BEIJING, Dec. 20 (Xinhua) -- China will solicit 20,000 messages which will be sent into space by a relay satellite for the Chang'e-4 lunar probe, according to China's Lunar and Deep Space Exploration Center.

The relay satellite will be launched in the first half of 2018 and Chang'e-4 lunar probe in the latter half of next year, according to the center affiliated with the China National Space Administration.

People all over the world can follow the WeChat account "slecbj" to submit their wishes from Dec. 19, 2017, to March 6, 2018.

The Chang'e-4 lunar probe will undertake the first ever soft landing on the far side of the moon and conduct in situ and roving detection and relay communication at the Earth-Moon Lagrangian 2 (L2) point, according to the center.

People on Earth cannot directly communicate with the far side of the moon, which is one of the difficulties for the Chang'e-4 lunar probe mission.

A relay satellite at the Earth-Moon L2 point, where gravity allows it to maintain a stable position between Earth and the moon, can redirect communication from Earth to the far side of the moon, solving the difficulty at a low cost.