Cosmic-ray “cavity” between Earth and Moon could reshape lunar missions

A study using data from China’s Chang’e-4 lander identifies a region of reduced galactic cosmic-ray radiation in Earth–Moon space—a cavity that appears during the Moon’s local morning. The lower-energy protons drop by about 20% in this window, likely caused by Earth’s magnetosphere extending farther than previously thought. If confirmed, this timing could help plan safer lunar surface operations for upcoming missions (including Artemis II) by reducing astronauts’ radiation exposure. The findings are published in Science Advances (2026).