Sally Ride, the first American woman to slip the surly bonds of Earth and fly in space, died Monday after a 17-month bout with pancreatic cancer. She was 61.

Ride, who held a Ph.D. in physics from Stanford University, was selected as an astronaut candidate by NASA in January 1978. She worked in ground-based communications before serving as a crew member aboard two Space Shuttle Challenger missions in 1983 and 1984. She also served on a Presidential Commission that investigated the 1986 Challenger accident.

In 2001, Ride founded Sally Ride Science, a company aimed at encouraging girls and young women to pursue science, math and technology careers.

Her integrity was absolute; her spirit was immeasurable; her approach to life was fearless, Sally Ride Science said in a statement Monday.

Ride is survived by Tam O'Shaughnessy, her partner of 27 years; her mother Joyce; her sister Bear; her niece Caitlin; and her nephew Whitney.