THE COUNTDOWN has begun on Hollywood's great space race -- an international rush for ticket sales that starts with the Dec. 7 launch of Paramount's $42-million "Star Trek" and ends with the December 1980 opening of Dino de Laurentiis $30-million "Flash Gordon."

Six space and science fiction movies -- collectively budgeted at $127 million -- will soar onto American screens, spinning off a trail of products including space toys, books, calendars, posters, pillowcases and even "Captain Kirk" after-shave lotion. And characters have been added to scripts expressly in order to create new opportunities for toymakers.

Producers will spend an estimated $30 million just to promote the films, following the flight path of "Star Wars" -- which has grossed $294 million in the United States alone on a $10-million investment.

The competition has become so intense, in fact, that Paramount and Disney are spending a phenomenal $9 million each on advertising and promotion of "Star Trek" and "The Black Hole" respectively, although some of the cost in each case will be borne by toy and book companies with tie-ins to the films.

"There has probably been no other single time when so many movies on the same subject -- space -- and relying on the same tricks -- special effects -- have hit the market at the same time," said Marshall Swerman of the independent film marketing company, PFT (Print-Films and Television). "But out in the market-place, our studies show that space films can hold up as long as they are good -- audiences are actually waiting for this glut. However, the public's expectation will not protect a bad film. But it can propel a good film to great profits."

This should be good news to the film companies, but IT DOESN'T ANSWER TH BASIC QUESTIONS: can all six films survive in the same marketplace? And will they have the power to carry millions of toys, books and television specials along with them?

Partial answers are less than a month away:

On Dec. 7 -- at 869 theaters nationwide -- Paramount plans to open "Star Trek," which was seven years in the planning and filming. Its sound stages have been closed to the press and even most studio personnel, and no more than a handful of top executives has seen the finished film. Although there are rumors that the film may not be ready on schedule it already has a record $20 million in guarantees from exhibitors, plus an undisclosed sum from ABC-TV, which bought the television rights 18 months ago.

The equally secret "Black Hole" from Walt Disney Productions will open at 700 theaters Dec. 21 with more then 500 commerical and merchandising tie-ins. "Black Hole" is not only the most expensive movie ever made by Disney -- with a reported budget of $20 million -- but their first PG feataure, breaking a rule established by Disney himself, that all films would merit a G rating or the equivalent.

"The opening weeks of these two films will let everyone know how the whole line of space films will probably go," said Swerman, whose PftY has finished a major space-movie marketing survey through its companion company, Information Regitry. "Our results show that theater-goers expect the next big trend to be space movies. But after 'Star Wars,' they are waiting for films with stronger plots -- like stories should make the difference."

For exhibitors, the fate of the first two space-busters is still uncertain."Exhibitors have had to play a type of Russian roulette with both 'Black Hole' and 'Star Trek,'" said Alan Friedberg, president of the National Association of Theater Owners (NATO). "The bids on 'Star Trek' had to be in to Paramount by Dec. 28 of 1978. The same was basically true of 'Black Hole.' That means 1,300 theater-owners or their represenatives had to bid top prices for those films without seeing a single frame.

The sequel to 'Star Wars,' he 'Empire Strikes Back,' was much the same way. We call it blind bidding, and it's absurd -- we have to take the word of the producer that his film is good."

Frieberg says that space mania is no guarantee of success, recalling how exhibitors got stung on blind bidding for "Exorcist II" During the demonic movie fad) and "Moment By Moment" (in the romantic movie fad).

"We can only hope that 'Star 'Trek,' 'Black Hole' and 'Empire Strikes Back' will not sting us again," said Friedman, who doubts that any of them will equal "Star Wars." "That was a movie that people went to see over and over again. It was a repeater. Those are hard to find."

Whatever the market will bear, these films will follow "Star Trek" and "black Hole" into 1980 (all cost estimates are from the studios involved):

"The Empire Strikes Back," 20th Century Fox's $25-million sequel to "Star Wars" which opens May 17 in Washington. (Harrison Ford, as Han Solo, will not be killed off as previously announced. He lives through the intergalactic struggle to make his stalwart way toward "Star Wars III," "IV" and, reportedly, "V." The sequels are planned through 1990).

"Superman II," the $25-million addendum to the first with returning Christopher Reeve, Margot Kidder, Valerie Perrine and -- reportedly for several seconds -- Marlon Brando. It includes, says Warner's, special effects designe specifically for this second film.

"The Incredible Shrinking Woman," Universal's $14-million science-fiction epic staring Lily Tomlin and relying on a special film process that will reduce the actress' image to a tiny dot on the screen. "When she moves through this big world in her smaller size she will achieve incredible deeds," says producer Jane Wagner.

"Flash Gordon," now filming in London on special sound stages (which alone cost $3 million) that have some special-effects capabilities built in -- such as projection screens built around stationary sets. "We will be able to show motion in this film and a feeling of outer space in ways that were impossible until now," said a spokesman for De Laurentis films.

The competition has produced a battle of space-budget reporting from the studios. In the four weeks since "Star Trek" reached its cost peak, announcements from the other studios have been frequent, with each hiking its figures. For instance, Universal's estimated total for "Shrinking Woman" doubled in less than two weeks: jumping from $7 to $10 million, and then from $10 to $14 million, in one 10-day period.

(Some of the cost overruns for Paramount's "Star Trek" resulted from a controversy last winter, during which the studio fired one special-effects company in mid-production and hired Douglas Trumbull and John Dykstra, the wizards of "Star Wars." a reported $11 million had already been spent on special cameras and animation techniques before the change.)

All six films have two things in common -- hype and merechandising tie-ins. Each could hardly exist without the other.

An executive at Walt Disney Productions explained that, of the $9 million promotional budget, merchandisers will spend $3 million. They are "the companies we have licensed to distribute toys, books and other items. We give them a deal on tie-ins for 'The Black Hole' and they give us a deal by spending millions on advertising."

"Star Trek," "Flash Gordon," "Superman II" and "The Empire Strikes Back" will follow that general pattern according to spokesman for the studios involved.

Even for space films, the ad budgets are reaching incredible levels. (Three years ago when "Star Wars" opened, 20th Century Fox spent only $1.3 million in promotion and advertising. For the reissue this summer the studio spent $1.9 million).

NATO's Friedberg believes that the giant ad promises "were needed because of the blind biding. Since the exhibitors could not see even clips fro the films, they knew they could at least count on big advertising campaigns to sell the tickets."

Although officials at Paramount Pictures refuse to discuss the ad compaign or the merchandising tie-ins for "Star Trek," a senior vice president at Paramount -- who declined to be identified -- told the Los Angeles Times that "both the campaign for 'Black Hole' and 'Star Trek' will be as like as two peas in a pod. and both of them will be based on the hypes for 'Star Wars' and 'Superman.'"

The extenstive Disney hype, however, is being made public. And Swerman says he believes the campaign may be the prototype for the other five films:

First, Disney will allocate $6 million for radio, television and newspaper advertising in a push that will start around Dec. 1, 20 days ahead of release.

Mego Toys is producing six million "Black Hole" dolls, 375,000 model kits, hand-held and table-top games, "Black Hole Electronic Calaculators," motorized robots and space vehicles. As part of their franchising agreement with Disney, said an official of Mego, the toy company will spend about $1.5 million in print and television advertising for the products.

Dole Corp. of Hawaii is conducting a $1-million "Black Hole" context -- backed by magazine advertising and displays in more than 8,000 supermarkets.

Ballantine Books has already printed one million copies of the "Black Hole" novel -- they hit the bookstores after Thanksgiving -- along with 150,000 calendars (from Random House); 200,000 picture-book versions of the film and 600,000 Disney Book Club editions of the movie novelization. Golden Books will offer one million children's books about the movie along with puppets, coloring books, puzzles, four poster storybooks and displays in 20,000 bookstores. Ballantine willl augment these displays with 7,000 bookstore displays of their own.

Disney's music division will release one million albums of the soundtrack, and the Educational Media Co. -- with whom Disney has worked closely in the past -- will distrubute an 8mm abridged version of the film for schools.

Miscellaneous products include 300,000 "Black Hole" stationary kits, 100,000 posters, 325,000 T-shirts, 50,000 sets of pajamas, 90,000 units of sheets and pillowcases. There will also be kites, lunch boxes, sport shirts, sneakers, shoes, robes, hats, scarves, bech towels, sleeping bags, curtains and watches.

For "Star Trek," 8,000 bookstores across America have already put up mammouth "Star Trek" bookstands with more than 33 different books, calendars, transfers, coloring books, Starship Enterprise bludprints, and even a "Star Trek Cookbook" in two volumes. And an entire line of "Captain Kirk" toiletries is already available including the "Captain Kirk" after-shave lotion.

For "Star Wars," however, "all of our merchandise will relate to the film -- we won't have any toiletires or comb-and-brush sets," said Sid Ganis of LucasFilm, the company created to merchandise the spin-offs from "Empire" and all other "Star Wars" sequels.

Fresh characters open up fresh mercahndising possibilities, and Paramount executives say "Star Trek" abounds with them. There are at least 200 new types of characters, including: a seven-foot-fall chieftain from the planet Betelgeusia; a swashbucklying lieutenant commander, played by Stephen Collins; and a sensuous space beauty named Illia, a bald lady navigator played by Persis Khambatta, a former Miss India. All three characters have already become toys.

Swerman -- whose firm has studied the history of "Star Wars" as a textbook of success -- siad that, in addition to repeat attendance, the second ingredient is secrecy. "Perhaps that's why Paramount is so closed-mouthed about the film," said Sweman. "A tight control on any publicity for these films only makes the public more curious -- the media can let too much out."

During the year of filming, Paramount publicists allowed only 12 journalists on the set -- and those visits were in carefully controlled areas for interviews with stars William Shatner and Leonard Nimoy. The "Star Trek" press kits contain only the selections of stills that were taken a year ago at the start of filming.

Over at 20th Century Fox, where the campaign for The "Star Wars" sequel is already in the works, the mastermind of the first campaign is confident. "I don't intend to repeat any of the publicity tricks we used for 'Star Wars,'" said Fox vice president Ashley Boone. "But I feel that, by the time we open, there won't be anyone in American -- or in most parts of the world -- that doesn't know about this picture."

Ironically, "Empire" in the summer of 1980 will have the same competition as the original "Star Wars" -- a revamped reissue of "Close Encounters."

"Steven Spielberg has re-edited the film and added about 25 minutes." said a spokesman for Columbia Pictures. "And the ending may have been altered -- but we can't talk about that at this time."