Challenger

Challenger was an American space shuttle that blew up seventy-three seconds after take-off on 28 January 1986, killing all seven of its crew. The Eighth Doctor once said that its explosion affected the odds NASA gave for there being a "major problem" with their space shuttles. Before the explosion, NASA said there was a one-in-a-hundred-thousand chance of there being a malfunction; afterwards, those odds went up to one-in-a-hundred. (PROSE: Father Time)

When Isaac Summerfield II first met Joel Mintz in 1983, he asked him where he was when Challenger blew up. (PROSE: Return of the Living Dad)