IT HAS BECOME a publishing practice, and not a nice one, to take long novellas by major writers, double- slug the type, widen the margins and bring out hardcover editions as books. This has been done to Ursula K. Le Guin's The Eye of the Heron (Harper & Row, $11.95). This novella first came out in a $1.95 anthology in 1978. The publisher makes no secret of this, telling you on the dust jacket and the copyright page. What you get for $10 more is a permanent edition of the novella, and what you don't get is the five stories by other writers which originally appeared with it.

As for the novella itself, it's not one of Le Guin's best. There are some wonderful patches of description, a few good characterizations, and Le Guin reminds you what it's like to live in a society where everyone (but a select few) has to walk everywhere.

The setting (especially the background, how the people got there) doesn't make much sense. Essentially, her space colony of Victoria was settled by two groups: a) prisoners, who have turned into the Bosses and b) pacifists, who have turned into peasants. The straw-man Boss society is set up to fail, the peasant society to undergo a lot of grief in the name of noncooperative, nonviolent protest. (It would have been much more logical for the governments of Earth that didn't want either the criminals or pacifists to set them down in Antarctica, or the middle of a desert, or anywhere in the solar system. This is a prison planet, which is fine if you've got a galaxy-spanning civilization, but all these people came from Earth, on one-way rockets. This is real pulp thinking, something Le Guin has never done before.) I hate to give it the oldest of genre criticism, but here it is: except for a few alien bugs and some giant rabbit-like beasts, there's no reason this couldn't have taken place somewhere on Earth, just post-gunpowder, perhaps during the Thirty Years' War.

The main character, Luz, is a Boss' daughter. The Eye of the Heron is the old science fiction standby, the tale of conversion-to-the-rebels, with an overlain consciousness-raising, and some few hard truths about what it takes to be a real pacifist and how far short people always fall of the ideal.

If you're a Le Guin collector, you'll get this anyway. If not, my advice is to wait for the next novel or story collection.

"All starship futures," science fiction writer Ed Bryant once said, "are essentially Southern Californian." And this is another one, but at last someone has done something with it.

Norman Spinrad has written some good books, some great idea/too-bad books, and a couple of unreadable novels. Now, with The Void Captain's Tale (Timescape/Simon & Schuster, $13.95) he has come up with an idea, a style and a narrative that perfectly fits his talent.

There is the Southern California/starship syndrome: lots of hedonists and gourmands on interstellar flights, drugs, decor and our old science fiction friend, the Jump, whereby a ship in one place jumps to another, through some hyperspace or other dimension, circumventing all the relativistic effects of trying to go faster than light.

There have been jumps in science fiction before, most notably Cordwainer Smith's "Game of Rat and Dragon" (1955). Spinrad explores new ground in the mechanism for the Jump; in this case, the Jumps are triggered by the orgasms experienced by the Void Pilots, specially- trained women whose enhanced sensory experiences take the ships across three-light-year leaps.

In other hands, or even from an earlier Spinrad, all this would be just too much. But the sex, though ever- present among the crew and Honored Passengers, is understated. The tale, narrated by the Void Captain, becomes one with ever-deepening levels of meaning and symbolism.

Spinrad has the complications start when the Void Captain meets and talks with the Void Pilot, a rare event in the society he posits. (All the other Void Pilots seem to be, from hints dropped about them, the futurological equivalent of shopping-bag ladies.) From this point we enter the closed world of the starship Dragon Zephyr and its worlds-hopping passengers, some of whom have never made a planetfall in their lifetime, but got from ship to ship between ports. We also start the slow and inevitable realization by the Void Captain of what is going to happen, what he's going to do.

For this jumbled future, Spinrad has created one of those synthetic languages (a sort of pig-Earth, a use of polyglot phrases from dozens of locales around the world) which causes a little reader discomfort for the first few pages, but slowly and gradually comes to seem almost right.

I don't like to use an adjective to describe one writer's work that contains the name of another, but Spinrad has written a very (Barry) Malzbergian book, dark and somber in tone, subject matter and method. That his other long works have been poles away from this is a sign that he is growing, and in interesting ways. All the blurbs I've seen are right: this is Spinrad's best book.

Inside Stanislaw Lem is a great writer trying to get out. And judging by his latest book, His Master's Voice, translated from the Polish by Michael Kandel (Harcourt Brace Jovanovich/Helen and Kurt Wolff, $12.95), that writer has been trying to get out for a long time. The novel was first published in 1968 and is just being brought out over here. It should have been translated when first published. It could only have helped Lem's reputation.

Its subject matter is similar to that of Don DeLillo's Ratner's Star: the gathering together of a Manhattan Project-sized think tank to attempt to decipher what seems to be an endlessly repeating (every 416 hours) message from the stars. There the similarities end. Lem's novel is supposedly the memoirs, penned in 1966, of Peter Hogarth, mathematical whiz, of his part in the project, called HMV (for His Master's Voice).

Lem takes you through many of the trials, errors and false starts of the massed scientists as they attempt to decipher the message (which by the way is in the form of neutrino emissions, rather than the more expected radio noise). In doing this Lem, like his scientists, overlooks many possibilities which you will think of, even if, like me, you have little interest in physics and can't balance a checkbook.

Then, halfway through, the narrator, convinced that he and the other scientists have deciphered a tiny part of the message all wrong (the analogy Lem makes is that of putting IBM punch cards in player pianos and getting out weird music) also comes to the conclusion that a small byproduct of their tinkering will cause the certain destruction of all life on Earth as soon as news gets out.

What Lem has tackled here are two or three themes too large for any writer. Like: what is the responsibility of a scientist to humanity? How could we ever tell if we were reading a message from the stars, caught in mid- sentence? What if, in reading the message wrong, we went off into sinister areas, just from the sheer concentration of so many minds working on one problem from so many angles? These are all questions I don't think any other writer has tackled before, or in such an oblique manner.

There are touches of real extrapolation in the novel, besides the main problems. There are two chance discoveries in deciphering the message. One, amplification of the message causes inorganic molecules to group in chains conducive to those which produce life; and two, that these substances then act in abnormal ways. These discoveries are presented, take center stage, then dropped as the narrative, and the concerns of the scientists, move beyond them.

The accidental discovery of the message itself has the real ring of truth, involving as it does research by graduate students on a theory later proved wrong, a chance newspaper article left on a subway, and the rabid publisher of a flying saucert, a magazine. Lem's listing of published works on the project sounds like real books, not names made up for a bibliography.

Which is not to say the book is a masterpiece. Lem has done his research so well that the book reads like it was written by a cranky old American mathematician, no mean feat for someone who lives in Krakow. The early chapters, after a sort of ur-biography of an overachiever, have verisimilitude, but by the 10th page of the introduction you want to yell "get on with it!"

The major problem is that the emotional and philosophical climax comes on page 144, and the book ends on page 176 with everyone still wangling over what happened or didn't happen 30 pages back.

This is not a book, as it might seem, about science and scientists, the military, or politics, though they are all in here. It is a book about the whole human race and what it's like to be part of it in the 20th century.

So there you have it. Science fiction remains an enigma even to its practitioners and fans. Three more different books you couldn't imagine: one 15 years old, one five, one just written. Whatever else these publishers are doing, they're not afraid of being wrong some of the time. Good books are bound to get through.