"People were there on the beach. It was really very exciting to see the launch, and to see the expectation from everybody for this mission. That was really something wonderful for a scientist to see," said Olivier Gasnault.  

He was referring to the launch of China's Chang'e-6 lunar probe on May 3 from the southern Chinese island province of Hainan.

Its mission was to land on the moon's far side and collect samples that scientists expect will help answer key questions about the early evolution of the solar system.

Gasnault, together with his colleagues at the French Institute of Astrophysics and Planetology (IRAP) in Toulouse, developed a radon detector — a device that measures radioactive gases and radiation — for Chang'e-6.

On Sunday, after several maneuvers, the landing module touched down in a huge crater known as the South Pole-Aitken Basin, the China National Space Administration said.

It's the second Chinese mission to land on the far side of the moon, the first being Chang'e-4, which landed there five years ago and still remains in operation.

Detecting radon on lunar surface

Scientists believe rock samples from the southern polar region of the moon could reveal insights into the early history of the solar system.

Also, within the South Pole-Aitken Basin, there are numerous permanently shadowed regions that are thought to contain ice, which is a valuable resource for future space exploration, as it could be used as a source of drinking water as well as to produce fuel and oxygen, among other uses.

Although the French radon detector does not search for water directly, the knowledge gained during the mission should help a great deal.

Gasnault showed DW a replica of the radon detector at his lab. Equipped with eight dish-shaped sensors, the "DORN" (Detector of Outgassing Radon) device is about the same size as a standard household microwave.

Radon, a radioactive noble gas, is a chemical element found in rocks. On the moon, the gas is continuously produced in the lunar soil, the so-called regolith, by the decay of uranium. DORN will allow scientists to study the concentration of radon present on the Moon's surface.

The detector is equipped with several sensors for this purpose, said Romain Mathon, an engineer who helped develop DORN.

"We needed to remain in the mass and volume envelope which was allocated by our Chinese partners," he added.

Close cooperation between European and Chinese space agencies

DORN is not the only European scientific measuring device in the Chang'e-6 mission.

The European Space Agency (ESA) and the Swedish Institute of Space Physics also deployed a detector for negatively charged ions to gain valuable information about the interaction between solar wind and the lunar surface.

"We used instrumentation technology that had a high maturity, with a lot of experience in developing very similar fly hardware. The developing time for this instrument was very fast by our standards, usually we would take quite some more time," James Carpenter, ESA's head of planetary science research, told DW

Mathon, the engineer, stressed that it was a challenge to meet the deadlines set by the Chinese side, as everything had to be completed between 2019 and 2022, despite the difficulties posed by the COVID-19 pandemic.

Geopolitical concerns

However, ESA fears that increasing geopolitical tensions could jeopardize future space cooperation with China.

Karl Bergquist, head of ESA's international relations department, has been coordinating the ever-intensifying European-Chinese cooperation in space since the early 1990s.

There has been closer scientific as well as interpersonal links, he said.

However, he added, "there are much more geopolitical tensions today than just eight or nine years ago. So there are more and more restrictions."

He cited cooperation on the manned space program as an example. There had already been several joint astronaut training programs between ESA and the Chinese space agency.

But they have de facto been put on hold "due to export controls by third countries," Bergquist said.

This is because the US bans cooperation with the Chinese in space technologies and exploration, he noted.

"We in Europe will use a lot of US components that we use in our missions. And these are components that we can use here in Europe. But of course we cannot export."

Even the unmanned European-Chinese missions could be at risk if Beijing expands its cooperation with Russia, Bergquist said.

"After the Russian attack on Ukraine, there are a whole set of EU sanctions imposed on cooperation with Russia. Then there is the International Lunar Research Station, which is a Sino-Russian initiative," the ESA official said.

If the Chang'e-7 or Chang'e-8 mission is part of the ILRS, it will be "very difficult or actually impossible for Europe to cooperate," he added. 

ESA planetary expert Carpenter, nevertheless, still sees no problem in collaborating with Chinese scientists, with whom he has also built up good friendships.

"It's really fantastic to see how China's lunar program has grown and become world class. We feel privileged and happy to be part of it. We are also interested in further cooperation exploring the solar system."

This article was originally written in German.