The three Apollo 10 astronauts are zipping through the desolate expanse of space, the Earth a small blue marble behind them, on a mission poised to set the stage for one of humanity’s seminal achievements, when, suddenly, astronaut Tom Stafford called out from inside the cramped spacecraft: “Oh — who did it?” After some confusion, he repeated himself: “Who did it?” He was laughing. Then astronaut Gene Cernan spotted the source of the commotion: “Where did that come from?” “Give me a napkin quick,” Stafford said, horrified. “There’s a turd floating through the air.” Ah, the glamour of space travel....