Chang’e-4 needs to go through several steps before touchdown, beginning around 15 kilometers (9 miles) above ground. It’ll adjust speed when it’s 8 km above, and adjust its position when it’s 6 km above, hovering for a while at the height of 100 meters, and using its hazard-avoidance instrument to calibrate its final landing spot in the last 30 meters, according to a demonstration from CAST.

The chance of a safe landing is just 50-50, China in Space author Harvey told Quartz, with risks at multiple points, from speed control to communications with the relay satellite to issues with the rover’s radar soundings and hazard -avoidance skills. China has practiced landing, radar, and hazard-avoidance tests in the western Xinjiang desert, which was selected as the best available analogue to the Moon, according to Harvey’s research.

“The scientists and engineers studied the area planned for the landing exhaustively to find a flat area with as few rocks, craters or slopes as possible. The map of the intended landing spot was then programmed into the CE-4 [Chang’e-4] computer so that when it arrives there, the radar soundings will be matched against the map and the guidance system will then bring it into the right spot,” Harvey told Quartz. “The Americans use a similar system for their Mars landings. It may sound simple in theory, but it is being done a long distance away without the possibility of human intervention.”

Farming on the moon, listening to the universe

Just like geologists on earth, scientists can better understand our satellite by studying its mantle, the layer between the core and the crust, to understand how it came into being, and what chemical elements helped form it. Humans have so far brought back some 382 kilograms of objects, including lunar rocks and core samples during the six explorations of the Moon from the Apollo missions carried out by the US between 1969 and 1972. But none of those came from the far side.

The far side has fewer “mare”—dark-colored portions that ancient astronomers took to be seas—and greater visible crater coverage than the near side. Scientists have yet to understand what led to the differences but Chang’e-4 might help change that.

The mission is carrying instruments developed by scientists in Germany, Netherlands, and Sweden to study the moon and the universe if the lander is able to land successfully.

German scientists at the University of Kiel helped develop the Lunar Lander Neutrons and Dosimetry, which is traveling on the lander and will measure lunar radiation levels, among other experiments. Swedish scientists from Institute of Space Physics and the National Space Science Center have designed an Advanced Small Analyser for Neutrals, which is traveling on the rover and will investigate how solar wind interacts with the lunar surface. On the Queqiao relay satellite, a radio antenna designed by researchers from Netherland’s Radboud University will pick up signals that can reveal the origins of the universe.

China scientists have also put seeds of potatoes and arabidopsis—a small flowering plant belonging to the mustard family—along with silkworm cocoons on the spacecraft, to test life sustainability on the Moon.

If China is successful, it will boost its confidence in the Chang’e-5 mission, slated for late 2019, Harvey said. China will use Chang’e-5 to collect and bring back samples on the Moon’s near side.

The ultimate goal for China, according to officials, is to put humans on the Moon—a milestone already achieved more than half a century ago by the US. China could achieve that in 2030, said Harvey, adding that “whereas Apollo made expeditions of one to three days, ‘flags and footprints,’ the first Chinese landing will be for a month and a base will be built not long afterward.”

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