Three Skylab 2 astronauts — Commander Charles Conrad, Science Pilot Joseph Kerwin, and Pilot Paul Weitz — reported experiencing recurring light flashes during their 1973 mission, according to a declassified NASA technical crew debriefing conducted on June 30, 1973, at the Lyndon B. Johnson Space Center in Houston. The document, prepared by the Training Office of the Crew Training and Simulation Division, records the crew's structured account of unusual visual phenomena observed during orbital flight.
What the Crew Observed
The debriefing transcript captures a detailed exchange in which all three crew members confirmed independently experiencing the flashes, though each described them somewhat differently. Kerwin noted they occurred most often while he was lying awake in the dark with his eyes closed, and that their frequency varied over time.
"I saw them most often when I was in the sack at night with my eyes closed but awake naturally. They tended to wax and wane in frequency... They were numerous at times — two or three per minute." — Joseph Kerwin, Skylab 2 Science Pilot
Conrad described a variety in the character of the flashes, distinguishing between localized spots or "sunbursts" and linear streaks, with the latter being comparatively rare.
"Some of them to me were a spot or sunbursts. Some were streaks. The streaks, in my case, were less frequent than the bursts. Most of them were in my peripheral visual field. Very few in the central visual field." — Charles Conrad, Skylab 2 Commander
Weitz added a detail consistent with what would later be understood as cosmic particle traversal of the eye: the perception of paired entry and exit flashes.
"I had a couple that I thought were cosmic particles. I saw an entrance streak and an exit streak. Where, bing-bing, it seemed like it was one side of the eyeball, and then the other side." — Paul Weitz, Skylab 2 Pilot
Conrad corroborated this, recalling instances in which a long streak was followed by a brief gap and then another long streak in rapid succession — consistent with a charged particle passing through ocular tissue.
Laterality, Localization, and Misidentification Risk
A portion of the debriefing focused on whether the crew could determine which eye was producing the flashes. The exchange reveals a degree of scientific self-reflection among the astronauts. Conrad indicated that with concentration it was possible to isolate the flashes to one eye; Weitz said his appeared primarily in the left eye. Kerwin, by contrast, acknowledged he had not attempted to make the determination during the mission.
"I did not. That was foolish of me but I didn't try. I'm sure they are in one eye." — Joseph Kerwin
The crew also flagged a practical operational concern: the light flashes could be confused with the spacecraft's fire sensor indicator lights. According to the transcript, Conrad described occasionally mistaking a sensor wink for an internal visual event while resting with his eyes half closed. Kerwin noted that after sufficient exposure to both phenomena, crew members could distinguish between them.
"Once you've seen a few of each, there is question of which is which. They're not an hallucination." — Joseph Kerwin
Kerwin's explicit clarification that the flashes were not hallucinations reflects the crew's evident awareness that such reports required grounding in physiological plausibility — and perhaps anticipates the scrutiny such accounts would receive.
Disclosure Timing and Scientific Context
The debriefing reveals that the crew did not report the light flashes in real time during the mission. Kerwin stated the crew had judged it operationally unnecessary to surface the information during flight.
"We didn't feel it was operationally necessary for anybody to know about it right now." — Joseph Kerwin
A questioner during the debriefing raised the possibility that the frequency of flashes correlated with passes through the South Atlantic Anomaly — a region of weakened geomagnetic shielding known to increase cosmic radiation exposure for low-Earth-orbit spacecraft. Kerwin acknowledged he lacked the data to confirm or rule out the correlation. According to the debriefing document, no formal tracking instrument was in use during the periods when the flashes were observed.
The phenomenon the Skylab 2 crew described — now referred to in spaceflight medicine literature as cosmic ray visual phenomena (CRVP) or light flashes — is understood to result from heavy ions or high-energy particles interacting directly with retinal cells or the optic nerve, producing phosphene-like perceptions without any external light source. The Skylab 2 account represents one of the earlier structured crew debriefings on the subject in the American spaceflight program, predating the more systematic studies that would follow on later long-duration missions.