Back in 1959, the USSR's unmanned Luna 3 took the first photograph of the far side of the Moon — that's the half that always faces away from the Earth — from orbit, but no space program has ever landed a rover on it.
If all goes according to plan, that will soon change. China's space agency is launching a space probe on December 8 intended to land on the Moon's far side.
The Chang'e-4 lander and accompanying rover will need to navigate a far more rugged surface, covered in massive craters and with few larger flat areas — "lunar maria," in the jargon — that have traditionally facilitated Moon landings.
In 2013, China successfully landed the Chang'e-3 on the Moon to collect data about its surface. According to Science, the Chang'e-4 was originally a backup for the Chang'e-3 mission.
What makes the mission difficult is keeping in touch with a probe that's landed on the far side of the Moon, since the Moon itself will block most radio communications. To solve this, China launched a relay satellite called Queqiao back in May, which will pass on signals between Earth and the Chang'e-4.
If all goes well, the Chang'e-4 lander will land in a massive 2500 km (1550 miles) crater called Von Kármán near the Moon's south pole.
It will then explore the composition of the lunar surface of the far side of the moon, examining how it compares to the near side.
It will also set up a 3 kg (6.6 lb) container of seeds and silkworm larvae to see if they have a chance to coexist, and grow on the surface of the Moon.
Next year, China will launch the Chang'e-5 to retrieve 2 kilograms (4.4 pounds) of soil from a still untouched part of the near side of the Moon.
It may be our closest neighbor, but the Moon still has plenty of mysteries to uncover — especially its dark side. Next step: sending humans back to its surface for the first time in decades.
An earlier version of this story incorrectly claimed that NASA took the first photograph of the moon. It has been updated.
READ MORE: China sets out for the far side of the moon [Science]
More on China's moon landings:China Will Send Two Robots to Study the Moon