TAB D - The Fox Nuclear, Biological, and Chemical Reconnaissance Vehicle [129]
Before the start of Operation Desert Shield, the German government gave the United States 60 Fox vehicles (Fuchs Nuclear, Biological, Chemical (NBC) Reconnaissance Vehicles). These 60 vehicles were modified for US forces. These modifications included addition of the M43A1 chemical vapor detector as well as English language labels and English language software to the vehicle’s mobile mass spectrometer. The US designated the modified German vehicle the XM93 Fox NBC Reconnaissance Vehicle, but it was simply called the Fox (Figure 7). The Fox was one of several chemical warfare agent detectors deployed by the US Marines to detect Iraqi chemical warfare agents. The Marine Corps received ten Fox vehicles to support ground operations. Four Fox vehicles supported the 1st Marine Division; four Fox vehicles supported 2d Marine Division; one Fox stayed at Al Jubayl; and one Fox vehicle supported the 2d Force Service Support Group.[130] This narrative concerns the Fox vehicle which supported the 2d Force Service Support Group.
Figure 7. Fox NBC Reconnaissance Vehicle
The Fox is a six-wheeled light-armored vehicle designed primarily to detect, identify, and mark areas of persistent liquid chemical warfare agent ground contamination. Pressurizing and sealing the vehicle protects the usual four-man crew - driver, commander, MM-1 operator and surveyor or wheelman - from exposure to outside contaminants, and allows the crew to work without the constraints of protective masks and gloves.[131,132] The primary chemical warfare agent detection system in the Fox consists of the mobile mass spectrometer (MM-1) and an air/surface sampler. This system is primarily a liquid chemical agent detector. The addition of the M43A1 augments the Fox MM-1 system by providing a credible nerve agent vapor detector. The MM-1 detects chemical warfare agents by analyzing the ionic activity of a sample that has been collected either by raising liquid samples from the ground to the retractable sampling probe, using silicon sampling wheels, or by sampling the surrounding air.[133]
The MM-1 continuously monitors samples passing through it, checking for the presence of chemical warfare agents identified on a pre-selected target list of 1 to 22 chemical compounds. This target list consists of a four-ion "fingerprint" for each chemical warfare agent. During the initial identification step, the MM-1 fragments each sample into a unique pattern of ions and then compares each four-ion "fingerprint" on the target list against the sample, searching for a match.[134]
If the MM-1 makes an initial match, and the ion intensities are above a specific level (unique for each agent), an alarm is sounded, displayed on the MM-1 operator’s screen, and printed on a paper tape.[135,136] This initial alarm, however, does not verify the presence of a chemical warfare agent since there are many chemical compounds that have the same or similar ions as those compounds on the chemical warfare agent target list. These other compounds can therefore cause a false alarm for chemical warfare agents.[137] The initial alarms continue until either the intensity units fall below the alarm level or the MM-1 operator changes sampling methods or modes.[138]
The MM-1 operator must perform a spectrum analysis[139] in order to increase the confidence of the detection of the presence of a chemical warfare agent. A spectrum analysis involves optimizing the MM-1 by lowering the temperature of the sample line from 180 degrees Celsius to 120 degrees Celsius for better ion separation, discontinuing use of the sample wheels, cleaning the sample probe to remove residual ion activity (contamination), and lowering the probe to within three to five centimeters of the suspected contamination. This allows the MM-1 to acquire a better-prepared sample. The MM-1 then searches its 60-compound chemical library of four-ion-peak fingerprints, compares them against this improved sample, and attempts to match the chemical warfare agent fingerprints with the sample.[140,141]
Using the proper procedures, it takes several minutes to obtain a good ion spectrum readout and analysis. This process is necessary to properly evaluate the sample for any suspected chemical warfare agent, and to assure that initial indications were not affected by contaminants from the battlefield (e.g., smoke, diesel exhaust, and oil). Although an MM-1 operator can produce a spectrum in other ways, this is the proper and most accurate method.[142] The MM-1 operator should also print a tape, which saves the details of the spectrum as a hard copy historical record.[143]
Should the properly performed spectrum procedure identify a chemical warfare agent, the MM-1 operator and the Fox commander can be confident that the agent is present. Conversely, if the spectrum analysis does not identify one of the chemical warfare agents contained in the MM-1 library, the MM-1 operator and the Fox commander can be confident that the chemical warfare agent that was displayed during the initial alarm is not present. Further analysis of the spectrum tape printout by a mass spectrometry expert comparing the spectrum results to an established database of compounds can increase the confidence level of the detection.[144] Additionally, the MM-1 operators were taught to collect a specimen of the contamination (e.g., a soil sample) to further aid confirmation of the substance by thorough analysis in a laboratory. When the MM-1 can not match any of the compounds in the library to the sample, the MM-1 indicates "unknown" on the operator’s screen and the tape printout. A reading of "fats, oils, wax" is considered a false alarm.[145]
A variety of battlefield interferents can cause the MM-1 to register an initial false positive alarm. Compounds that cause the MM-1 to issue false alarms are common solvents, insecticides, riot control agents, diesel fumes, and fumes from explosives, and hydrocarbons (such as oil well smoke).[146,147] Experience and research since the Gulf War indicates that the MM-1 has a propensity to false alarm for lewisite.[148]
Although the MM-1 has a limited capability to detect chemical warfare agents in the air, the Fox vehicle was sometimes used for on-the-move vapor detection during the war. However, it is not optimized for this mission, nor is its alerting capability in this method of operation as good as that of other chemical warfare agent detectors.[149,150]
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