"Houston, we've had a problem."S

On the night of 13 April 1970 these words were heard in Mission Control during the Apollo 13 mission. There's been plenty written, televised, and filmed about Apollo 13 so I won't rehash that story. But did you know that there was a group of five NASA personnel on the ground who actually saw what was happening?

The five NASA employees were on a rooftop of Building 16A of the Manned Spacecraft Center in Houston. As reported by the Smithsonian Air and Space Museum:

There they watched a television monitor hooked up to a 16-inch Schmidt-Cassegrain telescope with a television camera mounted in place of the eyepiece. The monitor showed two dots flying in formation on their way to the moon: the brighter of the two was the spent third stage of the Saturn V launch vehicle; the dimmer one was the Apollo 13 spacecraft, which had separated from the third stage two days earlier.

"Houston, we've had a problem."

As one observer recalled:

the less bright dot was not a dot anymore. It was an expanded sphere, reflecting light. A disc. And I remember the guy who was in charge of the thing, Andy Saulietis,…he said, ‘What in the world is that?’ Every ten seconds it continued to grow a bit, and then started to fade as the gas dissipated into the vacuum of space. We watched it for two or three minutes I guess. In retrospect, none of us had the presence of mind to call next door to Mission Control and say, ‘Hey guys, you’ve got a problem.’

What they saw was the ruptured tank venting oxygen into space.

In case you're wondering if I have the famous line wrong, listen to this.

Images from NASA