On its face, Newt Gingrich’s January 2012 pledge to establish a permanent US colony on the moon by the end of his second term was the craziest campaign promise we’ve heard in some time, especially from a candidate in a major national race. It sounded like something out of a Ray Bradbury work, but even less realistic.

Gingrich would of course tell you there’s precedent: In 1961, John F. Kennedy famously promised to put a man on the moon by the end of the decade, and the United States did. But Kennedy’s pledge wasn’t part of his campaign—he made it to Congress after he was already safely in office—and it was a lot more realistic.

While Kennedy promised huge investment in NASA, acknowledging the moon mission would cost Americans a lot if it were to succeed, Gingrich wanted to make his moon base a reality by cutting the agency and using a portion of its budget to fund prizes for private industry competitions. That worked for the X prize for private space flight, but as Discover magazine’s Phil Plait pointed out, “going to the Moon and building a base would cost more than 1000 times as much as launching that sub-orbital rocket did, so it’s not at all clear an X Prize like this would work.”

And that’s where the craziness of Gingrich’s promise lay: It’s not science fiction, but economic fiction.