Researchers prepare to weigh Chang'e-6 lunar samples during a returner opening ceremony at the China Academy of Space Technology under the China Aerospace Science and Technology Corporation in Beijing, capital of China, June 26, 2024. (Xinhua/Jin Liwang)

BEIJING, April 23 (Xinhua) -- China will celebrate its 11th Space Day on Friday, while its Chang'e-7 spacecraft is undergoing final preparations at the Wenchang Space Launch Site in south China's Hainan Province before its planned launch in the second half of 2026. It will head to the moon to conduct environmental and resource surveys of the lunar south pole.

Over the past decade, China's Chang'e lunar exploration program has secured many achievements. Chang'e-4 realized the world's first soft landing on the far side of the moon. Chang'e-5 completed lunar sampling and return, while Chang'e-6 accomplished humanity's first sample return from the moon's far side.

The significance of China's lunar exploration program has transcended national achievement. It has made unique contributions to lunar study for the wider world and provided an open platform for international cooperation.

NEW DISCOVERIES ON MOON

The Chang'e program has driven new discoveries in multiple areas of lunar research, and the lunar samples collected by Chang'e probes have provided crucial evidence for scientists worldwide.

Chang'e-4 achieved the world's first soft landing on the far side of the moon in 2019, touching down in the South Pole-Aitken (SPA) Basin. The colossal SPA Basin was formed by a celestial collision over 4 billion years ago and has a diameter of 2,500 km and a depth of about 13 km. It is the oldest and largest impact crater on the moon and in the solar system, and it may provide the earliest information about the moon.

In 2020, Chang'e-5 landed in the north of the Mons Rumker in Oceanus Procellarum on the near side of the moon. Before Chang'e-5, no human probe had ever landed in the Oceanus Procellarum. It brought back 1,731 grams of samples, the first relatively young lunar samples obtained by humans, filling a gap in the chronology of lunar samples.

Chang'e-6 was launched on May 3, 2024, and landed in the Apollo Basin in the SPA region on the far side of the moon on June 2, 2024. Its return capsule carried 1,935.3 grams of samples back to Earth, completing the world's first sample return mission from the far side of the moon.

China, notably, has lent several batches of lunar samples for institutions to carry out study in fields such as lunar surface processes, volcanic activity age, lunar evolution processes, and mineral and volatile composition. These samples have greatly contributed to the understanding of the moon, providing unprecedented material evidence for the research community.

For example, precise dating of 2-billion-year-old basalt from Chang'e-5 samples extended the history of lunar volcanic activity by roughly 800 million years. Chang'e-6 samples, meanwhile, provide direct evidence for resolving the geological asymmetry between the near and far sides of the moon, and for tracing early large-impact events.

DEEP SPACE EXPLORATION

Beyond advancing lunar research, the Chang'e program has achieved a series of major breakthroughs in deep space exploration, opening new paths and developing novel technologies for humanity's exploration of deep space.

The lunar landing, sampling and return operations in the Chang'e program can provide the experience and technical foundation for similar missions to more distant celestial bodies, such as asteroids and Mars.

To support operations on the far side of the moon for the Chang'e-4 and Chang'e-6 missions, China launched the Queqiao-1 and Queqiao-2 relay communication satellites. They solved the challenge of direct communication between the far side and Earth, which was blocked by the moon itself, and provided new insights for deep space exploration.

China applied the experience gained from the Queqiao relay satellites during its Mars mission. When Tianwen-1 started Mars exploration in 2021, the Tianwen-1 orbiter provided relay communication services for the Mars rover Zhurong.

In addition, the Chang'e program has deployed spacecraft at Lagrange points on several occasions. In 2018, Queqiao-1 entered a halo orbit around the Earth-moon Lagrange point 2, becoming humanity's first relay communication satellite to operate there. In 2021, after completing its mission of sending the return capsule to Earth, the Chang'e-5 orbiter entered the sun-Earth Lagrange point 1.

Lagrange points are gravitational balance points in celestial systems such as the sun and Earth and Earth and moon, where spacecraft can remain stationed for long periods while consuming minimal fuel. The Chang'e program's exploration of Lagrange points has laid the foundation for the use of Lagrange points for solar observation and other deep space missions.

PLATFORM FOR OPEN COOPERATION

The Chang'e program has gradually formed an open platform for the peaceful use of space. International cooperation has drawn creative ideas from the world to be realized through the Chang'e program.

Chang'e-4 carried four international payloads from the Netherlands, Germany, Sweden and Saudi Arabia, while Chang'e-6 was equipped with four payloads from France, Italy, Pakistan and the European Space Agency (ESA).

Chang'e-7 plans to carry six international payloads from seven countries or organizations: Egypt, Bahrain, Italy, Russia, Switzerland, Thailand and the International Lunar Observatory Association.

The Chang'e-8 mission, which is scheduled for launch around 2029, will carry payloads from 11 countries and regions and one international organization. Developers of the instruments set to be aboard Chang'e-8 are from Asia, Europe, Africa and South America.

Meanwhile, the lunar samples brought back by Chang'e-5 have been opened for international application. In November 2023, the China National Space Administration (CNSA) launched a borrowing application process, receiving 24 applications from 11 countries and international organizations.

Seven institutions from six countries, namely France, Germany, Japan, Pakistan, Britain and the United States, passed the review and were granted access to lunar samples for scientific research.

Frederic Moynier, a professor at the Institute of Earth Physics of Paris, is among the international scholars to borrow Chang'e-5 samples. He highlighted their scientific value, citing the good condition of the rock fragments, the unexplored location where the samples were dug up, and the fact that these rocks were over a billion years younger than those collected during the Apollo missions, in explaining why the Chang'e-5 samples are so precious.

In China's future plan, Chang'e-7 and Chang'e-8 will become parts of the basic model of the International Lunar Research Station (ILRS), a scientific experimental facility consisting of sections on the lunar surface, in lunar orbit and on Earth, respectively. A total of 17 countries and international organizations, and more than 50 international research institutions, have joined the ILRS project.