Posted on Dec 8, 2018
Probing the lunar ‘radio environment’ to creating a mini biosphere: China launched the Chang’e-4 lunar probe rover early Saturday on a Long March 3B rocket from the southwestern Xichang Space Center at 2:23 am (1823 GMT) Saturday, according to the official Xinhua news agency. Destined to touchdown around the New Year on the far side of the moon at the Von Kármán crater in Aitken Basin in the craggy and complex terrain of the lunar south pole region, the mission is global first that would boost Beijing’s ambitions to become a space superpower.
“The main thing about this mission is not science, this is a technology mission,” said Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics. “The mission is a giant step to gather the engineering expertise needed to explore and settle the moon.”
Von Kármán crater is of interest to scientists because it is located within the oldest and largest impact feature on the Moon, formed by a giant asteroid impact billions of years ago.
Once the Aitken Basin, the rover faces an array of extreme challenges. During the lunar night—which lasts 14 earth days—temperatures will drop as low as minus 173 degrees Celsius (minus 279 Fahrenheit). During the lunar day, also lasting 14 earth days, temperatures soar as high as 127 C (261 F). The rover’s instruments must withstand those fluctuations and it must generate enough energy to sustain it during the long night.
The mission will also study the “radio environment” on the far side, according to Radio New Zealand, a test designed to lay the groundwork for future radio astronomy telescopes on the far side, which is shielded from the radio noise of Earth.
“Compared to the near side, the far side of the Moon is filled with deep basins and high mountains and has never been touched by humans or machines,” Jiao Weixin, a space science professor at Peking University, told the Global Times.
As the far side of the Moon it’s an ideal place to conduct low frequency radio astronomy observations because it’s shielded from electromagnetic interference from the Earth,, allowing for the study of a wide range of objects in space, a Beijing-based aerospace expert who requested anonymity, told the Global Times.
The static lander will carry a 3kg container with potato and arabidopsis plant seeds to perform a biology experiment. The “lunar mini biosphere” experiment was designed by 28 Chinese universities. “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.
“We have to keep the temperature in the ‘mini biosphere’ within a range from 1 degree to 30 degrees, and properly control the humidity and nutrition,” Xie Gengxin, chief designer of the experiment, told Xinhua. “We will use a tube to direct the natural light on the surface of Moon into the tin to make the plants grow.”
“Chang’e-4 is humanity’s first probe to land on and explore the far side of the moon,” said the mission’s chief commander He Rongwei of China Aerospace Science and Technology Corp, the main state-owned space contractor. “This mission is also the most meaningful deep space exploration research project in the world in 2018,” He said, according to state-run Global Times.
Unlike the near side of the moon that is “tidally locked” and always faces the earth, and offers many flat areas to touch down on, the far side is mountainous and rugged.
It was not until 1959 that the Soviet Union captured the first images of the heavily cratered surface, uncloaking some of the mystery of the moon’s “dark side”. No lander or rover has ever touched the surface there, positioning China as the first nation to explore the area.
“China over the past 10 or 20 years has been systematically ticking off the various firsts that America and the Soviet Union did in the 1960s and 1970s in space exploration,” said McDowell. “This is one of the first times they’ve done something that no one else has done before.”
A major challenge for such a mission is communicating with the robotic lander: as the far side of the moon always points away from earth, there is no direct “line of sight” for signals. As a solution, China in May blasted the Queqiao (“Magpie Bridge”) satellite into the moon’s orbit, positioning it so that it can relay data and commands between the lander and earth.
Adding to the difficulties, the Aitken Basin in the lunar south pole region is known for its craggy and complex terrain.
The probe is carrying six experiments from China and four from abroad, including low-frequency radio astronomical studies—aiming to take advantage of the lack of interference on the far side—as well as mineral and radiation tests, Xinhua cited the China National Space Administration as saying.
The experiments also involve planting potato and other seeds, according to Chinese media reports.
Beijing is pouring billions into its military-run space program, with hopes of having a crewed space station by 2022, and of eventually sending humans to the moon. Chang’e-4 will be the second Chinese probe to land on the moon, following the Yutu (“Jade Rabbit”) rover mission in 2013.
Beijing is planning to send another lunar lander, Chang’e-5, next year to collect samples and bring them back to earth.
It is among a slew of ambitious Chinese targets, which include a reusable launcher by 2021, a super-powerful rocket capable of delivering payloads heavier than those NASA and private rocket firm SpaceX can handle, a moon base, a permanently crewed space station, and a Mars rover.
The Daily Galaxy via Radio New Zealand, AFP and Global Times
Image credit top of page: Aiken Basin with thanks to Air & Space