On Thursday, China’s National Space Administration announced that they had successfully soft-landed the Chang'e 4 probe in the Antarctic-Aitken Basin on the far side of the Moon. The probe will deploy a rover and other instruments, and has already returned the first detailed images of a place where no human has ever set foot.
There is no “dark side” of the Moon outside of Pink Floyd albums. There is, however, a far side of the Moon—a side that always faces away from Earth. All previous lunar landings, including the manned Apollo missions, took place on the near side, the side of the Moon visible from Earth. There are good reasons for this. In particular, until recently there was no way to return a signal from the far side, meaning that when the Apollo astronauts orbited around the Moon, they spent part of each orbit in radio silence (though apparently, the radio was not perfectly silent, much to the delight of conspiracy theorists).
China’s successful landing on the far side follows the success of the Jade Rabbit rover deployed to the near side of the Moon. China has plans to launch a new permanent space station in 2020, and while several programs—both government and private—are considering manned lunar missions, the success of China’s lunar probe program makes it increasingly likely that the next human to set foot on another world will be from China.
The first probe to return images from that unseen surface was the Soviet Luna 3 probe launched all the way back in 1959, and though the images from that first probe were vague at best, they instantly revealed that the far side of the Moon bears little resemblance to the more familiar “face” that looks down on Earth. The far side has only two of the dark “seas” that spread across much of the near side. Instead, it’s marked by highly mountainous terrain, raised highlands, and of course, craters of all sizes. There are only two small seas on the far side (one of which the Soviets quickly named Mare Moscoviense—the Sea of Moscow). Apparently the dark lava flows that created the dark lunar seas almost all spilled out on the side facing Earth, for reasons that are still under hot debate.
Chang'e 4 will deploy a new rover to explore the unfamiliar lunar far side as well as conduct a series of radio astronomy observations. The same conditions that make it difficult to communicate with astronauts or probes on the far side, namely the bulk of the Moon in the way of signals from Earth, make it the ideal place to conduct observations away from the “radio pollution” created by terrestrial sources.
Chang'e 4 is able to communicate with Earth because it’s not alone up there. China also has a relay satellite—“Queqiao” or “Magpie Bridge”—holding station beyond the Moon to return the probe’s results. As the Planetary Society explains, that relay satellite doesn’t actually orbit the Moon. It orbits the “L2 Point” of the Earth-Moon system, allowing it a continuous view of the Moon’s far side along with line of sight communications with Earth.
The Chinese landing is the result of many years planning, and stands poised to return serious scientific data about both the Moon and beyond. But while it’s a great step for the Chinese program, it’s not the only lunar-bound explorer headed to our nearest neighbor in 2019.
Just days from now, the Indian Space Research Organization is expected to launch the Chandrayaan-2 mission. This launch will carry an orbiter, a lander, and India’s own rover to the Moon. While India is targeting the near side of the Moon, it is heading to a region near the lunar South Pole that has previously been unvisited and where several craters host potentially valuable water ice.
And just days after that, in mid-February, private Israeli-based company SpaceIL has scheduled a SpaceX Falcon 9 to carry their “Beresheet” lander to the Moon. That craft will be landing in a more conventional location, but it will be getting to the Moon in an unconventional way, using a series of very low-energy maneuvers that will turn the trip into a two-month, multi-orbit odyssey.
That’s not all. U.S. company Moon Express has another lunar lander on its way this year, this one riding on a relatively tiny Rocket Lab Electron launch vehicle. Actually … they have two: the MX-1E lander and the Lunar Outpost MX-3 lander. The MX-1E will carry a telescope capable of, among other things, looking back at Earth from the Moon, which should provide some unique views.
That’s still not all. Two other teams—one in Germany and another in India—are scrambling to complete their probes and secure rides (and funding) that would bring at least three more rovers to the Moon in 2019. Jade Rabbit expired in 2018 after more than 900 days of operation. But if everything goes as planned, there could be seven rovers and even more landers on the lunar surface before the end of the year. The year 2020 may be when someone has to launch the first lunar traffic light.