China said on Wednesday that it plans to launch two robots to the moon in December.

The new mission, called Chang'e-4, aims to set a lunar rover and lander on the far side of the moon.

The robots will study the geology and chemistry of the moon's most ancient and mysterious rocks.

Another goal of the mission is to see whether the region is quiet enough (from human activity) to build a sensitive deep-space radio telescope.

A bonus experiment on Chang'e-4 will try to grow plants and worms on the moon.

China's space agency this week shared new details about its upcoming Chang'e-4 mission, which aims to launch two robots to the far side of the moon.

The new mission, named after the mythical moon goddess Chang'e, is the fourth in an ongoing lunar exploration program. China ultimately hopes its efforts will lead to a crewed lunar landing — the first since NASA's Apollo program ended in 1972 — and perhaps domination of space around the moon.

Chinese officials said during a briefing on Wednesday that Chang'e-4 will rocket toward the moon in December. CCTV, a state-supervised media outlet, shared online video of the announcement.

The new mission "will be the first to realize a soft landing on and inspection of" the far side of the moon, an official said on Wednesday at China's National Defense Science and Technology Bureau in Beijing.

The Yutu or "Jade Rabbit" rover, part of China's Chang'e-3 mission, moving around the lunar surface in December 2013. China National Space Administration/Chinese Academy of Sciences

Chang'e-4 is made from backup hardware for Chang'e-3, a nearly identical mission that launched the Yutu or "Jade Rabbit" rover along with a stationary probe to the moon's near side in 2013. Given Chang'e-3's success, officials said at the time that the backup hardware would be retrofitted for Chang'e-4.

The current plan includes studying some of the moon's most ancient rocks — which could help scientists understand the moon's extremely violent history — as well as scouting for a location to build an unprecedented telescope to study the Big Bang's afterglow, according to Air and Space magazine.

Chang'e-4 will also test some hardware that China plans to use for Chang'e-5: a mission designed to collect about 4.4 lbs of dust and rocks from a northwest part of the moon and bring those samples back to Earth.

How China will talk to a robot on the far side of the moon

An illustration of China's Queqiao relay satellite near the moon. CNSA/CAS

The moon is very good at blocking light and radio transmissions from Earth to its far side. (A lunar "dark side" is something of a misnomer, since the moon rotates about once a month.)

When Apollo astronauts orbited the moon, for example, they temporarily and expectedly lost contact with mission control in Houston each time they passed behind the 2,159-mile-wide ball of rock.

But China is already poised to get around this problem — literally — because it successfully launched a precursor mission called Queqiao in May.

Queqiao is a telecommunications satellite now parked in a gravity-neutral spot in space, called a Lagrange point, that overlooks the far side of the moon but maintains a line-of-sight to Earth.

"The name Queqiao means 'magpie bridge' in Chinese and comes from a Chinese folk tale, a love story about a flock of magpies that form a bridge crossing the Milky Way once a year to reunite lovers known as the Cowherd and the Weaver Girl, as well as their children" according to a blog post by Luyuan Xu at the Planetary Society.

Queqiao will act as a "bridge" between Earth and the Chang'e-4 mission after its robots land. Specifically, the lander will communicate with both the rover and Queqiao relay satellite, and the satellite with mission control at China National Space Administration.

Where Chang'e-4 will land and explore

Although the final landing site has been selected, that decision isn't yet public, according to Space News.

But officials previously said the landing site for Chang'e-4 will be near the moon's south pole, where some craters hide water ice in permanent shadows — ideal spots to build permanent human outposts.

One previously mentioned and likely landing zone is Von Kármán crater.

A view of the moon's Von Kármán crater. James Stuby/NASA (CC0 1.0)

The crater also exists within a huge and ancient feature called the South Pole-Aitken Basin, which was the site of a cataclysmic impact about 3.9 billion years ago.

This collision event left behind a 1,550-mile-wide crater and is also thought to have punched through the moon's crust, spewing some of its mantle within Aitken Basin.

Scientists think that chunks of the lunar mantle may rest inside Von Kármán crater. If Chang'e-4 can find, sample, and study some of them, humanity would get an unprecedented view into the moon's internal structure and origins.

A rendering of a lunar rover for China's Chang'e-4 moon mission. China Aerospace Science and Technology Corporation (CASC)

Chang'e-4 would also deploy an experiment to take images of the sky in low-frequency radio waves — a feat that's practically impossible on Earth, given how noisy humans are with our electronics.

Nevertheless, these frequencies are essential to understanding the universe's and our own origins.

"We need these signals to learn whether and how the universe inflated rapidly in the first trillionth of a trillionth of a trillionth of a second after the Big Bang," Joseph Silk, an astronomer at Johns Hopkins University, wrote in Nature earlier this year.

Lunar silkworms, potatoes, and mustard

Silkworms may be the next animal to visit the moon. Nguyen Huy Kham/Reuters

China designed its solar-powered moon rover to last about three months and its lander to function for about a year.

In addition to the rock-sampling and radio-astronomy experiments, the mission will carry a miniature ecosystem of life on Earth.

The lander will hold a seven-inch-long aluminum container, designed by 28 universities, will be packed with potato seeds, Arabidopsis (mustard) seeds, and silkworm eggs, according to People's Daily, a state-supervised media outlet in China.

Zhang Yuanxun, chief designer of the aluminum container, explained the goal for these seeds and worms in the Chongqing Morning Post, according to People's Daily.

"The eggs will hatch into silkworms, which can produce carbon dioxide, while the potatoes and seeds emit oxygen through photosynthesis," Yuanxun said. "Together, they can establish a simple ecosystem on the moon."

This story has been updated with new information. It was originally published on August 15, 2018.

Na Li contributed Mandarin Chinese translation assistance to this story.