Sally Ride was a 27-year-old Ph.D. candidate, looking for postdoctoral work in astrophysics, when an item in the Stanford University newspaper caught her eye. NASA was looking for astronauts. She was one of only six women to be accepted, out of 8,000 applicants. She joined NASA in 1977, and underwent years of rigorous physical and scientific training. In 1983 she became the first American woman in space, flying a six-day mission on the Space Shuttle Challenger. Her second mission lasted…