In 1965, when astronaut Ed White became the first American to walk in space, mission control had to tell him at least twice times to come inside. “It’s the saddest moment of my life,” he said, as he climbed back inside his Gemini IV spacecraft after just 20 minutes of floating free. In the 19 years that followed, walking in space was a singular joy no American female had ever experienced, but that ended during the October 1984 flight of the space shuttle Challenger, when Kathryn Sullivan stepped outside for 3-1/2 hours of hard, zero-g work. For many Americans, the idea of a spacewalk had long since lost its novelty, but for American women, Sullivan’s achievement was one more critical step in the slow leveling of the space playing field.