Using a smokescreen to throw an enemy off your trail might sound more like a James Bond maneuver than a military one. In fact, the US Army regularly uses the devices to provide cover for its troops in battle.
However, the smokescreens it uses currently consist of technology developed around the time of World War II, so clearly it was time for an upgrade. A team of engineers at the Army's Edgewood Chemical Biological Center in Maryland is currently evaluating four different smokescreen compositions that will replace the chemicals that have been used until now in the grenades.
One of the issues with current smoke-producing grenades, which use hexachloroethane (HX) to do their job, is that they create an irritant smoke that contains zinc chloride -- and a squadron of coughing soldiers is not the best way to achieve stealth on the battlefield.
So the first smoke-maker still uses the HX, but eliminates the zinc, making the smoke easier on the lungs. Like the original compound, it can pull water out of the air to dramatically increase the amount of smoke it produces. "The chemical reaction of the HX composition produces slightly less combustion products and has a higher efficiency, so the result is a similarly dense smoke cloud," Joseph A. Domanico, senior engineer for the Pyrotechnics and Explosives Branch at Edgewood, said in a statement. "This combination makes it the most exciting smoke composition in a long while."
The second composition consists of chlorine atoms encapsulated in a plastic matrix. According to the military, the plastic matrix keeps the chemicals from contaminating the groundwater after the smoke has been unleashed -- although it's not clear if groundwater contamination is a concern with the other compounds under consideration (but we've asked and will update when and if we find out). Nor is it clear how a chlorine-based smoke would affect the lungs (again, asked and waiting).
Aside from its eco-friendly benefit, this compound still might not be the front-runner because it produces a dark gray to black color which doesn't reflect as much light as white smoke, making it a poorer concealer.
The third composition consists of magnesium and aluminum powder -- two chemicals that are used in fireworks to create their signature white sparks and trails. They do the same here, creating a camouflage cloud of bright white. What's more, the powder can be blended in a bowl with a superglue-like binder, making it a bit of an on-field DIY smokescreen contender.
For the final composition, lithium salts are used. In fireworks, these are usually used to create a red color. But in this preparation, they undergo a chemical reaction which unleashes a bright white smoke cloud that feeds itself by drawing large quantities of water from the air.
"The compositions will be tested and evaluated in combat conditions, from cold to hot environments; in forest, desert, and urban terrains; and whether or not friendly troops and civilians are in the combat zone," according to a statement about the smokescreens on the US Army's website.