IF YOU think you've got any budding scientists around the house, it just may be time to put them in touch with some role models -- model rocketeers, that is.

The ideal introduction to the rocketeering hobby takes place at the NASA/Goddard Space Center in Greenbelt on the first and third Sunday of each month, when more than a hundred people are likely to show up to watch the hour-long ritual of sending homemade rockets charging into the sky at speeds of up to 350 miles per hour.

This is one program that understands spectating's never quite enough, and NASA officials, themselves avid rocketeers, eagerly help the kids have a blast for themselves.

On a recent Sunday, NASA official Ed Pearson, presiding over the launchings with microphone in hand, gives instructions to the several dozen participants before summoning the first group forward to prepare for launching. With rockets in hand, they approach the metal rail of the launch pad respectfully. After the hours of painstaking labor and dripping glue on the kitchen table, they are anxious to see if their $4.95 rockets possess the right stuff.

They're about to find out.

"T minus five," Pearson begins, leading them in his daylong missile mantra, "four- three-two-one . . ." and with the push of a remote control button: "Flash!"

Fizzing and hissing, the rocket zips two hundred yards into a patch of blue, leaving behind a trail of smoke and a chorus of "Wow!" from the terrestrial crowd.

But what goes up must come down -- and that can be just as much fun for the rocketeer as the launch itself. As the rocket reaches its peak, popping its nose cone and puffing out a parachute, its young builder darts out of the launching area, head tilted backward, in pursuit of his craft.

"Nice catch," Pearson says, and the crowd applauds. It's just one of about a hundred rockets to be launched on this Sunday at the center, yet Pearson will describe each as if it were NASA's latest hot project.

From an impressive U.S.S. Enterprise to an unassuming Alpha 3, the rockets are as varied as the kids who own them, and Pearson bolsters each kid's sense of accomplishment by making him feel special about his rocket.

One of those is Louis Breger, 51/2, of Kensington; he says he likes chasing after the rockets best of all.

"It's an absolutely wonderful family activity," says Louis' father, Joel, who also enjoys the exercise, fresh air and relaxed camaraderie of the NASA outing.

Something of an adjunct to the program himself, the elder Breger comes prepared with a tackle box full of repair glue and accessories to offer help when needed. He's also brought a half dozen rockets -- testimony to the two years he and his family have spent attending "Rocket Sundays."

Enthusiasm like that of the Bregers, and the NASA officials' general helpfulness, gives Rocket Sunday a decided advantage over experimenting in your own backyard. NASA offers controlled conditions: safety inspections, an ignition system, rails to guide the missiles, and friendly advice.

Rocketeering is an affordable hobby; even the smallest allowance can be saved for the $4 dollars or so it costs for a beginner's rocket at most hobby shops. Most rockets are rather simple devices: often a balsa tube with fins and a cap, propelled by a powdered-fuel cartridge; but they still take several hours to build and paint.

On this Sunday, 13-year-old Jason Long, who's visiting from Washington state and says building the rockets is what he likes best, can't acheive liftoff on his first flight. So Herb Desind, a Laurel schoolteacher, assists by fixing the igniter clip to establish better electrical contact. Sure enough, Jason's rocket blasts off on the next try.

"I've been doing this since 1970," says Desind, 40, who logs all his flights. One of his rockets even contains a camera which actually takes photographs from the air.

He uses the photos and rockets "as a lever to get the students interested in physics."

That rocketeering serves as a link between classroom, hobby and career is not so alien a notion. Some of NASA's astronauts and top engineers, including some in the space shuttle program, got their start with model rocketeering, says Alan Williams, who works at Goddard.

One guy who wouldn't mind his own seat at NASA space-flight control is 12-year-old Jeff Fineran of Greenbelt, who's caught the bug over the last year. He says he wants to learn more about aerodynamics. "Besides," he says, "it's nowhere's near as rough as football."

RIGHT ON TARGET

Rocket Sundays take place from 1 to 2, on the first and third Sunday of each month throughout the year at the NASA/Goddard Visitor Center and Museum, off Route 193 in Greenbelt. To get there, take the Baltimore- Washington Parkway north to Route 193; follow signs to visitors center. The museum is open Wednesday through Sunday, 10 to 4. For more information and tour reservations, call 344-8981.

NASA also sponsors a similar launch program on the first Saturday of each month, from 1 to 2, at its Wallops Flight Facility, Wallops Island, Va. (U.S. 50 across Chesapeake Bay Bridge to Salisbury; U.S. 13 south into Virginia, left on Rte. 175; it's six miles to the visitors center on the right. 804/824-5833 or 804/824-3411 ext. 584.

TOURING THE MUSEUM

To either get you in the mood for launching your rocket or bringing you back to earth afterwards, you might visit the flight museum at the visitors center in Greenbelt.

Opened in 1976, the museum was established to entertain and educate the public about the space program and application of technology.

Among other things, you can: get a bird's- eye view of the East Coast from a Landsat montage; see live space shuttle coverage when a mission is underway; check out actual satellites and spaceships, including the Gemini XII; stand behind a cardboard astronaut suit; chat with a talking computer and learn about Dr. Robert Hutchings Goddard, the American rocket pioneer, for whom the center is named.