Sally Ride was the first American woman in space, but her work on Earth meant just as much

Sally Ride in space in 1984.Space Frontiers/Getty Images

Today would have been Sally Ride's 64th birthday. Ride, who became the first American woman in space on June 18, 1983, died of pancreatic cancer in 2012. But she remains an iconic figure in science — in part due to her milestone but also because of her influential work on behalf of science education for kids.

What makes Ride's life story so intriguing is that she never had a pat explanation for her most famous accomplishment. In 1984, PBS's NOVA asked Sally Ride what had to be a common question at the time: "Why do you want to go into outer space?"

Instead of waxing philosophic about the honor of being the first American woman in space, seeing Earth from above, or any of the other possible PR-friendly answers, Ride's reply was refreshingly uncertain.

"I don't know what the reason is," she said. "It's just something that's inside people that they can't explain."

That answer defines what got her into space in the first place — a willingness to pursue her passion doggedly without hiding the mystery at its heart.

Sally Ride's relentlessness got her into space

NASA

Sally Ride leaving a training session in Houston.

The first time the New York Times mentioned Sally Ride, in 1969, the paper commented on her tennis game. At the time, Ride was a top-ranked tennis player at Swarthmore who, according to the Times, "dominated the match from the outset with deep forceful hitting."

Later, Ride left Swarthmore for Stanford and then earned a master's degree and PhD in physics. It seemed like she had a set career path. But, as she said in a 2011 speech, everything changed with a single newspaper ad.

A couple of months before earning her PhD, she was reading the Stanford Daily when she saw an announcement that NASA was looking for female astronauts. She applied that afternoon.

It wasn't luck that got her the job, but her PhD and academic interests that helped her beat out most of the other 8,000 applicants who vied for the position. Ride was one of just 35 women who made it into the first class of astronauts for the Space Shuttle program, embarking on six years of grueling astronaut training. (Though there were benefits — she joked that being an astronaut made it easier for her non-scientist dad to explain what she did for a living.)

NASA had to adjust to the idea of women in space. It had to add a locker room for the new class of female scientists, as well as update what went onto the Challenger Space Shuttle. Lynn Sherr's Sally Ride: America's First Woman in Space recalls one notable incident: when male NASA engineers asked Ride how many tampons she'd need for her one-week journey, they suggested 100. Ride gracefully replied that she wouldn't need quite that many. "We just want to be safe," the engineers replied. Despite those superficial hiccups, the mission was a success.

NASA

Sally Ride floating in space (she recommended weightlessness, if you had the chance to try it).

After the spaceflight, Ride was the focus of exhaustive media attention, but she kept her focus on work, going into space again in 1984, assisting in the Challenger Space Shuttle explosion investigation in 1986, and later becoming a special assistant to the NASA administrator.

Life in NASA was a high-intensity environment. As she said in 1984, "every day is different and every day is long." In 1987, on her 36th birthday, she left to move on to the next step in her career.

Sally Ride never became a celebrity — she was always a high-profile geek

Amy Graves/Getty Images

Sally Ride in 2009.

Ride left NASA to pursue her intellectual interests. In 1989, she became a physics professor at the University of California San Diego, and she even had a stint as president of Space.com from 1999 to 2000. She's probably best-known for her efforts with Sally Ride Science, an outreach company that encourages kids — and particularly girls and minorities — to consider careers in STEM (science, technology, engineering, and math) fields.

Sally Ride never acquired celebrity flair. Like Neil Armstrong, the first man on the moon, she was reserved about her accomplishments. Despite multiple attempts to draft her back into NASA administration, she didn't go back into the public eye at that level (though there are exceptions — she did appear on Touched by an Angel, but she played herself).

She compartmentalized her life in other ways, too. Only after Ride's death did it become public knowledge that Tam O'Shaughnessy was her partner of 27 years — making Ride the first known LGBT person in space as well as the first American woman. That sense of privacy wasn't surprising — throughout her public appearances, Ride remained soft-spoken, never flashy. Today, that consistency may ensure her legacy always includes her intellect, not just her courage.

Ride didn't open up her soul for public consumption with tell-all memoirs or reality show cameos. Yet what Ride revealed in that 1984 Nova interview held true throughout her life. She didn't know why she wanted to go to space, but she knew she couldn't change the curiosity that drove her.