Chang'e 4

FIRST EVER MISSION TO THE FARSIDE OF THE MOON

China’s moon exploration agenda includes the first-ever robotic landing on the moon’s farside, Chang'e 4 launched on 11th Dec 2018 – a mission that requires a relay satellite ‘Queqiao’ beyond the moon to link communications between Earth and the farside probe, landed successfully on the 2nd Jan 2019. (See also Chang’e-5)

Amazingly due to the extreme conditions on the Moon the Chang'e 4 lander that was originally designed to operate for 12 months and Yutu 2 for just three months, Both craft have already exceeded their warranties, and both are still going strong March 2020; the duo recently woke up to begin their 15th lunar day of science work.

Chang'e 4 Lunar Landing In Detail

The Rover Yutu 2 successfully left the chang'e 4 lander.

Yutu2 deployed 3 Jan 2019

After sending the rover off from a ramp, the spacecraft deployed three 5-meter (16-foot) low-frequency radio antennas, the Chinese space agency said. Chang'e 4 also has sent back images taken with a topographical camera.

Researchers hope that low-frequency observations of the cosmos from the far side, where radio signals from Earth are blocked by the moon, will help scientists learn more about the early days of the solar system and even the birth of the universe's first stars.

Queqiao relay satellite

The ‘Queqiao’ relay orbiter(satellite) launched in May 2018 and on the 14th June was successfully inserted into a halo orbit around the second Earth-moon Farside Lagrange point L2, some 65,000-85,000 kilometers from the moon. The Halo Orbit at L2 allows Queqiao to relay communications back to the Earth from the Farside of the Moon (This is a First)

Earth Moon L2 at the top (Farside)

Queqiao relay satellite enters L2 orbit, showing the Halo Orbital path around L2

Chang’e-4

The Apollo basin was the most likely target for Chang'e 4 until Von Kármán crater was selected. This is a large, double-ring impact basin on the lunar farside.

Once landed a small rover will be used that has a panoramic camera, ground-penetrating radar, and an infrared spectrometer.

These were other possible Chang'e4 landing sites, 186 kilometer diameter Von Kármán crater was selected.

The landing will target candidate landing sites in the South Pole-Aitken Basin (SPA), with the selected site understood, but not officially announced, to be the 186-kilometer-diameter Von Kármán crater.

186 kilometer diameter Von Kármán (lunar crater)

Chang’e-4 was launched by a Long March 3B carrier rocket from the Xichang Satellite Launch Center, southwest China, at 1:23 p.m. Eastern Dec. 7 for a 110-hour journey to the moon.

landing took place in the 2nd January 2019, following sunrise over the main candidate landing within the Von Kármán crater in late December.

Chang'e-4 + Yutu 2 rover on the Far side of the Moon

The South Pole-Aitken Basin is a 2,500-kilometer-wide, 12-kilometer-deep ancient impact crater of intense scientific interest which could contain exposed material from the moon’s upper mantle and clues to the history and development of the moon.

Render of the Chang’e-4 lander, with rover on top, on the lunar surface

The lander carried a container with six live species from Earth - cotton, rapeseed, potato, fruit fly, yeast and arabidopsis (a flowering plant) - to try to form a mini biosphere.

"The far side of the moon is a rare quiet place that is free from interference of radio signals from Earth," mission spokesman Yu Guobin said.

"This probe can fill the gap of low-frequency observation in radio astronomy and will provide important information for studying the origin of stars and nebula evolution.”

Experiments

"biosphere" experiment

To study the respiration of seeds and the photosynthesis on the moon a small "tin" in the lander contains seeds of potatoes and rockcress (Arabidopsis thaliana, a flowering plant related to cabbage and mustard, as well as a model organism for plant biology), as well as silkworm eggs. It includes dirt, nutrients and water. Sunlight will filter into the container through a "tube," and small cameras will watch the little environment.

"Why potato and Arabidopsis? Because the growth period of Arabidopsis is short and convenient to observe. And potato could become a major source of food for future space travelers," said Liu Hanlong

The Chang’e-4 mission is to be followed by China’s first sample return mission, Chang’e-5, which could launch in late 2019 on a Long March 5 rocket.