This isn’t science fiction: The military considered using heat rays on protesters

We break down what they are—and why they’re not (quite) as scary as they seem.

This isn’t science fiction: The military considered using heat rays on protesters
[Source Photo: Shutterstock]

On June 1, Trump displayed one of the most telling moments of his presidency, as he deployed the National Guard to clear out protesters from Lafayette Square and St. John’s Church near the White House for his own photo opp. The Guard fired tear gas and rubber bullets to do so.


The response to citizens was not just painfully cruel, but truly dangerous. Rubber bullets are known to maim and even kill, and exposure to tear gas has been linked with a greater propensity for long-term bronchitis. That night in the square, protesters were beaten with batons, rammed with riot shields, shot with rubber bullets, and left with lingering injuries.

Now a new report shows that the military police had attempted to acquire another weapon from the National Guard to oppress protesters that night: a heat ray.

[Photo: Lance Cpl. Andrew Huff/United States Department of Defense]
In the story first reported by NPR, Major Adam DeMarco of the D.C. National Guard says he was copied on an email request for an Active Denial System (ADS)—known colloquially as a heat ray. The email went out just hours before authorities descended on the park, not leaving enough time to source the device.

But what, exactly, is a heat ray? How does it work? And is it dangerous?

An Active Denial System in a demonstration to members of Congress, the departments of Defense and Homeland Security, and the National Guard in 2017 [Photo: Jamal Beck/United States Department of Defense]

What is a heat ray?

A heat ray is a large antenna designed by the military that looks like an oversize DirecTV dish. It’s either mounted on a vehicle or can be deployed as a large stand-alone unit. It fires completely invisible electromagnetic waves that penetrate the skin 1/64 of an inch deep—the depth of your nerves—creating an intense burning sensation if you stand in its path instead of getting out of the way.

[Photo: United States Department of Defense]
It’s technically the same sort of technology behind your kitchen microwave, but operating at a much lower frequency (the heat ray runs at 95 Hz while the microwave runs at 2.45 GHz). That means the heat ray’s wavelengths are shorter and less able to penetrate an object and transfer energy the way your microwave does to heat your food.


Notably, the heat ray has range: The electromagnetic beam can reach over half a mile and is unaffected by wind, though its exact range appears to be classified.

[Image: United States Department of Defense]

What’s the purpose of a heat ray?

While research on direct energy weapons goes back decades, the ADS was developed as part of a 1997 effort by the Defense Department’s Joint Non-Lethal Weapons Program. The first working versions of the ADS were demonstrated in 2002. The technology was developed by the military as a less violent method for crowd dispersal and guarding a perimeter. Such “less lethal” technologies were first developed for our troops fighting overseas to avoid unnecessary bloodshed, but are increasingly being adopted by U.S. police departments.

In a meeting with leaders of the Department of Homeland Security, Customs and Border Protection officials also discussed deploying heat rays at the U.S.-Mexico border in 2018, but that idea was dismissed by Kirstjen Nielsen, who was the secretary of homeland security at the time.

Scenes from a Department of Defense concept rendering. [Image: United States Department of Defense]

What does it feel like to be shot with a heat ray?

The burning is strong enough that people can’t handle the pain for more than four to five seconds at most.

[Image: United States Department of Defense]
In 2008, 60 Minutes correspondent David Martin participated in a demonstration of the heat ray at work, taking several shots on his own body through the course of his reporting. Even though he was wearing several layers of clothing, including a heavy winter jacket, it hurt.

“To me it felt like scalding water,” he said.


But unlike a rubber bullet or tear gas, which can injure people and leave them in pain long after the attack, the heat ray’s burning sensation stops as soon as you step out of its path and leaves no damage to your skin.

Can you block a heat ray? (asking for a friend)

Kind of! But you need to do so quite accurately.

The beam is wide enough to hit your entire body at once, and it can be panned across a crowd much like a fire hose. In that aforementioned 60 Minutes segment, Martin used a plywood board as a shield with at least some benefit. It seemed to protect his torso, but still created unbearable pain on his exposed feet. Next, he tried a mattress, which covered more of his body and seemed to mitigate the effects of the beam more. “It hurts, but you can keep going,” Martin said.

Is it dangerous?

Heat rays are a far more modern technology than rubber bullets, which were developed in the 1970s to simulate the strike of a baton from a distance. Rubber bullets use blunt trauma, which can lead to bruising, blood clots, blindness, and death if they hit a particularly vulnerable part of your body.

The heat ray appears to be safer than rubber bullets, at least according to the military, which devoted 15 years of research to studying the technology, over which time 13,000 volunteers were exposed to the beam to gauge injury potential. The military claims there’s a 0.1% chance of injury, which can come in the form of red skin or blistering. In the case of Martin, he was “zapped” 17 times during his reporting and was left with no visible marks or lingering discomfort.

According to a Penn State risk assessment, the biggest concern seems to be damage to the eyes, if the ray excites the corneas for too long without shielding. But the military believes the blink response generally protects from this issue.


As for longer-term health concerns, ranging from infertility to birth defects, citing its research the DOD says, “We are very confident there will be no long-term adverse side effects.”

The ray also has automated systems that are designed to limit injury more than less-lethal munitions. Namely, the length of time that the beam can blast someone is limited by the software, not the adrenaline and poor decision-making of an overeager police officer.

So wait … are heat rays safer than rubber bullets and tear gas?

There’s certainly an argument to be made that heat rays could be a safer method of crowd control than other “less lethal” alternatives. But does that mean such military-born technologies—which force compliance through an onslaught of pain—should be used against protesters who are exercising their constitutional right to organize and voice dissent?


About the author

Mark Wilson is a senior writer at Fast Company who has written about design, technology, and culture for almost 15 years. His work has appeared at Gizmodo, Kotaku, PopMech, PopSci, Esquire, American Photo and Lucky Peach