On January 28, 1986, the Space Shuttle Challenger broke apart 73 seconds after launch, killing all seven astronauts aboard. This episode of the What Went Wrong series reconstructs the failure of the right solid rocket booster's O-ring seals, using launch footage, engineering diagrams, and interviews to walk through how cold weather at Kennedy Space Center compromised the rubber seals meant to contain the booster's burning gases. It covers the warnings raised by Morton Thiokol engineers the night before launch, who argued the O-rings might not seal properly in the near-freezing temperatures, and the management decisions that overrode them. The film traces the problem back through earlier flights, where damaged O-rings had already been observed and downplayed, arguing that commercial pressure to keep the Shuttle program's launch schedule pushed known risks aside. The result was the destruction of the orbiter and the deaths of its crew, and a program grounded for over two years while the cause was investigated.