Many of the scientists and mathematicians who worked on the project that carried the U.S. into space, to the moon, and eventually to Mars, were women.According to NPR, at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., women were essentially the calculators that charted the course to space in the 1940s.

In Nathalia Holt’s new book, Rise of the Rocket Girls: The Women Who Propelled Us, from Missiles to the Moon to Mars, she tells the story of these women, like Barbara Paulson. Paulson said that while her sisters prepared to be secretaries, she decided to put her math skills to use. In a time before computers, the Jet Propulsion Laboratory needed a team of people to do the calculations, and that’s where women like Paulson came in.

Paulson recalls being asked to graph the results coming in to the JPL from the Explorer 1 satellite, using only a mechanical pencil, graph paper, and a light table. But that was all she needed to determine that the satellite was exactly where they hoped it would be. “As I look back on so many things, I get more excited now than I did then. But it was exciting. I mean, it was great news that it was … in orbit around the Earth,” Paulson told NPR.

Holt said she hopes her book will inspire more young women to go into science and math fields. “In 1984, 37 percent of all bachelor’s degrees in computer science were awarded to women, and today that number has dropped to 18 percent,” she told NPR.

The women featured in Rise of the Rocket Girls were incredibly successful in the field of science, at a time when the majority of American women did not pursue careers at all. And what is even more impressive is that according to Holt, “There is hardly a mission that you can find in NASA that these women haven’t touched.”

To hear more often-overlooked stories about space exploration, be sure to check out Vintage Space.