Sally Ride was an exuberant, young physicist who became the first American female in space in 1983 and then spent decades inspiring girls to take up science.

Yet there was so much people didn't know, including the fact that she lived with another woman for 27 years.

(Simon and Schuster)

"There is no question in my mind that if Sally Ride had been openly gay and if she had applied to NASA, number one, she never would have been selected as an astronaut," said Lynn Sherr, who first met Ride while covering the shuttle program and has written a new biography on the astronaut. "Number two, she never would have flown and number three, she never would have been the first American woman in space."

Related: Sally Ride, the first woman in space, dies.

Ride died after a 17-month battle with pancreatic cancer in July 2012. She was 61 years old and had lived in California.

In 1983 and again in 1984, she flew as a mission specialist on the space shuttle Challenger, conducting experiments, operating the shuttle's robot arm - and breaking through a very high-altitude glass ceiling.

Sherr, a former ABC News correspondent and author of "Sally Ride: America's First Woman in Space," reveals many of Ride's secrets, including that the astronaut was so shy that she saw a shrink amid the hoopla over her first shuttle ride.

"She sacrificed a lot to be the public figure that we wanted her to be," Sherr said.

Despite her shyness, according to the biography, Ride attended a secret meeting with a Russian female cosmonaut at the height of the Cold War, against strict orders from the State Department.

And later, during the investigation into the Challenger explosion in 1986, Ride acquired and then leaked a key document showing that NASA management had prior knowledge of the faulty equipment believed to have led to the disaster.

"She was the person I thought she was," Sherr said. "But she was much more. She had so much more to her."

ABC News' Dan Harris and Ned Potter contributed to this report.