During Apollo 7, astronaut Donn Eisele's sextant star sightings were sometimes obscured by flurries of vented, frozen urine crystals.
Notes on verification
Confirmed by NASA official mission history, Astronautix (citing 'Chariots for Apollo'), Wikipedia (citing French & Burgess), and a contemporaneous 1968 retrospective, all converging on the same fact. [cascade flags: wikipedia_dropped_other_sources_exist | tier=silver indep_score=0.867 clusters=3 claim_tier=notable]
Sources
- The Flight (and Fights) of Apollo 7 - Smithsonian Magazine (seed:science_and_space)
- http://www.astronautix.com/a/apollo7.html (corroboration)
- https://www.nasa.gov/missions/apollo/about-apollo-7-the-first-crewed-apollo-space-mission/ (corroboration)
- https://galacticjourney.org/october-26-1968-phoenix-from-the-ashes-apollo-7/ (corroboration)