Somebody took a wrong turn on the way to Utopia. "Battlestar Galactica," it was almost unanimously predicted last summer, would be the No. 1 guaranteed hit of this television season a certified "Star Wars" rip-off smash.

Now the old trawler is limping into port with so-so ratings and an uncertain future. Its place on next fall's ABC schedule is by no means secure. It has become "Rattletrap Galactica," defying the soothsayers who foresaw its triumph.

The ratings were sky-high at first, when the program about a lost tribe of humans wandering through another galaxy exploded onto the air.But as the weeks went by, the ratings for this "rag-tag fleet" of supersonic nomads got raggier and taggier.

Now, the mission could be scrubbed after only one season-a meltdown for "Galactica". And that's no feldergrab.

Why did it happen" "There are thousands of reasons," says supervising producer Don Bellisario, who still believe ABC will renew the show. But special effects maestro John "Star Wars" Dykstars, who produced five hours of "Galactica" and left the series, thinks it all boils down to logistical dilemmas; you can't make a show this fancy and elaborate when under the laser gun of hectic TV production schedules.

Originally, "Galactica" was supposed to be only a miniseries totaling seven hours of programming. But then ABC ordered it up as a weekly show, and network brass did it late in the year for such a complicated production.

"It was very late," says Dykstra. "But that's nothing new. Television works late. They have two calendars in TV-the one they talk about and the one that's real. I still think it has much greater potential as a miniseries than as an episode show."

If "Galactica" is not renewed, it will be a major concession of failure by ABC and no fun for Universal Studios, since TV shows only become really profitable for producers when there are three or four years worth lying around to syndicate.

On the other hand, NBC President Fred Silverman says that if ABC does renew the series, that will be an admission of vulnerability, of not having anything in the wings with more potential than this marginal also-ran.

"If ABC renews that show, that will prove they are in real trouble," Fred Silverman syas. And when Fred Silverman talks, even E.F. Hutton listens.

Thus we have this stranded band of interstellar gypsies flouncing around the galaxies with nowhere to go. And they won't know if ABC has a future for them until April 15 or later. In all of the universe, nothing is more absolute than low ratings.

"I can't argue with numbers," says Bellisario. "We have dropped down. There's no one thing to blame. Sunday night is the hottest viewing night of the week and the other networks hit us with everything they could."

There were additional hangups. The traditional curse of science fiction on television, where it draws culty but rarely enormous audiences; the technical problems of getting special effects done on time; and the fact that the show, like most sci-fi, fails to draw the most coveted of TV demographic groups: women 18-49.

So "Galactica" is constantly being tinkered with. To lure women, a basketballish game called Triad was invented; it is played by handsome young men wearing slingshots for shorts. "And we're going to play up the female leads on the show," says Bellisario, which helps explain why cast member Maren Jensen keeps popping up on the covers of silly magazines.

To broaden the appeal of the program still further, it ironically or not is becoming less and less a science fiction series. Now, with series star Lorne Greene riding herd over his sons and the Galactica's arkful of transients, the program's plots have degenerated into stock domestic drama-a Ponderosa of the cosmos. "Galatica" could have been the first smash hit in television to make ti on visual spectacle, but that angle has been largely jettisoned in favor of meat, potatoes and corn.

"I really haven't been watching it a lot," says Dykstra, "I'm not in love with most television, I don't watch much TV. The little parts I have seen have vered much more toward standard stories than action-adventure."

Dykstra says the program doesn't entice him because the effects are no longer the main attraction. "If you are going to put on 'Joe Smith, Motorcycle Rider,' you've got to have a new stunt every week or people won't keep tuning in. The writing on "Galatica" is good, but they're doing only personality stories; so people don't get the magic they were promised. And in order to make that convincing you need more lead time than they have in TV."

Those menacing but highly photogeneic Cylons have been keeping a low profile lately while the good ship Galactica went off on other courses, manyu of them straight into the black hole of soap opera. But the insidious muttering androids will return April 29 for the season's last episode-perhaps the last episode of all. Bellisario says the Cylons were a handicap to the program but it wasn't their fruit; the real villains were the network censors.

"They took the balls out of the Cylons," Bellisario laments. "And so they became rather laughable. Since we are an 8 o'clock show, the network is very tough on us about violence. We had some leeway because we said, 'Look, we're only killing machines.' But when you have 150 Cylons agains three humans and the humans always emerge without a scratch, the audience won't take them seriously. We just couldn't take them seriously. We just couldn't make them believable as adversaries." In other words, what ABC wants is a science fiction show with as little science fiction as possible, and an action adventure show with as little action and adventure as possible.

If the truth be told, "Galatica" has been a disappointment in more ways than its ratings. The special effects on the old "Star Trek" show may have been tacky by "Galactica" standards, but at least the scripts had some sort of idea behind them. Often alegorical, somethimes genuinely thoughtful.

"Galatica" is just a lost of buzzing around interrupted by discussion in L.A. podspeak about caring and relationships. The only prevailing theme-unfortunately and perhaps accidentally-seems to be that civilizations are best left in the control of the military and that peacemakers and deliberators tend to be the dupes of fiends.

On show after show, the "warriors" of the Gallactica urge brinksmanship, displays of might and an attack-now, talk-later strategy. Thelord high poobahs want to try reconciliation and trust; some are depicted as nambypambies, others as soft on Cylonism.

The military is always proven correct. The hatchet buriers are always proven wrong.

"No, no, I wouldn't say it is a fascists show at all," says Bellisario. The question has been asked half-jokingly. "But we are doing action-adventure television. If they just ran into wonderful warm people every week, the ratings would really be in the toilet. You've got to have advertisaries, jeopardy and crisis."

Besides, Bellisario says, he can't worry about political sub-texts. He has to sweat out getting the show on the air. Because of all the technological bric-a-bra, the last six episodes of "Galatica" did not finish shooting "any earlier than 10 days prior to air time"-a perilously close margin-and then, editing and dubbing has gone on as late as the Saturday morning before the scheduled Sunday night telecast.

"I really don't have time to worry about subtleties," says Bellisario. "I just get it made and out."

Indeed, this is the great comsic dilemma of the loudest and ostiless crashes in TV history; the first seven hours alone cost more than $7 million to produce. But Bellisario is determined to remodel the show so that it will become "the hit it was always predicted to be"-next season, if there is one.

Meanwhile, a theatrical version of the first show, having been successfully tested in various domestic and foreign markets, will open in dozens of American theaters this summer as a way for Universal to make a bundle even out of a possible flop. "Buck-rogers in the 25th Century," originally made by Universal to be a NBC movie, has been released instead to theaters first and is toting up rosy grosses, a Universal spokesman says.

The spokesmman, a wry type, is asked why he thinks "Galatica" failed to be come the socko smach everyone expected. "Well, it did," he says, "for three minutes, anyway." CAPTION: Illustration, no caption, by Bill Perkins-The Washington Post