| Information > Factsheets > Tethered Aerostat Radar System |
 |
TETHERED AEROSTAT RADAR SYSTEM
Mission
The Tethered Aerostat Radar System is a low-level surveillance system that uses aerostats as radar platforms. An aerostat is a lighter-than-air, inflatable, aerodynamic balloon filled with helium and air. 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. Currently there are two aerostats located at Cudjoe Key, Fla., operated by the State Department and the Air Force. The State Department aerostat transmits TV Marti, which sends American television signals into Cuba for the Office of Cuba Broadcasting. The other aerostat is dedicated to the counter drug and NORAD air sovereignty mission.
Features
The aerostat is a large fabric envelope filled with helium. It can rise up to an altitude of 15,000 feet while tethered by a single cable, which has a maximum breaking strength of 42,600 pounds. The minimum operating height varies from site to site. For example, Cudjoe Key is at sea level; consequently the minimum altitude for this site is 500 feet. On the other hand, the minimum operating altitude at Marfa, Texas, is 4,000 feet due to the mountainous terrain surrounding the site.
The current aerostat network consists of two sizes of aerostats (275,000 cubic feet and 420,000 cubic feet) and two varieties of radars. The 420,000 cubic foot aerostat is about two times the size of the Goodyear Blimp. It measures 208 feet long by 65 feet across the hull, with a tip-to-tip tail span of 100 feet.
The 275,000 cubic foot aerostat lifts a 1,200 pound payload and the 420,000 cubic foot aerostat lifts a 2,200 pound 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 called a ballonet. A sophisticated subsystem maintains constant pressurization of the ballonet, which maintains the shape of the aerostat's hull at all altitudes. The hull is constructed of a lightweight polyurethane-coated Tedlar fabric that weighs only eight ounces per yard. The fabric is resistant to environmental degradation, minimizes helium leakage and provides structural strength to the aerostat.
The windscreen compartment contains the radar and is pressurized by the ballonet. The airborne power generator consists of an airborne engine control unit that drives the generator, and a 100-gallon diesel fuel tank. All systems are operated by the aerostat's telemetry link to start and stop the engine and its generator. Finally, the rigging consists of the flying suspension lines connected to the main tether and mooring suspension lines.
The aerostat radar data is available to NORAD and U.S. Customs and Border Protection. In addition, this information is available to a blockhouse ground station below, where a flight director, seated before banks of meters and television screens, monitors the aerostat's performance. All radar data is transmitted to the ground station, where it is digitized and transmitted to various control centers for display. Doppler weather radars are also installed at all sites. The sites obtain up-to-date forecasts and weather warnings from the Air Force Weather Agency.
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. During the launch sequence, the power winch releases the tether until the aerostat reaches operational altitude. When the aerostat is lowered, it is secured to a mooring tower and a rail system. While moored, the aerostat weather vanes with the wind.
Operational availability is generally limited only by the weather (60 percent standard) and routine maintenance downtime, which is minimal. Since the aerostats are stable in winds below 65 knots, the aerostat program provides low-cost, one-of-a-kind radar coverage uniquely suited for its given mission. Notwithstanding weather, aerostat and equipment availability averages more than 98 percent system wide.
Background
The Air Force operates the largest and most continuously operational system of aerostats in the world. The first aerostats were assigned to the Air Force in December 1980 at Cudjoe Key, Fla., with the original 250,000-cubic foot aerostat. An additional site was constructed and operated by the Air Force at Cape Canaveral, Fla., in 1983. This site was deactivated a few years later. 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. Congressional language in 1992 transferred management of the system to the Defense Department, with the Air Force as executive agent. Under Air Force management, through contract consolidation and system standardization, the operations and maintenance cost per site has been reduced from $6 million in fiscal year 1992 to the current rate of $3.5 million.
For security and safety reasons, air space around Air Force aerostat sites is restricted for a radius of at least two to three statute miles and an altitude up to 15,000 feet.
General Characteristics
Primary Function: Low-level, downward-looking radar; aircraft detection
Prime Contractor: The sites are currently operated and maintained under contract with Lockheed Martin Systems Management. ILC Dover and Tethered Communications L.P. (T-COM) manufacture the aerostats. Lockheed Martin manufactures the radars.
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
Date Deployed: 1978
Operational Sites: Yuma and Fort Huachuca, Ariz.; Deming, N.M.; Marfa, Eagle Pass, and Rio Grande City, Texas; Cudjoe Key, Fla.; and Lajas, Puerto Rico. Sites located at Morgan City, La., and Matagorda, Texas, are in a cold-storage configuration. Contract management office and logistics hub are located in Chesapeake, Va.
Air Combat Command, Public Affairs Office; 130 Andrews St., Suite 202; Langley AFB, VA 23665-1987; DSN 574-5007 or (757) 764-5007; e-mail: [email protected]
August 2007
| |
|
|
|
|
Printable Fact Sheet