Forty years and one day ago, December 14 at 5:54:37 p.m. EST, humans left the moon for the last time. But how did the two men who made that departure — taking their last small steps, their last great leaps from the lunar surface — mark that occasion? What parting words did they leave to the moon, and to their fellow humans, and to history?

As Miles O'Brien notes in his tribute to yesterday's bittersweet anniversary, the commander of the Apollo 17 mission, Gene Cernan, had prepared a speech to mark his crew's lunar departure. It was appropriately lengthy and lofty. He delivered it like this:

As I take man's last step from the surface, back home for some time to come (but we believe not too long into the future), I'd like to just say what I believe history will record: That America's challenge of today has forged man's destiny of tomorrow. And, as we leave the Moon at Taurus-Littrow, we leave as we came and, God willing, as we shall return: with peace and hope for all mankind.

But these were not, technically, the last words ever spoken on the moon. Cernan and his crew, on the contrary, maintained a decidedly less-epic dialogue as they did the delicate work of lifting their little spaceship off the lunar surface — dialogue that was mostly pragmatic and mission-moderated, but dialogue that was also, occasionally, the casual conversation of guys who are having an adventure together.

So then. What were the last — really the last — words?

According to Apollo 7 astronaut Walter Cunningham in his book The All-American Boys, Cernan's final words on the moon were: "Let's get this mother out of here." (Or as O'Brien spells it, awesomely, "let's get this mutha.") And there would be, indeed, something wonderfully poetic about "let's get this mother" — excuse me, mutha — "outta here" as our parting words to the moon: something very human and honest and inscribed in its time.

But the "outta here" thing is likely, alas, apocryphal. According to NASA's official transcript of Apollo 17's return to Earth, what Cernan actually said was in part a response to a malfunction his fellow astronaut, Jack Schmitt, was encountering with a camera: "Now, let's get off. Forget the camera."

This was followed by a countdown and, alas, due to some other minor equipment malfunctions, static. But not, at least per the transcript, with any mention of mothers. "During the mission review in Santa Fe," NASA mentions as an aside in that transcript, "Gene was surprised not to hear those words" — because Cernan himself recalled his final words they way Cunningham had quoted them. However, NASA continues: "What seems likely is that what he was remembering was his at 188:01:25 [the "let's get off" moment in the transcript] and that, in later tellings, the wording changed to the more colorful version Cunningham quotes."

Here's the relevant section of the transcript:

188:00:38 Cernan: Take your final look at the valley of Taurus-Littrow, except from orbit. (Pause) Okay, one minute, Houston. We're 50 seconds now, and we're Go. 188:00:51 Fullerton: Roger. You're looking good here. 188:00:55 Schmitt: I'll get that (camera) at 30. 188:00:57 Cernan: Okay. (Pause) 188:01:10 Schmitt: Camera's not going to run without me holding it. 188:01:20 Cernan: Okay. Average G, 20 seconds. [Cernan - "This was a routine in the PGNS to start recording data from the accelerometers."]

188:01:23 Schmitt: Ah, shoot! 188:01:25 Cernan: Okay. Now, let's get off. Forget the camera. (Garbled)... MPEG Clip by Kipp Teague (30 sec; 3.9 Mb) 188:01:27 Schmitt: Ten seconds. 188:01:28 Cernan: ...10 seconds. 188:01:29 LM Crew: Abort Stage. 188:01:30 Cernan: ...pushed. Engine Arm is Ascent. 188:01:32 Schmitt: Okay. I'm going to get the Pro. (Pause) 99 Proceeded 3, 2, 1...

188:01:39 Schmitt: Ignition.

So there it is — sort of. "Let's get off."

But could the garbled section of the transcript been, actually, the reference to "this mother" that Cernan remembered? Or was "forget the camera" essentially the last meaningful communication humans delivered on the moon? The best answer, ultimately, may be that we don't know. And that we can't know. Because, despite all the technology we have to connect us to our astronauts — as easily as we can talk with them, and tweet with them, and otherwise interact with them — the fact remains that they are, up there, separate from us. They are, finally, alone. And they alone know what goes on in those little bits of Earth that we send away, hoping they will return.

Graphic courtesy NASA/GSFC Visualization and Analysis Lab

This article originally published at The Atlantic here