Editor's note: John Zarrella was the CNN network correspondent on site when the 1986 Challenger shuttle disaster occurred. He recalls that day:
When I went to the Kennedy Space Center on January 28, 1986, to cover the launch of the space shuttle Challenger, I was expecting it to be routine, like the launches I had covered in the past. The only thing different this time was the excitement that surrounded the first teacher-turned-astronaut, Christa McAuliffe.
It was brutally cold, and the weather caused the launch to slip several times during the morning. Just before launch, I walked down to the countdown clock, as was tradition among the journalists, and waited for liftoff. I remember that typical winter clear-blue sky as Challenger took off.
A little more than a minute into the launch, from where I was standing, you could see a cloud of smoke and then what looked like fireworks shooting out from the cloud.
All of us standing there had no idea what it meant. We just looked at each other with puzzled faces as we waited for the orbiter to appear from behind the cloud. After a few seconds, we realized that something was really wrong.
That is when I ran about 30 yards to where my photographer, Steve Sonnenblick, was filming. I knew he had a closer view through the lens of his camera. In a panic, I said to him, "What happened?" He replied, "The (expletive) thing exploded." At that point I just thought, "Oh my God."
I immediately ran to the NASA newsroom. When I walked through the door, it was total chaos. Reporters were screaming at the NASA public affairs officers, demanding that they be taken out to the space shuttle landing strip.
A lot of people thought if the shuttle had survived, the astronauts might try an RTLS (return to launch site) abort. The NASA folks were screaming back that no one was going anywhere until they had a better understanding of what had happened.
At times you really felt like fistfights were going to break out. No one ended up going out to the landing strip because mission control in Houston quickly reported that the vehicle had exploded.
That was the beginning of monthslong coverage of what was at the time the worst disaster in NASA history. I will never forget that image. When I close my eyes, I can see what I once thought looked like fireworks: the Challenger and its crew gone in 73 seconds. The nightmares I had of space shuttles exploding finally ended, but it took several years.