An article from The Planetary Society written before the lunch gives more information of the mission.

http://www.planetary.org/blogs/guest...satellite.html

China's fourth lunar mission, Chang’e 4, is expected to begin on May 21 with the launch of a Long March 4C rocket from the Xichang Satellite Launch Centre in the southwest of China. The launch will carry a spacecraft named Queqiao, which will serve as a communication relay satellite between Earth and the lunar farside. The name Queqiao means "magpie bridge" in Chinese and comes from a Chinese folk tale, a love story about a flock of magpies that form a bridge crossing the Milky Way once a year to reunite lovers known as the Cowherd and the Weaver Girl, as well as their children.