A GROUND SEGMENT OF the Department of Homeland Security’s Rapidly Deployable Chemical Detection System (RDCDS) will be rolled out before the end of the year. The system is designed to sniff out suspicious chemicals in public venues that have been designated as a National Security Special Event (NSSE) or given a Special Event Assessment Rating (SEAR) of Level I or II.

The ground element is but the newest component of a system that includes one aircraft with associated detection capabilities, five meteorological stations, a communication system, and the RDCDS operations center. The eight initial ground detection nodes will be incorporated into the network supporting NSSEs and SEARs.

SEARs events are rated according to a risk-based approach that weighs consequences, vulnerabilities, threats, and preparedness. The ratings run from I to V, with I being the riskiest. Generally, major sporting events like championships and major tournaments are categorized as a SEAR-IV.

The goal of the RDCDS is to provide chemical detection and protection at public venues that are large enough to present attractive targets to terrorists, says Christopher Kelly, associate director of strategic communications in the Department of Homeland Security’s (DHS’s) Science and Technology department, which has been in charge of the project.

The RDCDS ground segment being developed by Sandia National Laboratories is about the size of a lateral filing cabinet, some four feet wide, three feet high, and two feet deep. It includes a video camera and communications equipment. The entire contraption is called a “node.”

Each node has eight chemical detectors designed to sniff out about 40 different types of chemicals, which fall into two categories. The first class of chemicals comprises warfare agents, such as VX nerve gas, mustard gas, and sarin gas. The second class is chemicals manufactured for commerce that are used to make products but that have toxicity as a secondary property. A classic example is chlorine.

The nodes are wirelessly networked and communicate using several different wireless networks, so if one mode drops out, there are backups. Multiple nodes are used at once.

A recent test run at McAfee Coliseum, home of baseball’s Oakland A’s, used eight units strategically placed around the stadium, including several on the perimeter so that if there were chemicals present, they could be detected before winds wafted them inside the grounds. More units were placed inside to pick up chemicals released within.

“The multiple detectors give us some overlapping capabilities, so when we do get a detection, we are confident it’s what we are looking for,” says Ben Wu, the lead researcher for Sandia on the project.

The system is designed to detect chemicals accurately and quickly at fairly low density levels. It is armed with two different types of color-coded alarms. One is cautionary, denoting levels that are above the norm. The second is the safety level, in which chemical density in the air presents a health concern for individuals.

Cameras are positioned to help the process of detection. “Once the first level is reached, we start looking at the video cameras to see if anything suspicious is going on,” says Wu. “We’re not concerned until the second threshold is reached.” All of the nodes give a live video feed, which doubles as a security mechanism to ensure that no one is tampering with the units.

One operator can oversee all the nodes from a central station. Operators have a graphical user interface with multicolored lights that indicate caution or full-fledged warnings.

There is no limit to the number of nodes that can be used. “You can use a hundred nodes if needed, and the system configures itself to accept any additional ones,” says Wu. The network can also be configured to accept additional types of detectors looking for other threats such as radiological, nuclear, or explosives.

When Sandia ran its pilot test of the system inside the Oakland coliseum, the crux of the exercise was to fine-tune the detection equipment’s ability to differentiate between background “noise”—cigarette smoke, cologne, automobile exhaust, hot dogs—and threatening chemicals. The next step was an open-air test of the system using real chemicals. It was conducted in the desert to guarantee consistent meteorological conditions.

As its name suggests, the units can be rapidly packed up and shipped to far-flung locations. Michael Janes, the public and media relations officer for Sandia, says the units can reach any domestic locale within 24 hours.

DHS says the RDCDS will be aimed at protecting large-scale, populous affairs held at places like the coliseum. “The detectors can be rapidly deployed to provide sequential defense of several venues within a large event to provide rapid characterization of the event and an evaluation of the response options,” says Kelly. SEAR-II events will be evaluated on a case-by-case basis to determine whether they merit use of the RDCDS.