Demining or mine clearance is the process of removing either land mines, or naval mines, from an area, while minesweeping describes the act of detecting of mines. There are two distinct types of mine detection and removal: military and humanitarian.
Minesweepers use many tools in order to accomplish their task. Tools have historically included many trained animals, including dogs and rats, but most often in the modern world minesweepers rely on metal detectors or vehicles with a wide variety of mechanical tools attached to them. There also are or have been other methods developed to detect mines, including the use of trained marine mammals, bacteria, acoustics, and other more exotic methods.
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In the combat zone, the process is referred to as mine clearance. According to the doctrine of the U.S. and other armies, mine clearance is carried out by combat engineers.
The military priority is to breach the minefield quickly in order to create a safe path for troops or ships. Speed is vital, both for tactical reasons and because units attempting to breach the minefield may be under enemy fire. Both anti-personnel mines and anti-tank mines also must be removed, although only in the lanes through which troops or vehicles are planned to advance.
The risk to sappers is far greater because they may be called upon to perform clearance as tactics dictate, including in all-weather conditions and on schedule. Command may accept casualties in the process. Furthermore, it is accepted that mine clearance will be imperfect and there may be casualties from undiscovered mines. One advantage is that, in military operations, sappers are dealing with recently-laid mines that respond predictably to clearance, have not 'migrated', and have not degraded (unless old stock was used). In this they are often aided by technical intelligence on current adversary of mine types, which are usually of a single type.
In these mine clearance operations, the methods that are applied for detection and removal are quicker, but less exacting. These methods include those that detect and remove in a single action, such as mechanical demining, carpet bombing, burning of the land or the use of Bangalore torpedoes or mine-clearing line charges.
In times of relative peace, the process of mine removal is referred to as demining. This is a thorough, time-intensive process that seeks to locate all mines so that the land or sea area may be safely returned to normal use. It is vital that this process be exhaustive. Even if only a small handful of mines remain undiscovered, incomplete demining can actually lead to an increase in civilian mine casualties as local people re-occupy an area they previously avoided in the belief that it has been made safe. In this context demining is one of the tools of mine action. Coordinated by Mine Action Coordination Centers run by the United Nations or a host government, civilian mine clearance agencies are tasked with the demining. In post-conflict areas, minefields are often contaminated with a mixture of explosive remnants of war (ERW) that includes unexploded ordnance as well as landmines. In that context, the humanitarian clearance effort is often referred to as battle area clearance.
In some situations, clearing landmines is a necessary condition before other humanitarian programs can be implemented.[1] A large-scale international effort has been made to test and evaluate existing and new technologies for humanitarian demining, notably by the EU, US, Canadian and Japanese governments and by the Mine Action Centres of affected countries.[2][3]
The main methods used for humanitarian demining on land are: manual detection using metal detectors and prodders, detection by specially trained mine detection dogs, and mechanical clearance using armored vehicles fitted with flails, tiller or similar devices. There is an organization, APOPO, that is training African rats to detect landmines much as dogs do, offering a local solution to countries in Africa.[4] In many circumstances, the only method that meets the United Nations' requirements for effective humanitarian demining, the International Mine Action Standards (IMAS),[5] is manual detection and disarmament.[6] The process is typically slow, expensive and dangerous, although demining can be safer than construction work if procedures are followed rigorously.[7] New technologies may provide effective alternatives.
Metal detectors were first used, after their invention by the Polish officer Józef Kosacki.[8] His invention known as Polish mine detector Allies used to clear the German mine fields during the Second Battle of El Alamein when 500 units were shipped to Field Marshal Montgomery.[9][10]
The first step in manual demining is to scan the area with metal detectors,[11] which are sensitive enough to pick up most mines but which also yield about one thousand false positives for every mine.[6] Some mines, referred to as minimum metal mines, are constructed with as little metal as possible - as little as 1 gram (0.035 oz) - to make them difficult to detect. Mines with no metal at all have been produced, but are rare. Areas where metal is detected are carefully probed to determine if a mine is present; the probing must continue until the object that set off the metal detector is found.
Well-trained dogs can sniff out explosive chemicals like TNT in landmines, and are used in several countries.[12]
Like dogs, Giant pouched rats are being trained to sniff out chemicals like TNT in landmines.[13] These rats are currently working in minefields in Mozambique and are trained in Tanzania by APOPO.[14] The rats are called HeroRATS.
These animals also have the advantage of being far lower mass than the typical human. They are less likely to set off small mines intended to injure or kill people, if the bomb-sniffing animal crosses directly over the top of a buried mine.
Special machines effectively combine mine detection and removal into one operation. In the past, these machines were applied in both mine clearance and demining but are now generally used only for demining. They can be used to verify land that is not expected to be contaminated or as an extra layer of security after an area has been cleared by another method, such as dogs.
The machines consist of a special vehicle that is driven through the minefield, deliberately detonating the mines it drives over. These vehicles are designed to withstand the explosions with little damage. Some are operated directly with armour to protect the driver; some are operated under remote control.
Recently, armies developed armored demining vehicles, and a specially armored bulldozers, that are remote controlled. This eliminates the risk to life of the operator. Notable examples are the Caterpillar D7 MCAP (USA) and Raam HaShachar Caterpillar D9N (Israel).
Deminers may be issued personal protective equipment (PPE) such as helmets, visors, armoured gloves, vests and boots, in an attempt to protect them if a mine is set off by accident. IMAS specifies standards for such equipment but draws attention to its limitations and states that at close quarters, antipersonnel fragmentation mines and antitank mines overmatch PPE currently available.[5] PPE can afford significant protection against antipersonnel blast mines, and these are more common. Related technologies that have been developed to improve safety include large, pillow-like pads strapped to the bottoms of shoes that distribute weight and dull the impact of footsteps, as very slight disturbances of the ground can tip off old, unstable, or intentionally sensitive mine triggers.
In demining, once an object has been detected it is removed by one of the following methods:
Some removal methods that are not applied in humanitarian demining, but are common in mine clearance, include:
Along the China-Vietnam border were numerous minefields. These are the legacy of the border clashes in the 80's. The mines are mainly anti-personnel, and have kept large areas of arable land from use by local farmers. A typical demining process deployed by the Chinese is as follows. Firebreaks are dug around the minefield to be cleared. Then engineers would set the minefield on fire with flamethrowers. Key factors of this burning process are: thick vegetation covering the minefields; most anti-personnel mines are buried very close to the ground level; the mines are made of mostly either wood, thin metal or plastic. This burning process would usually destroy about 90% of the mines, as the mines are either detonated or melted. Mines which have trip wires would have these wires burned off. Demining teams then would plow the area with mine detectors. When the teams have cleared the mines, they would walk over the field hand in hand themselves to show to the locals that all the mines have been cleared.[23]
In 2003, the Rand Corporation published a comprehensive report on innovative methods of land mine detection.[24]
Conventional metal detectors rely on electromagnetic signals with frequencies of the order of 10–100 kHz, which are not sensitive to plastic or wooden mine bodies and the high explosive block itself. The only part of a low-metal mine that they may be able to detect is the detonator. Much higher frequency signals (of the order of 1 GHz) are employed in Ground Penetrating Radar (GPR) and these signals are also sensitive to the non-metallic parts of the mine. Unfortunately, as they are also affected by innocuous objects such as tree roots and stones and by local changes in soil moisture, it is difficult to distinguish a mine on a GPR image.
A hybrid approach employing both GPR and metal detector sensors in a single instrument has been developed by several companies and research organisations.
Recent research by the University of Montana has revealed that honey bees can, with minimal training, be used to detect landmines with a far greater accuracy and far higher clearance rate than dogs or rats.[25]
Recent experiments with the Gambian giant pouched rat, also known as the Giant African Pouched Rat, have indicated that it has the required sensitivity to smell, can be trained reliably with food-reward incentives, and is typically too small to set off the mines.[26] These rats also offer a local solution to many African countries because they are indigenous to East Africa. These rats are trained by a non-profit, research organization called APOPO and are called HeroRATs. Additionally, experiments with electrode-guided rats suggest that demining could one day be accomplished by guiding "ratbots" into areas that humans are unable to reach.[27]
Engineer Thrishantha Nanayakkara and colleagues at the University of Moratuwa in Sri Lanka have come up with a method where a dwarf mongoose is trained to detect landmines by smell and guided by a remote-controlled robot.[28][29]
The U.S. Navy Marine Mammal Program uses sea lions and dolphins, among other species, in the detection of seamines.[30]
The mustard Arabidopsis thaliana, one of the best-studied plants in the world, normally turns red under harsh conditions. But using a combination of natural mutations and genetic manipulation, scientists from Danish biotechnology company Aresa Biodetection, created a strain that only changes color in response to the nitrous oxide that leaks from landmines and other explosives. Because nitrous oxide can also be formed by denitrifying bacteria, there is some risk of false positives using this technique, and researchers are attempting to make the plant less sensitive. The plants would aid demining by indicating the presence of mines through color change, and could either be sown from aircraft or by people walking through demined corridors in minefields. As of February 2005, no studies have been conducted with actual landmines, though successful studies have been done in greenhouses. In order to prevent the spread of this genetically modified organism into the wild, the plants have been further modified so that they will only sprout when provided with an external growth factor.[31]
A bacterium, known as a bioreporter, has been genetically engineered to fluoresce under ultraviolet light in the presence of TNT. Tests involving spraying such bacteria over a simulated minefield successfully located mines. In the field, this method could allow for searching hundreds of acres in a few hours, which is much faster than other techniques, and could be used on a variety of terrain types. While there are some false positives (especially near plants and water drainage), even three ounces of TNT were detectable using these bacteria. Unfortunately, there is no strain of bacteria capable of detecting RDX, another common explosive, and the bacteria may not be visible under desert conditions. Also, well-constructed munitions that have not had time to corrode may be undetectable using this method.[32]
There are two principal techniques to detect land mines through nuclear reactions. Both rely on the use of neutrons.
The first such technique relies on the fact that the vast majority of explosives used in land mines are very nitrogen rich when compared with other materials. To detect such anomalies one may make use of the nuclear reaction
In practice a detection system using this reaction works by subjecting the mine to thermal neutrons while searching for the characteristic gamma ray emitted from the excited state in nitrogen-15; these photons will only be observed when an object containing nitrogen is being subjected to the neutron irradiation.[33] One possible neutron source is californium-252 which undergoes spontaneous fission. A better neutron source is to use a sealed tube electrostatic D-T neutron generation tube, this has the advantage that the tritium is much less radiotoxic than the californium so in the event of an accident such as an explosion, the nuclear mine detection equipment would pose a smaller threat to humans. This type of explosive detection has been proposed for use in airport security and for the detection of explosives in trucks coming into military bases.[34][35][36]
An alternative way of spotting land mines through nuclear reactions with the help of neutrons is that of measuring the thermalization of neutrons. In this technique the soil is irradiated by fast neutrons and the flux of thermal neutrons scattering back is measured. The motivation for this technique is that explosives contain much higher concentrations of hydrogen, which is a very effective moderator of neutrons.[37]
It is possible to detect land mines by directing sound waves at the area to be demined, which causes the land mines to vibrate, and then using a laser to search for vibrations on the surface by means of the Doppler shift - this technique is termed Scanning Laser Doppler Vibrometry. Such devices have been constructed, e.g., at the University of Mississippi,[38] at MIT[39] and by the Kayser-Threde Company.[40]
Polish mine detector
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