NASA-UAP-D022, Gemini 9 Debriefing, 1966 

Gemini IX (renamed Gemini IX-A) was the seventh crewed flight of the Gemini series, launched on June 3, 1966. The mission’s primary objectives included a spacewalk and multiple scientific and medical experiments. This document, dated June 16, 1966, is a transcript of a NASA debriefing of astronauts Thomas Stafford and Eugene Cernan. Pages 2-5 of this document contain the astronauts’ accounts of their observations of “flashing lights” and “sparkles” during the mission.