Astronaut Scientific Debriefings, 1962-1963

When John Glenn reported luminous specks around his Mercury capsule in 1962, the sighting became a small scientific problem in its own right. This file gathers memoranda, letters, reports and interview transcripts from the scientists and NASA staff who tried to work out what Glenn, and later Wally Schirra, had seen. It is the paper trail behind the “fireflies” story.

What the file contains

The core is NASA’s interviews and debriefings with the two astronauts about their observations. Around them sit scientific materials on atmospheric phenomena, short descriptions of luminous particles, notes on what it was like aboard the spacecraft, and a circa-1955 theoretical study of how meteor particles behave as they enter the atmosphere — suggesting natural sources were among the possibilities considered.

Only parts of the large file are relevant: NASA points readers to five page ranges, beginning at 34–35 and ending at 122–127; the biggest block, 64–113, runs to about fifty pages.

How it resolved

The investigation’s eventual answer appears elsewhere in the release. NASA concluded the fireflies were frozen condensation coming off the spacecraft, as its note on Gordon Cooper’s Faith 7 audio explains. Schirra’s own on-orbit description of “lathe shavings” coming from the capsule is in his Sigma 7 recording, and Scott Carpenter’s Aurora 7 “snowflakes” sit between the two flights. This file documents the inquiry that came before that conclusion.