Context

China has launched Chang’e-4, a first probe ever to explore the dark side of the Moon.

About

Mission:

• A Long March-3B rocket, carrying the probe including a lander and a rover, blasted off from the Xichang Satellite Launch Center in southwest China's Sichuan Province.
• The exploration will gain first-hand information about the terrain and lunar soil components and other scientific data, which will help enrich human understanding of the moon and the universe.

Dark Side:

• Since the moon's revolution cycle is the same as its rotation cycle, the same side always faces the earth. The other face, most of which cannot be seen from earth, is called the far side or dark side, not because it's dark, but because most of it remains unknown.
• Nobody had ever seen the far side of the moon before the Soviet Union launched the Luna 3 probe in 1959, which was the first-ever mission to photograph the far side.
• The United States Apollo 8 mission sent three astronauts to fly around the moon in 1968, the first time that people saw the moon's far side with their own eyes.
• Remote-sensing images show the far side is thickly dotted with impact craters and has much fewer lunar mares than the near side. Scientists infer that the lunar crust on the far side is much thicker than the near side.
• The far side is such a place, as the body of the moon shields against radio interference from the earth. From there, astronomers can study the origins and evolution of stars and galaxies, peering into the dawn of the universe.
• Gravity balances the orbital motion of the satellite and makes it very fuel-efficient.

China’s Chang’e mission:

• Named after Chinese moon goddess "Chang'e", China's lunar exploration program, which began in 2004, includes orbiting and landing on the moon, and bringing samples back to earth.
• The country's first lunar probe, Chang'e-1, was launched in 2007, making China the fifth country to develop and launch a lunar probe on its own.
• Chang'e-2, launched in 2010, created a full lunar map showing the details of the proposed landing site of Chang'e-3.

Chang'e-3, launched in 2013, was the first Chinese spacecraft to soft-land on and explore an extraterrestrial object. The scientific instruments on its lander are still operating, making Chang'e-3 the longest working man-made probe on the moon.