ISS Astronauts See Cosmic-Ray Light Flashes Every Few Minutes, Highlighting Mars Radiation Risk
Updated
Updated · spacedaily.com · Jun 23
ISS Astronauts See Cosmic-Ray Light Flashes Every Few Minutes, Highlighting Mars Radiation Risk
2 articles · Updated · spacedaily.com · Jun 23
Summary
ISS astronauts regularly report brief flashes or streaks of light with their eyes closed—an effect traced to cosmic rays passing through the eye and visual system.
Apollo crews first described the phenomenon in 1969, and later missions counted roughly one flash every few minutes after dark adaptation in the cabin.
Mir and ISS experiments including SilEye and ALTEA matched astronauts' reports with silicon detector data, linking the flashes to energetic protons and heavy nuclei.
Researchers say the particles can either ionize the retina directly or create Cherenkov light in the eye's fluid, though the exact balance between those pathways remains under study.
The flashes are a visible sign of the broader radiation hazard in space, one expected to intensify on Mars missions beyond Earth's magnetic shielding.
With cosmic rays proven to damage brain cells, what is the true neurological cost of sending humans to Mars?
Could living fungi provide the ultimate radiation shield for future Mars-bound spacecraft?
Can Organ Chips on Artemis II lead to personalized medicine that reverses radiation damage in astronauts?
Measuring Space Radiation: The Science Behind Astronaut Light Flashes and Mitigation for Mars Missions
Overview
Astronauts on long missions often see flashes and streaks of light, even with their eyes closed. These flashes are caused by single cosmic-ray particles passing through living tissue, especially the eye, creating visible tracks. About 80 percent of NASA and ESA astronauts have reported this experience. Scientists believe high-energy particles from cosmic rays may directly stimulate light-sensitive cells in the eye, but the exact mechanism is still under investigation. The health impact of these flashes during extended space travel is not fully understood, making this a key area for ongoing research as we plan future deep space missions.