David Ross gingerly drops the single-engine plane onto the private runway and taxis to the nearby hangar. "Welcome," he says with a chuckle, "to Matagorda Space Port."

The only thing you can see from the landing strip is the Gulf of Mexico, some palm trees, a lot of cattle and a big house. It's as if Orville and Wilbur Wright have come to J.R. Ewing's Southfork.

But Ross, a 31-year-old scientist wearing cutoff jeans and a red polo shirt, isn't joking. A few miles down a narrow road, the first commercial space venture in U.S. history is rapidly taking shape, in the middle of a cow pasture on the South Texas coast.

Two companies -- Space Services Inc. of Houston and GCH Inc. of Sunnyvale, Calif. -- have joined forces to challenge the National Aeronautics and Space Administration's monopoly on space travel, and the free-enterprise spirit has everyone here giddy with excitement.

Although technical difficulties yesterday delayed the first test-firing of the 55-foot-long rocket's engines, developers still are looking toward an August launch, assuming the Federal Aviation Administration can cut through its red tape fast enough.

By NASA standards, the first test launching will be a chip shot -- 14,500 feet up and a few miles out into the Gulf. But you've got to start somewhere.

By 1983, the companies hope to begin commercial operations, ferrying communications and other satellites into outer space for firms that don't want to wait on NASA or are looking for lower cost. Eventually the companies expect to be able to handle 10 to 12 launches a year.

"Mmmmoooooooooooooooooo."

That's the sound of the young man driving a Harvester Scout down the ranch road from the landing strip to the launch pad. He's trying to get the cows out of the way so Ross can show a group of visitors the operation. The cows pleasantly return the greeting and scamper out of the way. The island is also full of deer and waterfowl. The endangered whooping cranes use the island's marshes as a winter habitat, but they're in Canada now, missing history in the making.

The launch pad, a few miles up the island from the landing strip, is 144 square feet of foot-thick concrete. Scattered around are pressurized canisters of helium, a huge tank of liquid oxygen, lengths of pipe and lots of cow manure.

The 18-foot steel launch stand that holds the rocket sits on top of the concrete slab. The rocket was built for about $1.5 million in GCH's Sunnyvale plant and shipped here by truck. Everything went fine, except in New Mexico, where the driver had to take evasive action to slip away from authorities who wanted to make sure his papers were in order. No hard feelings.

Across from the pad is the pond that will provide cooling water during liftoff. Right now it's a haven for alligators, which, the crew reports, like to eat salami off the stick. The pond is about four feet deep, and when the rocket starts firing, the alligators will have to head for low ground because about half the pond is emptied onto the white-hot pad.

Up the island another 600 feet is mission control. It's a tiny brown trailer surrounded by makeshift shelves piled high with such exotic space gear as a chain saw and some garden hose. Not exactly what he engineers at NASA put up with.

A few sweaty young men are building a sandbag wall in front of the trailer, just in case the gleaming white rocket forgets the script.

The crew of scientists, some of whom have been here since late May, have overcome all kinds of problems. There are no roads leading onto the island, so everything has to be brought over on barges or in small planes. The plastic tools used on some of the electrical equipment have melted under the hot sun.

The crew found itself in the middle of a family feud and had to abandon its first launch site. And U.S. Customs officials got nervous, when small planes began making regular night landings on a remote airstrip lined only by reflectors.

Ross is chief scientist of the operation. His team includes Jim Fruchterman, 22, wearing a yellow "Four Wheeler" T-shirt and hoping to be an astronaut someday; Clifton Horne, 27, a sandy haired scientist with a baritone voice, and Eric Laursen, 29, wearing a plaid flannel shirt and his hair pulled back in a pony tail and talking about eventually doing business on the solar system's other eight planets.

This is about as well-educated a work crew as you'll find on any construction site, and everyone pitches in. Ross, in addition to being chief scientist, is the pilot for the plane that shuttles eveyone back and forth to the island and he handled the crane that set up the launch stand.

Says Ross: "It's a labor of love."

GCH and Space Services Inc. expect to put about $20 million into the operation before going commercial. SSI, headed by David Hannah Jr., is the financial and marketing end of the business. GCH, headed by Gary C. Hudson, 31, handles the rocket that will provide the transportation into space.

Hannah and Hudson met a few years ago in Houston and found they had similar dreams of making money off space. Hannah rounded up investors, mostly from Texas. One is Dallas oilman Toddie Lee Wynee, who owns the part of the island being used for the launch. And Hudson set out to build the rocket.

What they ended up with is a liquid oxygen- and kerosene-fired rocket that is similar to the Redstone vehicle that carried Alan Shepard into space May 5, 1961, and the Delta-class rockets currently used by NASA.

It is called Percheron, after a breed of workhorse.

"The building of a launch vehicle is really a trivial task," Hudson says, as if this is going on everywhere. "I just started out to do this with the idea I was not trying to build a space shuttle or a moon mission or enhance the prestige of our country, but to carry a payload into space for a low price."

For commercial ventures, the rockets will be clustered in groups of three or seven, depending on size of the payload and how far into space the satellite must go.

SSI and GCH expects to charge $3 million to $5 million to send a satellite into low orbit. Such satellites are used for photographying the earth to monitor crops or hunt for oil or minerals. The companies will charge about $15 million to $16 million to send up communications satellites, which hover 22,500 miles above the earth.

NASA charges about $22 million to get a payload into space.

NASA's attitude is a mixture of admiration and skepticism. "We wish them luck," said Steve Nesbitt, a public information officer in Houston. "We think perhaps they may not realize the full complexity of what they're getting into."

Down on the island, the boys, as SSI president Hannah calls them, have no illusions about that. But they like being the free enterprise David cast against the government Goliath. "You don't know," says Fruchterman, "how much that appeals to all of us."

If it weren't for the mosquitoes and the cow manure, and that untested rocket, they'd have nothing to worry about.