Sarah Gillis is an American aerospace engineer and commercial astronaut renowned for her pivotal role in advancing private spaceflight. Born on January 1, 1994, in Palo Alto, California, and raised in Boulder, Colorado, she cultivated a passion for music, particularly the violin, from an early age. Her trajectory shifted when former NASA astronaut Joe Tanner inspired her to pursue aerospace engineering. Gillis earned her Bachelor of Science in Aerospace Engineering from the University of Colorado Boulder in 2017. While still a student, she interned at SpaceX in 2015, focusing on human-in-the-loop testing of the Dragon spacecraft. Post-graduation, she joined SpaceX full-time, eventually becoming the Lead Space Operations Engineer responsible for overseeing astronaut training programs for both NASA and commercial missions, including the historic Demo-2, Crew-1, and Inspiration4 flights .

In September 2024, Gillis served as a mission specialist on Polaris Dawn, a groundbreaking private spaceflight operated by SpaceX. During this mission, she and commander Jared Isaacman performed the first commercial spacewalk, making Gillis the youngest person to do so at age 30 . The crew reached an apogee of 870 miles, the farthest humans have traveled from Earth since the Apollo era, setting a new record for women in space alongside crewmate Anna Menon . A classically trained violinist, Gillis also performed John Williams' "Rey's Theme" aboard the Dragon spacecraft, marking the first live violin performance in space. This event was part of a global collaboration to inspire unity through music and support charitable causes .