Remember active thermal camouflage, the military technology that seemed so, well, hot a few years ago?
In May 2010, an Israeli startup called Eltics wowed YouTube with a video showing a special tiled system that, when tacked on to a vehicle, could render it invisible to infrared (IR) sensors—or, with the push of a button, disguise it as something else. Not to be outdone, the defense giant BAE Systems unveiled its own ADAPTIV solution, which the company said would be production-ready in about two years.
That was in September 2011. Today, ADAPTIV is still years away from being fielded on a tank or ship, and the Israeli solution has stalled at the early prototype stage for the lack of funds. However, experts in camouflage and IR imaging believe that this temperature-based cloaking technology is still doable.
Since their advent in the 1970s, thermal imagers—sensors that use the mid- and long-range IR spectrum (3.5 to 5, 7.5 to 14 microns) to cut through night, fog, and smoke—have been slowly but inexorably taking over the modern battlefield. One can now find this technology on tactical drones and sniper rifles.
The U.S. military has tried, and continues to try, special dyes and materials in uniforms to shield a soldier's IR signature from these imagers. "But you are running up against the laws of physics," camouflage expert retired Lt. Col. Tim O'Neill says. "The heat must escape somehow, or you will reduce the soldier to a hot, stinky puddle."
Passive IR camouflage also yields ho-hum results, says Peder Sjölund, ADAPTIV project manager at BAE Systems. So by the mid-1990s, the Swedish government began experimenting with active temperature modulation to hide IR signals. These early attempts ran into snags with excessive power requirements and systems that were too fragile for use on the battlefield. Finally, in 2005, Swedish Defence Material Organisation initiated the Steerable and Controllable IR Signature program, which helped fund ADAPTIV.
Designed to blend in with the temperature of its surroundings or mimic the IR signature of something else (for instance, a low-priority Humvee or an enemy tank), ADAPTIV is often shown in the form of 5.5-inch hexagonal tiles. (That's only the land vehicle version of the system. The actual size of the tile depends on the host platform and its normal distance of engagement). Think of the tiles as hot and cold pixels comprising a large thermal picture.
"When the enemy is closer," Sjölund says, "you need higher 'resolution,' so the 'pixels' have to be smaller. You don't want a thermal pattern that doesn't look natural." For example, a vehicle engaged in urban warfare would need hand-size tiles to fool IR imagers at a distance of 200 to 300 meters. But a naval ship, used to combat ranges in the nautical miles, could have a larger tile. Either way, perfection isn't necessary. Even when ADAPTIV cannot fool the human eye, it can frustrate a targeting algorithm.
Although ADAPTIV is a super-secret system, Sjölund has a ready response to most objections to his system. He insists that the 1000 to 2000 tiles required to cloak an infantry fighting vehicle will not slow it down or chew into its fuel reserves (though he won't say how much it weighs). Likewise, a so-called "vehicle interface sheet" prevents IR hotspots from flaring up should a tile be lost in combat.
He does grant that synthetic aperture radar, mounted on an aircraft or drone, could image a ground vehicle using ADAPTIV. But, he says, "the system would passively reduce the radar cross-section of a platform because the tiles have an inherent capability of absorbing radio waves."
Sjölund also won't discuss the technical-readiness level (TRL) of ADAPTIV and when it will be tested in an operational environment. The active thermal camouflage hasn't deployed with any military yet, and even if ordered tomorrow, the system would take years of additional trials and customization before it could be fielded.
"The system will have to be built to customer specifications," he says. "It won't be sitting around in boxes."
Eltics, meanwhile, seems even further behind with its Black Fox solution. When discussing thermal camouflage, former Eltics CEO and current shareholder Ronen Meir focuses on existing and pending patents. "We created a way to make a window thermally invisible, so soldiers can look outside their vehicle and have greater situation awareness," he says. He also says that Eltics has come up with a way for a commander to remotely program the IR disguises of Black Fox–shrouded vehicles.
Still, when prodded on details, Meir admits that Black Fox is at TRL 5. This means the prototype has undergone some environmental testing and the basic technology is fairly integrated. But a system usually has to reach TRL 9 before it is ready for prime time.
Without the deep R&D pockets of BAE Systems, Eltics will need outside help to turn Black Fox into an operational system. "We are looking for large investment of $5 million or more from a strategic partner," Meir says.
Disappointments aside, experts believe that active thermal camouflage is still possible. After all, thermal imagers might be able to see through polyethylene — as Boston Marathon bombing suspect Dzhokhar Tsarnaev discovered when he was found hiding in a tarp-covered boat. But most other things block them, so it's just a matter of heating and cooling the outer layer of a vehicle to fool an imager.
"Thermal imagers don't tell you if something is actually hot or cold," Fred Colbert, president of Colbert Infrared Services, Inc. "They measure radiance." And radiance can be disguised.
O'Neill agrees that, when possible, using active thermal camouflage is easier than trying to bottle up IR emission. But he adds that such systems require a stealthy way of venting the heat generated by powering them. "Think about when you are running an air conditioner: the air inside your room is cool, but the air being vented outside isn't," he says.