Wednesday – December 10, 2014
Border Patrol Blimps
Upon our arrival here at the Imperial Dam BLM, LTVA on November 18th, we were fascinated by daily sightings of a large, white, unmarked blimp that appeared in the same location and never moved. We speculated that it might be an experimental surveillance-type drone, operated by the U.S. Army Proving Ground. Since it was stationary, elevated several thousand feet in altitude, and always positioned in the same location north of the Imperial Dam BLM, we believed it had to be tethered to the ground. We marveled at the length of cable that would be required to tether a blimp to this altitude.
We subsequently learned, through wikipedia, these blimps are a Tethered Aerostat Radar System (TARS). They are an American low-level surveillance system that uses aerostats (moored balloons) as radar platforms.
The aerostats are large fabric envelopes filled with helium, and can rise up to an altitude of 15,000 feet while tethered by a single cable. The largest lifts a 1000 kg payload to an operating altitude providing low-level, downward-looking radar coverage. The aerostat consists of four major parts or assemblies: the hull and fin, windscreen and radar platform, airborne power generator, and rigging and tether.
The hull of the aerostat contains two parts separated by a gas-tight fabric partition. The upper chamber is filled with helium and provides the aerostat's lifting capability. The lower chamber of the hull is a pressurized air compartment. The hull is constructed of a lightweight polyurethane-coated Tedlar fabric. An airborne engine drives the generator, supplied by a 100-gallon diesel fuel tank.
Beginning in the late 1990s, the aerostat sites were equipped with Lockheed Martin 420K aerostats. The 420K's envelope shape, fin design, and cable attachment points are further optimized for high aerodynamic stability and easy ground handling. While Lockheed Martin is the prime contractor for the 420K aerostats, the envelopes are built by ILC Dover.
As of 2004, all TARS sites except one were equipped with the 420K aerostats. The exception is Cudjoe Key, which uses two smaller, but otherwise similar, Lockheed Martin 275K blimps. One carries the L-88(V), a light-weight L-88 derivative, while the other is used to transmit the "TV Marti" TV program into Cuba.
Operators launch the aerostat from a large circular launch pad containing a mooring fixed or mobile system. The mooring systems contain a large winch with 25,000 feet of tether cable. Operational availability is generally limited only by the weather and routine maintenance downtime. The aerostats are stable in winds below 65 knots. Aerostat and equipment availability averages more than 98 percent system-wide.
For security and safety reasons, air space around aerostat sites is restricted for a radius of at least two to three statute miles and an altitude up to 15,000 feet .
The primary mission is to provide low-level radar surveillance along the southwest border of the United States and Mexico, the Straits of Florida and the Caribbean in support of federal agencies involved in the nation's drug interdiction program. The secondary mission is to provide North American Aerospace Defense Command with low-level surveillance coverage for air sovereignty in the Florida Straits. The aerostat radar data is available to NORAD and U.S. Customs and Border Protection.
The first aerostats were assigned to the United States Air Force in December 1980 at Cudjoe Key, Fla. During the 1980s, the U.S. Customs Service operated a network of aerostats to help counter illegal drug trafficking. Their first site was built at High Rock, Grand Bahamas Island, in 1984. The second site was built at Fort Huachuca, Ariz., in 1986. Before 1992, three agencies operated the TARS network: the Air Force, U.S. Customs Service and U.S. Coast Guard. Congress in 1992 transferred management of the system to the Defense Department, with the Air Force as executive agent. The Budget Control Act of 2011 slashed funding for the Air Force, which tried to shut down the project. However, the Department of Homeland Security picked up the project and continues to fund its continuing operation.
Technical and Operational Data
Primary Function: Low-level, downward-looking radar; aircraft detection
Volume: 275,000 and 420,000 cubic feet
Tether Length: 25,000 feet
Payload Weight: 1,200-2,200 pounds
Maximum Detection Range: 200 nautical miles
Yuma, Arizona – U.S. Highway 95, Milepost 58
Fort Huachuca, Arizona
Deming, New Mexico
Eagle Pass, Texas
Matagorda, Texas (currently in a cold-storage configuration)
Rio Grande City, Texas
Cudjoe Key, Florida
Lajas, Puerto Rico
Morgan City, Louisiana (currently in a cold-storage configuration.
On one of our visits to Quartzsite, Arizona we viewed the YUMA TARS, tethered, near mile marker 58 on U.S. highway 95. North of mile marker 58, near mile marker 76, all northbound traffic is diverted off U.S. highway 95 and routed through a border patrol checkpoint.
Tomorrow another adventure begins.