Technologies and Anti-Submarine Warfare

IntroductionThe purpose of this selectionof open source literature is tohelp inform the assessment ofthe relevance of existing andemerging technologies toAnti-Submarine Warfare(ASW) and their likely impactover the next 20 years.

Ever since submarines firstemerged as an effective tool ofwarfare in the first world war, anti-submarine technologies havedeveloped alongside. It has been agame of cat and mouse, mostfamous during WW2 whenGerman U-boats stalked theAtlantic. Opinion is dividing on thestrategic implications of recenttechnical developments potentiallyrelevant to anti-submarine warfare:is it a continuation of the historic'cat and mouse' paradigm, or mightemerging technologies, advancedcomputing and miniaturisationoutstrip countermeasures so as totransform the undersea battlespacein favour of the detectors?

This question has seriousimplications for the practice ofbasing nuclear-tipped ballisticmissiles on submarines, whoseprincipal advantage is stealth.Stripped of their stealth,submarines - slow, vulnerable andwith low situational awareness - areotherwise poor platforms forstrategic systems.

“Miniaturizing the sensors and having large numbers of sensors,we can start to own the underwater battlespace in a way thatmakes it less attractive. Takes away the tactical strategic advantageof the submarine.” - Kevin LePage, Program Manager, NATO Centre for Maritime Research and Experimentation, quotedby Reuters, 4 May 2015http://uk.reuters.com/video/2015/05/04/natos-annual-submarine-warfare-exercise?videoId=364103210

“The ability to track submarines and then communicate theirposition brings with it many significant challenges. Now wededicate considerable resource to assessing these emergingcapabilities. And we judge that there is no inherent reason, for theforeseeable future, to believe that unmanned submarines will besubstantially more difficult to counter, than manned submarines.”- Rt. Hon Michael Fallon MP, UK Defence Secretary, PolicyExchange, 23rd March 2016www.gov.uk/government/speeches/the-case-for-the-retention-of-the-uks-independent-nuclear-deterrent

“Seabed Warfare: Adversary seabed infrastructure and unmannedanti-submarine sensors and systems will be vital future militarytargets to be disabled, confused, deceived and/or destroyed in anew seabed warfare mission capability.”- Report to Congress: Autonomous Undersea Vehicle Requirementfor 2025. Prepared by: Chief of Naval Operations, Feb 2016https://news.usni.org/wp-content/uploads/2016/03/18Feb16-Report-to-Congress-Autonomous-Undersea-Vehicle-Requirement-for-2025.pdf

Rapid development in autonomous underwater vehicles

“Autonomous Undersea Vehicles are a key component of the Navy’seffort to improve and extend undersea superiority. Theseunmanned vehicles will be able to operate independently from orin cooperation with manned vehicles, conducting tasks in supportof maritime missions such as Intelligence, Surveillance, andReconnaissance (ISR), Seabed Warfare, and Deception. Thisexpansion if undersea superiority will also rely upon fixedundersea sensors and systems, which provide similar benefits inspecific geographic locations. AUVs and undersea fixed systemswill operate where manned submarines and shops can't orshouldn’t.”- Report to Congress: Autonomous Undersea Vehicle Requirementfor 2025. Prepared by: Chief of Naval Operations, Feb 2016.Executive Summaryhttps://news.usni.org/wp-content/uploads/2016/03/18Feb16-Report-to-Congress-Autonomous-Undersea-Vehicle-Requirement-for-2025.pdf

British Pugwash britishpugwash.org

Launching of an MK 18 MOD 2 Swordfish UUV a reconnaissance device made by Hydroid (USA)

Technologies and Anti-Submarine Warfare2

There are some who see the role for submarineschanging radically. In his report: The Emerging Erain Undersea Warfare (January 2015), Bryan Clark, aformer submariner and Senior Fellow on underseawarfare based at the Centre for Strategic andBudgetary Assessments (CSBA) in Washington D.C.believes that emerging technology will lead to amajor shift in the operating missions for thesubmarine, and that there will be a major increasein area denial capabilities.

“Dramatic changes are occurring in thetechnological reality that should inform newoperational concepts, which will havesignificant implications for the kinds ofundersea capabilities that should be developedand the ways in which larger naval and jointforces should evolve to complement them. Inparticular, a new family of undersea vehiclesand systems will be essential to maintainAmerica’s undersea edge by reducing thegrowing vulnerability of today’s principalundersea platform, the manned submarine.” – Bryan Clark, The Emerging Era in UnderseaWarfare, January 2015, P 18http://csbaonline.org/publications/2015/01/undersea-warfare/www.youtube.com/watch?v=TLmM8PK2bos

“Undersea networks could enable coordinatedsurveillance or attack operations with swarmsof UUVs operating autonomously orcontrolled from a manned submarine or otherplatform.” - Bryan Clark, The Emerging Era in UnderseaWarfare, January 2015, – P16http://csbaonline.org/publications/2015/01/undersea-warfare/

“From an operational point of view, the reportnotes that “manned submarines will likelyneed to shift from being frontline tacticalplatforms like aircraft to being host andcoordination platforms like aircraft carriers.”This would be a big change from how largeportions of the U.S. submarine fleet are usedtoday. The aircraft carrier comparison wouldalso imply that future submarines would needto be bigger than today’s Virginia-classsubmarines, in order to accommodate a hostof new systems, as well as an array ofunmanned vehicles and weapons.”- The Diplomat: The End of the Submarine asWe Know it commenting on Bryan Clark’s reportabove.http://thediplomat.com/2015/01/the-end-of-the-submarine-as-we-know-it/

In a five page article for The Guardian investigativejournalist, Julian Borger, writes of his findings at NATO’sCentre for Maritime Research and Experimentation(CMRE) at the naval base in La Spezia in Northern Italy.

“In La Spezia, the technicians are working onovercoming these current limitations. One ishow to sustain autonomous robots under thesea for long periods, but that is close to beingcracked, with combinations of solar and thepower generated by a drone’s descent throughthe water. The next big issue will be getting thedrones to “see” and communicate through theoceans. Experiments are under way into laser-based techniques for finding objectsunderwater; for the time being, the lemon-coloured robots in La Spezia use sonar liketheir manned precursors.

Operating in “blue water”, the open ocean, is achallenge, but Kevin LePage, the Americanprincipal scientist at CMRE, believes it is just amatter of time. “I think it will be used in bluewater. The technology is completely applicable.”

His Portuguese colleague, Emanuel Coelho,adds that the capabilities of anti-submarinedrones will be amplified by intelligence. Bigsubmarines can be picked up in coastal waterand then tracked by relays of drones andaircraft. “Submarine forces are getting verynervous,” Coelho says, “because they never knowwhen they are being detected or not.”- Julian Borger, One False Click, The Guardian16th January 2016www.theguardian.com/technology/2016/jan/16/trident-old-technology-brave-new-world-cyber-warfare

British Pugwash britishpugwash.org 3

New US ASW Programmes“DARPA (Defence Advanced Research Project Agency, an agencyof the US Department of Defence) considers ultra-quiet as wellas highly lethal submarines as an asymmetric threat and inresponse has launched the Distributed Agile SubmarineHunting (DASH) program that intends to reverse theasymmetric advantage of this threat through the development ofadvanced standoff sensing from unmanned systems.”

DARPA’s Distributed Agile Submarine Hunting (DASH) “DARPA’s program Distributed Agile Submarine Hunting, orDASH, effort is to find an adversary’s quiet submarine usingadvanced standoff sensing from unmanned underwater systems.

Through a scalable number of collaborative sensor platformsthat use multiple sensing modalities, the program willdemonstrate system solutions to detect and localize submarinesover large areas in both shallow and deep water environments.

Two complementary prototype systems — part of DARPA’sPhase 2 development effort in the Distributed Agile SubmarineHunting program — have demonstrated functional sonar,communications and mobility at deep depths in recent tests, itsaid.”

Transformational Reliable Acoustic Path System(TRAPS)

“The first prototype is the Transformational Reliable AcousticPath System (TRAPS) developed by a team led by ScienceApplications International Corp. It is an expendable, low-size,weight and power (SWaP) fixed passive sonar node for large-area coverage and operates from the deep seafloor.

The significant field of view, along with the advantage of low-noise phenomena at extreme depths will permit a scalablenumber of collaborative sensor platforms to detect and tracksubmarines over large areas. These nodes will communicate to astationary surface node via wireless acoustic modems, withfurther secure RF reach back to the performer’s facilities viasatellite.”

Submarine Hold at RisK (SHARK)“The program will achieve breakthrough technology forlong-range detection and classification, communications,energy management, sensor and platform integration, androbust semi-autonomous processing and control fordistributed sensing platforms.”

The above four quotes are from:http://www.myidst.com/home5/international-defence-security-and-technology/military/sea-232/russia-is-inducting-ultra-quiet-submarines-darpa-planning-advanced-submarine-sensing-and-hunting-technologies/

Sensing,detection andcommunications

“...the drive to digitise allIntelligence SurveillanceReconnaissance (ISR)capabilities and fuse datacollected by the same usingdigital networks presentsfurther opportunities: toincrease the potency of specificsensors and exploit multiplesensors”www.ausairpower.net/SP/DT-ASW-Sensors-Dec-2010.pdf

Processing power“While the physics behind mostof these alternative techniqueshas been known for decades,they have not been exploitableuntil very recently becausecomputer processors were tooslow to run the detailedmodels needed to see smallchanges in the environmentcaused by a quiet submarine.Today, “big data” is providingthe capability to runsophisticated oceanographicmodels in real time so thesedetection techniques can beused. And as computerprocessors continue to shrink,some of them will soon besmall enough to fit on ships,aircraft, UUVs, and deployablesystems placed on the seafloor.”- Bryan Clark, The EmergingEra in Undersea Warfare,January 2015, p10http://csbaonline.org/publications/2015/01/undersea-warfare/

Technologies and Anti-Submarine Warfare4

SonarThe capacity of the sea to act as an acoustic waveguide,allowing sound waves to travel long distances within a‘trapped mode’ with minimal sound loss, forms thebasis of the technique used by OAWRS, ocean acousticwaveguide remote sensing. This passive sonartechnique is the basis for undersea detection ofsubmarines. It is also used for real time imaging andmonitoring of fish populations over thousands ofsquare miles, even when within one metre of theseafloor.

Historically passive sonar has been used to detectand track nuclear submarines. The US, for exampleinstalled the passive Sound Surveillance System(SOSUS) network in areas such as the 'GIUK Gap', thechoke point for the, then, Soviet submarines passingthrough the gap in the Atlantic between Greenland,Iceland and the UK.

However, as the acoustic vulnerability of submarinesbecame apparent, and submarines became 'quieter',work has proceeded on active sonar and non-acousticmethods of detection.

Until recently only active sonar above 1,000Hz infrequency was used in undersea surveillance. Nowhowever, with developments in computer processing,sonar using lower frequencies becomes feasible, givinga much greater operational range. The limiteddefinition in the resulting image consequent on thelonger wavelength is countered by the ability ofadvanced computer processing to refine it.

Low frequency, less than 1000 hz, active sonar is nowdeployed with passive sonar on the US NavySurveillance Towed Array Sensor System (SURTASS).

“Ocean acoustics waveguide remote sensing(OAWRS)--- was developed recently forinstantaneous imaging and continuousmonitoring of fish populations and marine lifeover continental-shelf-scale areas, coveringthousands of square kilometers, at an areal ratetens of thousands to millions of times greaterthan that of conventional methods. This rate ispossible because OAWRS relies on the capacity ofthe ocean environment to behave as an acousticwaveguide, in which sound propagates over longranges via trapped modes. With these modes,generated sound waves suffer only cylindricalspreading loss rather than the spherical losssuffered in conventional fishfindingtechnologies.”- BOX 11 | Ocean Acoustic Waveguide RemoteSensing: Visualizing Life Around Seamounts ByNicholas C. Makris, Srinivasan Jagannathan, andAnamaria Igniscahttp://acoustics.mit.edu/faculty/makris/oceanography_published.pdf

“ASW capabilities. Efforts to protect submarinesfrom being detected since the Cold War haveemphasized quieting, since passive sonar is thepredominant sensor used for ASW. But today agrowing number of new ASW systems do notlisten for a submarine’s radiated noise. Forexample, low-frequency active sonar is nowwidely used by European and Asian navies invariable depth sonar (VDS) systems and will bepart of the U.S. Littoral Combat Ship (LCS) ASWmission package. Non-acoustic ASW technologiesthat detect chemical or radiological emissions orbounce laser light off a submarine are becomingmore operationally useful due to improvedcomputer processing and modeling of theundersea environment.”

“Platform enhancements. The sameadvancements that are improving ASWcapabilities will also enable a new generation ofsophisticated counter-detection technologies andtechniques. For example, against passive sonar asubmarine or unmanned undersea vehicle (UUV)could emit sound to reduce its radiated noiseusing a technique similar to that of noisecancelling headphones. Against active sonars,undersea platforms could—by themselves or inconcert with UUVs and 4 other stationary orfloating systems—conduct acoustic jamming ordecoy operations similar to those done byelectronic warfare systems against radar.”- Statement by Bryan Clark, Senior Fellow, Centerfor Strategic and Budgetary Assessments before theHouse Armed Services on Seapower and ProjectionForces Subcommittee on “Game Changers –Undersea Warfare” Oct 2015:http://docs.house.gov/meetings/AS/AS28/20151027/104095/HHRG-114-AS28-Wstate-ClarkB-20151027.pdf

A Bluefin-12 AUV, manufactured by General Dynamics(USA) is a lightweight and modular drone

British Pugwash britishpugwash.org 5

Hydrodynamic pressurewave detection (optical &radar)

“Submerged submarines, no differently thansurface vessels, produce a wake of disturbed waterwhen running, produced by vortices in the waterexcited by the motion of the submarine hull andscrew. This wake expands in a roughly conicalshape behind the submarine, as it dissipates inintensity with distance and time. When the frontof the wake impinges on the surface of the waterabove and behind the submarine it produces asurface disturbance in the shape of a non-linearparaboloid Curve…. Ultimately, once SyntheticAperture Radar wake detection technologymatures, it will provide a potent capability todetect submarines from orbital and high flyingairborne platforms. This will drive submarines togreater depths and lower transit speeds, andresult in further design changes in hull shaping toproduce the least detectable wake patterns.”www.ausairpower.net/SP/DT-ASW-Sensors-Dec-2010.pdf

Antineutrino detectionAntineutrinos are elementary particles, electricallyneutral and produced in the reactor core of all nuclearreactors and nuclear explosions. They are almostmassless, and carry no charge. They interact only veryweakly with matter so can pass very easily throughmatter.

Now, 50 years after their discovery, there is a greaterunderstanding of their properties and theirapplications in the field of nuclear nonproliferation.Although the size of current detectors means theirapplication in the field of ASW is not immediate, it isworth noting as a technology that may be pertinent asit develops over the next 20 years.

“Antineutrinos naturally arise from decaysthroughout the Earth, whether they originatefrom a hypothetical natural reactor at the Earth’score or from man-made nuclear reactors ornuclear weapon testing. No level of shielding canprevent this detection.”- Hanohano Neutrino Detector Final Report 2006www.phys.hawaii.edu/~sdye/CEROS_final_report.pdf

“Antineutrino detector research is the perfectmarriage between basic science and applicationsthat are relevant to the Laboratory’s nationalsecurity missions.”- Adam Bernstein, of Lawrence Livermore,Antineutrino Detectors Improve ReactorSafeguards. Lawrence Livermore National Lab 2008https://str.llnl.gov/str/JulAug08/pdfs/07.08.4.pdf

“It is now possible to monitor the operationalstatus, power levels, and fissile content of nuclearreactors in real time with simple detectors atdistances of tens of meters from the reactor. Thishas already been demonstrated at civil powerreactors in Russia and the United States, withdetectors designed specifically for reactormonitoring and safeguards.”- A. Bernsteina, G. Baldwinb, B. Boyerc, M.Goodmand, J. Learnede, J. Lundb, D. Reynab, R.SvobodaaNuclear Security Applications of AntineutrinoDetectors: Current Capabilities and Future Prospectshttp://arxiv.org/pdf/0908.4338.pdf

There are currently several large antineutrinoexperiments being pursued by the fundamental physicscommunity. There are also associated experimentsexamining the potential of the technique for detectingnuclear powered submarines.

“We discuss a somewhat futuristic plan for aworld network of enormous neutrino detectorswhich may be employed for monitoring theactivity of all reactors on earth.

The array discussed here would certainly also beable to detect nuclear submarines and ships outto substantial range, if they are running atreasonable power levels (when in port they areusually nearly shut down). A 10 MWt marinereactor would contribute about one sigma to theworld total nuebar count rate at 1,000Km in twodays and would thus be marginally detectable. At100 km range however it would be easilydetectable.”- John G Learned: Thinking Big about Detection ofNeutrinos from Reactors at Long Distances, 2004www.phys.hawaii.edu/~jgl/post/gigaton_array.pdf

“We study the effect of naval nuclear reactors onthe study of neutrino oscillations. We find thatthe presence of naval reactors at unknownlocations and times may limit the accuracy offuture very long baseline reactor-based neutrinooscillation experiments.”- Nuclear Propelled Vessels and NeutrinoOscillation Experiments. http://arxiv.org/pdf/hep-ex/0207001v1.pdf

Technologies and Anti-Submarine Warfare6

Blue-green lasers and LIDAR

A networked detection, surveillance and, potentially,destructive ASW system needs rapid, sustained andcovert data transfer between submerged vehicles,between submerged and surface vehicles, and tosatellite, aircraft or UAVs. This has always beendifficult as radio waves are poor in penetrating waterand ultra-low frequency electromagnetic waves havelow bandwidth. Light waves used very successfully interrestrial telecommunications are generally absorbedby water and so are normally not considered viable forundersea communications.

However, light absorption by water depends on thewavelength of the light, and some wavelengths aremore weakly absorbed. Thus, work with blue and blue-green lasers is beginning to have a major effect onunderwater communications and detection.

“Radio frequency (RF) and acoustical techniquesof underwater communication suffer fromvarious drawbacks such as extremely low datatransmission rates (few bps), smaller range, andmulti-path reflections and so on. Laser basedcommunication using blue-green lasers is apotential technique for high bandwidthunderwater wireless communication because ofits high data transfer rate, reasonably large range,small size, low power consumption, immunity tointerference and jamming and covertness oftransmission.”

“A new approach for underwater sensornetwork which is in the most happening area ofresearch these days is:- Blue-green laser in theunderwater communication. Most of laser cannot penetrate through the sea due to be absorbedby the sea, but the blue-green laser (the length ofwave is about 470 ~ 570nm) has the minimumenergy fading in the sea, whose fading rate isabout 0.155~0.5db/m. Hence, the blue-green lasercan propagate from several hundreds of meters tokilometres in the sea, and this feature of blue-green laser in the sea is said the window effect.Based on the window effect of blue-green laser,some submarine communication systems havebeen developed.”- Vikrant, Anjesh Kumar, Dr. R.S.Jha,Comparison of Underwater Laser CommunicationSystem with Underwater Acoustic Sensor Network International Journal of Scientific & EngineeringResearch, Volume 3, Issue 10, October-2012 www.ijser.org/onlineResearchPaperViewer.aspx?Comparison-of-Underwater-Laser-Communication-System-with-Underwater-Acoustic-Sensor-Network.pdf

“Laser based communications using blue-greenlasers is a potential technique for highbandwidth underwater wireless communicationbecause of its high data transfer rate, reasonablylarge range, small size, low power consumption,immunity to interference and jamming andcovertness of transmission.”- Blue-Green Laser Communications and LIDARcritical technologies for Anti Submarine Warfareand Network centric Operations. July 2015

“DARPA (Defence Advanced Research ProjectAgency, an agency of the US Department ofDefence) has launched in June 2012 Tactical RelayInformation Network (TRITON) researchprogram to develop a blue-laser submarinecommunications system able to link submergedsubmarines with nearby aircraft for anti-submarine warfare ASW).

The Navy is interested in submarine lasercommunications to reduce reliance on towed-buoy receivers, to enhance the communicationsreliability and date throughput to ballistic missilesubmarines and fast attack submarines for ASW.

QuinetiQ under its Submarine EnablingAirborne Data Exchange and Enhancementprogram (SEADEEP) has already demonstratedcommunications through the air-water interfaceequivalent to rates available with widebandinternet communications at home, according tothe company.”- http://www.myidst.com/home5/international-defence-security-and-technology//sea-232/blue-green-laser-communications-and-lidar-critical-technologies-for-anti-submarine-warfare-and-network-centric-operations/military

“Fibertek has developed for the U.S. Navy’s Spaceand Naval Warfare Systems Command (SPAWAR)a green underwater laser system capable of multi-rate high- bandwidth communication up to 1 Gbsin clear or littoral waters at 10 to 100 metersrange. The system is currently being evaluated insimulated and representative waters, over avariety of link geometry and water conditions.”- US Navy SPAWARSwww.public.navy.mil/spawar/Pages/default.aspx

A Blackghost UUV, built at Cambridge University in 2008, can navigate through underwater obstacle sourses

without outside control

British Pugwash britishpugwash.org 7

“Lasers operating in the blue-green regionof the light spectrum (420 : 570 nm) haveseveral applications in the area of detectionand ranging of submersible targets due tominimal attenuation through water (lessthan 0.1m –1) and maximum laserreflection from estimated target (likemines or submarines) to provide a longrange of detection.”- Blue-Green Laser Communications andLIDAR critical technologies for AntiSubmarine Warfare and Network centricOperations. July 2015www.myidst.com/home5/international-defence-security-and-technology/military/sea-232/blue-green-laser-communications-and-lidar-critical-technologies-for-anti-submarine-warfare-and-network-centric-operations/

“Bathymetric lidar is used to determinewater depth by measuring the time delaybetween the transmission of a pulse and itsreturn signal.

A team at the Georgia Tech ResearchInstitute (GTRI) has developedbathymetric lidars that are much smallerand more efficient that the current full-sizesystems. The new technology, developedunder the Active Electro-OpticalIntelligence, Surveillance andReconnaissance (AEO-ISR) project, wouldlet modest-sized unmanned aerial vehicles(UAVs) carry bathymetric lidars, loweringcost substantially.

And, unlike currently available systems,AEO-ISR technology is designed to gatherand transmit data in real time, allowing itto produce high-resolution 3-D underseaimagery with greater speed, accuracy andusability.

These advanced capabilities couldsupport a range of military uses such asanti-mine and anti-submarine intelligenceand nautical charting, as well as civilianmapping tasks.

Lidar has completely revolutionized theway that ISR is done in the military – andalso the way that precision mapping is donein the commercial world," said Grady Tuell,a principal research scientist who is leadingthe work. "GTRI has extensive experiencein atmospheric lidar going back 30 years,and we're now bringing that knowledge tobear on a growing need for small, real-timebathymetric lidar systems."- Georgia Tech Research Institutewww.gtri.gatech.edu/casestudy/smaller-lidars-could-allow-uavs-conduct-underwater

Magnetic field detectionMagnetic Anomaly Detectors (MAD), or 'magneticgradiometers' measure local variations in the magnetic field ofthe earth. A large object made of a ferrous metal, such assteel, will distort the local shape of that magnetic field andthereby leave a trace of its location.

Versions of MAD were used in WW2, and they form amainstay of ASW on planes and helicopters, using towedarrays.

David Hambling, freelance technical scientific journalist:

“ ...the most conspicuous feature of the China’s newShaanxi Y-8Q submarine hunter is a seven-metre long‘stinger’ on the tail housing an MAD. The US P-8APoseidon does not include a MAD, although there is oneon the version of the plane supplied to India. Instead, itwill rely on remote MAD carried by drones. In January2015, BAE Systems was awarded an $8.9 millioncontract to provide a High Altitude ASW UnmannedTargeting Air System (HAASW UTAS) for the Poseidon.This will use a MAD, along with associated software,carried by a drone launched from the aircraft. Thesedrones will be small, deploying compact, sensitive,miniature MAD sensors based on an Atomic VapourMagnetometer, under development by the US Navy.”- David Hambling: The Inescapable Net - UnmannedSystems in Anti-Submarine Warfarewww.basicint.org/sites/default/files/BASIC_Hambling_ASW_Feb2016_final_0.pdf

Technologies and Anti-Submarine Warfare8

SQUIDsSuperconducting Quantum Interference Devices(SQUIDs) can detect very small amounts ofmagnetic flux, even a single quantum of flux,based on the Josephson effect. These detectorsoperate at very low temperatures so requirecryogenic cooling, which currently limits their use“in the field”. These difficulties would be reducedif high temperature superconductors could beused. Classified SQUID miniaturisation workdoes appear to be proceeding.

This again is miniaturised technology that canbe placed on aerial drones or satellites.

“In the longer term, a type of magnetometercalled a SQUID – “SuperconductingQuantum Interference Devices” – is likely torevolutionise the field. SQUIDs areextremely sensitive and are used medically tomeasure the tiny magnetic fields generatedby the brain. In the past SQUIDs have beendifficult to use in the field because of theneed for cooling with liquid nitrogen, butmicro-cryogenic coolers have recentlybecome available so that a SQUID-basedsensor could go anywhere. Future SQUID-based MAD will have much longer rangethan existing MAD.”- David Hambling: The Inescapable Net -Unmanned Systems in Anti-Submarine Warfarewww.basicint.org/sites/default/files/BASIC_Hambling_ASW_Feb2016_final_0.pdf

Electro-optical / Infra-red / Thermalimaging technologies

“Thermal Imagers and stabilised highdefinition television telescopes have beenwidely integrated on LRMP aircraft andASW helicopters but have mostly been usedfor the identification and tracking of surfacevessels. The technology has been proposedfor use in tracking submarines bybioluminescence in surface wakes, or to trackminute temperature increases in a surfacewake. Both applications would be moresuitable for an infrared hyperspectralimaging sensor but to date there have beenno public disclosures on the development ofsuch.”- www.ausairpower.net/SP/DT-ASW-Sensors-Dec-2010.pdf

Electromagnetic Manoeurve Warfare

“The mission of EMW is to optimize the piecesacross the air, surface and subsurface to helpminimize electromagnetic signatures andmaximize Navy asset abilities to detect potentialadversaries. The environment has a significanteffect on the Navy’s ability to transmit, receiveand analyze data. “We’re working diligently tomap the invisible terrain that we have to mapwith EMW, which is constantly changing in theocean environment,” said Gallaudet.” - Rear Adm. Tim Gallaudet, oceanographer of theNavy (OCEANAV), also the commanding officerfor the Navy’s Meteorology and OceanographyCommand (CNMOC) at Stennis Space Center. Sea Technology Jan 2016 http://www.sea-technology.com/features/2016/0116/1.php

ConclusionThe incentives to develop more effectiveanti-submarine technologies are strong.Detecting an opponent’s undersea assetsis critical to changing the balance ofcapabilities. This has always been thecase since the advent of submarines, butso far, leading submarine builders havebeen able to stay one step ahead of thedetectors, largely because of the nature ofthe undersea environment. But this doesnot mean it will always be so. Thisdocument does not come to anyparticular conclusions around the likelytrends in technology development, but itstarts to raise a question-mark over thefuture of stealth based upon extendedundersea deployment.britishpugwash.org