Howard Stern played it safe on his debut for Sirius Satellite Radio (NASDAQ:SIRI). The show kicked off with secret cast member revelations (that will be matched to the appropriate Stern regular next week), the truth about his romantic trip over the holidays (no marriage for Howie), and the addition of Star Trek star George Takei as the show's announcer (at least through the end of the week).

Foul language and lewd acts were kept in check, perhaps deliberately. Stern is looking to duplicate -- and ultimately surpass -- his terrestrial radio success, so there's no point in going for the jugular overnight. Starting tame also helps Stern prove his point that his show won't be raunchy for raunchy's sake.

I do have my reservations, though. Stern is playing to a smaller audience this time around. There are 3.3 million Sirius subscribers. Between the service's 125 different channels and the fact that members aren't listening 24/7, Stern may be lucky to reach a million daily listeners for now. It's a far cry from the eight-figure crowd that the popular radio host was commanding in his syndicated, terrestrial life.

Will the smaller audience keep star celebrities and top-shelf adult entertainers away? Interviews have always been a Stern forte, and it would be a shame to see that dry up. A bigger concern is the quality of the show's callers. For the most part, the first batch of phone callers was pretty lame. When Stern ruled the terrestrial airwaves, it drew the dysfunctional masses out of the woodwork. His Wack Pack was born as the country's irregular ranks would call in. These days, you won't find too many recovering crack addicts or misshapen drunkards paying $12.95 a month to tune in. Stern's new crowd will be a major upgrade for advertisers, but it's likely to prove to be infertile soil for new wacky on-air personalities.

I'm sure Stern will be fine on that front. If the wacky can't find Stern, Stern will find them. He already has a segment that will involve four prostitutes hosting their own version of The View. He has also started to flesh out the two Sirius channels that he will preside over, bringing back Bubba the Love Sponge for a daily late-afternoon show.

Even though rival XM Satellite Radio (NASDAQ:XMSR) commands a much larger audience -- 6 million subscribers and counting -- Stern's momentum helped Sirius sign more new users this past quarter, and that trend is likely to continue in the current quarter.

Strength in satellite radio will be good for both companies. It's why XM was recommended to subscribers of the Rule Breakers ultimate growth newsletter service back in the fall. It's also why Sirius may not be as overpriced as some cynics may think if both companies gain more pricing flexibility in the future.

Satellite radio remains a mostly North American phenomenon. WorldSpace (NASDAQ:WRSP) has had a much tougher time. Despite broadcasting over a much larger potential market than the stateside providers, WorldSpace is still shy of the 100,000-subscriber mark. So, yes, it could be worse for Stern.

It will likely become better, too. Sirius expects to nearly double its subscriber base in 2006. The early adopters are locked in place. Now it's time for the mainstream masses to stream in. Let's hope, for Stern's sake, that a few of those signing on have a little wacky blood pumping through their veins.

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Longtime Fool contributor Rick Munarriz is a Sirius subscriber but does not own shares in any of the companies mentioned in this story. T he Fool has a disclosure policy. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early.