Apollo 17 Crew Medical Debriefing, 1972
An audio recording of Apollo 17 astronauts debriefing NASA doctors about something that genuinely puzzled them: flashes of light appearing in their vision during the mission, even with their eyes closed. What they were experiencing was cosmic rays passing directly through the eye and hitting the retina — a strange biological effect that this era of deep-space missions helped establish as real and measurable. It's a rare firsthand account of astronauts trying to describe, in real time, a phenomenon that science was still catching up to.
This file contains segment 1 of 2 of the Apollo 17 post-mission medical debriefing at the Manned Spacecraft Center (now Johnson Space Center), Houston, Texas. In the recording, crew members discuss the “light flash phenomena,” a then novel, now well-documented biological effect where high-energy cosmic rays pass through the eye and strike the retina, causing the perception of light streaks or flashes. Two of the three crew members reported observing these flashes at various points during the mission, including in lunar orbit and while on the lunar surface. The debriefing continues in the next file (NASA-UAP-D029).