China's rover to Dark side of moon. Know every thing related to this.

China has launched the world’s first lander and rover to far side of the moon, the Chang’e-4 lunar probe mission.

About Chang'e-4

• China has launched the Chang'e-4 lunar probe missionon board Long March 3B rocket from the southwestern Xichang launch centre X in Sichuan, south-west China.
• The Chang’e-4 involves two missions namely a relay satellite, Queqiao and lander-rover satellite.
• In May 2018 China launched the Chang’e-4 relay satellite, Queqiao which is used to communicate between the rover on the far side of the lunar surface and earth.
• Chang'e-4 is the first ever probe to land on and explore the far side of the moon. 
• Chang’e-4 is a lander-rover combination which is set to explore both above and below the lunar surface.
• Chang'e-4 will land its rover in the Aitken Basin’s Von Karman crater in the South Pole region. 
• Von Karman crater is the largest crater in our solar system.
• Chang’e-4 will also conduct the first radio astronomy experiments from the far side of the Moon.

Significance

• This will be the first ever mission to the unchartered territory of far side of the moon.
• Unlike the near side of the moon the far side is mountainous and rugged.
• The moon’s far side has a different composition and thus the probe will help characterise the geology and the composition of rock and soil in the far side of the moon.

 Relay Satellite Queqiao

• A major challenge for such a mission is communicating with the robotic lander on the far side.
• This is because the far side of the moon always points away from earth and is not in "line of sight" for transmission of signals. 
• Thus China launched a relay satellite called Queqiao in May 2018.
• The Queqiao relay satellite in the moon's orbit can relay data and commands between the lander and earth. 

Why do we see only one side of the moon?

• We always see the same side of the moon as a result of the Moon’s synchronous rotation.
• It takes precisely the same amount of time for the Moon to rotate on its axis as it does to complete one orbit around the Earth.