Rocket propellant research had its heyday in the mid-20th century, when the space race and the Cold War meant chemists had plenty of money and long leashes. Few of their most interesting ideas ended up in working rockets, but they charted new areas of chemical space, some of which, like boron chemistry, have proved useful in other fields. Geopolitical shifts, along with a growing emphasis on health, safety, and the environment, dampened propellant chemistry in the last decades of the 1900s. But the need for high-performance propellants hasn’t gone away, and neither has chemists’ interest in pushing the envelope. In this episode of Stereo Chemistry, we hear from chemists who lived through the heady days of the ’50s and ’60s and the ones carrying rocket chemistry’s torch today. A script of this episode is available here.  Music credits: “Leaving Earth” by Stanley Gurvich  “Plain Loafer” by Kevin MacLeod  Rocket launch sound illustration adapted from NASA audio  Image credit: NASA