Scott Bakula hasn't yet lost his sense of wonder, and he doubts he ever will, at least as long as he's the star of "Quantum Leap."

"I get to do so many wonderful things, and I think it's that sense of wonder that makes the show go," he says, leaning back in a trailer dressing room on the back lot at Universal Studios. "That first moment in each show is the key. We've always got them wondering what's next, and can I do whatever it is I have to do?"Bakula never has much doubt that he can do whatever he must on the show (which airs Wednesdays at 9 p.m. MST on KUTV-TV).

But like the audiences, he doesn't get much notice about what his next challenge will be.

"I usually get the scripts about two days before we start shooting them," he says. "And then all I study is my lines. I had never ridden a Harley-Davidson motorcycle before we did a cycle episode, and then I had to do a stunt on it. That was tough. Riding a horse and roping a cow was tough, too."

Bakula deliberately gives each new challenge little preparation because his character, Sam Beckett, never gets any notice before leaping from one adventure and one body into the next.

"When we did a trapeze episode, I actually got to train with a professional for four lunch hours," Bakula grins. "But then I had to unlearn it all because Sam couldn't look like he knew what he was doing up there."

Bakula, 36 and looking a bit more boyish off camera than on the screen, leans back and smiles as he says, "I love to try new things, and I love learning new things. So this part is perfect. I'll be on a horse in one episode and rappelling in the Alps in the next and playing the piano the one after that."

The myriad activities reflect the life Bakula led while growing up in St. Louis.

"I'm lucky because when I was young, I did a lot of things," he says. "I was active in sports, music and theater. And the writers know that. They use my abilities in their scripts. It's been a really nice marriage between me and the writers."

Words like "lucky" and "nice" roll easily from the lips of Bakula, who makes a conscious effort not to let the big success of his show spoil him.

Bakula, his wife and 6-year-old daughter still live in the same house they occupied in the unpretentious Silver Lake district of Los Angeles before anyone ever heard ot "Quantum Leap." The family still drives two cars purchased before big money started coming in.

"The biggest problem with the show's success is having time for relationships with my family," Bakula says. "You have to make sure the show doesn't take over your life. But each year it's been on, we've gotten better at managing it."

A big shock at first were the 12-hour days needed to put together each of the one-hour programs.

"I worked in half-hour shows before, and you have comfortable hours there," the actor says. "You work from 10 to 6 and can actually eat dinner with your family every night."

Not now. Except for a Christmas break in taping, Bakula hasn't taken a day off since September. And each day's activities are fast and furious.

"Last spring I did my first feature film (`Sibling Rivalry'), and the biggest difference was getting off the treadmill and adjusting to the slower pace," he said. "It was amazing sometimes when I'd work on a Monday and we'd finish and they'd say, `See you Friday.' I actually had some weekdays off!"

But Bakula doesn't mind the pace of "Quantum Leap" because he knows it's a must in making 22 one-hour shows each year.

"The only question I had at the start was whether we could make a show every week as good as the pilot," he says. "You have to put in the hours to get the product."

Bakula says he never had any doubt "Quantum Leap" was a good idea that could catch on with viewers - but he also was taking nothing for granted.

"I felt very good about the writing from the beginning," he said. "I'm a big believer that you have to have good words before you have anything else. And I was so happy to be with Dean Stockwell (his sidekick on the show). But I never thought about whether the show would last.

"There's no point thinking about that. You can have a great show and get stuck in a lousy time slot and you're gone. Or the network executives may love the program, and then they all disappear and you get a different bunch that hates it. So you have to enjoy your work and realize it's a waste of energy to worry."

True to his own advice, Bakula doesn't worry at all about the show's future. Instead, he basks in its success.

"I've lost some privacy," he smiles. "But I'm still surprised by the recognition I get everywhere I go, literally all over the country. All kinds of people, too. There was even an Indian cabbie in Washington, D.C., who the minute I got in the car started shouting `Quantum Leap,' `Quantum Leap.' "

Bakula figures he'll keep on leaping for years to come and hopes the show stays as unpredictable as it's been so far.

"There are still a bunch of places to go and people I'd like to be," he says. "All kinds of people and all kinds of places. I love the way we're not limited by gender and ethnicity. It would be very white-bready of us if I just leapt into white, male bodies. That would be very boring, and we never want to be boring."