Jernigan began working for NASA in June 1981 at the Ames Research Center while earning her degrees at Stanford and Berkeley.
She worked in the Theoretical Studies Branch as a research scientist until June 1985 when she was among the 13 people selected as astronaut candidates.

She entered the NASA Astronaut Corps in July 1986.
Her first trip to space was on June 5, 1991.
She flew on five Space Shuttle program missions (three on Columbia and one each on Endeavour and Discovery) and logged over 1512 hours in space.
In her last mission on  Discovery in 1999, she performed an extra-vehicular activity for 7 hours and 55.5 minutes.

Jernigan has served as Deputy Chief of the Astronaut Office, assisting with the management of both military and civilian astronauts and support personnel and as Deputy for the Space Station program where she developed and advocated Astronaut Office positions on the design and operation of the International Space Station.
She also represented NASA management on the U.S. negotiating team in Moscow during technical interchange meetings designed to resolve crew training, crew rotation, and operational issues.

Jernigan retired from NASA in 2001 and currently serves as Deputy Principal Associate Director in the Weapons and Complex Integration (WCI) organization at Lawrence Livermore National Laboratory.
Jernigan began working for NASA in June 1981 at the Ames Research Center while earning her degrees at Stanford and Berkeley. She worked in the Theoretical Studies Branch as a research scientist until June 1985 when she was among the 13 people selected as astronaut candidates.
She entered the NASA Astronaut Corps in July 1986. Her first trip to space was on June 5, 1991. She flew on five Space Shuttle program missions (three on Columbia and one each on Endeavour and Discovery) and logged over 1512 hours in space. In her last mission on  Discovery in 1999, she performed an extra-vehicular activity for 7 hours and 55.5 minutes.
Jernigan has served as Deputy Chief of the Astronaut Office, assisting with the management of both military and civilian astronauts and support personnel and as Deputy for the Space Station program where she developed and advocated Astronaut Office positions on the design and operation of the International Space Station. She also represented NASA management on the U.S. negotiating team in Moscow during technical interchange meetings designed to resolve crew training, crew rotation, and operational issues.
Jernigan retired from NASA in 2001 and currently serves as Deputy Principal Associate Director in the Weapons and Complex Integration (WCI) organization at Lawrence Livermore National Laboratory.
Tamara E. Jernigan