Her five space shuttle flights include the Discovery mission in May 1999 for the first docking with the International Space Station (ISS). She has logged more than 1 512 hours in space and nearly eight hours of extravehicular activity. She next served as the lead astronaut for ISS external maintenance before leaving NASA. Jernigan served as a research scientist at NASA's Ames Research Center from 1981 to 1985, when she was selected as an astronaut.