Sally K. Ride, the first American woman in space and an advocate for science education who served on the presidential commissions that investigated the Challenger and Columbia shuttle disasters and another that recommended a shift to commercial manned spaceflight, died July 23 after a bout with pancreatic cancer. She was 61.

Photo: NASA.

"Sally Ride died peacefully on July 23rd, 2012 after a courageous 17-month battle with pancreatic cancer," according to a statement on the Sally Ride Science website. "Sally lived her life to the fullest, with boundless energy, curiosity, intelligence, passion, joy, and love. Her integrity was absolute; her spirit was immeasurable; her approach to life was fearless."

In a statement released by the White House, President Obama said "Michelle and I were deeply saddened to hear about the passing of Sally Ride. As the first American woman to travel into space, Sally was a national hero and a powerful role model. She inspired generations of young girls to reach for the stars and later fought tirelessly to help them get there by advocating for a greater focus on science and math in our schools.

"Sally's life showed us that there are no limits to what we can achieve and I have no doubt that her legacy will endure for years to come. Our thoughts and prayers go out to Sally's family and friends."

Said NASA Administrator Charles Bolden, a former shuttle commander: "Sally Ride broke barriers with grace and professionalism -- and literally changed the face of America's space program."

"The nation has lost one of its finest leaders, teachers and explorers," he said in a statement. "Our thoughts and prayers are with Sally's family and the many she inspired. She will be missed, but her star will always shine brightly."

Most recently the president and CEO of Sally Ride Science, the former shuttle astronaut held a doctorate in physics and was one of the initial group of six women selected by NASA in 1978 to train for upcoming shuttle flights. Joining Ride were Shannon Lucid, Rhea Seddon, Kathryn Sullivan, Judy Resnik and Anna Fisher.

Valentina Tereshkova, a Russian cosmonaut, became the first woman to fly in space in 1963. But in the U.S. space program, NASA astronauts were chosen primarily from the ranks of military test pilots and through the Mercury, Gemini and Apollo programs they were all male.

But with the space shuttle, NASA created a new class of astronaut, the "mission specialist," and opened the door to non pilots with advanced degrees and professional experience in science and high technology.

Ride was a perfect fit, seeming to embody the "right stuff" image of an astronaut with easy grace and a ready smile that endeared her to millions.

After serving as a mission control "capsule communicator," or CAPCOM, for two missions, Ride rocketed into history as the first American woman in space on June 18, 1983, when she blasted off aboard the shuttle Challenger for mission STS-7, a six-day flight to deploy two communications satellites and to launch and retrieve a small science satellite.

Ride became instantly famous, a role model for women and young girls around the world, breaking through the ultimate glass ceiling and into the previously male world of the astronaut corps.

"The fact that I was going to be the first American woman to go into space carried huge expectations along with it," Ride said in a NASA interview marking the 25th anniversary of her first flight. "That was made pretty clear the day that I was told I was selected as a crew. I was taken up to Chris Kraft's office. He wanted to have a chat with me and make sure I knew what I was getting into before I went on the crew. I was so dazzled to be on the crew and go into space I remembered very little of what he said.

"On launch day, there was so much excitement and so much happening around us in crew quarters, even on the way to the launch pad," she said. "I didn't really think about it that much at the time -- but I came to appreciate what an honor it was to be selected to be the first to get a chance to go into space."

During a meeting at the White House later, President Ronald Reagan said, "Let me just remind you when we had lunch here in the white house before your flight that somebody said sometimes the best man for the job is a woman. You were there because you were the best person for the job."

Ride blasted off a second time in 1984, using the Challenger's robot arm to launch an Earth observation satellite. She logged some 343 hours in space during her two missions and had been named to a third flight when the shuttle program was grounded in the wake of Challenger's destruction on Jan. 28, 1986.

Ride was selected to serve on the Presidential Commission on the Space Shuttle Challenger Accident, chaired by former Secretary of State William Rogers, a panel that included such luminaries as Nobel prize winning physicist Richard Feynman and Apollo 11 commander Neil Armstrong, the first man on the moon.

Ride was still an active-duty astronaut when the panel did its work in the spring of 1986 and her grilling of NASA engineers about a long history of O-ring problems like the failure that doomed Challenger was memorable. She could not hide her amazement that mid-level NASA managers approved continued shuttle flights despite a known, potentially fatal defect.

Ride left the astronaut corps and resigned from NASA in 1987, becoming a science fellow at the Center for International Security and Arms Control at Stanford University. She joined the physics department at the University of California-San Diego in 1989 and served as director of the California Space Institute.

Long an advocate for science and math education, Ride set up Sally Ride Science in 2001 "to pursue her long-time passion for motivating young girls and boys to stick with their interests in science and to consider pursuing careers in science, technology, engineering, and math," her website said in its statement.

Ride was the co-author of seven science books aimed at children and helped organize the GRAIL MoonKAM program, letting kids in classrooms around the country take pictures of the lunar surface with a NASA satellite currently in orbit around the moon.

Ride was married to shuttle astronaut Steven Hawley in 1982, but the couple divorced in 1987. Her website said Ride was survived by her companion, Tam O'Shaughnessy, her mother, Joyce, a sister a niece and a nephew.

"She had the rare ability to understand the essence of things and to inspire those around her to join her pursuits," her website said.

"Sally's historic flight into space captured the nation's imagination and made her a household name. She became a symbol of the ability of women to break barriers and a hero to generations of adventurous young girls."