Christina Birch, 35, of San Pedro beat out some 12,000 other applicants to be part of the agency's next class of 10 astronauts.
Birch earned a doctorate in biological engineering from MIT and taught at UC Riverside and Caltech.
She is also an accomplished cyclist, who earned two medals at the Pan-American Games.
She begins her two years of astronaut training next month.
Including the 10 new members of the 2021 class, NASA has selected only 360 astronauts since the start of the space program with the original Mercury Seven in 1959.