Unmanned aircrafts are an ideal choice when operations are required in environments that would be hostile to a manned aircraft or its crew. Airborne sampling or observation missions related to chemical, biological, radiological and nuclear (CBRN) threats would be ideally suited to unmanned aircrafts. Sensors can be fitted to a range of types, from a small man-portable system for local tactical use, to large aircraft-sized systems for global monitoring. The smaller systems can be sacrificed in a safe area once data has been gathered rather than having to recover to an airfield where it would have to be decontaminated, or risk contaminating personnel and other equipment.
This ‘dirty’ role involves the detection and identification of CBRN, high-yield explosives and toxic industrial material agents and substances. Unmanned Aerial Vehicles (UAV) can be used to support these aspects of a survey team’s mission. Specific tasks that can be performed by UAV include marking and timing the team’s route, scanning for hazards, conducting air monitoring, checking for corrosives, and detecting radiation, chemical warfare agents, and biological hazards.
Clarification, containment, and combat of incidents that are caused by uncontrolled emissions of dangerous gases and liquids or CBRN weapons remain an emerging challenge. Instead of sending specially equipped forces with expensive transport and measurement devices into the contaminated area, an autonomous, wirelessly connected swarm of micro-UAVs, equipped with lightweight mobile sensor systems, could be used in the future. Utilizing a MUAV swarm enables the calculation of gas concentrations and also allows for propagation forecasts, which assist rescue forces in averting danger by evacuation at a very early stage. Widespread chemical plumes can have a spread of 20 km or more which could be tracked by using several UAVs in a swarm and assigning a relay functionality to each UAV or by using public wireless networks. Relevant incident areas are usually urban or metropolitan where infrastructures of cellular networks are available such as GSM, UMTS/HSPA or Mobile WiMAX.
The sophistication of UAV’s instrumentation and sensor systems will increase, providing data levels similar to or better than manned aircraft. Increases in performance are likely to be incremental, rather than revolutionary, with the greatest effect on unmanned aircraft likely being the decrease in sensor size and associated packaging. Research effort for sensors is likely to be focused on sensor integration, fusion and on board analysis. The timely distribution of analyzed data will be a key issue and work is required to determine the best mix of on-board versus off-board analysis.
One company involved in this sector of the market is the Washington-based Research International Inc., which has developed a pioneering UAV-based product called the “Flying Laboratory” that has full CBRN monitoring capabilities. A second-generation ion mobility spectrometer (IMS) is mounted onboard a UAV to provide toxic gas detection and up to 20 chemical warfare agents and toxic industrial gases can be detected at part per billion to part per million concentrations. A UV particle fluorometer is used to detect any unusually high biological aerosol levels, and a gamma spectrometer is used in combination with two Geiger counters to detect and identify nuclear materials and monitor radiation levels. One of the Geiger tubes is used for monitoring general background radiation levels, while the second, capable of detecting either alpha, beta or gamma radiation, is mounted so that it monitors radiation emitted from particulates captured by an aerosol sampling filter included in the payload. An on-board air sampling circuit can grab a biological or radiological aerosol sample if the biological or radiological sensors detect unusual conditions. This sample is either collected onto a compact 44 mm diameter high-flow electret filter with a 50 percent collection point of 0.5 microns, or with a lower flow electret filter with 99+ percent efficiency at 0.3 microns. The latter is used for radiological sampling.
A single-board computer is used to combine, analyze and store digital data created by the various CBRN sensors. Sensor data, along with GPS coordinates and time, is stored on a 32GB SD memory card for post-flight analysis.
Its system detectors typically respond in 1 to 2 seconds while the gas detector has the largest latency period, of about four seconds, which corresponds to less than +-45 meters uncertainty in position at cruising speed, or about +-26 meters at the lowest possible speed. Research International Inc. is also partnering with the Russian company ENICS to offer the world community a range of UAVs with integrated CBRN capability.
The German armed forces already operates CBRN-capable UAVs including the EMT LUNA tactical UAV that can deploy a wide range of payloads such as EO/IR, SAR, SIGINT or CBRN sensors and relay payloads. It can stay aloft for 8 hours and is able to respond to fast changing mission requirements. Also designed to meet the urgent requirements of the German Bundeswehr is the EMT ALADIN Mini-UAV that can carry EO/IR and CBRN sensor payloads.