Drone Swarms: A New Challenge For Air Defence Part-I

Swarming is being projected to be the next big thing in warfare. Some scholars even categorize swarming as a potential fourth evolutionary stage of warfare- the first three being melee, mass and maneuver.  While militaries today predominantly conduct maneuver warfare,  swarming could well become the mainstay in the future.

Not theoretical anymore

Drone swarming, in particular, is a field that seems to be moving quickly towards operationalization.  It was only in November 2014, US Under Secretary of Defense, Frank Kendall asked the US Defense Science Board to examine:

‘the use of large numbers of simple, low­ cost (i.e. ‘disposable’) objects vs. small numbers of complex (multi-functional) objects.’ 

And by October 2016, the US Air Force Test Pilot School in association with US Naval Air Systems Command had launched some 103 small ‘Perdix’ drones from  three US Navy F/A-18 jets. The 3D-printed Perdix drones weighing just a few hundred grams were released from dispensers normally used for flares and were intended to suppress enemy air defences by acting as decoys, or by locating radars which could then be destroyed.

In  early 2017, Intel would  use 300 drones to illuminate the night sky by forming an  American flag during  Lady Gaga’s Super Bowl halftime show . Not to be outdone, within a week the Chinese company Ehang would put on a spectacular New Year show  by using some 1,000 drones to form a map of China and the Chinese character for ‘blessings’. While the two ‘flag formation’ examples given above were obviously for non-military use, they do represent the wider availability of advances in swarming technology, something that is now clearly being developed for military use.  In the near future,  the US Navy‘s Low-Cost UAV Swarming Technology (LOCUST) programme aimed at fusing unmanned aircraft into a swarm, as well as whatever will follow the  Perdix trials mentioned above are the efforts to watch out for.

Stigmergy anyone?

Now, the current generation of swarms being envisaged are based on behaviourial models inspired by examples from the natural world. Foremost among these are  the ways in which ‘social insects’ such as bees, ants and termites cooperate and orchestrate the division of labor among their respective ‘networks’as encapsulated by the so called ‘stigmergy‘ principle,  which was introduced in the 1950s by French ecologist Pierre-Paul Grassé  and refers to a form of self-organization based on insect behavior. Grassé observed that termites using pheromones left a trace of their activity behind so as to inform the activity of other termites, with each subsequent action building upon the last. By collaborating in this way, a coherent, almost systematic pattern of activity emerges, allowing these simple organisms to build complex structures. Stigmergy itself forms the basis for ‘Swarm Intelligence’, a term that was introduced in the context of cellular robotics in 1989 by Gerardo Beni and Jing Wang.

Be that as it may, the two essential features  required for swarming to work are connectivity and autonomy.  Connectivity is required to facilitate the seamless coming together of  drones that are distributed in a seemingly amorphous mass at the right moment. Also, with connectivity, drones  can ‘aggregate’ and ‘disaggregate’, i.e. they can join or leave the swarm, as if one cure.  One could even have a situation where a  single drone might detach to get a closer look at a target  and then either return or be used to carry out an attack, i.e. ad-hoc detachments for specific tasks from a swarm may be possible.

The control of drone swarms is done by using a decentralized planning control algorithm handling both stationary and moving obstacles, which owing to its decentralized nature is  more resilient than centralized algorithms that have a single point of failure. However, in a decentralized algorithm each entity (drone) has only partial information of the operating environment and the other drones (for example, it can only see a few neighbors). The drones in a swarm therefore need to communicate  with each other for information sharing and coordination of actions.

Is there enough juice?

Battery life is a big issue for small drones. But a swarm can have a ‘hive’, i.e a base station where individual drones return for recharging while the rest continue with their missions. This way, the overall swarm itself may have considerable endurance, provided the base station or network of base stations remains operational.

At the end of the day, the importance of the swarm does  not  lie in the individual components which may be expendable but rather in the synchronization of the  behavior of the collective which makes the execution of complex missions possible. Drones in  a swarm would usually serve a narrow role as an individual element within the mass, while the mass itself, which need not always be comprised by a fixed number of elements, strives to achieve its more complex assigned task.

Operational Advantages of Drone Swarms

The information-processing and communications requirements of swarming makes swarming ideal for drone systems. Autonomous yet cooperative behavior of multiple drones operating under human command at the mission level offer many advantages on the battlefield in terms of greater coordination, intelligence and speed.

Swarms of uninhabited vehicles have several potential advantages:

• Dispersal of combat power, which forces the enemy to expend more munitions.
• From a focus on individual platform survivability, the system moves towards swarm resiliency. As long as there are a minimum number of drones in terms of mission sufficiency, the swarm as a  whole  is resilient against attack.
• The combat power of the swarm undergoes graceful degradation  even as individual platforms are attrited, as opposed to a sharp loss in combat power if a single, more exquisite platform is lost.

• Dynamic self-healing networks – Swarming behavior allows drones to act in a dynamic self-healing network. In-built redundancy and resilience caters for the loss of a number of drones and yet allows the operator to maintain surveillance coverage over an area,  even as continuous self-healing communications and adaptive networks take on new tasks.
• Swarms can saturate enemy defenses. However advanced contemporary  air defence systems  may be, they cannot handle so many threats at a  time. Swarms can overwhelm enemy defenses, with ‘leakers’ getting through to neutralize the target.
•  Swarms can perform distributed sensing and attack by dispersing assets over a wide area. A swarm can conduct distributed focused electronic attack, syncing up its electromagnetic signals to provide focused point jamming.

Potential Capabilities

The US Marine Corps (USMC) has a project for a range of drones for use on land, sea and air which envisages drones to be the first wave to hit the beach ahead of humans, while locating enemy positions, and possibly attacking them. The swarm may also provide defence against swarms of enemy drones. To explore this angle, USMC is setting up swarm-versus-swarm wargames. (There have already been drones designed to capture other drones.)

The Defense Advanced Research Projects Agency (DARPA), the Pentagon’s advanced science agency, envisages foot soldiers having their own swarm for reconnaissance, especially in urban areas and inside buildings.

Suppression of Enemy Air Defences(SEAD) is one of the tasks that the swarm could carry out effectively. All air defence systems can handle only a specified number of aerial threats and can be potentially  overwhelmed by a swarm of drones. Air defence radars could be jammed, or made ineffective by using deception or simple saturation measures, leaving the entire air space vulnerable.

Though the individual drones may be too small to sink a ship on their own or destroy a tank, they could potentially knock out on board systems  such radar, missile launchers or other key assemblies, leaving them vulnerable to other attacks. The swarm might carry out high-risk reconnaissance missions, collecting imagery or other data from targets too well-defended for a manned aircraft to approach. Similarly, in defensive operations, a swarm can form a protective cordon against the target to be defended, or even attack the offensive swarm.

In the years ahead, Drone Swarms will be used for more tasks as their capabilities evolve.

Select References

Paul Scharre, Unleash the Swarm: The Future of Warfare, https://warontherocks.com/2015/03/unleash-the-swarm-the-future-of-warfare/

Natasha Lomas, MIT creates a control algorithm for drone swarms, Apr 22, 2016 https://techcrunch.com/2016/04/22/mit-creates-a-control-algorithm-for-drone-swarms/

David Hambling, Drone swarms will change the face of modern warfare Thursday 7 January 2016, http://www.wired.co.uk/article/drone-swarms-change-warfare

Sam Thielman, Robot swarms: scientists work to harness the power of the insect world, Sep 18, 2015, https://www.theguardian.com/technology/2015/sep/18/robot-swarms-drone-scientists-hive-mentality

 Kelsey D. Atherton, The Pentagon’s new drone swarm heralds a future of autonomous war machines, January 11, 2017, https://www.popsci.com/pentagon-drone-swarm-autonomous-war-machines

 Kyle Mizokami, The Pentagon’s Autonomous Swarming Drones Are the Most Unsettling Thing You’ll See Today, Jan 10, 2017, http://www.popularmechanics.com/military/aviation/a24675/pentagon-autonomous-swarming-drones/

Colonel Mandeep Singh(Retd) joined the Indian Army in December 1982 and was commissioned into Air Defence Artillery.  He commanded an Air Defence Group during Operation Parakaram and also commanded his Regiment along the Line of Actual Control with China.  

© Delhi Defence Review. Reproducing this content in full without permission is prohibited.