Eyes in the Sky
Aerostats and towers give sensors a lookout on the battlefield
- By David Perera
- May 26, 2008
Unmanned aerial vehicles aren’t the only high-tech eyes in the sky in the Defense Department’s inventory. The Marine Corps is buying more tower-mounted thermal and infrared surveillance systems for use in the Middle East, awarding Raytheon a $60 million contract April 9.
The system, named the Ground Based Operational Surveillance System (GBOSS), is the Marine Corps’ version of the Army’s Rapid Aerostat Initial Deployment (RAID) system. The principal difference is that GBOSS has two oppositely pointed cameras, while RAID has only one, said Col. Glen Lambkin, Army project manager for Night Vision/Reconnaissance, Surveillance and Target Acquisition division, which oversees the RAID product office. The system’s towers measure 107 feet and come equipped with map overlay software, a radio frequency data link and a power generator.
The sensors can also be deployed on a helium- and air-filled aerostat, and although orders for tower-mounted RAID systems are gushing in, orders for aerostats have not. For example, the Central Command recently placed an order for hundreds more RAID towers, Lambkin said.
Operational constraints favor acquiring more tower-mounted systems rather than more aerostats, at least for now, military officials say. Aerostats offer greater visibility over the ground, but they also require more infrastructure. An unimpeded view at 1,000 feet covers about 30 miles in any direction, whereas a RAID tower has an estimated range of five to six miles, according to Charlie Lambert, president of SkySentry, a Colorado Springs-based aerostat consulting firm.
A shift in Army tactics in Iraq also favors towers over aerostats, Lambkin said. The Army has reduced its operations from large bases and instead sets up locates in smaller outposts located in communities.
With a tower, “you set up your guy wires, and install your electronic equipment. ... There is not a lot of overhead, so to speak,” Lambkin said. “If you need to move small units around relatively quickly, you may want to choose the tower-based system, particularly where you’ve got a smaller unit.”
Towers “require more planning, and they require a little more protection because it is a high-value asset,” Lambkin said. The aerostats are not highly pressurized, so bullets won’t bring them down instantaneously, but constantly dealing with hole punctures is a downside, said Lambert. There’s also the cost.
A RAID aerostat probably costs about $2 million to put into operation and another $1.5 million to operate for a year, Lambert estimated.
“You just don’t get much distance with a tower compared to an aerostat, but aerostats are more expensive, no doubt about it,” he added.
However, it would be a mistake to conclude that towers are necessarily better than aerostats, RAID officials said. “There is a definite advantage to each,” said Peter Choate, Raytheon’s RAID program manager. “If you’re on a bigger base, you can fly an aerostat quite easier, because your protection, your infrastructure is there already. They each have their different missions.”
Lambert, an aerostat advocate, said it’s possible to conquer some of the constraints of RAID aerostats by sending them higher, into the stratosphere. At 60,000 feet and above, an aerostat would act like an ersatz geostationary satellite, negating the need to choose between portability or distance, Lambert said. The Army’s Space and Missile Defense Command and the Air Force Research Laboratory both have projects investigating low-cost stratospheric aerostats.
The Air Force anticipates buying 13 tethered aerostats by fiscal 2015 to replace its aging fleet of helium- and air-filled balloons deployed along the United States’ southern border, according to an order issued March 24.
The white Mylar balloons, anchored to the earth by a cable as long as 15,000 feet, are part of the Tethered Aerostat Radar System (TARS) program, a decades-old effort that provides radar surveillance along the border to detect drug runner aircraft that fly low and slow. The Air Force assumed control of the program in 1992 and operates the airships in eight locations generally near the United States’ border with Mexico. TARS platforms tend to operate at an altitude of 10,000 feet and above, where an unencumbered line of sight can reach about 140 miles in any direction. The Air Force said it will transfer existing radar payloads onto the replacement aerostats.
The system’s boosters like to point out that TARS is one of the cheapest airborne surveillance systems in existence, costing only about $300 per hour to operate.
However, the program’s history is mixed. Unlike the still-theoretical high-altitude airships, TARS operate in the middle of weather conditions, which can significantly degenerate their effectiveness.
The Air Force holds TARS to only a 60 percent operationally availability standard — although actual availability averages about 98 percent, according to the military service.
Meanwhile, weather can destroy aerostats; when Hurricane Dennis swept through Florida in 2005, it destroyed two $3 million TARS platforms. The hurricane arrived too quickly for the Air Force to deflate the balloons, which were torn apart by wind.
A former North American Aerospace Defense Command official recalled that whenever the aerostats were pulled down because of bad weather or maintenance, drug runners found that the coast was clear.
“The intell was 100 percent for the adversary,” the official said, speaking on condition of anonymity. “The druggies would say, ‘Oh the aerostat’s down,’ and come across the border like flies.” TARS is also associated with a 1981 event in which one Floridabased aerostat broke free.
According to The Miami Herald, local fishermen then tied the aerostat’s tether to their boat. Warming air caused the aerostat to then lift the boat out of the water, with the fishermen still in it. Eventually, the Air Force sent F4 fighters to shoot down the runaway balloon over the Gulf of Mexico.
Aerostat promoters point to the Army’s Persistent Threat Detection System, operational in active U.S. military theaters since late 2004, as a better example of the early warning capability of aerostats. Those aerostats are smaller versions of TARS platforms — they carry a 495-pound payload to about half a mile high in the air. They come equipped with a high-resolution electro-optic/infrared sensor integrated with other existing sensors. Their goal is to provide constant wide-area surveillance for mortar, rocket-propelled grenade and small arms attacks. The Army named it one of its best inventions of 2005.
Lockheed Martin won a $77.5 million contract in 2006 to provide the Army with as many as 20 more of those aerostats.
David Perera is a special contributor to Defense Systems.