Summary
About one hour and 41 minutes into the final Project Mercury flight, Faith 7 pilot Gordon Cooper notes seeing "John's fireflies," a reference to John Glenn's term from an earlier Mercury mission. NASA later determined the fireflies were frozen condensation separating from the spacecraft, whose white, green-hued appearance came from sunlight reflecting off the ice.
Detail
Mercury-Atlas 9 (MA-9), call sign Faith 7, was the final and longest flight of Project Mercury. Approximately one hour and 41 minutes into the mission, pilot L. Gordon Cooper Jr. noted that he could see "John's fireflies," referring to the term John Glenn had coined during the earlier Mercury-Atlas 6 mission.
NASA later determined that the "fireflies" were frozen condensation separating from the spacecraft body, and that their white, green-hued appearance resulted from sunlight reflecting off the frozen condensation.
This audio excerpt was released through the PURSUE declassification.
