<p>Whether ship or mere simulator, the Apollo had so far impressed most people at NASA as a slapdash machine. It was temperamental, error-prone, and impossible to work with for more than a little while before something broke down.&nbsp;</p><p>TIME’s Jeffrey Kluger takes you through the Apollo 1 mission and the events that make it one of the most harrowing space missions of all time</p>

S1E4: Gus Grissom

Space does not wish you well. It has no shortage of ways to kill you, and in the fifty years humans have been flying spacecraft around the Earth and out to the moon, the mortal perils have been evident. But ten of the missions were the most harrowing of all. Some of them ended in tragedy, some ended successfully—but all of them involved astronauts playing for the very highest stakes in the very deadliest place.  Countdown tells the tale of those ten missions—some of them American, some Russian. Written and narrated by Jeffrey Kluger—author of Apollo 13 and Apollo 8—Countdown recreates the space crises that every astronaut has feared, and that an unlucky handful were forced to live.