Jan. 28 marks the 35th anniversary of the space shuttle Challenger disaster, which killed all seven astronauts on board after exploding soon after lift-off.
The dead astronauts include pilot Michael Smith, Judith Resnik, Dick Scobee, Ronald McNair, Ellison Onizuka, Gregory Jarvis, and Christa McAullife.
Months after the disaster, the cause was revealed: O-ring seals failed, causing leaks in the right booster rocket. An investigation found some workers had warned NASA about the danger of launching Challenger because the O-rings grew brittle in cold weather. But NASA was under pressure to keep to its ambitious flight schedule and the risk was deemed acceptable.
