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home > May 26, 2008 issue > article
Eyes in the sky
By David Perera
Special to Defense Systems
Aerostats and towers give sensors a lookout on the battlefield
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.
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