China is preparing to write one of the most important chapters in its history. Three weeks after the successful launch of the Xichang Chinese space base on December 7, the Chang exploration module will attempt to land on the dark side of the moon this Thursday, January 3. China is discrete in this area. Neither the day nor the exact location of the moon's landing was communicated. According to experts, it should intervene in the night, probably around one in the morning (Paris time), for the first morning in Beijing.
This mission is first in the world. Neither the United States nor Russia have yet explored the dark side of the moon. This unknown part of our natural satellite was photographed only by satellites (starting with the Russian mission Luna 3, in 1959) that allowed us to map it. But no car has ever touched the ground and many mysteries have yet to be clarified.
Chang & # 39; and 4, named after the moon goddess in Chinese mythology, embarks on board a rover and many tools. If everything goes as planned, the probe will be responsible provide radio astronomy data isstudy the resources of the lunar soil to determine whether the establishment of a permanent human base is feasible by 2030.
No direct communication
The main difficulty of the rover will be to communicate with the Earth. As the Moon rotates synchronously around the Earth and to itself, its hidden face is always pointing towards the opposite of our planet and no direct radio communication is possible. All operations must therefore be carried out independently.
Although the technique is feasible (this is also the way NASA rovers landed on Mars, due to latency of communications), this is a great record for Chinese teams. The only missions they have sent into space to date have been "simple" satellite orbits or rover landings on the visible side.
To communicate with the rover and relay the data back to Earth, scientists will use the Queqiao satellite, launched last May. Now he is in a position that allows him to see both the Earth and the other side of the Moon and act as a relay between the two.
Scientists expect to make great discoveries on the far side of the moon. For example, Chang & # 4 could explain why this face is so different from the side that is visible.
It will also reach the goal of Chang & # 39; and 4 on the lunar plane biology experiments. It will carry mulberry bombyx eggs (which give silkworms), potato seeds (which managed to grow in the reduced gravity of the International Space Station) and Lady Cress (a resistant plant used in the laboratory).
The hatching and germination will be filmed by a camera and analyzed by teams from Earth. The different factors necessary for plant growth, such as light, temperature, humidity and nutrients must be adjusted.
The other difficulty that the rover will encounter will be the challenge of climate. The illuminated side knows that temperatures rise 150 ° Cwhile in the shadow they descend to -150 ° Cor -250 ° C where the sun does not reach, in deep crevasses. Extreme temperatures to which Chang & # 39; and 4 and his plant samples will have to deal.
A long-term mission
Begun in 2000, this space program consists of five phases. The first lunar probe, Chang & # 1; and 1, was sent in 2007. It was then followed by its double Chang & # 39; and 2 in 2010, then Chang & # 39; and 3 in 2013. This last landed on the surface lunar (visible side) in 2013, not far from Mare Imbrium, in the middle of the equatorial area. These different probes allowed to build a three-dimensional map of the surface of the Moon, as well as analyzing its composition.
Last November, the Long March-4C rocket sent the lunar orbit Queqaio, a telecommunications satellite that will allow Chang & # 4; and 4 to communicate with the Earth when it is on the other side of the star .
Chang & # 39; and 5, which is the last stage, will be sent in 2019: the rover that will land on the visible side, in the Ocean of Storms, and will bring a handful of two kilos of lunar rock that will have then for the mission to bring back to Earth.