In January 2019, China made history as its Chang'e 4 probe touched down on the moon's far side, making it the first spacecraft to have a soft landing on the uncharted region. This year, China returned to the moon's mysterious far side to bring back some souvenirs.
Historical Liftoff
On May 3, the China National Space Administration lifted off the robotic Chang'e 6 lunar exploration mission. It was launched at 5:27 a.m. EDT in Hainan province off a pad at the Wenchang Space Launch Site while riding the massive Long March 5 rocket.
The spacecraft comprises a lunar orbiter, a lander, an ascender, and an Earth-reentry module. If everything goes according to plan, the lander will land inside the Apollo crater, one of the largest impact craters in the Solar System. The crater is also part of the South Pole-Aitken (SPA) basin, which contains ancient rocks that hold clues about the moon's early history and evolution.
While exploring the moon's surface, the Chang'e 6 lander will gather 4.4 pounds (2 kilograms) of lunar dirt and rock. Some of the samples will be scraped from the surface, while others will be drilled from up to 6.5 feet (2 meters) underground. The collected materials will launch aboard the ascender, which will connect with the lunar orbiter.
After that, the samples will be taken to the reentry module, which rides aboard the orbiter. The orbiter will return to Earth while releasing the reentry module for a journey through the Earth's atmosphere. The journey, from the recent launch to the arrival of the samples on Earth, is expected to last 53 days.
The mission architecture of Chang'e 6 is similar to that of Chang'e 5, China's first-ever lunar sample-return mission, which sent material from the near side of the moon in December 2020. This is unsurprising since Chang'6 was designed as a backup to Chang'e 5.
The success of Chang'e 5 made China the third nation to achieve a lunar sample-return mission after the U.S. and the Soviet Union. Apollo astronauts gathered most of the lunar material sent to Earth, bringing 842 pounds (382 kilograms) of the samples between 1969 and 1972.
The Hidden Face of the Moon
The Moon rotates in precisely the same time as it takes to orbit our planet, a phenomenon known as tidal locking. As a result, observers on Earth see only one face of our celestial neighbor, called the near side.
Aside from being more familiar than the far side, the near side is also easier for humanity to explore. This explains why every surface mission, such as NASA's crewed Apollo expedition, targeted that region. However, sending a rover or lander mission to the far side of the Moon could involve challenges in communication since a lunar orbiter might be required to send messages to and from mission control here on Earth.
According to astronomers, there are compelling reasons to explore the far side of the moon up close. It is believed that the materials from early Earth that formed the moon remain unchanged on its far side. This makes the uncharted region an untapped repository of Earth's history inaccessible anywhere else.
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