Houston, we have a problem

"Houston, we have a problem" is popularly quoted as a phrase spoken during Apollo 13, a NASA mission in the Apollo space program and the third meant to land on the Moon. After an explosion occurred on board the spacecraft en route to the Moon at 55:54:53 (03:07 UTC on April 14, 1970), Jack Swigert, the command module pilot, reported to Mission Control Center in Houston, Texas: "Okay, Houston ... we've had a problem here." After being prompted to repeat his words by Jack R. Lousma, the capsule communicator at Mission Control, Jim Lovell, the mission commander, responded: "Ah, Houston, we've had a problem."

The 1995 film Apollo 13 used the slight misquotation "Houston, we have a problem", which had become the popularly expected phrase, in its dramatization of the mission. The phrase has been informally used to describe the emergence of an unforeseen problem, often with a sense of ironic understatement.

Background
The Apollo 13 Flight Journal lists the timestamps and dialogue between the astronauts and Mission Control.

055:55:19 Swigert: Okay, Houston ...

055:55:19 Lovell: ... Houston...

055:55:20 Swigert: ... we've had a problem here. [Pause.]

055:55:28 Lousma: This is Houston. Say again, please.

055:55:35 Lovell: [Garble.] Ah, Houston, we've had a problem. We've had a Main B Bus Undervolt.

In Chapter 13 of Apollo Expeditions to the Moon (1975), Jim Lovell recalls the event: "Jack Swigert saw a warning light that accompanied the bang, and said, 'Houston, we've had a problem here.' I came on and told the ground that it was a main B bus undervolt. The time was 21:08 hours on April 13."

In media
In the 1995 film Apollo 13, the actual quote was shortened to "Houston, we have a problem". Screenwriter William Broyles Jr. made the change, stating that the verb tense actually used "wasn't as dramatic". Broyles and American University linguist Naomi S. Baron said the actual line spoken would not work well in a suspense movie. Movie viewers knew what had happened, while Mission Control did not at the time. The quote ranked at No. 50 on AFI's 100 Greatest Movie Quotes in June 2005.