A Long March 5 rocket took off from the Wenchang Space Launch Site in Hainan province on May 3, 2024. After flying for about 37 minutes, it successfully placed the Chang’e 6 robotic lunar probe (月球探测器) into an Earth-moon transfer trajectory (转移轨道). Several days later the probe was programmed to land on the moon’s far side and started its tasks, which would last about 53 days.

This is the world’s first try to bring samples (样本) from the moon’s far side. For China, it’s the second sample-return moon journey. Chang’e 5 successfully brought samples from the moon in the winter of 2020. Up to now, 10 moon sample-return tasks have been carried out by the United States, the former Soviet Union (前苏联) and China, but all these samples were collected from the moon’s near side.

The moon’s far side has always been a subject of scientific wonder because of its many mysteries. It’s facing away from Earth and it can never be seen from Earth. It was once called the “dark side of the moon” even though it receives just as much sunlight as the near side.

Chinese researchers have found that the soil on the far side is much thicker than that on the near side, but they haven’t found out the reason. Samples brought back by Chang’e 5 have helped scientists find that there were volcanic (火山的) activities on the near side around 2 billion years ago. Some scientists thought maybe volcanoes became inactive on the far side about 4 billion years ago. Is it true? Samples from the far side will allow them to know the answer.

“Comparing the make-up of the far side samples from Chang’e 6 with those collected from the near side will be of great scientific value to the international community,” said Martin Sweeting, a famous professor of space engineering.