The Space Transportation System launched like a rocket, worked in orbit for up to two weeks as a laboratory and construction site, and glided home as an unpowered airplane. This episode traces the Space Shuttle from its origins in the post-Apollo budget squeeze, when Max Faget’s vision of a fully reusable two-stage space plane collided with U.S. Air Force demands for a 60-foot payload bay and 29,000-kilogram lift capacity for spy satellites. We explain why eastward launches carry more than polar ones and how that compromise shaped a vehicle that could never be the cheap space taxi it was promised to be.

From there we get into the hardware: solid rocket boosters that could not be shut off, RS-25 engines running at 104 percent of their original rating, throttling down through Max-Q, 30,000 silica tiles that stayed cool enough to touch, and five redundant flight computers that voted on every decision. We cover the Canadarm, the evolving crew suits, the year-end rollover bug that kept the shuttle grounded over New Year’s until 2007, and the cultural failures behind the Challenger and Columbia disasters, ending with the program’s retirement in 2011 after 135 missions.

• How Air Force payload requirements and Nixon’s 1972 approval locked in the shuttle’s bulky three-part design
• What happens during ascent: 71.4 percent of thrust from the SRBs, cryogenic propellants, and engine throttling to survive maximum aerodynamic pressure
• The thermal protection system and the fly-by-wire General Purpose Computers with a separately coded backup
• The O-ring failure on Challenger, the foam strike on Columbia, and the normalization of deviance identified by sociologist Diane Vaughan
• Why the shuttle lacked a launch escape system and how its retirement left the U.S. dependent on Soyuz until Crew Dragon in 2020