Stuart Witt, a former test pilot who runs the airport in this weathered desert town, was working at his desk when he heard the explosion.

“I turned and looked out the window,” said Witt, 54. “There was a trace of dust in the air over by the east-side test area.”

His assistant suggested it was a sonic boom, a frequent occurrence in the desert airspace near Edwards Air Force Base.

But Witt knew better. Sonic booms come in pairs. This was one loud explosion, so powerful it was heard in Palmdale, 30 miles away.

The blast, which killed three men and injured three others, occurred during a fuel-flow test in July at Scaled Composites, the famed aerospace company that is building a suborbital rocket plane for Richard Branson’s Virgin Galactic space line.

For this desert hamlet of 3,700, located, as they say, “a full tank of gas and a full bladder north of Los Angeles,” it was a space-age wake-up call.

Fifty years after the Soviets launched the satellite Sputnik 1 into space, Mojave has found itself at the center of a private space race that boosters say is as important -- and risky -- as the nationalistic race between the Soviets and the United States.

This time, a group of ambitious entrepreneurs is leading the competition to launch regular Janes and Joes into space.

“Mojave is the place to be,” said Jeff Greason, a co-founder of Xcor Aerospace Inc., one of the larger rocket companies that has sprouted in the desert. “This is the Silicon Valley for the new industry.”

Half a dozen companies, from big-time operations like Scaled Composites to lemonade-stand-scale business with a handful of engineers working in stifling warehouses, dot the barren landscape around the Mojave Air & Space Port. Each company has its own remote testing site in the midst of the chaparral.

“The same things bring people to Mojave that brought Orville and Wilbur to Kitty Hawk,” Witt said. “Freedom from encroachment, industrial espionage, the press and a steady breeze.”

Dave Masten, the head of Masten Space Systems Inc., a bootstrap firm with five employees, has another explanation for the rocket boom in Mojave. The vastness of the landscape has inspired a high level of tolerance for dreamers and wayfarers.

Masten made a chunk of money in software development, then moved from the Bay Area to Mojave to join the private space race. He has spent a million dollars but has yet to launch anything more than a few feet above the surface of Earth.

He likes the camaraderie he’s found in the desert. “People come by to beg a cup of lox,” he joked, referring to the liquid oxygen used for rocket fuel.

Besides, testing rockets in the Bay Area would be considered antisocial.

“Here, we can do it anytime, anyplace, and nobody cares,” Masten said.

Atrip to Mojave is in one sense a journey to a place out of another time. Though the dim, low-ceilinged bars that once dotted the coast have been replaced by jazz clubs, the desert northeast of Los Angeles looks as stingy and friendless as it did before the arrival of the railroads.

At the end of a long drive out Highway 14 -- beyond the boom-and-bust desert metropolises of Palmdale and Lancaster, beyond the once-secret test facilities at Edwards Air Force Base -- the desert resolves into a crouched, narrow strip of fast-food establishments and motels still boasting of private showers and a TV in every room.

Yet Mojave’s isolation has made it “an optimistic place,” said Bill Deaver, a town historian and the brother of Michael K. Deaver, the recently deceased deputy chief of staff to President Reagan.

Deaver, a gruff-voiced man of 71, arrived in 1948. His father, Paul, was a gasoline distributor; his mother, Marion, wrote for the Bakersfield Californian, covering experimental aircraft flights at Edwards in the 1950s and 1960s.

According to Deaver, publisher of the Mojave Desert News, the town was founded by Southern Pacific Railroad in 1876 as a stopover on the line between San Francisco and Los Angeles. It became a watering hole for parched miners who flooded into the area after gold was discovered on nearby Soledad Mountain.

While some dug for gold at the Elephant-Eagle, Yellow Dog and Golden Queen mines, others dug out borax, a mineral used in detergents. The trip by 20-mule team from Death Valley to the railroad station at Mojave took 15 days and covered 160 miles.

In modern times, the airport has developed into a focal point of local industry. It was used to train military pilots during World War II and the Korean War. More recently, it’s been largely known as a boneyard for decommissioned passenger jets.

What has persisted through good times and bad is the vast emptiness of the place. It’s the reason the Air Force’s flight test center is at Edwards, along with NASA’s Dryden Flight Research Center.

The first space entrepreneur in Mojave was inventor Gary Hudson, who started Rotary Rocket Inc. in the late 1990s. He wanted to build a rocket with helicopter blades that would lift the craft into the atmosphere. Rockets would then ignite, sending the craft into space.

The craft was built by Scaled Composites, which was started by pioneering aircraft designer Burt Rutan. Rutan came to the desert in the 1960s to work at Edwards, and later broke away to build experimental aircraft on his own.

But the rotary rocket managed only a few test flights before Hudson ran out of money, a common problem that still haunts private rocketeers.

Rutan latched on to the rocket idea and decided to build his own. He was driven in part by a $10-million competition sponsored by the X Prize Foundation to create the first privately funded manned spacecraft.

In 2004, Rutan’s ungainly looking SpaceShipOne and its pilot, Mike Melvill, journeyed to an altitude of 100 kilometers, winning the Ansari X Prize.

It was a milestone in spaceflight. Virgin Galactic has already started booking flights aboard a Rutan-built craft for $200,000 a trip. The company hopes to begin launching in 2009.

Today, the private space industry makes up about 10% of the business at the airport, Witt said.

People “have a sense of pride” over the airport’s role as a birthplace of private spaceflight, Deaver said.

The town is facing increasing competition in becoming the center of private space travel. In addition to Mojave, the Federal Aviation Administration has licensed five other private spaceports, including Narrow Cape, Alaska; Wallops Island, Va.; and Burns Flat, Okla.

A variety of rocket companies, such as Amazon.com founder Jeff Bezos’ Blue Origin in Texas, and PayPal co-founder Elon Musk’s Space Exploration Technologies Corp. in El Segundo, have sprouted around the country.

But Mojave has its advantages, including experience, history and battle-hardened nerves.

After the demise of the rotary rocket, some of the engineers continued working on rockets. Greason co-founded Xcor Aerospace in 1999, and today it is the second-biggest space company in the area after Scaled Composites.

It has 35 employees and was recently named to Inc. magazine’s list of the 500 fastest-growing companies in America.

“I’m not an Internet gazillionaire,” Greason said. “We had to claw our way up. Not taking salaries the first couple of years helped.”

Xcor is building a vehicle for the Rocket Racing League, a proposed venture pitting rocket-powered planes against each other. After that, the next milestone is a suborbital vehicle that would compete with Virgin Galactic.

Instead of eight passengers, Xcor’s vehicle would carry one pilot and one passenger.

Land is cheap and rents are low, Greason said. Also, “nobody complains about making noise, or sending plumes into the sky.”

Indeed, Mojave has taken the explosion at Scaled Composites in stride. In some ways, it’s nothing new to a town built on mining and experimental aircraft.

The town’s history with big explosions dates to 1884, when 90 cases of gunpowder stored at the railway depot ignited. The resulting fire destroyed much of the town.

Vicente Rodriguez, a cook at Mike’s Roadhouse Cafe, said he worried sometimes about what was going on at the airport. “But I think they know what they are doing.”

Deaver, the newspaper publisher, said he hadn’t “heard a peep” of protest from anyone in town over the rocket projects.

“We don’t want to interfere with the creativity here,” Deaver said, “but we want to know who’s on the site and what they are doing.”

Greason said all the spaceflight companies knew there would eventually be an accident like the one at Scaled Composites.

“It was inevitable,” he said. “It was a regrettable thing, but it is a fact of life. There are hazards and risks” to building rockets.

The explosion took place at 2:30 p.m. July 26 as workers were conducting a flow test of the propellant system for SpaceShipTwo, the successor to Rutan’s X Prize craft. A tank of nitrous oxide, often used by hot rodders to boost horsepower, ignited. The test was conducted at room temperature and did not involve lighting the rocket motor.

“We felt it was completely safe. We had done a lot of these [tests] with SpaceShipOne,” Rutan said at the time. “We just don’t know” why the explosion occurred.

Through a spokeswoman, Rutan declined a recent request to talk about the accident that claimed the lives of Charles Glen May, Todd Ivens and Eric Dean Blackwell.

After the accident, Witt hired a consulting firm to review the airport’s procedures and training. He has also told the half-dozen other rocket companies at the airport that he wants to know in advance of tests with dangerous chemicals.

Because the accident occurred on the ground, rather than in flight, it is being investigated by Cal/OSHA, the state agency charged with monitoring workplace safety.

Greason hasn’t changed any of Xcor’s practices yet, and other rocket builders said they doubted the accident would have a major effect on operations.

“The fallout is going to be negligible,” said Peter Diamandis, chief executive of the X Prize Foundation and a guru of the private spaceflight revolution. “These people gave their lives pursuing a dream. . . . But accidents on the ground do not relate to the safety of vehicles in flight.”

The accident has not slowed the entrepreneurs’ enthusiasm for space.

Hudson, despite his failure with the rotary rocket, is back in town with a new business model. A company he co-founded, T/Space, is part of the new contingent of rocket companies. He recently bought a house in town to be closer to the space work.

As with the occasional retiree in a battered pickup still searching the hills around Mojave for gold, the solitude of the desert seems to breed an unreasonable gumption.

“Two types of people come out here,” said Jonathan Goff, an engineer with Masten Space Systems. “Some are chasing dreams, and some are running from reality.”

Masten, his boss, added sardonically: “Or both.”

john.johnson@latimes.com