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Radiation Levels on the Moon 200 Times Greater than on Earth, China's Chang'e-4 Lunar Lander Finds

SCMP, September 28, 2020

By Echo Xie

In this 3D illustration, astronauts place the Chinese flag on the surface of the moon, file, September 27, 2020

 

Findings come as various countries and entities are planning to put people on the lunar surface in coming decades Radiation exposure on moon would be 2.6 times greater than what astronauts are subjected to aboard International Space Station

With more nations planning to send people to the moon in the coming decades, a study by Chinese and German scientists has shown for the first time how much radiation astronauts will be exposed to on the lunar surface.

The result is an indicator of how much protective shielding future astronauts will need.

According to the new study, an astronaut will be exposed to an average daily dose of 1,369 microsieverts of radiation on the surface of the moon, or about 2.6 times more than the International Space Station crew’s daily dose.

The study was published in the peer-reviewed journal Science Advances on Friday.

The measurements were taken by the Chinese lunar lander Chang’e-4, which landed on the far side of the moon on January 3, 2019.

The “Lunar Lander Neutrons and Dosimetry” experiment, developed by Germany scientists, measured radiation during the lunar “daylight”, from January 3-12 and January 31 to February 10, 2019.

“The dosimeter’s placement inside the Chang’e-4 probe provides partial shielding, much as an astronaut’s spacesuit would to their body, so the findings are quite applicable to human explorers,” Robert Wimmer-Schweingruber, a physicist at the University of Kiel in Germany and co-author of the study, was quoted as saying by Science magazine.

The radiation levels measured on the moon per hour were about 200 times higher than on the surface of the earth, and five to 10 times higher than on a long-haul passenger flight from Frankfurt to New York, Wimmer-Schweingruber said in a statement.

“Since astronauts would be on the moon for much longer than passengers flying to New York and back, this represents considerable exposure for humans,” he added.

But astronauts can and should shield themselves as much as possible during longer stays on the moon, such as by covering their habitat with a thick layer of lunar soil, he said.

Space radiation is one of the major risks to astronauts’ health as chronic exposure to galactic cosmic rays could cause cancer, cataracts or degenerative diseases of the central nervous system or other organ systems, the study said.

It added that exposure to larger solar particle events with insufficient shielding may cause severe side effects.

The study’s findings come at a time when some nations are making long-term plans to land humans on the moon.

Last week, Nasa announced its intention to land the first woman and the next man on the moon in 2024 as part of the Artemis mission, which intends to send crews for long-term stays.

China plans to send astronauts to the moon before 2036, a senior People’s Liberation Army officer said in 2016.

If a manned mission departs to Mars, the new [moon] findings enable us to reliably estimate the anticipated radiation exposure in advanceRobert Wimmer-Schweingruber, physicist

At the time, Lieutenant General Zhang Yulin, deputy commander of the China Manned Space Programme, said it would take the country 15 to 20 years to land astronauts on the lunar surface.

The findings are also important for future interplanetary missions. Since the moon has neither a protective magnetic field nor an atmosphere, the radiation on the surface of the moon is similar to that in interplanetary space, apart from the shielding by the moon itself, according to scientists.

“The measurements in the study can be used to review and further develop models that can be used for future missions,” Wimmer-Schweingruber said. “For example, if a manned mission departs to Mars, the new findings enable us to reliably estimate the anticipated radiation exposure in advance.”

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Echo Xie is a Beijing-based reporter focusing on Chinese politics and policy. She joined the Post in 2019. Previously, she worked for CSMonitor Beijing Bureau and Jiemian news. She has a master's in journalism from Shantou University.

https://www.scmp.com/news/china/science/article/3103241/radiation-levels-moon-200-times-greater-earth-chinas-change-4 

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