What does the Pentagon want with a swarm of robot bats? This is not the plot of a cheap techno-thriller. This is a real question, posed by the Defense Enterprise Science Initiative, in a grant announcement posted last year and updated earlier this month. Through the DESI, the Pentagon is soliciting work from university-industry teams on four big topics. One of them, perhaps the most eye-catching, is for bio-inspired highly maneuverable autonomous UAVs. In other words, bat drones.

From the announcement:

The biological study of agile organisms such as bats and flying insects has yielded new insights into complex flight kinematics of systems with a large number of degrees of freedom, and the use of multi - functional flight surface materials ... As a result of these advances, there exists a possibility of creating autonomous unmanned aerial vehicles (UAVs) that have significant improvements in maneuverability, survivability and stealth over traditional quadcopter or fixed wing designs.

Later on, the announcement gets into swarms:

The ultimate vision of this basic research program to yield advances that will enable the next generation of UAV platforms capable of autonomous operation. These platforms should effectively navigate a battlespace and respond to obstacles with minimal intervention from a human pilot. Research into the underlying principles of autonomous flight may yield new platform - independent algorithms. ... If used in swarms, new concepts for communications, data fusion and distributed control could also be considered.

Drones are a synthesis technology. Miniaturization of motors, increased power in batteries, cheap navigation sensors, and widespread affordable computing power all combine to give us small, cheap flying machines, and fuel technologies for larger, more accomplished devices.

Bat drones, then, should be seen as one possible end-state of this design much like bird-shaped drones. Propeller driven fixed-wing drones and rotor-powered quadcopters are loud, and distinct, clearly signally to anyone nearby that this is a machine, likely filming something for the humans piloting it somewhere within line of sight.

What bat-drones offer, no matter what power source they ultimately use, is discretion. If the bat-bodies can fit sensors, and if they can travel through flapping flight, then a swarm of bat drones released at dusk, looks like nothing out of the ordinary. Apart from satellites and high-altitude flights, the great downside to all surveillance from above is that people on the ground can figure out when and if they’re being watched.

Bat-drones already exist, at least on an experimental and research level. Flexible wings mean robots that can fit through narrow openings, or recover almost effortlessly after bumping into something in flight. Landing is harder, but not impossible to imagine a bat-drone that could snag a special perch and then hang out and recharge until the sun sets. Perhaps the future of these drones is in infrared sentries and scouts, returning to solar-powered roosts, before going on patrol again.

There are other, more immediately practical shapes for robots, but hiding as wildlife is a new trend in this arena, and one we should expect to see more of in the next decade or two. And, wherever we see the proliferation of biomimetic machines, we should expect some danger of backlash towards the species they imitate. Once the first bat drone is discovered crashed in an insurgent camp, the world could become a dangerous place for bats themselves.

Kelsey Atherton blogs about military technology for C4ISRNET, Fifth Domain, Defense News, and Military Times. He previously wrote for Popular Science, and also created, solicited, and edited content for a group blog on political science fiction and international security.

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