America celebrates the fancy of flight, and the era of space-shuttle diplomacy begins tomorrow when the rocket ship Columbia is launched from Cape Canaveral in search of the unexpected.

On the eastern horizon of the Kennedy Space Center, in the eye of the wind, stands the muscular trident of the shuttle. It is white and it looks like a giant artillery shell with a Roman candle on either side, and attached to its spine, riding piggyback, is the rocket plane Columbia.

There is an undeniable glamor in the scale. The rocket is three miles from the press site, from where the nation's television cameras will record the liftoff now set for 6:50 a.m. tomorrow. Even at that distance it looks huge. Near the press site is the 525-foot-high Vehicle Assembly Building, standing like a mammoth, hollow hotel. In line, far behind, is the space center's landing strip. where future shuttles will glide home. The runway is three miles long.

The scale, and the wind, and the knowledge that this handsome, aerodynamic space plane is the first to carry men without having flown before, contributes to the chill of impending venture. Everyone feels it, this curious rearrangement of the molecules of ordinary experience. The Highway

A sign on Route A1A in Cape Canaveral says, "Up, up away, Space Shuttle Hurray." But there are only a few such signs, whereas in the days of the moon shots the strip was papered with slogans. The Moon Hut, a hamburger emporium with a far-out theme, looks sillier now. The people of Cape Canaveral and Cocoa Beach, survivors of six years without a manned space shot, declined to pin their hopes on the new program. The boom of liftoff is transient, and they have lived with the echo.

Nevertheless, there is a special liftoff sale Saturday at the Chrysler-Plymouth dealer at the corner of Nassau and Apollo boulevards. And the Super X food and drug store is staying open 24 hours a day and advertising "A Front-Row Seat in History" in its parking lot.

To those with their feet on the ground, the Cape is a peninsula of orange and grapefruit groves, and the delicate intersection of space and terra firma is everywhere to be seen and for mrs. Caroline Policicchio to see it.

Policicchio's groves on Merritt Island are only about six miles from the launch pad. Her brochure shows a space rocket rising over a grapefruit tree laden with "The Finest Fruit in the Universe." However, she's going to watch the launch on television. The reason is that she expects a six- to 12-hour traffic jam after blastoff.

Policicchio's daughter, Sarah Jones, is a public-affairs officer for Nasa."Sarah's working very hard on the shuttle," her mother explained, "but the real problem is that her dog is pregnant and we're afraid that the pups aren't going to make it, and it's a shame she can't be with them. These are greyhounds that she raises. Greyhounds that you race. We are very worried."

The problem with space exploration is that in between launches people have to go on leading their earthbound lives, and there are problems, and then they are expected to look suddenly to the stars. The Tour Bus

The press tour bus pulled onto the shuttle landing strip, which is so long that you can't see the end of it; it just disappears into a mirage. The eight-foot alligator looking at you from his sinkhole, however, is not a mirage.

Eventually, most shuttle flights will end on this strip at Kennedy Space Center, but for the initial flight it is a contingency landing field. If after liftoff there is a problem, the rocket plane can separate from the shuttle engines, turn back where it came from and get down safely. If that contingency plan goes into effect, it will mean that something has gone very wrong and John W. Young and Capt. Robert L. Crippen are flying for their lives.

The last stop on the tour is the launch pad itself, which rises like a concrete pitcher's mound near the edge of the sea in the sweeping wind. The external fuel tank and the two booster rockets squat in their gantry with the graceful orbiter on their backs. Nobody says much, because up close the impact of this thing from the planet Earth is very great.

The bus driver, who is serving out his time in the General Services Administration, likes this part of the trip. He never gets tired of getting close to the rocket. "I seen some of you guys cry like babies when they go off," he says. The Viewers

Earl Tooley generally looks toward sea trout this time of year. They are currently running like bandits in the canals and in the Banana and Indian rivers around the base of the mangroves. Live shrimp is the best bait.

Tooley, who retired after 43 years with du Pont, is down from Richmond. He and his pal, John Goodwyn, rent a 14-foot skiff every morning and have been catching some eight-pounders. They plan to watch the liftoff from behind their fishing poles. "You can go up the Banana pretty far, at least until you see the security guards in the patrol boats," Tooley said.

The folks who live within 10 miles of the space center do not, of course, live their lives with their eyes closed.

At Tingley's Marina and Fishing Camp, which is located under an attractive lavender drawbridge over a canal, it is blue coral crabs as usual, space shuttle or no. The boats come in with five or six 55-gallon drums brimming with them, and there are crabs on the floorboards and in the engine wells, snapping and fighting and ferocious as any ugly little critter gets. Years ago we thought that maybe something that lived on the moon or Mars might look like one of these crabs, but now the idea is ridiculous. So far.

"In the old days," Ann Tingley says, looking down the canal toward the launch pad, "they wouldn't tell us when a rocket was going up. It was a secret, because of the Russians. The Russians probably knew just when to look but we didn't. The thing is, once you hear the rumble, it's too late to see the liftoff. All you see is the rocket up in the sky.

"By 1960, we finally figured out that when they turn the lights off at the base, it didn't mean they were going home, it meant they were going to shoot one off. So I kept watching instead of going to sleep and up one went and then I heard the rumble and then the rocket stopped going up and pulled a U-turn right before my eyes and blew up all over the Banana River, and pieces of fire rained down onto a trailer court. We have souvenirs to prove it."

That was Polaris missile test code number A101, according to a former engineer who wishes to remain unnamed, and who now works "for Boeing, in computers.A101 was my first mission, as a matter of fact, and I remember it well. We could see there was a crack in the casing and the rocket was burning on the outside as it went up. After it started to come down, there was nothing to do but push the button at range safety and blow it up." The Flight

The early space program was also plagued with such incidents, but by the time astronauts got into the act the testing was so elaborate that no American has been injured after takeoff.

The shuttle has been tested a lot, too. However, since it can only fly with men at the controls, it has never actually been flown. Young and Crippen are therefore truly engaged in a maiden voyage. They are going to go up, try to stay there for 54 1/2 hours and 36 orbits and come back down. That would be a complete success. The Columbia is a space plane about the size of the DC9s that carry people from National Airport to Disney World. It is an 80-ton glider with a sink rate approaching that of a stone. Since the shuttle will be out of fuel when it lands they will have only one chance to land it -- no second chance is built in -- but because they are test pilots, this one-chance-to-land plan is considered quite within the realm of human capability.

The entire launch countdown was stopped Tuesday because three little wires had been scraped bare, and there are a million other components of hardware that worry space engineers into building elaborate backup systems for them. But nobody doubts that Young and Crippen will land the Columbia with one chance. The Media

There are about 3,800 reporters here, and within two hours after launch we should have the first TV report from aboard Columbia. All of the networks and news stations and radio outlets and pencil pushers are in the same location here, a little rise where ABC, CBS and NBC have built many condominiums for themselves with picture windows for their cameras. Newspaper reporters can be seen in a circus tent; muttering into their telephones about the portable, electronic word-processing equipment that they have brought along and cannot get to work.

In the meantime, NASA smothers them with facts and the availability of further facts. A steady drone of information is broadcast outside by loudspeakers so that there is no way to avoid being informed that Dr. C. R. Odell believes strongly that:

"The space telescope is not an experiment. We know it will work when it goes up in January of 1985. What will we find? We'll find the unexpected. There is no reason to believe that we know what the universe is really like. Now we'll be expanding our sample of the universe 100 times. We'll be able to see back in history. We'll be able to see the unexpected."

At first, some of the reporters make cynical jokes about the selling job being done on them, but then the joke wears thin. The wind is blowing and the blastoff is coming nearer. The Payload

Cargo specialist Warren Smith is happy to display the actual payload to be carried by the shuttle flight next September. It is an array of five experiments designed to examine the surface of the Earth.

Smith, who works in a vast, totally dust-free building, weirdly illuminated by mercury vapor lamps, is enthusiastic.

"With these experiments, you can map your Brazilain rain forest. You can look at your red bloom in the ocean. We're talking a sensitive package here." Smith works for a subsidiary of McDonnell Douglas called MDTSCO. One tour guide explained that acronyms are useful because they allow you to talk faster, but they are also a hindrance insofar as understanding what is said.

Smith's acronymic world is further complicated by the number of contractors and subcontractors involved in the space program. This makes tracing failures difficult.

"When something shows up wrong in a test, you ask, 'Who built this?' Well, one company built the outside. Then another one built another component. And then the component inside of that was built by somebody else and you go along until you finally come along to the 50-cent thingamabob that broke. You get the little monster in your hand and it wasn't made by any of you. It was made by some little tiny company far away with $100,000 in annual sales. So you call them on the phone." The Countdown

So the countdown continues, not toward Mars or the moon, but toward a further look into the mirror of space. By 1985, there may be a shuttle takeoff or landing every week.

The big rocket place is a means not an end. It is spiritual hardware for an uncertain era. Some find what they seek in Cape Canaveral at the combined temple and motel of Dr. Carl McIntire, the fundamentalist preacher whose complex is emblazoned by a large painting of the Earth as seen from the moon and the legend "Gateway to the Stars."

The space shuttle launching platform is faintly visible on the horizon behind the temple for those who must travel farther.