Why go to the same planet where so many missions have already gone? Well, because there's more! What about the Dark Side? Well, first it should be noted that the term "Dark side" comes from a rock song. A better term for the part of the moon not normally visible from Earth is the far side.
Because tidal forces on Earth have slowed down the moon's rotation, this far side is almost never glimpsed from Earth. It receives just as much sunlight as the front facing part of the moon, but it receives no reflected sunlight from Earth, or "earthshine." When spacecraft travel around to the far side, communications are blocked, or "go dark."
In 1959 a Russian unmanned space probe was the first craft to observe the this part of the moon and in 1968, Apollo 8 astronauts observed it during their orbit, however it has never been explored on the ground. Now China has entered the game and will be launching the first mission to the far side of the moon, entitled "Chang'e-4 in honor of the Chinese moon goddess Chang'e.
The mission will be part of China's space program CLEP (Chinese Lunar Exploration Program) and will attempt to land a probe and a rover on the surface of the far side.
"We are currently discussing the next moon landing site for Chang'e 4," Chief lunar exploration engineer Wu Weiren told the China Central Television network. "We probably will choose a site that is more difficult to land and more technically challenging. Other countries have chosen to land on the near side of the moon. Our next move probably will see some spacecraft land on the far side of the moon."
A similar probe, also carrying a rover was launched in 2013. The Chang'e 3 carried the now immobile Jade Rabbit rover to the moon's surface. It can still send back data even though it no longer travels the surface. The Chang'e 4 will have an entirely different mission however, due to the far side's geography.
The far side of the moon is dominated by the South Pole-Aitken basin, a huge impact crater, indeed one of the largest of its kind in our solar system. It is approximately 1600 miles in diameter and 8 miles deep. In images beamed back from space it appears as a large dark area in the southern hemisphere of the imposing far side.
Scientists hope that by landing the Chang'e 4 in this area they can learn much about the moon's interior by studying the rocks, soil and mountainous regions around the crater. This would yield unprecendented information on what the moon is composed of and where this material may have originated.
In addition to the science gained from the exploration of the far side surface, this part of the moon is an ideal location for radio telescopes to be place. Since this part of the moon faces away from Earth's interfering transmissions and atmosphere, it's possible these telescopes could reach new areas of space not examined before.
Of course there is also the issue of being first. In the space race, being first matters a great deal. The iconic images of Neil Armstrong placing mankind's first footsteps on the Moon are recognized across the globe as one of the most significant events of the 20th century. If the Chinese team is successful in landing a probe on the far side of the moon, they might be an even larger part of lunar history. Not only has there never been a landing on the far side surface, such a mission has never even been attempted because of the extreme difficulty involved in such an undertaking.
In an odd numerical discrepancy, Chang'e 4 will launch in 2020, after the Chang'e 5 mission in heads to the moon in 2017. This is because Chang'e 4 was originally a back up to Chang'e 3, but regardless of the numerology, China has made it clear that their goal is to head to the far side of the moon, keeping its eyes on the prize of being the first to go into that heart of darkness.
Source: NASA, Wikipedia, Space Daily.