In a historic first in space research, China has safely landed a probe Chang’e 4 on the far side of the lunar surface. Spacecraft had flown past it before but none had actually landed on it.
A major problem is that because that side never faces the Earth, no direct communication is possible. China solved that problem by putting another satellite in orbit around the Moon that can relay the signals between the Earth and the Moon.
But during the actual landing the craft was out of communication with ground control and landed on its own, hitting its target exactly.
During the final phases of the approach, however, Chang’e 4 was on its own and could not be operated remotely. Starting from an altitude of 15km, the craft used a rocket booster to decelerate and a high-tech camera and laser measurements to avoid boulders and ditches.
Chang’e 4 targeted the Von Karman crater, which was predicted to have a smooth volcanic floor and which sits within the great Aitken basin.
“This is a great technological accomplishment as it was out of sight of Earth, so signals are relayed back by their orbiter, and most of the landing was actually done autonomously in difficult terrain,” said Prof Andrew Coates, a space scientist at UCL’s Mullard Space Science Laboratory. “The landing was almost vertical because of the surrounding hills.”
The spacecraft and its robot explorer will be charged using solar energy, and its solar panels were unfolded after the landing. Although sometimes erroneously referred to as the ‘dark’ side of the Moon, the far side gets as much sunlight as the Earth does except that when that side receives it, it is opposite to the side that faces the Earth. But since the rotation of the Moon is locked into the orbital rotation of the Earth, we never get to see it directly.
Being in this shadow region has many advantages for research. Because it is in the shadow region, the telescope will be free of all the polluting effects that emanate from the Earth and there are plans to put a telescope on that side to take advantage of that.