China is ready to launch the first surface mission to the other side of the moon.
The Chang & 4; and 4 robotic mission is slated to be launched on top of a Long March 3B rocket on Friday (Dec. 7) around 1:30 p.m. EST (1830 GMT, 2:30 am on December 8, local time in China).
If all goes according to plan, the Lander-rover duo of Chang & # 39; and 4 will land on the Moon's Pole-Aitken (SPA) basin after a 27-day flight and then study the surface and subsoil of this region . [China’s Moon Missions Explained (Infographic)]
Both the lander and the rover were designed as backups for China's successful Chang & # 39; and 3 mission that landed a lander and a jeep named Yutu on the moon in December 2013.
As a prelude to Chang & # 39; and 4, China launched the Queqiao retransmission satellite last May. Now, the Queqiao is positioned at the Lagrange L2-Earth location – a place where the spacecraft can handle communications between ground controllers and the Lander-Rover mission on the far side.
Lots of scientific gear
Chang & # 39; and 4 are expected to land at Von Kármán Crater, within the SPA basin.
In a study published last month, Yingzhuo Jia of the University of Chinese Academy of Sciences, and his colleagues presented the main scientific objectives of the mission. (Jia is also with the State Key Laboratory of Space Weather, National Center of Space Sciences of the Chinese Academy of Sciences.)
The mission, Jia and team members wrote, intends to complete:
A low-frequency radio-astronomical study on the lunar surface;
An investigation of surface structure on the distant lunar side within the traveling area;
Studies of topographical and mineralogical composition of the lunar side in the patrol area of the rover.
The radioastronomical study is particularly intriguing. The lunar side is always turned away from Earth, so it is free from interference from our planet's ionosphere, man-made radio frequencies and auroral radiation noise. The solar radio emission is also blocked during the lunar night.
"This is why the lunar side is believed to be the best place for low-frequency radio-astronomy observations," the researchers wrote in the recent article.
The paper also detailed the eight scientific charges accumulated by the mission.
The Chang & 4; and 4 landing module carries the Landing Chamber (LCAM), Land Chamber (TCAM), Low Frequency Spectrometer (LFS) and Lunar Lander Neutron and Dosimetry (LND) supplied by Germany. The rover also has four instruments: the Panoramic Camera (PCAM), the Penetrating Lunar Radar (LPR), the Visible and Near Infrared Imaging Spectrometer (VNIS) and the Advanced Small Neutral Analyzer (ASAN) provided by Sweden.
LFS was recently developed for lander Chang & # 39; and 4; the other native Chinese cargoes are instruments inherited from Chang & # 39; and 3, the researchers wrote.
The Queqiao retransmission satellite also has an instrument called NCLE (Netherlands Low-Frequency Explorer). Lander's NCLE and LFS will conduct low frequency joint radio astronomy observations. [Moon Master: An Easy Quiz for Lunatics]
The LPR instrument will probably be able to detect the subsurface structure on the robot's patrol route and detect the thickness and structure of the lunar regolith. The device is a nanosecond pulse radar with bistatic antennas.
It works like this: an ultra-wideband nanosecond pulse is produced by a transmitter and then sent through the transmission antenna to the lunar surface. The echo signal from the underground target is received by the receiving antenna, amplified at the receiver and then restored as a data record.
Biological experiment also
According to news earlier this year from China's state-run Xinhua news agency, Chang & 4; and 4 will also carry a can containing potato seeds and arabidopsis, a small plant related to cabbage and mustard. You can also carry silkworm eggs.
This "mini lunar biosphere" experiment was designed by 28 Chinese universities, led by Chongqing University in southwest China. The cylindrical can, made of special aluminum alloy materials, weighs approximately 6.6 lbs. (3 kg).
The SPA basin is the largest and oldest impact basin of the moon. Although the terrain is low, this region is not filled with mare basalts, like other lunar basins, according to Jia and her colleagues, suggesting that it may have a special thermal history and unique characteristics of evolution.
Studying the materials in the region could therefore help reveal the composition of the crust and even the moon's mantle, the researchers wrote.
China's next lunar probe, Chang & # 39; and 5, was designed to bring selected samples of the Moon back to Earth. It is based on a progression of Chinese lunar explorers: the Chang orbiting 1 and Chang and 2 in 2007 and 2010, respectively, Chang and 3 in December 2013, and the Chang & # 39; and 5 T1, which launched a test capsule on a journey around the moon in October 2014. The capsule jumped back to Earth eight days after takeoff.
Leonard David is the author of "Mars: Our Future on the Red Planet," published by National Geographic. The book is a companion to the "Mars" series of the National Geographic Channel. A longtime writer for Space.com, David has been reporting on the space industry for more than five decades. Follow Us @Spacedotcom, Facebook or Google+. This version of the story published on Space.com.