Overview
- The peer‑reviewed study, published Wednesday in Science Advances, reports a previously unrecognized region shaped by Earth’s magnetism that reduces some cosmic rays at the Moon’s surface.
- Chang’e‑4 data across 31 lunar cycles show about a 20% drop in 9–34 MeV protons during the Moon’s local morning, and those lower‑energy particles are a major part of an astronaut’s skin dose.
- Researchers ran particle‑trajectory simulations and found a pattern that matches trends in NASA’s Lunar Reconnaissance Orbiter data, strengthening the case that Earth’s field deflects some incoming particles.
- The effect does not stop dangerous solar particle events, as Chang’e‑4 saw bursts that drove radiation to more than ten times normal levels late in the mission.
- Mission planners could use these lower‑radiation windows to time spacewalks and refine shielding needs, though procedures have not changed yet and models must be updated to reflect Earth’s farther‑reaching magnetic influence.