A burst of sparks, a whiff of smoke, and the space shuttle leaves the pad. With a piercing FFFSSSSSSSST!!!!!, it spirals up, then stalls for an instant in the sky. There's a mid-air jig as the parachute deploys. Mike Hanyi, 15, heads for the trees.

"Oh, jeez," he mutters, and scrambles down the knoll, racing the shuttle's earthbound drift. All eyes follow as he dives through a gate and scales the maple sapling in which his rocket's snagged. Swaying in the breeze, he grabs and pulls. Several Cub Scouts cheer.

"The thing is," the wiry youngster says, "if my rocket comes down in a tree I'll go after it every time. If the tree's too hard to climb, I come back with a saw. That could be thirteen dollars slipping through my hands."

At the Goddard Space Flight Center in Greenbelt, it's launch day again: a pageant of flight and fancy such as NASA still does proud. There's no primal roar of a Saturn V, nor blinding flash of fire, but hundreds of model rockets can be just as uplifting.

Ed Pearson, manager of the visitor center, is ground controller. "There goes a plane; do you think we could hit it?" he wonders at a faraway chugging of propellers. "Perhaps we could, but we're not gonna try."

Amid a crowd of scouts, some junior-high schoolers and a few grownup fans, he stands behind a console, speaking into a mike. Everyone keeps a respectful distance from the launch rail -- a sawhorse with room for six paper-and-balsa models -- connected to the console by thick black wires.

"T-minus five, four, three, two, one," Pearson says with practiced urgency, his thumb resting lightly on the starter. "It looks like there's a fruit fly on the nose cone. He's gonna get a surprise. . . Zero," he says, and presses the button.

Another rocket, fruit fly and all, FFFFSSSSSSSSSSSSTs toward heaven. Before day's end, dozens of Alphas, V-2s, Hanyi's space shuttle and others -- one, with a Darth Vader nose cone, carries a rock-candy payload -- will have made the round trip between earth and sky.

"You do get attracted by all the fire and smoke, especially if you're 13 years old," says Chris Tavares, 29, a local computer whiz who edits Model Rocketeer, the hobby's preeminent journal. "And you do start to enjoy the smell of sulphur after a while. But there's a lot more to model rockets than watching them go up and come down."

There is, for instance, the modeling itself, a pastime needing patience and persistence. "You wouldn't believe how detailed it can get," Tavares says. "In scale-model competition, you can have points taken off for having a better paint job than the original. Some people actually specialize in bird manure and scratches."

Says Quang Pho, 16, of McLean, "You have to get a lot of data about the actual rockets you're scaling, which involves a lot of paperwork and contacting NASA or the people at White Sands. It's considered a big success even to get the information."

Only then come the flights themselves, which include egg-lofting, spot landings, power-gliding, and even, in a recent case, supersonic travel. Tavares labels the last pursuit "exceeding the speed of balsa."

There's also the joy of successful recovery, in which Mike Hanyi is an expert. "If a tree's skinny and tall, it can be like a catapult, so you have to be pretty careful. The higher you go, the weaker it's gonna be. I remember one time I was about 50 feet up, next to a nursing home, and when I went for my rocket a huge branch broke off and fell right past the dining room where everyone was eating. I just hid out for a while.

"Another time, one of my favorite rockets got stuck in a tree in somebody's yard. As I was climbing, a man came out of the house and screamed at me, 'Get out of that tree, you'll get hurt!' So I just said, 'Take one more step and I'll jump.' He stayed away. He must've been worried about his insurance or something."

And then, of course, there's the excitement of battle, as in the World Space Modeling Championships, held two years ago on the field where the Hindenburg crashed in Lakehurst, New Jersey. Eight countries competed, but particularly memorable was the Bulgarian team, 10 men in sporty red jumpsuits. "I remember somebody high up in the Russian Embassy showed up to egg the Bulgarians on," Tavares says fondly. ("That would be our military attache," says the Soviet Embassy's press guy. "No, I'm only joking." Then, gravely: "I wonder if, in the present atmosphere, model rocketry is the best thing for us to be talking about.")

"The thing I like about people in model rocketry," Quang Pho says, "is that most of them really seem intelligent."

The hobby started officially in 1957, chasing the plumes of Sputnik. It was a makeshift pastime then, fraught with adventure. "There was an unbelievable number of 'basement bombing' accidents," says Dane Boles of Estes Industries, leading producer of engines, kits and accessories.

"People would try to make their own rocket engines, with gunpowder, zinc sulphur, kitchen chemicals and the like. There were just a lot of explosions; a few folks died."

Verne Estes, scion of Colorado fireworks wholesalers, solved the problem with an automatic device that could press solid propellant engines -- mostly charcoal, sulphur and potassium nitrate, wrapped in cardboard tubes and ignited by an electric spark -- of sufficient quality and in sufficient quantities to be both safe and financially rewarding.

"It took me several months in my garage to build that equipment," Estes, 52, says wistfully. "I called it Mabel 1." He went on to design the Astron Scout rocket kit, an example of which can be found at the Smithsonian, and sold his business in 1969, the year of the first manned moonshot. "Now I have a company in Pueblo," he says. "We make gift items, processed glazed tiles, and then we frame them in various manners."

In the last 24 years, some 200 million launchings have gone off without incident, while these days, according to Boles, "somewhere in excess of a million people enjoy the activity every year." The typical rocketeer, though, still is a teenage boy.

"I have a daughter who's seven years old, and I took her out with me to launch a few weeks ago," says Greg Kennedy, a loyal rocketeer for the last two decades, now a curatorial staffer at the National Air and Space Museum. "I think she halfway enjoyed it. But she stood about 25 feet back and held her ears."

At the Goddard launch, a chap named Herb Desind doesn't keep back, but rather crouches close to his rockets, checking cameras in the nose cones before they sputter off the pad. Desind, 37, of Silver Spring, didn't come to model rocketry until 12 years ago. Now he's the unchallenged Cineroc King.

"Cineroc is just the brand of a Super-8 camera I use," says Desind, a junior high school science teacher. "They don't make them any more, but I own about 80. People would kill for those cameras. I have maybe 70,000 feet of film I took from model rockets in flight.

"I've flown them off active volcanoes in Iceland, the Alps, Meteor Crater in Arizona, Hyde Park in London, Three Mile Island, Mount St. Helens, Puerto Rico, Norway, Luxembourg, Switzerland, Dublin, the Caribean, Hawaii, Florida, the RFK Stadium parking lot, and a friend of mine flew my cameras for me in Yugoslavia and Bulgaria.

"I've always been partial to aerial photography. It gives a whole new aspect to the world. Everything falls into place."

Later, he shows a visitor his collection. In a tiny bedroom crammed with cabinets full of reels and shelves brimming with rockets, Desind proffers a scrapbook. To the unpracticed eye the color photographs inside -- of the road system near RFK Stadium, the smokestacks by New Orleans' Superdome, the Anacostia River, a footfall field in Kearney, New Jersey, the parking lot of Eisenhower Junior High School, and other such wonders -- look blotchy and fuzzy.

"Look at this one," Desind says excitedly, pointing to a picture labeled Albuquerque. "I had the camera trigger right at apogee, so I could get the Sandia Mountains." He ushers his guest down the basement stairs, through a veil of drying laundry and into a niche where a projector and screen have been set up. He threads the reel and kills the lights.

"Now you'll really see something," he says. The movies, shot from such spots as a field in Glen Burnie and a parking lot in Laurel, look, to the novice, remarkably similar. First, a few blades of grass fill the screen. Then there's a glimpse of the top of Desind's balding pate. Then comes a great deal of spinning as the ground falls away. Houses and trees whirl by, making the viewer queasy. Then there's a shot of open sky, leavened by a swatch of parachute. The spinning continues as the ground comes near. At the end comes the grass again.

"I've also put rockets over the agricultural library in Beltsville," Desind says dreamily. "I've got shots of the roof. Let me tell you, that's a nice sight." ROCKETS AWAY -- There'll be a model rocket launch this Sunday at 1 at the Goddard Space Flight Center in Greenbelt. The event is a regular activity at Goddard, held the first and third Sunday of every month. Take Beltway Exit 22-A and follow signs to the visitors center.

Former heavyweight champion Muhammad Ali said yesterday he would encourage Sugar Ray Leonard to fight again "if everything is okay (with his eye) medically.

"I hope he doesn't have to quit because he's in the middle of his prime with another good five years," Ali said. "I hope and pray he's all right because I love him."

Officials at Baltimore's Johns Hopkins University Hospital, where Leonard is recuperating from eye surgery, said that more than 1,000 pieces of mail from well-wishers had arrived the last two days.