While the world’s astronomers watch images and data trickle in from NASA’s New Horizon’s flyby of the distant body nicknamed Ultima Thule, China is poised to to be the first country to land spacecraft on the far side of the moon. The landing could come as soon as Jan. 3 in the early morning GMT.
China’s probe, named Chang’e 4, which is currently orbiting the moon, will release a rover and lander combination that will be the first craft to successfully reach the side of the moon largely obstructed from observation from Earth. The mission launched Dec. 7.
The rover and lander will be able to gather information about the composition and formation of the far side, which has a distinctly different appearance from the near side. This includes insight into how much helium-3 is present, an isotope (or variant) of helium that can be used as spacecraft fuel. While scarce on Earth, previous observations of the far side from crewed and person-free craft make it likely a large amount is present.
The moon orbits Earth at the same speed at which it rotates around its axis. As a result, the moon always presents the same “near” face towards Earth, no matter from what vantage on Earth the moon is observed. While the far side is sometimes called the “dark” side, that’s relative to our lack of knowledge about it: The phases of the moon seen from Earths still occur, in reverse, on the opposite side.
Chang’e 4 and some future missions are paired with a communications relay satellite named Queqiao, launched in May 2018 into a unique, largely stable orbital point between the Earth and moon that allows it to have a “view” of the far side of the moon and the Earth at the same time. Radio waves can’t reach around the moon from the far side without some kind of relay system, and Queqiao provides the missing link.
The Chang’e series of Chinese spacecraft is named for a moon goddess, but Queqiao means “magpie bridge,” from a myth about those birds forming a path to the moon.
