An airship that the U.S. Army says
is the largest lighter-than-air vehicle ever used in U.S. military operations
will make its debut flight in August as part of an effort to field a system to
detect, track and shoot down cruise missiles.
Unlike ballistic
missiles that typically fly a stable and predictable flight pattern, cruise
missiles pose a particularly tough challenge because of their ability to fly low
and slow and change directions.
The weapon
systems now available for cruise
missile defense, such as the Patriot and Terminal High Altitude Area
Defense systems, rely on ground-based tracking radars that cannot see over the
horizon and can be negated by ground obstacles such as mountains. The Air Force flies radar-equipped
airplanes that can track cruise missiles from above, but these systems require
a lot of manpower and other resources to operate.
This led the Army to begin looking at
the potential for radar-equipped aerostats - tethered balloons resembling
blimps - to detect and track terrain-hugging cruise missiles. After a series of
demonstrations to prove the concept, the Army in December 2004 launched a program called the Joint Land
Attack Cruise Missile Defense Elevated Netted Sensor System (JLENS) with the
award of a $1.4 billion development contract
to Raytheon Integrated Defense Systems of Tewksbury, Mass.
Balloon
with a view
Raytheon is
working to deliver two JLENS systems, each consisting of two 242-foot (74-meter) long
helium-filled aerostats, a surveillance radar, a fire control radar, mobile
mooring stations and communications packages. One of the aerostats hosts a
surveillance radar, which provides 360 degree coverage, and the other carries a fire control radar, which receives
the surveillance data and generates targeting data for Army weapon systems.
The
aerostats will operate nearly 2 miles (3 km) above the ground on tethers,
providing the ability to detect and track cruise missiles as far as 124 miles (200 km) away in every direction, Army
Lt. Col. Steve Willhelm, the JLENS program manager, said in an interview. The
systems are designed to operate continuously
for 30 days, come down for eight hours of maintenance and go back up for
another 30 days.
The program
in December completed its critical design review and is in the fabrication and
integration phase. TCOM of Columbia, Md., is building the aerostats, the first
of which will make its first flight in August
up to about 2,952 feet (900 meters) above the ground at the company's
Elizabeth City, N.C., manufacturing facility, Willhelm said.
"This test will confirm the
confidence and maturity of the team to provide our warfighters this critical
cruise missile defense capability," Raytheon spokeswoman Maureen Heard said in
a written response to questions. "This system will allow Raytheon to continue
to be the world's best global capabilities integrator."
In December, the aerostat will be
transported to the Army's Dugway Proving Ground, Utah, to be mated with its
surveillance radar. The second aerostat and its fire control radar will be
mated at Dugway next May, and the two platforms will
be integrated as a system - or orbit - and begin limited testing in September 2010, Willhelm
said.
A
military legacy
Lighter-than-air
vehicles have been used in U.S. military campaigns since the civil war,
when manned balloons were lofted to give warning of incoming mortar fire. Today U.S. troops in Iraq use aerostats for force protection with
an Army program called the Rapid
Aerostat Initial Development. Raytheon is also the prime
contractor for the program, which uses a 55-foot (17-meter)
TCOM-built aerostat that floats 984 (300 meters) high
to perform surveillance with an electro-optical infrared sensor.
It has been tough to convince the
Pentagon that cruise missile defense can be done with an aerostat, but many of
the concerns about the effectiveness of JLENS have already been addressed in demonstrations, Willhelm said.
Aerostats have been riddled with bullets in testing and continued to operate for hours before
slowly descending to the ground, he said. Despite its size, the JLENS aerostat
will not be easy to target because its lack of relative motion makes it tough
for radars to discriminate, he said.
According
to an Army fact sheet, the JLENS can be operated at a
fraction of the cost associated with radar-equipped aircraft and provides
persistent surveillance with low manpower requirements.
Old
idea, modern missions
Despite these advantages and the U.S. military's history of
success with aerostats, proving they have a place in modern
warfare has been a constant challenge, Willhelm said.
"One of the
biggest challenges has been that this system is like nothing else the
Army has seen," Willhelm said. "People are thinking we're taking a step back
from being a 21st
century force."
But the system also has attracted
interest from some in the military for applications other than cruise missile
defense. For example, the JLENS program office has received inquiries about the
possibility of hosting surveillance and communications payloads to help meet
the insatiable needs of U.S. forces operating in Iraq and Afghanistan, Willhelm
said. The Army is studying how it might be able to swap JLENS payloads in and
out while still performing its primary mission of cruise missile defense, he
said.
"We're looking at ways to be
modular," Willhelm said. "Swapping out sensors is not built into our current
contract, but we're looking at ways to do that."
The first JLENS orbit will go
through an entire lifetime of use during the Army's test program, and the
second is scheduled to be delivered to the first JLENS battery in
September 2012, with initial operational capability
envisioned for one year later. If the test program is successful, a
decision on a production contract for 14 more JLENS orbits could be made in January 2012, Willhelm
said.
Army
spokesman Dan O'Boyle could not provide per unit cost estimates of the
production models.
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