China plans to launch a data relay satellite into Halo orbit near the Lagrange point L2 of the Earth-moon system at the end of May or in early June of 2018 and furthermore will send the Chang'e-4 probe to the dark side of the moon about half a year later to explore the South Pole-Aitken basin, said Liu Tongjie, deputy chief of China's lunar exploration.

After the launch, a data relay satellite will ensure communication between Earth and the lunar probe during an expedition to the far side of the moon, said Liu.

Due to gravitational forces, this part of the moon is not visible to Earth and has never been explored by humans. So the data relay satellite will be launched six months before the probe.

Earth can contact Chang’e-4 with the help of a “communication station” at the Lagrange point L2 of the Earth-moon system, 80,000 kilometers away from the moon.

The South Pole-Aitken basin is the largest known impact crater in the solar system at nearly 2,500 kilometers wide and 13 kilometers deep.

The unique environmental conditions and complex geological history has long been a puzzle, a hot issue and a point of focus for academic and engineering circles.

Currently the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) have been developing plans to explore the dark side of the moon. The ESA has put forward detailed proposals of exploration and plans to implement the plan in 2025.