China was preparing to launch a ground-breaking mission early Saturday to soft-land a spacecraft on the largely unexplored far side of the moon, demonstrating its growing ambitions as a space power to rival Russian Federation, the European Union and U.S.
The launch took place from the Xichang Satellite Launch Center in Sichuan Province on a Long March 3B rocket today, December 7, at 1:23 pm Eastern time (2:23 am local time in China). European scientists also helped China choose the Chang'e 4 landing site. Communicating with a far-side lander or rover is hard, because the entirety of the moon's solid, rocky body would block direct signals traveling to and fro.
It's launching the Chang'e-4 lunar lander Friday on a mission to explore the side of the moon that never shows itself to us here on Earth. The lunar far-side mission, Chang'e 4, which launched on December 7, 2018, was designed as a backup for Chang'e 3.
Chang'e is a series of probes that China has launched into orbit and landed on the moon.
Its plan to soft-land Chang'e 4 on the far side of the moon is challenging because any direct communications between the Earth and the rover once it is there will be blocked by the other hemisphere, scientists have said. The mission will include a low-frequency radio-astronomical study of the lunar surface, a shallow exploration beneath the surface, and a study of the topographical and mineralogical composition of the SPA basin.
Because the landers on the far side have no line of sight with our planet, they must send data back via a relay satellite named Queqiao, launched by China in May this year. The landers' are called the Landing Camera (LCAM), the Terrain Camera (TCAM), the Low Frequency Spectrometer (LFS), and the Lunar Lander Neutrons and Dosimetry (LND), which was provided by Germany.
The far side looks rather different to the more familiar near side.
The rover will carry a panoramic camera; a radar to probe beneath the lunar surface; an imaging spectrometer to identify minerals; and an experiment to examine the interaction of the solar wind (a stream of energised particles from the Sun) with the lunar surface. There are also few of the "mare" - dark basaltic "seas" created by lava flows - that are evident on the near side.
Chang'e 4 will also conduct some radio-astronomy work, taking advantage of the peace and quiet on the far side, which is shielded from the radio chatter coming from Earth.
"We want to study the respiration of the seeds and the photosynthesis on the Moon", Liu Hanlong, chief director of the experiment and vice president of Chongqing University, told the state-run Xinhua news agency earlier this year. Researchers will keep tabs on how these organisms live and develop on the lunar surface. "If Chang'e 4 is able to sample these materials, we will get to learn the composition of the moon's interior".
The nation launched the Chang'e 1 and Chang'e 2 spacecraft to lunar orbit in 2007 and 2010, respectively.
One reason no attempt has ever been made to visit the distant side of the moon is that the lack of a line of sight makes direct communications with a spacecraft hard.
All of this is leading up to the Chang'e 5 sample-return mission, which could launch toward the near side as early as next year.
And then there's the crewed side of things. Both include a large lander weighing about 1,200 kilograms, and from this a smaller rover about one meter across and weighing 140 kilograms is deployed on the lunar surface.
The country also plans to launch its first Mars probe by the end of this decade, according to a white paper on China's space activities issued in 2016.