During Mercury-Atlas 7, Aurora 7 pilot Scott Carpenter describes white particles that move at random and look exactly like snowflakes. He characterizes them as reflective, noting that some appeared to move faster than the spacecraft itself.
Mercury-Atlas 7 (MA-7), call sign Aurora 7, was the fourth crewed spaceflight and second orbital flight of Project Mercury. During the mission, pilot Scott Carpenter described white particles in view that appeared to move at random and looked exactly like snowflakes.
Carpenter characterized the particles as reflective, and noted that some of them seemed to move faster than the Aurora 7 spacecraft.
This audio excerpt was released through the PURSUE declassification.