DARPA puts millions behind effort to power drones with ground-based lasers

Can the U.S. military power an entire drone swarm—including its directed-energy weapons—by firing a laser at it? DARPA is paying Raytheon $10 million to start working on it.

“Under the two-year contract, Raytheon will create an airborne relay design to enable ‘webs’ capable of harvesting, transmitting and redirecting optical beams. These ‘webs’ will transmit energy from ground sources to high altitude for the precision, long-range operation of unmanned systems, sensors and effectors,” Raytheon announced last week. ‘

Two other teams, from Draper and BEAM Co, are also competing in the DARPA effort. 

It’s part of the agency’s Persistent Optical Wireless Energy Relay, or POWER, program. Raytheon’s contract follows the agency’s 2022 Broad Agency Announcement seeking companies to demonstrate drones or other platforms that can pass laser energy “from a ground-sourced laser through multiple airborne nodes and back down to a ground receiver.” 

According to DARPA, “Offboarding energy storage and generation from platforms opens up a novel design space where platform capabilities are no longer dependent on the quantity of fuel carried. This provides an opportunity for small, inexpensive distributed platforms with significant capabilities such as unlimited range or endurance.”

If that sounds very difficult, it’s because it is.

The idea of wireless power transfer goes back to Nikola Tesla’s 19th-century experiments with power transmission via radio frequency resonance through coils over short distances. He constructed towers to transmit energy over larger areas. When the experiments yielded disappointing results, he was forced to sell them to pay debts. 

Skip ahead to the 1960 and 1970s. Early research by NASA and others aimed to power things with microwave energy, including a rare demonstration of a microwave-powered helicopter in 1964. But the helicopter had to be relatively close to the power source. 

Fast-forward again, to April of last year. when researchers with the Naval Research Lab beamed 1.6 kilowatts of power over 1 kilometer at the U.S. Army Research Field in Blossom Point, Maryland. A Navy press release called it the “most significant power beaming demonstration in nearly 50 years.”

Although most such research has used microwaves, DARPA’s POWER effort calls for lasers, which promise to deliver more energy with a narrower beam. A 2004 NASA experiment powered a small UAV with an infrared laser.

Why is this concept important? As Heather Roff, a senior research scientist at CNA, wrote on Linkedin: “basing and logistics for air operations are major targets for an adversary. In an anti-access aerial denial (a2ad) environment being able to maneuver quickly and in a distributed manner would mean keeping major targets out of range, thus protecting assets. If you can communicate (as necessary) with such distributed systems and power them without having to ‘bring them home’ you can have persistent and distributed assets. Depending on the mission, role, and function, this is a potential balance against long range precision fires and it could provide SEAD when necessary.”

The downside? Said Roff: “It starts to look like aerial occupation.”