When Indiana Jones and the Kingdom of the Crystal Skull lands on movie screens just after midnight on Thursday, it will begin testing moviegoers' fondness for the big-screen icon — especially whether younger film generations have embraced the whip-toting adventurer.

I am more than ready for this movie. I saw the first three in theaters, and have them on DVD. I've gone back to the DVDs to prepare for Crystal Skull. But I'm also 56 years old.

The Indiana Jones brain trust of George Lucas and Steven Spielberg have to know they're taking a risk in revisiting something that began with Raiders of the Lost Ark (now retitled Indiana Jones and the Raiders of the Lost Ark) in June 1981. They just have to look at the gray and white hairs on their own heads, and how they have gone from being Hollywood youngbloods to elder statesmen.

Even if they insist you're as young as you feel, the calendar is daunting. It has been 19 years almost to the day since the last Indy film, Indiana Jones and the Last Crusade. More than 15 years since the last time Harrison Ford played Indy — in a brief appearance on TV's The Young Indiana Jones Chronicles.

Wittingly or unwittingly, Spielberg and Lucas used the inspiration of old-movie serials as the basis for a hero well suited to the Reagan era, when the movies first played.

Indiana Jones was a man whose education was a sidebar to action, who even alone was eager to charge into the middle of grim global conspiracies. A man who was willing to cut corners and bypass authorities. And one who would, as the trailer for Crystal Skull noted, protect ''the power of the divine'' and triumph over ''the armies of evil.''

In other words, he was the embodiment of Ronald Reagan's foreign policy.

As for the man who played Indy, Harrison Ford is now 65. He is an increasingly sporadic movie presence. He hasn't had a hit since What Lies Beneath eight years ago (and even that was Michelle Pfeiffer's movie more than his).

So there's little point in pretending that Indy still lives in the 1930s settings of the earlier movies and his chief rivals are the Nazis. Lucas, Spielberg and screenwriter David Koepp have set Crystal Skull in 1957. They have turned to the Soviet Union for villains. Indy's age is an issue; one Crystal Skull trailer has him facing a task and muttering it's ''not as easy as it used to be.'' So for the new movie, he has a much younger cohort named Mutt Williams, played by 21-year-old Shia LaBeouf. There has even been speculation that Mutt will prove to be Indiana's son.

LaBeouf might be crucial to bringing another generation into Crystal Skull, since he has established action credentials with younger adults thanks to his starring role in Transformers. He's a leap past Indy to an audience whose action-movie favorites are more recent: Iron Man and Spider-Man and various Batmen among them.

But even if Crystal Skull has made some calculated concessions to younger film fans, a nagging question is whether this movie will make creative sense. After all, Lucas made serious hash of Star Wars when he made three prequels to the three landmarks in the series.

And however nostalgic moviegoers might be about the first three Indiana Jones movies, even in their time they showed signs of wear.

Movie Web site Box Office Mojo recalculates movies' grosses into 2008 dollars, and has a huge decline between Raiders and the second film, Indiana Jones and the Temple of Doom, the darkest tonally of the three films. Although the third, Indiana Jones and the Last Crusade, was a creative rebound — thanks largely to Sean Connery's presence as Indy's father — it made less money in the U.S. than Temple of Doom when inflation is factored in. In addition, The Young Indiana Jones Chronicles, though a fine TV show, was not a ratings winner — although TV has as a rule required a larger audience for success than movies do.

Getting back to the movies, as is the case with any effects-laden project, the earlier movies' big moments can look a little cheesy compared to the computer-generated marvels of today.

Raiders of the Lost Ark holds up as an escapist action film setting the stage for blockbusters to come, but it was twice lucky. Tom Selleck was originally set to star, but could not get out of his Magnum, P.I., commitment to do so; though a good actor, he would have been a different Indiana, and so part of a different kind of movie than Raiders became. (One of the most memorable scenes in Raiders resulted from Ford's being ill one day.)

Even without Selleck available, Ford was not a sure thing. On a new DVD of Raiders, Spielberg says Lucas at first resisted casting Ford, since Lucas wanted Ford to remain identified as Han Solo, his character in Lucas' Star Wars films.

Temple of Doom, though admired in some circles for its darkness and violence, is in many ways a misfire of a sequel — especially when you contrast Karen Allen's female lead in the first film with Kate Capshaw's in the second. It also feels more mechanical than Raiders, technically elaborate but often heartless. And where Last Crusade has many pleasures, it is also the longest of the three films, with some dragging sections.

So history gives ample reason to be leery of Crystal Skull, or at least to lower expectations. But as much as I am trying to stay calm before the press preview of Crystal Skull, there's still 27 years of excitement swirling inside me.

Indy's back.