After the most trouble-free countdown of Project Mercury to date, Carpenter flew into space on May 24, 1962, watched by 40 million television viewers. He performed five onboard experiments per the flight plan, and became the first American astronaut to eat solid food in space. He also identified the mysterious "fireflies" observed by Glenn during "Friendship 7" as particles of frozen liquid loosened from the outside of the spacecraft, which he could produce by rapping on the wall near the window. He renamed them "frostflies."