Fighting in the Open: The Impact of Ubiquitous Sensors on the Future Maritime Battlespace



By CAPT John Litherland, USN (ret) **



From time immemorial, military forces have concealed their positions and movements from their opponents. Ground forces use terrain, weather, darkness and camouflage; maritime forces, out of sight of land, essentially vanish into the vastness of the ocean space, particularly its depths for undersea forces; and air forces have assiduously developed and deployed a variety of stealth technologies to conceal themselves from adversary sensors. However, the coming Age of the Sensors will largely negate these efforts across virtually every battlespace domain, leaving forces fighting in the equivalent of an open battlefield, in full view. This impending revolution, clearly evident in technology trends, will tilt the finder-hider balance irrevocably in favor of the former, profoundly changing the nature and methods of warfare in ways that the military has yet to even acknowledge or begin to prepare for.

This ubiquitous sensing revolution promises enhanced awareness of physical, social, and cyber environments by combining three technological trends: the proliferation of ever cheaper and more capable sensors into virtually every device and context, large data aggregation and ready access to it using vast cloud-based archives, and cross-spectral data fusion and sense-making algorithms running on ever more powerful processors. All of these trends are accelerating, most at exponential rates. For instance:

The worldwide total number of sensors has increased by more than three orders of magnitude in the past decade and will soon pass the one trillion mark, or more than 100 sensors for every person on earth. As we move from a “sensor-poor” to a “sensor-rich” world, the individual nodes can become simpler and cheaper, relying on proximity and processing instead of the high gain and selectivity built into today’s exquisite but expensive sensors.

Sensing capabilities have improved immensely in terms of both cost and performance due to the mass production of electronics. A complete inertial, electronic and satellite navigation system, which would have represented the epitome of military technology a few decades ago, today counts as just one of many sensors, costing only a few dollars’ value in every smartphone, more than 2 billion of which have been manufactured worldwide.

The worldwide digital data generation rate now exceeds 1 ZB (1021 bytes) per year and global storage exceeds 10 ZB, both also having grown by nearly three orders of magnitude in the past decade. Moreover, this data is increasingly accessible due to cloud storage and the communications infrastructure of the Internet.

The ability to fuse and make sense of unstructured data from disparate sensors and incommensurable formats is only beginning to appear, aided by ongoing growth in computer processing capability and powerful new data reduction algorithms.


At the same time, virtually every military stealth and signature reduction capability being used or developed today, whether in radio-frequency, visible, infrared, or acoustic spectra, appears to be asymptotically approaching some limit or constrained return on further research or investment. Typical signature reductions in these areas over the past decade are less than an order of magnitude, with little outlook for future breakthroughs. Moreover, costs both to develop and maintain these stealth capabilities are extremely high due to their limited applications and exotic materials. Finally, the effects of almost all low-observable technologies are limited to just a small portion of a specific spectrum, or to a limited target aspect, rendering them nearly useless against a sensor threat which is increasingly broadband, multi-spectral, and spatially dispersed.

Obviously the above are global trends, not specific to military technology or scenarios, but their implications are nonetheless clear. No military force operates without creating signature across several spectra, and this information will be increasingly susceptible to gathering by ubiquitous sensors, correlated with other data, and processed into meaningful locating information. Maritime forces, long reliant on the effective cover provided by the oceans’ vastness, will inevitably become “visible” from a shore no longer limited by its line of sight. Even undersea forces, operating from what is likely the last bastion of concealment beneath the waves, will eventually succumb to the avalanche of sensors and processing, yielding their much valued stealth.


Surprisingly, given the strength and persistence of these technological trends, little has been done to prepare our maritime forces for the coming fight in the open, newly-visible battlespace. Instead, resources are poured into ever-more exquisite active defenses and limited-return stealth technologies, neither of which will ever restore the tactical security enjoyed when the seas provided natural cover. Unfortunately, like the Emperor in his new clothes, we will likely be surprised to find our nakedness suddenly revealed in the face of our adversaries during some future maritime conflict. Open field fights, where both sides have knowledge of their adversary’s location, have historically become symmetrical and bloody slugfests, not our preferred means of fighting nor one which we could sustain for long. In addition, open seas’ visibility increasingly offers the adversary the option to wage maritime war from the land, where the inherent asymmetry of unsinkable ground against sinkable ships comes into play. Admiral Nelson’s dictum, that “a ship’s a fool to fight a fort,” remains true even though he never envisioned a “fort” with thousand-mile visibility.

Despite this bleak outlook, the U.S. Navy can take actions to better prepare for and preserve its capabilities for any coming fight. Locating an adversary is but part of the fight; to know one’s enemy, one must also be able ascertain his intentions. Maritime forces can deny an adversary this ability by focusing on the following critical concepts:

• Dispersal - rather than aggregating in large force elements which are easily tracked and whose intentions can be discerned by location, maritime forces must disperse over as much of the maritime battlespace as possible.

• Deception - instead of concealment, future naval forces must focus on targeting the adversary’s sensor complex with noise, false targets, and cyber-attacks, across multiple spectra.

• Range - when dispersed, maritime forces must be able to create effects at far greater ranges than typical of today’s weapons, allowing massing of effects without massing of platforms (a key network-centric warfare concept which the Navy is still struggling to achieve).

• Speed - together with range, the speed of both kinetic and non-kinetic effects will be critical to creating tactical surprise for the adversary, even when striking from a known position.

Unless the Navy prepares now to fight in the coming Age of Sensors, it risks becoming as vulnerable, even obsolescent, as the galleys at Lepanto or the battleships at Pearl Harbor were. By taking the steps outlined above, it will remain in the forefront of the globe’s maritime forces.


** = The opinions expressed here are solely those of the author, and do not necessarily reflect those of the Department of the Navy, Department of Defense or the United States government.