Space Radiation Environment
Background
The radiation environment in cislunar space directly affects spacecraft design, mission planning, and astronaut safety. Primary radiation sources include galactic cosmic rays (GCR), solar energetic particles (SEP), and secondary particles deflected by Earth's magnetic field. Understanding the radiation distribution in cislunar space is critical for crewed lunar landing and long-duration habitation missions.
Research Areas
- GCR distribution characteristics in cislunar space
- Cislunar radiation shielding effects
- Radiation dose assessment for crewed missions
- Radiation environment forecasting and early warning
Cislunar Galactic Cosmic Ray Cavity
A 2026 study discovered regions of significantly reduced GCR flux ("GCR cavity") in cislunar space, with direct implications for crewed lunar mission planning.
Representative Publications
[1] Shang W, Liu J, Xu Z, et al. A galactic cosmic ray cavity in Earth-moon space[J]. Science Advances, 2026, 12(13): eadv1908.
Based on LND (Lunar Lander Neutron and Dosimetry) experiment data from the Chang'e-4 lander, this study analyzed 31 lunar cycles of GCR measurements and found that when the lunar orbit is on the dawn side (prenoon sector, LP = 8-10 h_M), GCR flux in the 9-34 MeV energy channel decreases by approximately 20 +/- 7%. Mechanism: Under the Parker spiral configuration, when the Moon is on the dawn side, the interplanetary magnetic field (IMF) lines align with the Earth-Moon connection, and low-energy particles (gyroradius ~14-27 Earth radii) are deflected by Earth's magnetic field, forming a radiation depletion zone. Simulation results are consistent with LND and CRaTER data. The team estimates the Moon passes through this low-radiation window for about two days per orbit, and scheduling extravehicular activities during this window can significantly reduce radiation exposure. This finding extends the influence of Earth's magnetic field to the dayside beyond lunar orbit (~60 R_E).
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