When the Chang’e-4 mission landed in Von Kármán 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 the far side, and this time, its goal is to return the first samples from the “far side” of the Moon to Earth.
The Chang’e-6 mission, launched on Friday (3), is scheduled to spend 53 days exploring the South Pole-Aitken basin to study its geology and topography, in addition to collecting samples from different points in the crater.
The South Pole-Aitken basin is believed to be the oldest and largest crater on the Moon, covering almost a quarter of the lunar surface, with a diameter of approximately 2,500 kilometers. The impact crater is more than 8 kilometers deep.
Scientists hope that returning the samples to Earth will help answer lingering questions about the intriguing far side, which has not been studied as deeply as the near side, as well as confirm the origin of the Moon.
“The far side of the Moon is very different from the near side,” said Li Chunlai, deputy chief designer at the China National Space Administration. “The far one is mostly ancient lunar crust and highlands, so there are a lot of scientific questions to be answered there.”
No true ‘dark side’
During a NASA budget hearing on April 17, Congressman David Trone asked NASA administrator Bill Nelson why China was sending a mission to the “back side” of the Moon. .
“They are going to land on the far side of the Moon, which is the side that is always in darkness,” Nelson responded. “We’re not planning on going there.”
The far side of the Moon has sometimes been called the “dark side of the Moon,” largely in reference to Pink Floyd’s 1973 album of the same name.
But the phrase is a bit misleading for a few reasons, according to experts.
Although the far side of the Moon may appear dark from our perspective, it experiences a lunar day and lunar night just like the near side, and receives plenty of illumination. A lunar day lasts just over 29 days, while the lunar night lasts about two weeks, according to NASA.
The same side always faces the Earth because the Moon takes the same time to complete an orbit around the Earth and rotate around its axis: about 27 days.
Additionally, the far side of the Moon has been more difficult to study, which has led to the nickname “dark side” and created an air of mystery.
“Humans always want to know what’s on the other side of the mountain and the part you can’t see, so this is kind of a psychological motivation,” said Renu Malhotra, Louise Foucar Marshall Professor of Scientific Research and Regents’ Professor of Planetary Sciences at the University of Arizona in Tucson. “Of course, we have sent space probes that have orbited the Moon and we have images, so in a sense it is less mysterious than before.”
Several spacecraft, including NASA’s Lunar Reconnaissance Orbiter that constantly circles and takes images of the lunar surface, have helped clarify facts about the Moon.
Yutu-2, a lunar rover launched by Chang’e-4 in 2019, also explored loose deposits of pulverized rocks and dust covering the floor of Von Kármán crater, located within the larger South Pole-Aitken basin.
But returning samples to Earth would allow newer, more sensitive technology to analyze lunar rocks and dust, potentially revealing how the Moon formed and why its far side is so different from the near side.
Far Side Mysteries
Despite years of orbital data and samples collected during six of the Apollo missions, scientists are still trying to answer key questions about the Moon.
“The reason the far side is so fascinating is because it is so different from the side of the Moon that we see, the near side,” said Noah Petro, NASA project scientist for both the Lunar Reconnaissance Orbiter and the Artemis mission. III, which aims to land humans on the Moon for the first time since 1972. “For all of human history, humans have been able to look up and see the same surface, the same side of the Moon.”
But in 1959, the Soviet Union sent a probe to fly around the far side of the Moon and captured humanity’s first images of it.
“We saw this completely different hemisphere: not covered by large volcanic lava flows, marked by craters, a thicker crust. That tells a different story from the near side,” Petro said.
See photos of the April 2024 solar eclipse
-
1 in 11
Total solar eclipse seen using composite of 9 images taken from Mazatlán, Mexico
Credit: Hector Vivas/Getty Images -
two in 11
Partial eclipse on April 8, 2024 in Fort Worth, Texas, United States
Credit: Ron Jenkins/Getty Images -
3 in 11
Partial eclipse on April 8, 2024 in Fort Worth, Texas, United States
Credit: Ron Jenkins/Getty Images -
4 in 11
Effect of the diamond ring during the total solar eclipse on April 8, 2024 seen from Fort Worth, Texas, United States
Credit: Ron Jenkins/Getty Images -
5 in 11
Total eclipse of April 8, 2024 seen from Mazatlan, Mexico
Credit: Hector Vivas/Getty Images -
6 in 11
Total eclipse seen from Mazatlán, Mexico, on April 8, 2024
Credit: Hector Vivas/Getty Images -
7 in 11
Moon completely covering the Sun seen from Brady, Texas, United States
Credit: Brandon Bell/Getty Images -
8 in 11
Total solar eclipse seen before the game between the Cleveland Guardians and Chicago White Sox on April 8, 2024 in Cleveland, Ohio, in the United States
Credit: Mike Lawrie/Getty Images -
9 in 11
Audience watches the partial solar eclipse on April 8, 2024 from Rockefeller Center, in New York, United States
Credit: Michael M. Santiago/Getty Images -
10 in 11
Total solar eclipse on April 8, 2024 seen from Niagara Falls, New York, United States
Credit: Adam Gray/Getty Images -
11 in 11
Audience observing the total solar eclipse on the campus of Southern Illinois University, in the United States, on April 8, 2024
Credit: Scott Olson/Getty Images
Returning samples with robotic missions and landing humans near the transition between the two lunar regions at the south pole through the Artemis program “will help tell this fuller story of lunar history that we are lacking right now,” he said.
While scientists understand why one side of the Moon always faces Earth, they don’t know why that particular side permanently faces our planet. But that could have something to do with the Moon being asymmetrical, Malhotra said.
“There is some asymmetry between the side that is facing us and the other side,” she said. “What exactly caused these asymmetries? What really are these asymmetries? We have little understanding of this. That’s a big scientific question.”
Orbital data also revealed that the near side has a thinner crust and more volcanic deposits, but answers to why this is so have eluded researchers, said Brett Denevi, a planetary geologist at Johns Hopkins University’s Applied Physics Laboratory.
“It has a different kind of geochemical composition with some strange elements that produce extra heat. There are many models to explain why the near side is different from the far side, but we don’t have the data yet,” Denevi said. “So going to the far side, getting samples and doing different types of geophysical measurements is really important to solving this very old mystery.”
Chang’e-6 is just one of the missions heading to the far side of the Moon, as NASA also has plans to send robotic missions there.
Denevi helped design a mission concept for a lunar rover called Endurance, which will undertake a long journey through the South Pole-Aitken basin to collect data and samples before delivering them to the Artemis program landing sites near the lunar south pole. . Then, astronauts can study the samples and determine which ones should be returned to Earth.
Cracking the lunar code
One of the most fundamental questions scientists have tried to answer is how the Moon formed. The prevailing theory is that some kind of object collided with Earth early in its history, and a huge chunk that was flung off our planet formed the Moon.
Scientists also want to know how the Moon’s original crust formed. Volcanic flows created dark spots on the Moon, while the lighter parts of the surface represent the satellite’s primordial crust.
“We believe that at some point the Moon was completely molten, and it was this magma ocean, and as that solidified, the minerals floated to the top of this ocean, and that’s the clearest landscape we can see today,” Denevi said. . “Getting to the large tracts of primeval terrain on the far side is just one of the goals.”
Meanwhile, studying the impact craters that litter the lunar surface provides a story of how things moved during the early days of the solar system, at a critical time when life was beginning to form on Earth, Denevi said.
“While impacts were happening on the Moon, impacts were happening on Earth at the same time,” Petro said. “And so whenever we look at these ancient events on the Moon, we’re learning a little bit about what’s happening on Earth as well.”
Visiting the South Pole-Aitken basin could be the beginning of solving a multitude of lunar mysteries, Malhotra said. Although researchers believe they have an idea of when the crater formed, perhaps 4.3 billion to 4.4 billion years ago, collecting rock samples could provide a definitive age.
“Many scientists are sure that if we figure out the age of this depression,” she said, “it will unlock all kinds of mysteries about the history of the Moon.”
Share:
