Chang’e-4 Moon lander and rover.

The first phase of China’s bid to land a robotic mission on the far side of the Moon is reportedly nearing launch.

A projected May 21 launch of a Long March-4C booster is topped by a relay satellite named Queqiao (Magpie Bridge). This spacecraft is to be dispatched into a halo orbit of the Earth-Moon Lagrange Point L2 and relay signals between the Earth and the Chang’e-4 far side lander which will deploy a rover.

Meanwhile, China’s tracking ship Yuanwang 6 recently departed from a port in East China’s Jiangsu province to monitor the trajectory of Queqiao, the Chang’e-4 relay satellite.

Together with Queqiao, two microsatellites — “Longjiang-1” and “Longjiang-2” developed by the Harbin Institute of Technology — will also be sent into orbit to conduct scientific research.

Radio astronomy

The relay spacecraft is multifaceted. It carries the Netherlands-China Low-Frequency Explorer (NCLE) built by a team of scientists and engineers from ASTRON (the Netherlands Institute for Radio Astronomy in Dwingeloo), the Radboud Radio Lab of Radboud University in Nijmegen, and the Delft-based company, ISIS.

NCLE is considered a pathfinder mission for a future low-frequency space-based or Moon-based radio interferometer.

The constellation of three active NCLE antennas is mounted perpendicular to the upper side of the satellite body. The final assessment of the instrument took place early April in Beijing, clearing the way for the integration of the radio antenna package on the Chinese relay satellite.

Netherlands-China Low-Frequency Explorer (NCLE) hardware undergoes testing.
Credit: Astron

The objective of the NCLE mission is two-fold. In addition to the characterization of the lunar radio environment, NCLE will allow for radio science and astronomy, including constraining the 21-cm line Dark Ages and Cosmic Dawn signal, measuring the auroral radio emission from the large planets in our Solar system, determining the radio background spectrum at the Earth-Moon L2 point, studying the Solar activity and space weather at low frequencies, creation of a new low-frequency map of the radio sky, and study the Earth’s ionosphere and its interaction.

Far side mission

Chang’e-4 is to be sent to the Moon atop a Long March 3B booster with liftoff expected in late December.

 According to the state-run Xinhua news agency, the lander will carry a tin containing seeds of potato and arabidopsis, a small flowering plant related to cabbage and mustard. It may also tote along silkworm eggs to conduct the first biological experiment on the Moon.

Courtesy: Philip Stooke

This “lunar mini biosphere” experiment was designed by 28 Chinese universities, led by southwest China’s Chongqing University, The cylindrical tin, made from special aluminum alloy materials, weighs roughly 7 pounds (3 kilograms).

The tin also contains water, a nutrient solution, and air. A tiny camera and data transmission system allows researchers to keep an eye on the seeds and see if they blossom on the Moon.

Candidate landing region

The candidate landing region for the Chang’e-4 lander mission – expected to be hurled moonward this December — is 45°S-46°S 176.4°E-178.8°E, which is in the southern floor of the Von Kármán crater, within the South Pole-Aitken (SPA) basin.

Chang’e-4 will carry payloads for Germany, the Netherlands, Saudi Arabia and Sweden.

China’s lunar exploration program is designed to be conducted in three phases. The first phase is to orbit the Moon, which was completed by Chang’e-1 in 2009. The second phase is to land on the Moon, which was done by Chang’e-3 in 2013. The third phase is to collect samples and return them to the Earth, which will be advanced by Chang’e-4, Chang’e-5 and Chang’e-6.

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