The Chang’e-4 spacecraft has completed payload integration and space environment testing. It will launch in December atop a Long March 3B rocket from the Xichang Satellite Launch Center, in the southwest part of the country—the same site used for China’s five previous lunar-related missions.

Chang’e-4 will target the South Pole-Aitken (SPA) basin on the lunar far side. A landing in the SPA basin is one of lunar researchers’ top priorities, because it's the oldest lunar basin and may contain material on its floor that came from the lunar mantle. Being the first-ever landing on the farside, the mission is likely to gain a lot of attention and bring prestige to China’s space program, if all goes according to plan.

Chang’e-4 background

Chang’e-4 was manufactured at the same time as Chang’e-3, to provide a backup in case of mission failure. Chang’e-3 landed in Mare Imbrium in late 2013 and deployed a little rover named Yutu.

Following that success—which was the first lunar soft-landing by any nation since 1976—Chang’e-4 has been repurposed for this new, audacious mission.

Because the Moon is tidally locked to the Earth, we never see its far side from the ground. This means the mission requires a relay satellite to facilitate communications between Earth-based ground stations and the spacecraft. The relay satellite, named Queqiao, launched on May 20 and entered orbit around the second Earth-Moon Lagrange point on June 14.

According to Wednesday’s press event, the satellite and its 4.2-meter antenna are functioning well and are ready to serve as the ‘bridge’ between the Chang’e-4 and the Earth. You should read Luyuan Xu’s blog on the relay satellite, which also details the secondary science objective of the Netherlands-China Low-Frequency Explorer (NCLE), the folklore origins of the Queqiao satellite, and more.