Weapons of Mass Destruction, Detection

█ K. LEE LERNER/

BRIAN HOYLE

Weapons of mass destruction are weapons that cause a high loss of life within a short time span. Nuclear, chemical, and biological weapons fit this definition.

An atomic bomb exploded over a densely populated city could kill hundreds of thousands of people instantaneously and, as the lethal effects of radiation exposure take hold, causes many more deaths within days or weeks. Chemicals such as Ricin that disrupt nerve function are lethal upon exposure. Agents such as mustard gas can cause life-threatening burns. Chemical weapons can affect a wide geographical area because the chemicals are dispersed in the air.

Biological weapons take longer than nuclear and chemical weapons to cause damage. Because infections can subsequently spread through a population far from the site of contamination, and because the population may not be protected by vaccination or natural immunity to the microorganism responsible for the infection, the eventual death toll from an organized biological attack, however, could reach into the millions. Relevant modern day examples of biological weapons of mass destruction are anthrax (caused by Bacillus anthracis ), plague (caused by Yersinia pestis ), and smallpox (caused by the variola virus).

The damage from weapons that are less powerful or toxic can be minimized. For example, buildings can be fortified to withstand assaults from conventional explosives such as grenades. Thus, for such weapons, damage prevention can be the priority rather than detection. However, the damage from a weapon of mass destruction cannot be minimized once the weapon has been unleashed. Rather, the weapons need to be detected before they are used.

Detection of Chemical and Nuclear Weapons of Mass Destruction

Chemical and nuclear weapons are often delivered to their target in missiles. Sophisticated open-air launch facilities and large pieces of equipment are required for launch, and it is difficult to conceal such facilities from aerial surveillance. Planes, unmanned drones, and even satellites positioned over a region will all reveal the presence of a missile installation. Underground chemical storage facilities can also be revealed by the use of ground penetrating radar.

The materials that are commonly used in the construction of chemical and nuclear weapons can be detected. For example, an instrument called the Dual-Use Analyzer uses the phenomenon of eddy current. An electrical current is passed through a sample, and the conductivity of the metal produces a characteristic signal. If another metal is present, such as those used in chemical and nuclear weapons, another signal is produced. The rogue signal can be compared to a databank of signals produced by metals that are typically used in weapons.

Light or radiation. The airborne release of chemical weapons can be detected using light. Specifically, the scattering or absorption of a directed beam of laser light, or

the development of fluorescence when the aerosol cloud contacts laser or ultraviolet light, can detect a chemical cloud at a distance. This sort of detection is not specific. The identity of the compound in the aerosol cloud cannot be determined. But detection can provide some time for preparations (i.e., evacuation gathering in an airtight facility). Specific detection methods, however, are possible. Chemical groups behave in distinctive ways when exposed to different kinds of light or radiation. The measurement of the chemical behavior is called spectroscopy. The machines that perform the analysis are called spectrometers.

In mass spectroscopy, the mass (or molecular weight) of proteins is determined. The molecular weight is an important means of identifying a protein. In turn, the identification of a protein can provide a clue as to what chemical agent is present. Raman spectroscopy relies on the change in the shape and frequency of the wave of light (i.e., the wavelength) as it passes through a sample to identify the chemical groups that cause the wavelength change. In neutron spectroscopy, neutrons interact with the chemical groups of the sample. The patterns of these interactions can be measured and used to identify chemical groups. Neutron spectroscopy is especially adept at detecting plutonium, and thus is useful in the detection of nuclear weapons. Finally, optical spectroscopy relies on the use of ultraviolet and infrared light. The absorption of the light energy by sample chemical groups, and the giving off of light of a different wavelength by the groups, is used to identify compounds, particularly compounds present in certain explosives.