The first female American astronaut, Sally Ride, has succumbed to cancer.

Ride was age 61. She had battled pancreatic cancer for 17 months.

According to her website, SallyRideScience.com, her death was peaceful.

Ride was selected by NASA as an astronaut candidate in 1978. She flew on the space shuttle Challenger for STS-7 in 1983. Her second and final flight was 1984. She retired from NASA in 1987.

She would later become a professor of physics, director of the California Space Institute and founder of a self-named company dedicated to encouraging young people to study science.

President Barack Obama is calling her a national hero and a "powerful role model". In a statement, the president says Ride "inspired generations of young girls to reach for the stars" and "fought tirelessly to help them get there by advocating for a greater focus on science and math" in the nation's schools.

"The space community, teachers and students around the world have lost a great friend and role model," said Space Foundation CEO Elliot Pulham. "Sally was more than a trailblazing astronaut and brilliant scientist. She was deeply concerned about the state of education in the United States, and worked tirelessly to reach students, especially at-risk young women, with programs filled with hope and inspiration -- to enable our next generation of explorers."

In addition to Tam O’Shaughnessy, her partner of 27 years, Sally is survived by her mother, sister, niece and nephew.