It's where hundreds of people are busy doing secretive work for Uncle Sam and who-knows-what other customers.

You won't read about these high-tech, cloak-and-dagger projects in the newspaper or see them on the nightly news. Some participating in activities there don't return a reporter's calls, and they want little publicity.

To be sure, this local version of Area 51 doesn't have a questionable reputation for performing experiments on the bodies of space aliens, as does the super-secret Air Force test center in the Nevada desert.

What this locale does have is nearly 300,000 residents, numerous parks, golf courses and a mayor.

Welcome to Aurora.

At times a butt of local jokes, the 144-square-mile city actually is home to an aerospace-defense industry that's been generating jobs at a rapid clip.

And you'd be forgiven for knowing little about what these companies and their staffers are toiling over.

Much of the work is stamped "classified."

Not even Aurora's top elected official knows exactly what's going on inside his city's borders.

Mayor Ed Tauer, in fact, likes to joke to local aerospace-defense execs: "I have no idea what you're doing here. But I'm damn glad you're doing it here."

Eleven of these companies are known to have operations in Colorado's third-largest city. They are big . . . and small: Raytheon, Northrop Grumman, Merrick and Paragon Dynamics, to name a few.

What do their employees do?

They crunch and transmit satellite data that military brass and civilians can use to make tactical decisions.

Some integrate computer systems and write software related to fighting terrorism. Others develop software that controls orbiting satellites. Still others design sophisticated headquarters for such customers as the U.S. Army Space Command in Colorado Springs.

These 5,000-plus workers occupy a vital chunk of the Aurora economy. "Outside of retail, I would say the largest industry we have now is aerospace and aerospace-related," said Paul Tauer, who served as mayor from 1987 to 2003 before his son took charge.

Aurora's mother ship, so to speak, is Buckley Air Force Base, a sprawling 3,200-acre facility on the city's outskirts. Those inside Buckley's guarded walls rely on a global constellation of spy satellites to keep an eye out for hostile missile launches around the globe.

As a key military outpost, Buckley plays a big role in nurturing Aurora's aerospace industry.

"Many of the satellite operations that go on there make Aurora a prime spot for aerospace operations," said Douglas Hartmann, CEO of Paragon Dynamics, an Aurora company itself cloaked in secrecy.

Hartmann should know Buckley's importance. His company engineers satellite and ground-processing systems. But Hartmann won't say a lot more than that. Ninety-five percent of Paragon's work is classified.

Aurora's emergence as an aerospace-defense hub comes amid growth in Colorado's own space-related industries.

The state has the No. 4 space economy in the nation with more than 142,500 jobs, according to recent data. The annual payroll totals $9.7 billion.

Many of the companies have operations in Colorado Springs, Denver and Boulder. Recently, however, Aurora has been grabbing more headlines.

Chalk it up to an expanding federal defense budget, particularly in the post-Sept. 11 era. Also, officials at the Aurora Economic Development Council have been busy wooing and keeping aerospace-related companies and their higher-paying jobs.

Consider the case of Raytheon, Aurora's largest private employer with 2,600 people. That's up about 600 since the start of 2003. And this year the Waltham, Mass.-based aerospace-defense contractor unfurled plans to expand the company's already big Aurora footprint.

It's building a 150,000-square-foot office building to house up to 750 employees. The company's 45-acre Aurora campus already has four buildings. About 70 percent of the work done there is classified.

What is known is that Raytheon's systems and software engineers in Aurora build ground-control systems that control civilian and military satellites. The Aurora unit got a big shot in the arm in 2002 after landing a $1 billion deal to build ground systems for the nation's new weather-satellite system.

Century City, Calif.-based Northrop Grumman also is expanding. Last month, Northrop officials gathered with local dignitaries for a ribbon-cutting ceremony to toast the opening of an 80,000-square-foot addition to the company's office park in Aurora.

Northrop's approximately 1,000 Aurora employees perform sensitive work: Engineers and scientists develop algorithms and data-management techniques to collect and analyze data for military and spy operations.

The company's Aurora work force already has expanded 30 percent in the past two years. There's no sign the growth is set to halt.

"We are expecting a steady increase in our work force over the next two to three years," said Charles "Pepper" Fey, vice president of Northrop Grumman Mission System's data systems operations in Aurora.

Aurora wasn't always a cloak- and-dagger-type place.

When the East Colfax Trust Co. platted a subdivision called Aurora in 1889, it was little more than a prairie outpost. The once-sleepy farm town has undergone explosive change since then.

Former Mayor Paul Tauer recalled Aurora as "a nice homey town" when he bought a house there in 1962.

Retail was Aurora's dominant business at the time, with J.C. Penney, Woolworth's and grocers dotting the landscape. Many roads were dirt.

An early aerospace tenant was Stanley Aviation, which relocated to Aurora from Buffalo, N.Y., in 1954.

Founder Robert Stanley, a Navy test pilot, liked the Denver-Aurora area. It helped that Stanley - who had his own plane - secured land with access to the former Stapleton Airport. (The adventurous Stanley died in a 1977 plane crash in the Bermuda Triangle.)

Another early tenant: Merrick & Co., an engineering and architectural firm that serves the military. It also supplies high-tech geographic and mapping information.

Sears Merrick co-founded the company in 1955 and relocated it to Aurora from Denver in 1973.

"He could visualize the growth in Aurora. And he wanted to be part of that," said CEO Ralph Christie.

The roots of nearby Buckley Air Force Base date to World War II. The base was named after 1st Lt. John Buckley, a World War II flier from Longmont. In 1941, Denver donated land to the War Department. The next year, a $7.5 million deal was signed to build 700 structures.

Buckley has carried various names, including Denver Naval Air Station. It was renamed Buckley Air Force Base in 2000 and has been growing. More than 10,000 military and civilian types work there.

For local aerospace companies, Buckley offers valuable work and information - information that can spell new contracts.

"We have a steady dialogue with some of the customers over there about what they're going to need in the future," Northrop's Fey said.

The base also serves as a talent pool for companies wanting to hire departing military personnel.

Over the years, Buckley's satellite-based spy operations have attracted protests from peace activists, some of whom have even scaled the barbed-wired fencing there. The spying is yet another part of Aurora's secretive side.

"We can see things that are happening in Afghanistan and Iraq," said Col. Martin Whelan, vice commander of the 460th Space Wing at Buckley.

The secrecy surrounding Aurora's aerospace industry dates back decades. Paul Tauer recalled going to a celebration in the 1980s that marked the opening of a new building occupied by Hughes Aircraft Defense Electronics, bought by Raytheon in 1997.

"There were parts of the building that we didn't see," Tauer said. "It was top-secret kind of stuff."

Even today, Aurora officials can't always keep track of the growth in local aerospace-related companies.

"It seems every time we touch base with a company, they've grown more than we expected," said Dick Hinson, vice president of the Aurora Economic Development Council.

To be sure, the secrecy has eased, to a degree.

In contrast to Hughes, Raytheon has sought to reach out to the local community, although much of the company's work remains off-limits to the public.

"It's more of a public organization and much more engaged with the community," said Raymond Kolibaba, Raytheon vice president for space systems and the top executive for the company's Aurora operations.

He said Raytheon employees "spend a lot of time" doing local volunteer work.

"Part of that is giving back to the community," he said.

For example, workers have fanned out to give math and science tutoring at Rangeview High School, Gateway High School and Aurora Hills Middle School.

But that doesn't mean Aurora's aerospace-defense companies are throwing open their doors to the public.

Asked how much of his company's Aurora activities are classified, Boeing spokesman Joseph Tedino fired back a two-word e-mail: "Nearly all."

By the numbers

• What we know about Aurora's cloak-and-dagger industry:

11 Number of aerospace-defense companies known to have operations in Aurora

5,000+ Number of people the companies employ

10,000+ Number of military and civilian workers at Buckley Air Force BaseSources: Companies, Aurora Economic Development Council, Rocky Mountain News, Buckley Afb

Aurora's aerospace-defense players

Sources: companies, Aurora Economic Development Council, Rocky Mountain News

fillionr@RockyMountainNews.com or 303-892-2467