Though new technology is vital to improving mine clearance, there has been little research with few advances since 1942. There is not much impetus to generate the necessary research because mine accidents get little public notice and they rarely happen in developed countries. Presently, mines are detected individually by prodding, metal detection or sniffer dogs. Prodding is slow, confusing and dangerous, especially when the mines are laid in hard-packed or stony soil, or when they are fitted with anti-disturbance fuses. Metal detection works well with metal-cased mines, but metal in modern mines has been increasingly replaced by plastic. New mines will soon be undetectable by their metallic content.

Dogs can detect the vapor coming from the explosive filling of mines, but they are temperamental, require long training and tire quickly. Individual location takes time, as it has to be done with great delicacy. UN policy is to destroy mines by detonation using an explosive charge, although safe and reliable, is expensive in explosives and time.

EXPERIMENTS AND THEORIES

Although little research has taken place, mine clearance companies have carried out practical experiments on many conventional and unconventional mechanisms for destroying mines. Most have followed one of three main routes: neutralization, leaving the mine to rot; removal, with destruction at a later stage; or actuation, by pressure, heat or other methods.

Neutralization aims to render mines completely inactive, by biodegradation or mechanical disruption. Biodegradation involves generating some organism that feeds on certain elements of explosive chemicals, rendering them inert. Mechanical disruption involves destroying mines by breaking them up without actuating them, which has not been proved against steel-cased mines. Only trials will tell whether the mines will actually disintegrate without detonating. Some jumping mines can be neutralised by "crimping" or distorting the outer case so that the inner body will not jump free.

In Kuwait, sand was sifted by a machine, adapted from devices used to clean beaches at seaside resorts, which cut off and sifted the top three-inch layer of soil. The machine failed because stones and vegetation clogged the sifting screens, and mines were pushed around the edge of the cutter blade and remained uncleared. Currently, this method is only appropriate for fine dune sand.

Mine ploughs, used in minefield breaching, have proved ineffective for civilian clearance. Mines are not destroyed, but moved into the soil windrow thrown up by the plough blade, from which they have to be removed by hand, placing the deminer at greater risk than if the mines had remained untouched.

Air and water blasting can expose mines by removing the surrounding soil. Air blasting, using portable equipment, has proved especially effective for clearing trip wires hidden by dune sand. Water blasting is generally ineffective, however many mines are of near neutral buoyancy and merely move to new locations in the mud. Furthermore, the technique is problematic because considerable quantities of water are needed to even begin blasting.

CLEARING METHODS

Many mechanical minefield breaching methods use pressure to actuate and destroy the mines in situ. In practice, it is difficult to achieve uniform pressure over wide areas, and mines that have been in the ground for a long time may operate only after repeated pressure, or will not operate at all, so that the reliability required for mine clearance cannot be obtained. Pressure is usually applied by rollers, armored vehicles, flails or explosives. It is often erroneously assumed that mines can be set off by bullet impact, but in practice the main explosive filling is usually too insensitive to detonate. Unless the detonator is struck, the mine usually remains active. Therefore, bullet impact cannot be used as an effective method against buried mines.

Rollers to detonate mines were first designed in 1942, and are still used by many armies for minefield breaching. The Soviet system of breaching has been copied by a number of other nations. Unfortunately, few rollers can withstand repeated blasts of full-weight anti-tank mines. Mines can even slip between roller disks, especially when they are worn, further complicating the process. In general, rollers rarely give more than 70 percent clearance capacity.

Rotary flail devices were first deployed in the 1940s and further developed in 1982, but current flail systems are expensive to operate and unreliable, clearing less than 80 percent of the mines. Again, due to the sheer force of anti-tank mines, few are strong enough to survive repeated blasts.

HOT ENOUGH TO EXPLODE

The use of heat is often recommended as a way of detonating a mine or used to simply burn up the components. Various sources of heat have been tried, and more have been suggested but not yet put to the test.

In Afghanistan and Cambodia, occassionally fire was used to clear off the dry grass or undergrowth to expose hidden mines which at times would ignite the explosive filling of the mine. Unfortunately, buried mines are often unaffected by the heat, and some other form of clearance has to be done afterwards. Fire does however clear the undergrowth, which is at times an advantage.

Lasers and microwaves have both been proposed as methods to destroy mines, but so far neither of them has been tested. Heating the ground by microwave could potentially either cause the mine casings to deform, so preventing the detonator mechanisms from functioning, or heat the explosive fillings to self-ignition temperature (200-300 degrees Celsius). The power requirements for such a method of destruction are considerable; steel-cased mines and buried mines would be relatively unaffected.

As with microwave heating, most lasers need a great deal of power and would have to be vehicle mounted. Such a system is probably only suitable for surface-laid mines, although it is claimed that where a sub-surface mine can be precisely located, point initiation of part of the explosive might be possible.