A Chinese space probe entered a planned orbit Sunday to prepare for the first-ever soft landing on the dark side of the moon, authorities said.
This is the first time an attempt is made to explore the far side of the moon. Since the moon's revolution cycle is the same as its rotation cycle, the same side always faces Earth.
The other face, most of which cannot be seen from Earth, is called the far side or "dark side" of the moon, not because it is dark, but because most of it is uncharted.
The Chang'e-4 probe has entered an elliptical lunar orbit, with the perilune at about 15 km and the apolune at about 100 km, the China National Space Administration (CNSA) said.
Chang'e-4 entered the lunar orbit on December 12.
The control centre will choose a proper time to land the probe on the far side of the moon, according to CNSA.
The Chang'e-4 probe, including a lander and a rover, was launched by a Long March-3B carrier rocket on December 8 from the Xichang Satellite Launch Centre in Sichuan province.
The Chang'e-4 lunar probe will land on the Aitken Basin of the lunar south pole region on the far side of the moon, which is a hot spot for scientific and space exploration.
Direct communication with the far side of the moon, however, is not possible, which is one of the many challenges for the Chang'e-4 lunar probe mission.
China launched a relay satellite, named Queqiao, in May, to set up a communication link between the Earth and Chang'e-4 lunar probe.
The Chang'e-4 mission will be a key step in revealing the moon's mysterious side, a report by state-run Xinhua news agency said.
The scientific tasks of the Chang'e-4 mission include low-frequency radio astronomical observation, surveying the terrain and landforms, detecting the mineral composition and shallow lunar surface structure, and measuring the neutron radiation and neutral atoms to study the environment on the far side of the moon, according to CNSA.
Chang'e-4 mission has four scientific payloads developed by scientists from the Netherlands, Germany, Sweden and Saudi Arabia.