 50 times larger than the rest of humanity sees it from Earth, or from the International Space Station.

In the sky above our planet and its surroundings, the Moon always appears about the size of a pea. Only 24 people in all of history had seen it larger with their own eyes, without the aid of binoculars or telescopes: the crew members of the nine Apollo missions who, between 1968 and 1972, traveled to the lunar environment. All were men, Americans, and white. Now, four more astronauts — including a woman, a Black man, and a Canadian — have joined that select club of people who have seen the Moon up close and ventured to its far side.

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