Chinese lander reveals giant ‘cavity’ of radiation between Earth and the moon — and it could change how lunar exploration is done
Could being a “morning person” improve your health… on the Moon? Scientists have identified what appears to be a “cavity” of reduced cosmic radiation near Earth’s Moon. This discovery could help reduce astronauts’ exposure to harmful radiation on future lunar missions by scheduling certain surface operations for local morning times.
The discovery, based on data from China Chang’e-4 lunar landersuggests that Earth’s magnetic field could affect distances in space further than scientists previously expected. According to the researchers, this discovery challenges the long-standing hypothesis that galactic cosmic rays are almost uniform throughout the space between the Earth and the Moon, outside the protective magnetic field of our planet.
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Cosmic rays pose one of the most significant radiological hazards to astronauts traveling beyond low Earth orbit. These high-energy particles can penetrate spacecraft and human tissues, damaging DNA and increasing the risk of cancer. With more crew trips planned to the Moon, starting with NASA’s Artemis II With the mission launching as early as April 1, researchers said a better map of radiation intensity could help mission planners reduce astronauts’ radiation exposure during surface explorations.
“The next landings will probably take place in the polar regions”, which can be permanently sunny, Robert Wimmer-Schweingruberprofessor at the Institute for Experimental and Applied Physics at the University of Kiel in Germany and corresponding author of the study, told Live Science in an email. He added that lunar morning appears to be the best time to take excursions because it reduces the amount of radiation on astronauts’ skin by about 20 percent compared to average radiation levels on the Moon.
Calculate cosmic rays
I didn’t expect to see this “shadow” or this cavity,
Robert Wimmer-Schweingruber, professor at the Institute of Experimental and Applied Physics at the University of Kiel
To find this cosmic ray cavity, researchers analyzed data collected over 31 lunar cycles from January 2019 to January 2022, focusing on quiet periods on the planet. solar cyclewhen the measured space radiation came mainly from galactic cosmic rays. They looked for repeated changes in the number of protons measured by Chang’e-4 from the rays as the Moon moved through different parts of its orbit around Earth.
The Lunar Lander Neutron and Dosimetry instrument recorded protons from galactic cosmic rays in two energy ranges, which the researchers then grouped by lunar local time. They found that the lowest energy protons, in the range 9.18 to 34.14 megaelectronvolts, dropped by about 20% during the Moon’s local morning, during the waxing gibbous phase of the moon (in the period between a new moon and a full moon) compared to later times.
Because the dimming appeared in a specific, recurring part of the Moon’s waxing phase rather than all of time, the team inferred that the Moon was passing through a true region of reduced cosmic radiation, which they believed had been created as Earth’s magnetic field blocked some high energy protons. To study this idea, they performed simulations of the movement of protons in the Moon’s orbit and discovered the same cavity.
“I didn’t expect to see this ‘shadow’ or cavity,” Wimmer-Schweingruber said. “In retrospect, it seems completely logical, but I was very skeptical when I first saw this result,” and that’s why the team did so much testing, he added.
Expanding Earth’s magnetic influence
The results provide a new picture of the behavior of cosmic radiation between the Earth and the Moon. Scientists generally believed that once galactic cosmic rays passed through Earth’s magnetosphere, they were distributed fairly evenly throughout Earth-Moon space and were only minimally affected by Earth’s magnetic field.
“Basically, this result means that the Earth’s magnetosphere influences space even beyond its extension,” said Wimmer-Schweingruber. The team expected the Earth to affect the Moon in the future. magnetic tailthe long magnetic field flow extending from the sun to the night side of Earth, he noted, but they did not predict a similar effect ahead of the magnetosphere on the solar side.
Wimmer-Schweingruber said future studies with larger data sets could better define the size and behavior of this cavity, which could pave the way for a more practical era of lunar exploration. He suggested that a familiar rule of thumb might apply for safer lunar missions: It is “best for astronauts to venture onto the lunar surface at local morning hours,” Wimmer-Schweingruber said – “just like it is for humans on Earth!”
Shang, W., Liu, J., Xu, Z., Yue, C., Guo, R., Xiao, C., Shi, Q., Wimmer-Schweingruber, R., Guo, J., William, DA, Rankin, R., Tian, A., Zong, Q., Han, C., Park, J., Wang, H., Liu, W., Fu, S., Zhai, LM, . . . Chen, T. (2026). A galactic cosmic ray cavity in Earth-Moon space. Scientific advances. 12(1), eadv1908. www.science.org/doi/10.1126/sciadv.adv1908
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