The space shuttle Endeavor recently embarked on a 10-day mission with teacher Barbara Morgan aboard. She waited two decades for her chance to fly in space.
In 1986, Morgan was the alternate to Christa McAuliffe for NASA's Teacher in Space Program on Challenger's ill-fated flight. During launch, the shuttle exploded, killing all seven astronauts on board.
Endeavor's mission includes attaching a piece to the International Space Station and delivering 5,000 pounds of equipment and other materials to the ISS.
Sullivan took your questions about the difficulties and joys of spaceflight, the rigorous training and the challenges facing female astronauts in particular.
Sullivan became an astronaut in 1979 and the first American woman to walk in space in 1984. She has flown on three shuttle missions, including the 1990 Discovery flight that deployed the Hubble Space Telescope. She has logged more than 532 hours in space and in 2004 was inducted into the Astronaut Hall of Fame.
Currently, Sullivan is the director of the Battelle Center for Mathematics and Science Education Policy at Ohio State University's John Glenn School of Public Affairs.