A spacecraft segment of China’s Chang’e 6 mission successfully landed on the moon today, carrying samples collected from the far side of the moon in an unprecedented event, Chinese state media reported.

The ascender, which carries samples collected as part of the Chang’e 6 space mission, “raised from the ground” of the dark side of the Moon, an achievement “unprecedented in the human history of lunar exploration,” the agency said. official news agency New China.

Chang’e 6 touched down on Sunday in the huge South Pole-Aitken Basin, one of the largest known impact craters in our solar system, on the side of the moon not visible from Earth, New China explained, citing the Chinese space service.

The mission, scheduled for 53 days, began on May 3, with the main purpose of collecting samples from the side of the Moon that is rarely explored. The vehicle for this purpose was equipped with a drill, to collect samples from the lunar subsoil, as well as a robotic arm, to take samples from the surface.

After the samples were collected, China’s “national flag” was unfurled and placed “on the invisible side of the Moon for the first time,” New China added.

Scientists believe the dark side of the Moon—so called because it’s invisible from Earth, not because the Sun’s rays don’t reach it—is promising for research because the craters there haven’t been covered by ancient lava flows as much as those of the side that is closest and visible.

The samples from the far side of the moon are expected to help better understand how Earth’s natural satellite formed.