The Moon Mission

By Lu Yan

He Zhong witnessed a historic moment he will never forget. On November 24， when the rocket carrying the Change-5 spacecraft blasted off from the Wenchang Spacecraft Launch Site on the coast of the southern island province of Hainan， he was on site， about 2.8 km from the launching tower. He， a staff member of Chinese carmaker SAIC Motor， recorded the spacecraft soaring into the sky and shared the video.

“It was spectacular. The Change-5 shot into space bright like the Sun，” He told Beijing Review. “We are very proud to see the fruits of our countrys mature aerospace technology.”

A historic task

Named after Chinese Moon goddess， Chinas current three-step lunar exploration program started in 2004. The three steps are orbiting and landing on Moon， which were realized with the launch of previous Change missions， and bringing back lunar samples， the task at hand for Change-5.

Change-5 consists of an orbiter， a lander， an ascender and a returner. This is Chinas first attempt to retrieve samples from an interstellar body， and the worlds first after the former Soviet Unions unmanned Luna 24 brought back 170.1 grams of lunar samples to Earth in 1976.

“Domestic and overseas scientists will all have the chance to obtain the lunar samples brought back by Change-5 for research purposes，” Pei Zhaoyu， spokesperson for the Change-5 mission and Deputy Director of the Lunar Exploration and Space Program Center of the China National Space Administration （CNSA）， told Xinhua News Agency.

The goals of the Change-5 mission include investigation of the landing area to obtain onsite data related to the lunar samples， as well as systematic and long-term laboratory analysis of the samples. The mission will help promote Chinas science and technology development and lay crucial foundations for future manned lunar landing and deep space exploration， Pei said.

According to the CNSA， the entire mission is going to take 23 days. Compared with previous Chinese lunar expeditions， Change-5 will face a challenging gravitational environment and high requirements for accuracy control， increasing the complexity of the mission， according to Peng Jing， deputy chief designer of the Change-5 probe from the China Academy of Space Technology under the China Aerospace Science and Technology Corp.

During its return journey， the ascender will take off， and dock with the orbiterreturner in orbit. Peng said the unmanned rendezvous and docking in lunar orbit will be a historic fi rst for the world. “We could call it a milestone mission. Its success will help us acquire the basic capabilities for future deep space exploration such as obtaining samples from Mars， asteroids and other celestial bodies，” he told China Central Television （CCTV）.

Moon sample

In 1978， Chinese space scientist Ouyang Ziyuan received a special “present”—0.5 gram of lunar rock sample from Apollo 17. The sample was from a goodwill gift given to China by then U.S. National Security Advisor Zbigniew Brzezinski. The other half is on display at the Beijing Planetarium.

Based on the half gram， Ouyang together with other Chinese scientists produced a series of researches. “We could do a good job if we were able to bring back the samples ourselves，” Ouyang said in an interview with CCTV in 2007 after Change-1， Chinas fi rst lunar probe， was launched.

Ouyang hoped that one day his country would be able to launch a lunar exploration program and bring back rock samples. In the 1990s， after extensive research and preparation， he proposed the Change project. In November 2000， the Change-1 lunar probe project received government approval.

It has now been more than four decades since Ouyang obtained that lunar rock sample. And his dream is about to come true. In early December， Change-5 is expected to land on the northwestern region of Oceanus Procellarum， also known as the Ocean of Storms， on the near side of Moon. It will work there for about two days and bring about 2 kg of samples back to Earth. If the Change-5 mission proves successful， it will make China the third nation in the world to bring back lunar samples—right after the U.S. and the former Soviet Union.

“Unlike the samples collected by Apollo， which were dated over 3 or 4 billion years ago， Change-5 will collect younger samples dated about 1.2 billion years ago. It might give us new information，” Zhang Wei， a researcher with the Technology and Engineering Center for Space Utilization， Chinese Academy of Sciences， told Thecover.cn.

“One of the biggest roles of lunar soil is to help scientists understand the structure， physical properties and material composition of Moons surface， shedding light on its evolution. This will also help mankind understand and exploit lunar resources，”said Yu Tianshi， head of the exhibition department of Hunan Museum of Geology in Hunan Province in central China. A part of the lunar samples brought back by Change-5 will be stored in the museum.

Chinas Lunar Expeditions

● Change-1

Chinas first lunar probe， Change-1， was launched on October 24， 2007， making China the fifth country to develop and launch a lunar probe on its own.

Orbiting 200 km above Moon， it mapped 3D images of the lunar surface， analyzed the distribution of elements， measured the depth of lunar soil， and explored the environment between Earth and Moon. Chinese scientists acquired the fi rst complete map of Moons surface， thanks to Change-1.

● Change-2

Change-2， blasting off on October 1， 2010， gained a full lunar map with a spatial resolution of 7 meters， showing more details of the lunar surface than Change-1， which had a resolution of 120 meters.

It also took pictures of the Sinus Iridum， or the Bay of Rainbows， proposed landing site of Change-3.

After accomplishing its tasks， Change-2 fl ew to the L2 point of the Sun-Earth system， where gravity from the Sun and Earth balances the orbital motion of a satellite， to conduct scientifi c experiments.

It was then tasked to fly by the Toutatis asteroid， some 7 million km from Earth. Change-2 came within 3.2 km of Toutatis samples and captured images with a spatial resolution of 10 meters at a relative velocity of 10.73 km per second.

● Change-3

Change-3 was launched on December 2， 2013， and touched down on the Sinus Iridum 12 days later. It was the fi rst Chinese spacecraft to soft-land on and explore an extraterrestrial object.

The success made China the third country， after the former Soviet Union and the United States， to soft-land on Moon.

Change-3 included a lander and a lunar rover called Yutu （Jade Rabbit）， which took photos of each other while the rover circled the lander.

The probe acquired a geological profi le of Moon， detected the geological structure from the lunar surface to 330 meters beneath， and discovered a new kind of lunar rock. The findings could give scientists new insights into the evolution of Moon.

● Change-4

The Change-4 probe， launched on December 8， 2018， accomplished the fi rst-ever soft landing on the Von Karman Crater in the South Pole-Aitken Basin on the far side of Moon on January 3， 2019.

Change-4， including a lander and a Moon rover called Yutu-2， or Jade Rabbit-2， conducted low-frequency radio astronomical observation， terrain and landform survey， mineral composition and shallow lunar surface structure detection， and neutron radiation and neutral atom measurement.

Yutu-2 has far exceeded its three-month design lifespan， becoming the longest-working rover on Moon.

Based on data from Change-4， Chinese scientists have determined the thickness of the regolith and revealed the fi ne subsurface structures and evolutionary history of the probes landing site on Moons far side.

（Source： Xinhua News Agency）