With the accidental (and apparently innocent) crash of a DJI Phantom quadcopter on the White House lawn, there’s an urgency to the question of how the Secret Service can defend against a small drone that’s been launched with malicious intent.  The key is malicious — people who are actively hoping to evade detection (otherwise, rule and regulations will suffice, no?).  There’s two problems to solve, really.  The first is detection, and the second is stopping a drone.

Here’s 5 (bad) ideas for detecting a drone:

1. Most drones have radio transmitters on either the 2.4ghz or 5.8ghz ISM bands.  It would not be hard to detect these transmitters as they drift over the White House grounds.  You’ll probably be surprised to know this, but there’s a whole group of people who do this sort of thing as a hobby: Amateur Radio operators (aka hams). The hams could have something running in a few weeks with a bunch of these $15 gizmos,  or you could spend 6 months with a defense contractor and end up with a bunch of $100,000 gizmos.  Just call up the ARRL.
2. Similarly, the whine of the propellers will typically fall into a specific frequency range; they can be detected acoustically. A bunch of microphones around the grounds could alert you.  If they can detect the propellers of subs …
3. Heat signatures: Their motors will get warm when flying and can be detected via infrared.  You may have to trim some trees and resettle some birds.
4. Dogs — you can probably train dogs to bark at the sight or sound of drones.
5. Hold a contest: If all else fails, offer a $10K prize (and medal from the President) for someone who comes up with a solution.  It’s a two-fer: science contest and security fix.

And here’s 5 ideas for stopping one when you spot it:

1. There is a threat from drones with pre-programmed flight paths that will rely on GPS for navigation.  You can locally alter the GPS signal to throw off the flight path. (This is pretty iffy).  Just don’t get upset when people make a right turn into the White House and think it’s the JW Marriott.
2. Create air turbulence. A bit fantastic, but you could send very strong waves through the air to try to disrupt the flight of drones.  People have knocked small drones out of the air with helicopter downwash.
3. Use an Electromagnetic Pulse (EMP): You can fry a drone’s electronics with a strong pulse of radio energy.  Just don’t mis-aim, or you’re buying people a new set of wifi routers.
4. Water cannon — very green, too. Once it’s wet the flight is over.
5. Nets — I hope it doesn’t come to this, but you can always stop a drone with a net. Either put a net around the White House, or shoot a net up on a moment’s notice.

Whether any of these are useful or not, remember there are lots of ways to think outside of the box on this one.  Best of luck!