Air Force uses invisible fence to protect skies


March 10, 2012 - 6:00 am
Air Force Space Surveillance System operates just down the road from Maricopa. Photo by Pete Herzog.

It’s called The Fence and it sits about two miles north of Maricopa city limits on the Gila River Indian Reservation.

But don’t expect to see kids scrambling over this fence; it’s hundreds of miles high.

Officially called the Air Force Space Surveillance System, Maricopa residents pass by every time they travel State Route 347 to or from the Valley. It’s easy to miss. Headed southbound, drivers might spot a small sign that reads “U.S. Air Force Space Command, Gila River Site.”

Housed in a small building, the unassuming site plays a major role in safeguarding traffic in space.

Radar signals are sent into space across the entire United States on the 33rd parallel by three transmitting stations. The signals bouncing off thousands of low-earth orbit objects are recorded by six receiving stations.

“The reason it’s called The Fence is that we put up a very high, but very narrow, radar cross-section from San Diego to Georgia,” said Edd Allard, project manager for the system. “It’s like an invisible fence that goes into space and anything that flies through that fence, the energy from the signal bounces back to earth.”

The entire system is administered by a private company, Five Rivers Services, headquartered in Colorado Springs, Colo., at Peterson Air Force Base.

It is an Alaska Native Claims Settlement Act company, meaning it is Alaska-native owned.

The Fence was activated in 1961 by the U.S. Navy as a response to Sputnik, the Russian satellite that became the first man-made object to orbit the Earth.

Now it serves as more of a traffic cop.

More than 25,000 objects ranging from the size of the International Space Station to bits of debris from exploded satellites are orbiting the earth.

Although the system can track foreign satellites, its primary purpose is to help prevent collisions. That application came into public focus at the end of last year when several satellites fell to Earth and made national headlines.

“We’re tracking virtually everything that’s in low-to-medium Earth orbit,” Allard said. The Fence can see basketball-sized objects as high as 15,000 nautical miles (or 17,261 road miles), but does not track geosynchronous objects, the ones that remain over a fixed spot at about 22,000 miles in altitude.

The system is made up of nine installations stretched across the country on the 33rd parallel.

Three, including Gila River, are transmitting stations, while six receive the signals bounced off the orbiting objects. All the data collected is fed to the Dahlgren Naval Station in Virginia, which manages tactical control and command. The Alternate Space Control Center processes the information.

While motorists on SR 347 might notice the buildings and small sign, what is a little more difficult to pinpoint is the equipment actually sending the signal into space.

The antenna is a quarter of a mile long and sits low to the ground, almost obscured by the desert flora.

Station Manager Dale Rubel beams with pride at the role staff members plays in maintaining their portion of The Fence.

The station operates 24/7 with a crew of seven dedicated professionals.

All have helped run the operation for at least eight years and most significantly longer. Several also have long commutes, with only one living in Maricopa.

“I live in Thunderbird Farms,” said general maintenance specialist Raymond Bustos. “I’ve lived here since I was 6 years old, when Maricopa was nothing.”

Rubel, the veteran of the staff, has 41 years under his belt. Technical Supervisor Ronald Black has been on board 37 years and Bustos 31.

“Ronald lives near 83rd Avenue in Phoenix,” Rubel said. “I live in Casa Grande. We’ve got one guy who lives way up in Sun City and another in Apache Junction.”

Rubel said his crew’s job is to make sure the installation runs efficiently.

“Our efficiency rate is pretty impressive,” he said. “When I go to the managers conferences they are always telling us we do a good job and to keep up the good work.

“We have minimal down time, and we have a 275 KW generator in case we lose commercial power.”

He remembers the old days.

“We had this big, old, transmitter that sat inside here and was cooled by forced air,” Rubel said. “It was just as noisy as could be. We had huge air conditioners because the tubes generated a lot of heat. It was a challenge to keep this thing at an operable temperature.”

Now the installation is all solid-state electronics, providing a much more comfortable atmosphere for equipment and crew.

The staff takes being located on the Gila River Indian Community seriously. It is the only one in the system with ties to Native Americans.

Rubel pointed out that during the 1950s, when negotiations were held for use of the property, a peace pipe was used for consummation of the transaction.

He then pointed toward the Estrella Mountains, noting Hayes Peak, named for Ira Hayes, a member of the Gila River Community who helped raise the American Flag on Iwo Jima. Also nearby is what is commonly known as M Mountain, where Maricopa High School students painted the huge letter M as a means of showing school pride.

“But if you look at it closely it has been said to resemble a sleeping Indian with a feather headdress,” Rubel said.

There are dangers involved in the work. One involves dealing with high voltages and restricts what workers can do at night.

Then there is the wildlife.

“We’re very cautious about rattlesnakes,” Rubel said, also mentioning scorpions and Gila monsters as uninvited guests.

Then there is the man-made danger arising once in a while.

“From up in the air this looks just like a runway,” he said.

At each end of the compounds there are huge letters HAZ, but at times pilots seem to want to take a closer look.

“After 2001 things got really restricted and any time I see anybody doing flyovers we try to get the tail number.”

The old antenna field, which is now vacant, has been the site of landings and an old government map even listed it as an airstrip.

The station has even been called when mysterious lights were seen over Phoenix because of its designation as a Space Surveillance Station.

It is nothing quite that exotic, and yet it plays an important role in space exploration. The skies are safer because of the work done at the Space Command.



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