Idea number 354
Military airfields are big s**t magnets. They cannot be hidden, they cannot be moved. One of the biggest threats to our airfields in Southwest Asia, in the coming conflict, will be chemical attacks. To mitigate the threat, we need the ability to detect when and where a chemical has been released, to know which areas are contaminated and to what concentration. With this information we can predict when an area will be usable or even traversible again.

US and NATO forces already possess a very effective and inexpensive (expendable!) device to detect contamination, a detector paper that changes color when it is contacted with suspected chemical agents. Each country has its own model or designation of the paper, some adhesive-backed. It's a throw-away item, everybody carries a little pack of it.

Measuring droplet size is key to determining a few important parameters. Measuring change of droplet size over time also helps to predict how long the agent sticks around---"persistence"---which the base commander must know so he can balance the threat of the chemical against the loss of personnel to heat injuries caused by the clothing that protects them.

Idea number 354 would use a long ribbon of this paper, say 10cm wide in a 50 meter cassette just like an oversized VHS videocassette. It loads in a machine that exposes a 10x10cm window of this ribbon at any moment, horizontally facing the sky, advancing the ribbon about 20mm a minute. As the ribbon passes out of the window and back into the machine, it comes under a color scanner, just like the scanning head of a flatbed scanner you probably have connected to your home computer. The scanner notes change of color, from the olive drab of the paper as it is manufactured, to the red or yellow or blue-green that indicates contamination. A color change trips an alarm. A date/time stamp, including temperature, is imprinted on the paper at the trailing edge of the window exposed to the sky. An optional windcock attachment includes windspeed and direction (really useful information) in the stamp.

This device is networked through a narrowband connection on standard field wire to a PC in some command post, which polls as many devices as you've positioned. When the flag flies, the PC starts drawing all of the inputs in, and depicts the areas of the base with the highest concentrations of contamination, with a time resolution that does not overload (air quotes here) the Boss who Needs the Info.

The PC can also hold the devices in non-scroll mode until an attack is expected, can speed up the ribbon movement to catch more-precise measurements of droplet size (timestamps continue every minute while the detection is active), slow it back down, stop the scroll if it's a false alarm, and so forth.

If no chemicals land in the window, the machine scrolls the ribbon to the end, then reverses direction and scrolls back. The cassette doesn't have to be replaced unless it has detected something, and then it will be retrieved and shipped off to a lab for verification (and evidence) anyway.

The active dyes in this paper could be masked in a pattern that helps the scanner to measure droplet size with usable precision.

Anybody want to guess what this box would cost? Remember, it needs to be painted in sand color, powered by either battery or AC mains, and handled by high-school graduates. Over-engineer it a bit.

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