The Chang’e-4 lunar probe will undertake the first ever soft landing on the far side of the Moon. However, direct communication with the far side of the Moon is not possible, which is one of the many challenges of the Chang’e-4 lunar probe mission.
The relay satellite, named Queqiao, will be responsible for transmitting signals between the Earth station and the Chang’e-4 lander and rover.
Relay satellites are communication satellites that can provide data relay and monitoring services for spacecraft, improving the efficiency and emergency capability of various satellites. They also enable data from earth resource and environmental satellites to be transmitted in real time.
The Chang’e-4 probe will also carry scientific payloads for four countries, including the Netherlands and Germany.
The Queqiao satellite will relay signals between the rover and our planet. It will be stationed at Lagrange Point 2.
Chang’e 1 and 2 orbited the Moon, and Chang’e 3 was a lunar lander and rover on the Moon’s near side.
China plans to return a sample from the Moon with Chang’e 5 which they plan to launch in 2019.