"THE CORE" is "Armageddon" all over again . . . except down instead of up.

In place of that 1998 film's team of astronaut-roughnecks who rocketed skyward to nuke an asteroid out of the sky, we're instead presented with a team of "terranauts" (Hilary Swank, Aaron Eckhart, Delroy Lindo, Stanley Tucci, Tcheky Karyo and Bruce Greenwood). Tasked with drilling thousands of miles into the center of the Earth, they must detonate a warhead that will restore the rotation of the planet's soupy outer core, which has become mysteriously becalmed, leading to a deterioration of the Earth's electromagnetic field. And why does this matter? Because pacemakers stop working and pigeons who can no longer navigate appear to attack us (leading to an opening sequence that out-birds "The Birds" in terms of sheer avian horror).

Oh yes, and if the ensuing static electricity storms don't toast us while we're waiting for the bus, the sun's microwave radiation leaking through new holes in the atmosphere will cook us like so many Hot Pockets.

Sure, I'll buy that (I'm a newspaper critic, not a geophysicist).

Like "Armageddon," "The Core" might be based on an ever-so-slightly ludicrous premise. The giant drill bit/ship they build, for instance, is fashioned out of a substance dubbed, appropriately, "unobtainium." Not only is the space-age Roto-Rooter impervious to heat (what luck, considering it's 9,000 degrees outside), but it converts heat to energy. And never mind that they are able to build it in a couple of months without anyone finding out about its zillion-dollar price tag. A computer geek named Rat (D.J. Qualls) is drafted by the feds to "hack the planet," crippling the flow of information through the Internet.

All that aside, the movie gets the job done, and I'm not talking about whether our heroes are ultimately able to save the world or not (what do you think?). It's a popcorn flick, after all, and you don't ask a lot of heavy lifting from movies designed to sell buttery carbohydrates.

In the final analysis, you have to credit the inspired casting for keeping director Jon Amiel's fanciful vehicle on target. Eckhart and Swank aren't exactly chopped liver, not to mention Lindo and Tucci. The pair of unexpected stars (I mean unexpected for a special-effects-laden film like this) share a great scene about halfway through. In it, Eckhart, playing an absent-minded college geophysics teacher and all-around genius, and Swank, a brilliant but untested NASA shuttle copilot, get to scream their kidneys out at each other over a decision that cost the life of one of the crew. If you imagine the same scene acted by, say, Vin Diesel and Amanda Peet, flexing and pouting for the camera, you'll know exactly how close to the edge of the toilet "The Core" could have come.

It's brainless, to be sure. That goes without saying, and it's not intended as criticism. As a pure adrenaline rush, though -- admittedly one with more than its share of thespian muscle -- "The Core" is a two-hour pleasure cruise.

THE CORE (PG-13, 135 minutes) -- Contains brief obscenity and science-fiction intensity. Area theaters.

Aaron Eckhart and Hilary Swank bring strong acting chops to "The Core."