China launched the Chang’e-4 lunar probe to explore the far side of the moon on Dec 8. Xinhua
As our closest neighbor in space, the moon has been the subject of popular myths, songs and poems since ancient times. And it has no less fascinated scientists.
But even after centuries of research many questions remain to be answered about Earth’s only satellite.
Perhaps the Chang’e-4 lunar probe will be able to reveal more of its secrets. On Dec 8, the probe lifted off from Xichang Satellite Launch Center in Sichuan province. It is the first probe to the far side of moon.
The Earth’s gravity slows the moon’s rotation, matching it to the speed of its orbit. Thus, the far side of the moon is always dark and has never been seen.
It’s this sense of the unknown that makes the far side of the moon such an interesting place for scientific and space exploration. Long exposed to solar winds, the far side may have the special soil and minerals in its upper mantle.
For this reason, Chang’e-4 will study the effect of solar winds on the lunar surface and any minerals found beneath the spacecraft. Chang’e-4 is also carrying flower seeds and potato and silkworm eggs to see whether life is possible on the moon. If it is, then the moon will become a more likely destination for space travel in the future.
However, due to communication problems, exploration of the dark side will not be easy.
As the far side is blocked off from us, radio noise coming off Earth is also blocked. This is why China launched the relay satellite Queqiao in May – so that communication between Earth and the probe could go ahead.
由于月球背面背对着我们，来自地球的无线电噪声也因此被屏蔽。这便是中国于今年5月发射中继卫星鹊桥号的原因 —— 如此一来，地球与探测器之间的通讯能够继续进行下去。
Power supply will also be a challenge to the mission.
Chang’e-4 gets energy from the sun through its solar panels. However, a lunar day has the length of 28 Earth days. This means that the probe will need to orbit the moon for over 20 days to be in a position to be able to land in moon daylight and so use its solar panels.
According to Xinhua, if everything goes well, the satellite will land on the far side on Jan 2.
The New York Times described the journey as “groundbreaking”, and wrote that it will “give clues to the history and development of the moon”.