Commonly misquoted as "Houston, we have a problem", this is how Jim Lovell as the commander of Apollo 13 matter-of-factly declared the start of a life and death struggle in space to mission control at the Johnson Space Center.

The official NASA transcript runs like this (times given are the elapsed time since lift off):

Jack Swigert: Okay, Houston, we've had a problem here.
CapCom: This is Houston. Say again please.
Jim Lovell: Ah, Houston, we've had a problem. (pause) We've had a main B bus undervolt.