Video space. The final frontier for Star Trek. These are the voyages of the starship Enterprise. Its 21-year mission: to explore strange new worlds; to seek out new fans and new critical appreciation; to boldly go where no series has gone before.

Star Trek IV: The Voyage Home warps out on videocassette this month, more than two decades after the original television show first beamed into our living rooms. Its release coincides with the premiere of the lavish "Star Trek: The Next Generation," locally syndicated on WDCA (Channel 20) and WBFF (Channel 45). Canceled after three short seasons, "Star Trek" drifted through the black hole of reruns for 10 years before exploding like a super nova onto the big screen.

Star Trek IV, while not an outright comedy, adopts a much lighter tone than the previous three movies. The 20th-anniversary film transports Admiral Kirk, Mr. Spock and the stalwart Enterprise bridge crew to present-day San Francisco where they not only save the Earth, they save the whales as well. If the film never sinks to the caricatural depths of Roger Moore's James Bond movies, it is partly because the stars -- William Shatner, Leonard Nimoy (who also directed), DeForest Kelley, James Doohan, Nichelle Nichols, Walter Koenig and George Takei -- have a respect for the series that made them famous.

Indeed, for all its jocularity, The Voyage Home is consistent with the Star Trek vision, depicting intrepid Earth people, logical Vulcans, ruthless Klingons, a fascinating extra-terrestrial threat and a message contemporary Earthlings could appreciate. If we somehow muddle through the problems of our own time, life in the future may not be so bad.

Along with The Voyage Home, Paramount Pictures is releasing 10 more episodes of the old TV series. All of Paramount's "Star Trek" titles -- the first three movies ($19.95), 61 out of 74 television episodes ($14.95) and the unsold first pilot, "The Cage" ($14.95) -- are video best-sellers. Though they feature some of the best-written, -acted and -directed science fiction ever filmed, only the most loyal Trekkers (true fans dislike the term "trekkie") are expected to collect every title. The following 10 are recommended for a basic Star Trek library.

Star Trek - The Motion Picture -- The first theatrical feature provided a triumphant reunion for the old TV gang. Earthbound Adm. James T. Kirk reclaims a streamlined Enterprise and his former mates to ward off an invading alien cloud. He must first discover the reason for Spock's colder than usual behavior. A sumptuous technological feast beautifully directed by Robert Wise and scored by Jerry Goldsmith, whose music was unfortunately discontinued in later films.

Star Trek II: The Wrath of Khan -- The original series always stressed character over special effects, and new producer Harve Bennett brought back that philosophy. He also brought back Ricardo Montalban as Kirk's arch-enemy, Khan. Montalban and Shatner try to out-ham each other throughout this rousing space swashbuckler that courageously kills off the popular Mr. Spock.

Star Trek III: The Search For Spock -- In science-fiction, and in Hollywood, anything can happen, and Spock's resurrection is no exception. Screenwriter Bennett, however, might have picked a less goofy method of doing it. Kirk's bridge crew loyally follow him in an illegal attempt to recover Spock's body. Only the Trek stock company retains credibility in this weakly acted entry, somewhat bolstered by Nimoy's enthusiastic direction.

The City on the Edge of Forever -- This time-travel masterpiece is far superior to Star Trek IV. Kirk and Spock journey back to Depression-era New York to stop Dr. McCoy from altering history. The brilliant, beautifully executed story by science-fiction luminary Harlan Ellison won the genre's coveted Hugo award. A pre-cosmeticized Joan Collins plays the attractive romantic lead.

The Corbomite Maneuver -- Literally, a space odyssey, it updates the story of Ulysses and the Cyclops. When a superior alien force gives the Enterprise crew mere hours to live, Kirk struggles to find an escape. The riveting episode examines man's resourcefulness under pressure.

Space Seed -- Could modern genetics lead to the creation of physically and mentally advanced beings? How could normal humans deal with a race of Napoleons or Caesars? Those are two of the fascinating concepts explored in this entertaining precursor to The Wrath of Khan. Both Montalban and Shatner are considerably more restrained than in their later close encounter.

A Taste of Armageddon -- Suppose they gave a war and were unable to wage it. The resulting peace, if forced upon the combatants, would seem even more distasteful. Such is the premise of one of the most intelligent and morally manipulative TV shows ever made. The episode introduced the Klingons and features a tremendous performance by John Colicos.

Who Mourns for Adonis? -- "Star Trek" anticipated Erik Von Daniken's Chariots of the Gods book by years, speculating that the old Greek gods were actually alien visitors. Nostalgic for human worship, Apollo kidnaps Kirk and company, only to learn you can't go home again. A touching, vintage entry enhanced by an impressive score.

The Changeling -- That man must eventually confront his technological obsession has seldom been more ominously revealed. The Enterprise beams a super-destructive machine aboard and must maintain its interest before it fulfills its prime directive. John Meredith Lucas' superbly mounted story features more special effects than most shows and served as the inspiration for Star Trek: The Motion Picture.

The Tholian Web -- "Star Trek's" third and last season saw a marked decline in script quality, but this episode is one of the best. Kirk is pronounced "lost in space," and Spock and McCoy's differences, formerly suppressed, jeopardize their command. With Shatner missing for most of this show, the supporting characters get to demonstrate the reasons for their popularity. A budding (and daring, for late-'60s television) romance between Lt. Uhura and Capt. Kirk never got the chance to develop.