An explosive-detection technology developed for aviation safety
could improve the ability of U.S. forces to locate and clear landmines,
said Army and Navy scientists.
Unlike other areas of warfare, military countermine operations
have not benefited significantly from advances in technology during
the past several decades. Battlefield mine detection today essentially
relies on metal-detector beachcombing devices that have been used
since World War II.
To be sure, the U.S. Army is developing more advanced minesweeper
vehicles equipped with ground-penetrating radar, infrared sensors,
as well as the old metal detectors. But these systems suffer from
high rates of false alarms and, because a lot of the work involves
manually digging out mines or mine-like objects, the process is
painfully slow.
The big breakthrough that has eluded scientists in the United States
and elsewhere could come soon, as a result of research and development
work funded by the Army, the Navy and the Defense Advanced Research
Projects Agency (DARPA).
The technology that experts say could revolutionize mine detection
is called quadrupole resonance, or QR. It is a variation of the
commonly used magnetic resonance imaging (MRI) technology, which
physicians rely on to diagnose patients. It is also the same technology
that scans baggage at airports and can detect explosives.
The MRI machines found at hospitals are large magnets, which affect
the magnetic properties of the nuclei of the water in the human
body. Those magnetic properties enable the machine to generate an
image.
QR, however, does not use a magnet. The technology operates under
the principle that a magnetic resonance signal can be detected from
explosives without applying a large external magnetic field.
This is how QR works:
But Federal Aviation Administration (FAA) officials came to NRL
in 1983, looking for advice on how to use the QR technology for
detecting explosives inside luggage. "I felt that the technique
was worth looking at a second time," said Garroway. Since 1987,
funding for QR work has come from the FAA and the Defense Department.
In 1997, DARPA decided to support QR research for use in mine detection.
Some rudimentary work had been done on this technology by the former
Soviet Union, said Garroway. But after the end of the war against
Afghanistan in the early 1980s, the Soviets dropped those efforts.
NRL patented the technology at various times. In 1993, the lab
gave an exclusive license to Quantum Magnetics, a San Diego-based
company. Since 1997, the company has received $38 million in contracts
from DARPA and the Office of Naval Research to develop mine-detector
prototype systems for the Army and the Marine Corps.
The "beauty" of QR, explained Garroway, is that it is
highly sensitive to the chemistry of explosives. If a bag containing
explosives is scanned using QR, the machine flashes a red light.
And, so far, tests have shown that the technology accurately detects
the presence of explosives, without false alarms.
It is estimated that, in mine-clearance operations, for every real
mine, there are between 100 and 1,000 false alarms.
The problem with virtually all the existing technologies used to
find hidden explosives, such as X-ray or radar, is that they pick
up too many ancillary objects, said Garroway. "A landmine may
give a signal, but a rock or a piece of metal also may give a signal."
QR sensors pick up the so-called resonance frequency, which is quite
specific for different explosives. Combat mines typically contain
the explosives RDX, TNT and Tetryl. "If you can detect those
three explosives, you can detect most of the others," said
Garroway.
And, unlike electromagnetic systems, QR sensors can detect plastic-encased
mines. About 60 percent of anti-personnel landmines and 75 percent
of antitank mines buried around the world are metal-cased.
"The most difficult mines to detect are the small plastic-cased
mines, which only have a small fragment of metal," said Lowell
Burnett, chief executive officer and president of Quantum Magnetics.
"It’s very difficult to distinguish these plastic-cased
mines from shell fragments, cartridge casings and other metallic
debris scattered around the battlefield."
But despite promising developments in QR, the technology is not
nearly mature enough, Garroway said. "There is still a lot
of work to be done. It’s a tough problem. ... We would consider
ourselves very successful if there was a system out in three to
five years."
Garroway does not expect that QR technology will be any more expensive
than ground-penetrating radar, but it will be costlier than the
conventional electromagnetic metal detectors.
Electromagnetic systems not only have a high rate of false alarms,
but also are manpower-intensive, which makes them dangerous, he
said. "The current method is to dig up the mine, inches away
from your hand and a foot away from your face."
Vehicle Systems
The mine-detection prototypes currently in development by Quantum
Magnetics include a vehicle-mounted system for the Army, and a backpack-size
device for the Marine Corps.
For countermine operations, the Army currently relies on the so-called
Interim Vehicle-Mounted Mine Detector (IVMMD), which was developed
in South Africa. The four-wheeled IVMMD, which looks like a road
grader, was designed to detect metal-cased antitank mines on roads.
A complete system includes three platforms: a mine detection vehicle,
a towing vehicle and mine detonation trailers.
The Army has 10 IVMMD systems. One is at the Army’s engineering
school in Fort Leonard Wood, Mo. The other nine are stored in a
California depot. These systems are used only for military operations,
not for humanitarian demining.
To replace the interim vehicle, the Army is developing the Ground
Standoff Minefield Detection System (GSTAMIDS). Block 0 is the first
iteration, explained Brian Green, project management engineer at
the Army’s program office for mines, countermines and demolitions.
Block 0 has a multi-sensor array with metal detection, ground-penetrating
radar and infrared capabilities. The goal is to clear 20 km of road
in 12 hours.
The QR sensors will not be part of GSTAMIDS until the Block I upgrade,
Green said in an interview. Block 0 development should be complete
by fiscal 2002 and could go into production by fiscal 2003.
Block I work will begin this year, and the development phase is
expected to last 36 months.
The benefit that QR brings to the GSTAMIDS is that it can confirm
or deny the presence of explosives without having to dig up every
suspect object, explained Vivian George, Army project engineer.
Ground-penetrating radar (GPR) has a lot of false alarms, but that
is the only technology available today to detect plastic-enclosed
mines, she said. "We have been looking at GPR since 1945, and
nobody has been able to make it work very well."
The QR system would confirm or deny the presence of explosives
after the radar has detected a potential mine.
Finding buried explosives is a much harder problem that scanning
baggage that contains a hidden bomb, Green said. "It’s
much easier to put a suitcase into a scanner than it is to move
something down the road and have to look underground and look for
smaller targets that are cased in plastic and metal."
According to George, "It’s much easier to create a uniform
magnetic field inside a tube, like the luggage scanner. When explosives
are underground, you can’t run them through the tube. You
have to design a coil that can project the magnetic field into the
soil" and receive signals from underground.
The concept for the GSTAMIDS Block I is to have the mine-detection
vehicle upfront and a separate QR-equipped vehicle following behind.
The lead vehicle puts a splat on the ground, indicating there’s
a potential mine. The trailing QR vehicle has a transmitter that
sends signals or pulses down to a detection coil, made of copper.
The coil analyzes the slat and the system produces a red light if
explosives are found.
"If there are explosives, that is considered a mine threat,
even if it’s ordnance," said George. "If there is
no mine threat, then you don’t waste time digging, as you
would with the Block 0 system."
Unlike the IVMMD, the GSTAMIDS vehicle has a hydraulic arm, resembling
a crane, to dig up mines remotely, from inside the vehicle. But
unlike the Block 0 version, the QR-equipped Block I system saves
operators time because they only will dig up objects that contain
explosives, she said.
The Block 0 system requires a crew of five. That is an improvement
over current operations, which require a company of engineers, who
proceed at a speed of less than 1/2 km an hour. That means it would
take them days to clear a 40 km area. With the Block I system, said
George, the goal is to move at 7 km per hour and clear the 40 km
route in six hours.
George said her office has received many requests from other nations
to share the QR technology for mine detection. The French, Germans,
Canadians and English are "dabbling with QR," she said.
"What I have told them is to wait, and let the United States
spend the money, do the research and the engineering. If it works,
I am sure we can find a way to do technology transfer."
There also could be potential technology spin-offs for humanitarian
demining, which involves removal of anti-personnel mines that were
laid in many Third World countries–during civil wars, for
example. "Humanitarian demining is more challenging because
anti-personnel mines have a small amount of explosives," said
George. Those small mines, however, maim and kill thousands of civilians
each year.
"If the [Navy’s] QR backpack system works, that has
more potential for humanitarian demining," said Green.
The Army would have an interest in the backpack system that is
in development for the Marine Corps, said Green. "But that
is significantly more challenging than what we are trying to do."
Burnett, the president of Quantum Magnetics, said that QR mine
detectors were tested successfully in March 1999, at Camp Pendleton,
Calif., in Bosnia, in July 1999, and at Fort Leonard Wood, in October
and December 1999.
He agreed that the backpack system will be "difficult"
to achieve, because of the size requirements. It will have a wand-like
detector to sweep the ground. The backpack holds the electronics
and the battery power. As the coil moves over the ground, it flashes
red or green lights, depending on whether there are explosives underground.
The backpack system has the same technology as the vehicle prototype.
But squeezing all the electronics into a man-portable system is
a huge "engineering challenge," Burnett said. "Our
goal for the backpack is to get the weight down to less than 35
pounds." By comparison, "the system we took to Bosnia
weighed more than 500 pounds."
Garroway, the Navy scientist, said he is "optimistic"
that QR will become a mainstream technology. But he cautioned that
no single technique by itself is going to be a complete solution.
"I anticipate that QR will be combined with other techniques,
he said. "All these techniques will be complementary in some
sort of integrated package."
One important consideration is the confidence that any system offers
the soldiers, said George. Today’s systems, she said, fail
to do that.
"If you have a system that soldiers are confident in, they
are confident in using the route after it’s been cleared.
Now, they don’t trust the system."