The Mercury 7 might have had the right stuff and made the headlines, but behind the scenes 13 women were being tested to become astronauts. This hidden history of the fight for women astronauts is uncovered in Rebecca Siegel’s new book “To Fly Among the Stars.” We’ll speak with Siegel about the program and the lasting impressions these women left on the trajectory of gender equality in space flight.

Then, as astronomers discover more and more planets outside our solar system, how do we know what they’re made of? Our panel of expert scientists answer a listener question about uncovering the stuff that makes a planet and what’s hidden on its surface — that’s on this week’s “I’d Like to Know” segment.