One of the most fundamental questions that space scientists are still striving to answer is: How was the Moon formed?
When the Chang’e-4 mission landed on the Von Karman crater on January 3, 2019, China became the first and only country to land on the far side of the Moon—the side that always faces away from Earth. Now, China is sending another mission to that remote area, and this time, their goal is to bring back the first samples from the far side of the Moon to Earth.
No True “Dark Side”
The Chang’e-6 mission is expected to spend 53 days exploring the South Pole-Aitken basin (on the far side of the Moon) to study geological and topographical features as well as to collect samples from various locations on the crater.
Li Chunlai, Deputy Director of Design at the China National Space Administration, stated: “The far side of the Moon is very different from the near side. Essentially, the far side consists of the ancient lunar crust and highlands, so there are many scientific questions that need to be addressed there.”
The term “dark side” of the Moon is sometimes referred to as the “far side,” which experts believe is used incorrectly for several reasons.
Exploring the Moon has always been a goal for space scientists. (Image: NASA).
Although the far side of the Moon may seem dark from our perspective, it also experiences lunar day and night just like the near side and even receives more sunlight. According to NASA, a day on the Moon lasts over 29 Earth days, while night lasts about two weeks.
Two professors, Renu Malhotra and Louise Foucar, researchers at the University of Arizona in Tucson, stated: “Humans have always been curious about what lies on the other side of the mountain and the part we cannot see, which is a kind of driving psychology.”
Some spacecraft, including NASA’s Lunar Reconnaissance Orbiter, continuously orbit and photograph the lunar surface, helping to illuminate the Moon’s mysteries. The Yutu-2, a lunar rover launched by Chang’e-4 in 2019, has also explored rock debris and dust scattered across the Von Karman crater, located in the South Pole-Aitken basin.
However, bringing samples back to Earth will allow the latest and most sensitive technologies to analyze lunar rocks and dust, potentially revealing how the Moon was formed and why the far side is different from the near side.
The Mysteries of the Far Side
Despite orbital data and the samples collected during the six Apollo missions over the years, scientists are still trying to answer important questions about the Moon.
Noah Petro, a member of NASA’s projects for both the Lunar Reconnaissance Orbiter and Artemis III, which aims to send humans to the Moon for the first time since 1972, stated: “The reason the far side is so intriguing is that it is so different from the side of the Moon that we see. Throughout human history, we have looked up at the same surface, the same side of the Moon.”
However, in 1959, the Soviet Union sent a probe that flew over the far side of the Moon and captured the first images of it for humanity. “We saw this hemisphere as completely different: not covered by vast volcanic lava flows, pockmarked with craters and having a thicker crust,” Petro said.
According to Petro, collecting samples through robotic missions and sending humans close to the transition point between the two lunar regions at the South Pole through the Artemis program will help to tell a fuller story about the Moon’s history that we currently lack.
Professor Malhotra noted that while scientists understand why one side of the Moon always faces Earth, they still do not know why that side is permanently oriented toward our planet. It may be related to the Moon’s asymmetry. “There is some asymmetry between the two sides of the Moon. What exactly caused these asymmetries? What are these asymmetries really? We have very little understanding of that. It’s a big scientific question.”
Brett Denevi, a planetary geologist at the Johns Hopkins University Applied Physics Laboratory, noted that orbital data also reveals that the near side has a thinner crust and more volcanic deposits, but the reason for this remains beyond researchers’ understanding.
Chang’e-6 is just one mission aimed at the far side of the Moon, as NASA also plans to send robotic missions there. Denevi has helped design the mission concept for a lunar explorer named Endurance, which will embark on a long journey through the South Pole-Aitken basin to gather data and samples before bringing them to Artemis’s landing site near the Moon’s South Pole. Later, astronauts will be able to study the samples and determine which ones will return to Earth.
Nasa scientist Petro believes: “When impacts occur on the Moon, they also occur simultaneously on Earth. Therefore, studying these ancient events on the Moon means we are also learning a bit about what is happening on Earth.”
According to Professor Malhotra, the exploration of the South Pole-Aitken basin could be the starting point for answering numerous mysteries about the Moon. While researchers believe they have an idea of when the crater formed—likely 4.3 to 4.4 billion years ago—collecting rock samples could provide a more accurate age.
