When Mae Jemison was a little girl, she dreamed of blasting off into space on a rocket ship. She was so excited as she watched the Apollo Moon landings, but she wondered why none of the astronauts were women. Mae loved science and was so bright that she started college at just 16, and was training to be a doctor by the age of 20. She joined the Peace Corps, using her medical knowledge to help people in countries all around the world. Upon returning to the United States, she was accepted into NASA's astronaut program.