On a windy hill at Greenbelt's Goddard Space Fight Center on a cold Sunday afternoon, about 40 children and their parents huddle together or bounce up and down to keep warm. In front of them, a dozen would be Goddards and von Brauns, including a girl of nine, command a makeshift launch pad - a six-foot-long rack supporting six rockets. A public-address announcement fills the chilly air with sounds of science. "The panel is armed. We have continuity. Range safety is go."

Then "T minus 5, 4, 3, 2, 1. We have ignition . . . Aw, nuts,"

"Burnout," youngsters mutter into their mufflers.The nine-inch-high homemade model rocket emits a puff of smoke and falls back without leaving the rack.

The hobbyists - from local rocket-builder clubs - emulate the great man the space center's named for, Dr. Robert H. Goddard, who, 52 years ago on March 16, launched the first successful liquid-propelled rocket. It flew for 2 1/2 seconds, a good deal less time than young rocketeers get today.

Outside the visitor center stands a mannequin clothed to look as Goddard did that historic day. His overcoat flaps in the wind. Walking past the lifelike figure, an eleven-year-old says, "It's cold, isn't it, sir?"

It's much warmer inside the center, a small-scale monument to NASA, and to American's 20 years in space. As you enter, you pass scale models of every conceivable satellite. Televisions play footage of Mercury and Gemini takeoffs, and moonwalks. A six-foot videa screen continuously replays the most recent space shuttle test launch.

A "live via satellite" display tells us that "Communications satellites are now keeping us abreast of world events as they happen." Underneath, a TV screen flickers. Henry Kissinger is visiting the pyramids with Sadat.

Exhibits overhead tell of star birth, black holes, supernovae and the like. They're quaint displays compared to those at the Air and Space Museum, but the commentary is easier to hear and understand.

Upstairs, a telemetry exhibit beeps to show how a satellite signals information to the ground. By touching a heat-sensitive groove on the display, you can change the pitch of the beep that indicates what the temperature is.

Gesturing the the groove, a grandfather tells a boy who's standing nearby: "Stick your finger in there." The grandson pulls back and says, "You try it." "No, go ahead, it won't hurt you." "What if it does?" And so forth.

The two displays at the space center are inoperative. One is a solar telescope. The other, two telephones connected by satellite: When the phones are working - soon, they hope - you can hear your own voice bounced back from an equatorial satellite 22,000 miles away.

Of course, Goddard visitor center's got its token piece of moon rack.

Down the hill, Building 14 is accessible to the public. Visitors sit on auditorium chairs and peer into a glass-enclosed control center as a recorded voice explains what's happening. Inside, the nerve center of about 14 satellite-tracking stations details and oversees the day's tracking priorities and schedules. Exhibits in the lobby include light-up satellite weather-picture maps and a photo roster of every astronaut who ever left the ground, and some who didn't.Holding their helmets, they look like an assemblage of first-string football players.

Back outside, not all rockets shot off by the rocketeers on the hill are going blooie.

One soars hundreds of feet, its two-inch-long motor sparked by a 12-volt car battery wired to the launch rack. Some come down in one piece to be flown again. Others take flight but suffer parachute malfunction and fall to crumble on a parking lot.

These are the only rockets ever launched here. Goddard Space Flight Center's role is to develop earth-orbiting satellites and operate NASA's worldwide tracking and communications network.

The crowd has been slowly moving downwind.Since no one wants to bear the full force of the wind, the group's been playing an unconscious leap frog, trying to stand behind someone who's blocking the gusts. It's hard to believe, but we're told it's only 13 mph. Visitor center manager Ed Pearson, who's been keeping track, announces he'll stop the launches if wind speed reaches 20 mph.

The crowd has been waiting for something, and it's a big mother of a rocket poised on its own launch rack: a home-designed special, 2 1/2 feet tall, built by an older rocketeer named Phil Barnes. Pearson announces that his bird holds seven motors and a 50-foot-long green steamer. Young boys in the crowd ooth appreciatively.

"T minus 5, 4, 3, 2, 1. Ignition" . . . Pop!

One motor fires, not enough for lift-off but enough to send the great green steamer billowing out the nose of the rocket and onto the hill THE DIRECTIONS

Take Beltway exit 28 and follow signs to Goddard Space Flight Center. Goddard is open to visitors Wednesday through Friday from 10 to 3 and Saturday and Sunday from 10 to 4. THE CLUBS

Members of the National Association of Rocketry launch on Goddard grounds every first and third Sunday of the month between 1 and 2 p.m. Model rockets are made from kits or home-designed of cardboard, balsa wood and lightweight plastic - not metal, which is considered "amateur rocketery," a different class. If you're interested in joining a model rocket club, here are some representatives you can call.

National Association of Rocketery Headquarters Astro-Modeling Section (NARHAMS), Ed Pearson, 577-7775.

Northern Virginia Association of Rocketery, (NOVAAR), Chris Tavares, 370-8629.

Starfire Rocket Club, Ed Saylor, 577-5376 (Seabrook/Lanham).

Laurel Area Rocket Club (LARCs), Greg Kennedy, 490-5662.

Star Spangled Banner Section, Dottie Galloway, 301/987-4395 (Saverna Park/Annapolis).

Wheaton Association of Rocketery (WAR), Steve Honecker, 649-2537.