Today China successfully landed a rover on the farside of the Moon. The Chang’e 4 lunar probe touched down in the South Pole-Aitken Basin, the largest, deepest and oldest known crater in the solar system, at 10:26 am Beijing time on Jan. 3rd.
From Earth, we can see only one side of the Moon. The other side, the farside, is perpetually hidden from view. Apollo astronauts have flown over the farside of the Moon, and many satellites have photographed the Moon from behind–revealing it to be a rugged, heavily cratered landscape startlingly different from the side we typically see.
China’s rover will be the first to explore a farside crater, probing it with ground-penetrating radar and measuring its mineral composition with an infrared spectrometer. If water is present, the rover might find it.
The first pictures of the landing site have been relayed to Earth by the Queqiao satellite, which China launched in May 21, 2018, specifically for this purpose. This is what the South Pole-Aitken Basin looks like from the inside:
The landing was remarkable. Mission control had no line-of-sight contact with the lunar farside, so the lander had to perform many complex maneuvers autonomously.
(1) As it descended to an altitude of about 2 km, onboard cameras captured the shadows of objects on the lunar surface, identifying large obstacles such as rocks and craters so the probe could avoid them.
(2) At 100 meters up, the probe hovered to identify smaller obstacles and measured the slopes on the surface. Its computer calculated again and selected the safest site.
(3) At 2 meters above the surface, the engine stopped. Then the golden lander with a silver rover on top touched down on the desolate gray surface with four legs, throwing up some dust. The probe performed the entire landing process, lasting about 12 minutes with no intervention from ground control.
Now we are at the far side of the Moon…