“The Astronaut Farmer”Warner Bros. PicturesDirected by Michael PolishWritten by Michael Polish and Mark PolishStarring: Billy Bob Thornton, Virginia Madsen, Bruce Dern, J.K. Simmons, Tim Blake Nelson and Bruce WillisRated PG/104 minutesOpens Feb. 23, 2007Three out of four stars

“The Astronaut Farmer” walks a fine line between magic and absurdity. So fine is that line, you might say it’s fishing wire and the guy walking it is a 400 pound trapeze artist who just imbibed a keg of beer. Just when you think the movie is about to teeter over into disbelieving laughter or gagging preciousness, director Michael Polish and his co-writing brother Mark Polish throw in a joke, a performance or a moment of otherworldly oddness that balances everything out and makes us forget how incredibly insane the entire premise is.

Billy Bob Thornton takes a break from playing leering sleazeballs to star as the awfully nice Charles Farmer, a simple ex-NASA man who never realized his space-travel dreams because of a family tragedy. He retired and, perhaps noticing his last name and letting out a resigned sigh, became a farmer in the Southwest.

There’s a brilliant sequence at the beginning in which Charles, dressed up in his old astronaut suit, searches for a lost lamb in barren plains that could easily be mistaken for Mars. He then clomps into his farmhouse, still suited up to battle moon people, and interacts with his family as if they see him in this outfit every morning (they probably do).

Charles never gave up on his space travel dreams-indeed, he’s building a rocket ship in his barn. Reread that.

Yes, and his family is totally OK with this. The kids I can understand; his two little girls (Jasper Polish and Logan Polish, the director’s kids) and his teenage son, Shep (Max Thieriot), have probably always known their father as the dad who has rocket blueprints and physics calculations spread out across his workbench. His wife, Audrey (Virginia Madsen), however, has got to be the most patient and loving wife in movie history. She reacts to Charles’ rocket obsession like another wife might react to her husband’s obsession with restoring old hot rods: with absolutely no concern at all, as long as he still spends time with the kids.

Indeed, Charles has his heart in the right place, even when he takes his kids out of school so they can help him finish the rocket. You’d think Audrey would put her foot down at a time like this, and she does question her husband’s decision, but Charles argues that they won’t miss many classes and Audrey relents. If every guy could find a wife with this much unquestioning trust, there would be a lot more adultery going on.

Is Charles a good father? And the more important question: Did that personal tragedy that wrenched him from NASA mess with his mind? Perhaps. A lot goes unsaid in this movie, but you can sense from the rhythm of the conversations between Charles and Audrey, and in the carefully constructed performances by Thornton and Madsen, that their marriage has already endured these questions and doubts and pushed on to the sort of “let-him-have-his-dreams” respect that only a very strong love could allow.

Hard to swallow? Just gulp real hard.

Word gets out that Charles is preparing for launch, which attracts the attention of the media-who make him out to be a local hero/nut-job-and NASA, who faces embarrassment if Charles succeeds. J.K. Simmons (the scenery-chewing editor in chief from “Spider-Man”) does his hard-nosed, jaw-shifting, no-bull thing as a head-honcho NASA prick, and Bruce Willis makes a fun un-credited cameo as one of Charles’ old astronaut buddies who tries to delicately talk him out of blasting off.

There’s a scene in a high school gymnasium in which Charles and his aw-shucks lawyer (Tim Blake Nelson) plead their case to one of those long tables of frowning government-types, including Simmons and Willis. Charles talks about chasing dreams and giving a small-town man a chance. Just as the scene becomes cloying, a gangly teenager bursts in to shoot some hoops and the frowning government-types have to shoo him out. Why hold such an important meeting in a high school gymnasium anyway? Was the roller-skating rink not available? It’s throwaway moments like this that give “Astronaut Farmer” its appeal.

Other throwaway bits include the by-play between FBI agents Mathis and Killbourne (played by Mark Polish and “Napoleon Dynamite’s” Jon Gries). Their black suits and stone faces clash humorously with the folksy town. And I liked lines of dialogue such as when Audrey tells her husband prior to launch, “Be home for supper”–a line that might be banal in any other situation, but achieves a nice, ironic silliness when spoken here.

Of course, the entire story is completely absurd, especially when the life insurance policy of Audrey’s sick dad (Bruce Dern) conveniently saves the day at one point. The Polish brothers realize how ridiculous their story is and never push it too far in the direction of reality. There’s a surreal aloofness to everything, from the characters to the town to the space mission, which is charming, if never really believable. But just go with it. Dream a little.

“Weeeeeeee! You know, son, this reminds me of that time in ‘Nam when we found something like a kilo of?” Billy Bob Thornton tells one of the director’s kids about a big score in “The Astronaut Farmer.”