World's first Acoustic Picket Line at REPMUS26 - Naval News

World's first Acoustic Picket Line at REPMUS26 - Naval News

Listening by the Hundreds: Oshen's Acoustic Picket Line and the New Arithmetic of Undersea Surveillance

A British start-up's four-foot sailboats were tested against live targets at NATO's largest uncrewed-systems exercise. The concept is sound, but the burden of proof has barely started.

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BLUF

At REPMUS 2026 off Portugal, Plymouth-based Oshen deployed six wind- and solar-powered C-Star micro-USVs, each carrying one hydrophone, as a distributed "acoustic picket line." This was the first test of the concept against live targets. The concept replaces a few expensive towed arrays with many cheap, expendable listening nodes. Those nodes would localize contacts by using several sensors at once and then cue high-end ASW assets such as Type 26 frigates and P-8As. The timing fits the Royal Navy's Atlantic Bastion program and NATO's push to connect hundreds of heterogeneous uncrewed systems to a common data backbone. The C-Star's endurance is well documented: it gathered data inside a Category 5 hurricane and made the first fully autonomous Atlantic crossing. Its value as an ASW sensor is not yet proven. No REPMUS detection results have been released. Physical limits still apply: a single near-surface omnidirectional hydrophone on a small hull, detecting quiet modern submarines, in the sea states of the GIUK Gap. The next data point comes next month, when eight C-Stars join the AUKUS Maritime Big Play experimentation in San Diego.

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The Demonstration

REPMUS (Robotic Experimentation and Prototyping using Maritime Unmanned Systems) is the Portuguese Navy's annual proving ground for uncrewed systems. The 2026 edition ended on 25 September at Tróia, on the Portuguese coast, and is dedicated to testing and integrating uncrewed systems with conventional forces. NATO Allied Command Transformation reports that REPMUS 2026 drew around 1,500 participants from 36 navies, alongside industry and academic partners operating hundreds of uncrewed craft. One exercise guide puts the total at more than 300 uncrewed surface, underwater, and air systems working a box of more than 400 square nautical miles. (Some secondary reporting gives different participation figures. The ACT numbers are used here.) Task Force X-Arctic Takes its Next Step at REPMUS 2026 - NATO's ACT +2

Within that crowd, Oshen deployed six of its 1.2-meter robotic sailboats, each fitted with a hydrophone, to create a distributed surveillance network tested against live targets for the first time. The hydrophones come from Systems Engineering and Assessment (SEA), and the constellation can hold position to create an acoustic barrier across a given stretch of water. The company says the barrier's shape and density can be adjusted to the threat picture. It also says multiple sensing points can yield a target's location rather than just its bearing, allowing other assets, including towed arrays, to be directed toward a contact. World's first Acoustic Picket Line at REPMUS26 - Naval News +2

The processing architecture matters as much as the hulls. CEO Anahita Laverack has described the C-Stars as processing audio onboard at the edge and relaying only the most crucial information back for constellation-level analysis. Oshen's engineers spent the months before the exercise working with Navy counterparts so that the company's command software would integrate with NATO's, and C-Star readings were fed into a central database shared among Alliance partners. LinkedInNaval News

Oshen's defense and oceanography lead, Gordon Jones, summarized the argument: a network of many hydrophone platforms is "wider, more resilient and harder for an adversary to characterise" than one built on a handful of towed arrays. Laverack framed the goal as taking a capability that depends on scarce assets and making it something that can be "deployed at scale, cheaply and continuously." Naval NewsDefence Blog

As of this writing, neither Oshen nor NATO has published detection, classification, or localization results from the REPMUS serials.

Why the GIUK Gap, Again

The picket line is aimed at a familiar piece of water. Since the Cold War, the Greenland–Iceland–UK Gap has been the chokepoint for tracking submarines moving into the open Atlantic, when the U.S. Navy's SOSUS seabed hydrophone network monitored the same waters. The geography is large. The gap comprises roughly 200 miles between Greenland and Iceland and 500 miles between Iceland and Scotland, and Russia has commissioned more than 30 submarines since the mid-2000s. Defence BlogForces News

The demand signal is rising while British supply is falling. The Royal Navy reports that its activations to monitor Russian activity rose 25 percent over the first seven months of 2026 compared with 2025. In April, Defence Secretary John Healey disclosed a month-long operation in which UK and allied forces tracked an Akula-class submarine and two GUGI deep-sea research submarines operating in the UK's exclusive economic zone. The Royal Navy rotates its five remaining Type 23 ASW frigates through Operation Ceto, the standing mission to detect submarines trying to shadow British SSBNs. Royal Navy steps up monitoring of increased Russian activity in UK waters +2

London's answer is Atlantic Bastion. The program is meant to connect ships, submarines, aircraft, and uncrewed vessels through AI-enabled acoustic detection feeding a digital targeting web, with capabilities due in the water in 2026. Type 26 frigates, with mission bays that can host uncrewed systems, are expected to be the centerpiece of the network. At UDT 2026, Captain James Lovell described the first of the program's pillars as expanding ASW sensing coverage with fixed systems, autonomous platforms, and existing assets, including the "introduction of massive sensors" to complement crewed platforms. The spring 2026 industry demonstrations covered seabed acoustic detection, USVs with acoustic and towed arrays, drones carrying sonobuoys, and gliders and acoustic floats. Planners anticipate an eventual government-owned, government-operated force of uncrewed platforms for persistent North Atlantic ASW. New Royal Navy undersea warfare technology unveiled to counter threat from Russia +4

NATO is building the connective layer in parallel. At REPMUS, ACT's Task Force X-Arctic connected nearly 300 capabilities to its digital backbone, and its mission-engineering layer tasked and re-tasked systems automatically and continuously. The effort supports Arctic Sentry, the enhanced vigilance activity led by Joint Force Command Norfolk and launched in February 2026, and aims for a fully digitized multi-domain situational awareness demonstration in the North Atlantic and High North by summer 2027. A picket line of cheap sensors becomes useful only when a C2 fabric like this can absorb its output. NATO ACTNATO ACT

The Platform: Endurance Is Proven

The C-Star's seakeeping record is strong for a vessel this small. The U.S. Navy's Naval Meteorology and Oceanography Command, which has tested the boats off Mississippi, puts their weight at about 100 pounds, and one person can launch one from the back of a boat. AutoNotion

Its most cited credential comes from NOAA. During Hurricane Humberto in September 2025, one C-Star measured a minimum pressure of 955 millibars and gusts above 150 mph in the Category 5 eyewall. Together with a rise in measured sunlight, the pressure drop confirmed it had passed through the eyewall to the edge of the eye. The National Hurricane Center referred to the C-Star data in an official forecast discussion. The NHC's final Tropical Cyclone Report states that C-Star surface observations helped construct Humberto's best track. Ocean robot first to collect data in Category 5 storm - NOAA/AOML +2

On 13 September 2026, C-Star PC13 finished the Microtransat Challenge east of Barbados after 127 days and 2,926 nautical miles from Gran Canaria, with no intervention from the Oshen team. The fully autonomous prize had gone unclaimed for 16 years despite more than 30 attempts, including by the U.S. Naval Academy. One caution for precision: a Norwegian vessel, SB Met, completed a Microtransat crossing in 2018, so PC13's distinction is the fully autonomous, no-intervention prize rather than the first crossing of any kind. The voyage was not flawless either: around the halfway point PC13 developed erratic steering, which Oshen attributes to rudder friction. Oshen autonomous vessel completes first unaided Atlantic crossing - Smart Maritime Network +2

On acoustics specifically, the public record is thinner. The company's own website reports that in Royal Navy-funded trials off Iceland, a C-Star hydrophone detected maritime assets up to 10 nautical miles away in storm conditions. Neither the target type nor the target's radiated noise level has been published. Oshendata

The Industrial Case

Oshen is trying to win on the production line. It took three years to build its first 15 C-Stars. The Plymouth factory now produces 15 every six weeks, another 100 are on order, and headcount has grown from seven in September 2025 to almost 30. A roughly $5 million round led by Lunar Ventures, with AlbionVC, Twin Track, and Concept Ventures, will fund manufacturing expansion and work in passive acoustics, subsea infrastructure protection, and ASW. Under a UK Defence and Security Accelerator project, the company is also testing a distributed passive acoustic network with ZeroUSV and MarineAI. In August, ZeroUSV launched two C-Stars from its 12-meter uncrewed Oceanus12, with software running the sequence. That demonstration points toward mothership-deployed pickets that do not need a crewed vessel for laydown. Oshen raises $5M to scale autonomous ocean robots for defence missions – Resilience Media +3

The company is small compared with its U.S. peers. Saildrone has raised more than $100 million, and Sofar Ocean nearly $70 million. Even sympathetic coverage notes it is unclear whether Oshen's hurricane data and production record will translate into naval purchasing decisions. Tech Funding NewsTech Funding News

Engineering Reality Check

The following assessment is the author's analysis, not company or Navy data.

Localization, not just detection. A single omnidirectional hydrophone has no array gain and no bearing. The claim that a constellation yields position rather than bearing depends on combining data across nodes, through time-difference-of-arrival, amplitude comparison, or cross-fixing of detections. That needs tight time synchronization (GNSS provides it, and GNSS is contested in the High North), accurate node positions on hulls that drift, and a good sound-speed profile. Node geometry determines localization error in the same way it does in multistatic radar. A thin line of sensors will produce poor fixes along its own axis.

The near-surface problem. A sensor near the surface is exposed to breaking waves, rain, wind, and hull and flow noise, all of which rise with sea state. That penalty is heaviest in the weather the GIUK Gap produces most of the year. More fundamentally, a hydrophone hanging near the surface may sit above the sonic layer while a submarine operates below it, in a shadow zone. This is the problem that pushed Cold War ASW toward deep seabed arrays and variable-depth towed bodies. The public record does not say how deep the SEA hydrophone deploys or whether a deeper, longer cable is planned.

Target strength. A 10-nautical-mile detection of unspecified maritime assets in a storm is encouraging if those assets were surface ships. It says little about a quiet SSN or a GUGI special-mission boat. Against those targets, a single-element sensor's effective range could be a small fraction of that figure, unless onboard processing can exploit narrowband tonals over long integration times.

Barrier arithmetic. Suppose, for illustration, a 2-nautical-mile reliable detection radius against a quiet submarine. The roughly 600 nautical miles of combined gap width then needs on the order of 150 nodes for a single contiguous line. Doubling for depth-in-barrier, and adding spares for attrition and rotation, pushes the total into the high hundreds. That is roughly consistent with Oshen's own suggestion that picket lines of 1,000 C-Stars could support the Royal Navy's new submarine-hunting frigates between Iceland, Greenland, and Britain. At 15 hulls every six weeks, current production would need several years to field such a force. Tripling output changes that calculation materially. Oshendata

Data links and C2. Satellite links from a four-foot hull carry little bandwidth, so edge detection and classification are required, not optional. False-alarm management across hundreds of nodes, much of it caused by fishing traffic and marine mammals, will decide whether operators trust the network. It will also decide whether an automated tasking layer like Task Force X-Arctic's can use the output without saturating watch floors.

Survivability versus exploitation. Low observability and expendability are real advantages. The company notes that an adversary cannot easily tell which vessels are active or what they carry. Unattended hulls can also be recovered by the other side, fouled by fishing gear, or spoofed. Hardware anti-tamper measures and GNSS-resilient timing deserve attention before any operational deployment.

None of these points defeats the concept. They define what the next round of trials must measure: probability of detection against realistic quiet targets across a range of sea states, localization error as a function of node geometry, false-alarm rates, and the time from cue to prosecution by a crewed asset.

From Tróia to San Diego

Oshen plans to bring eight C-Stars to the Maritime Big Play exercise in San Diego next month to test the same picket-line concept in a U.S. setting. Maritime Big Play is an AUKUS Pillar II program. Under it, Australia, the UK, and the United States rapidly test and integrate autonomous systems, with 2026 work focused on ASW, maritime strike, and seabed warfare. Its priorities include shared command-and-control software, a common autonomy baseline across the three nations, and a joint test and reference environment. Oshen already has a U.S. foothold: a Cooperative Research and Development Agreement with the U.S. Navy covering single-beam sonar applications. In a two-week trial with CNMOC off Cat Island, Mississippi, C-Stars fitted with single-beam echo sounders mapped the seabed to depths of about 80 meters. British robot sailboats test submarine picket line +4

For the U.S. Navy, the test matters beyond the GIUK Gap. The same model could apply to Pacific chokepoints and to the protection of undersea cables and pipelines, where persistent, low-cost coverage is scarce.

Implications

The acoustic picket line is best understood as a tripwire, not a replacement for ASW. It is a cheap, persistent, attritable layer meant to shrink the search area that scarce frigates, P-8s, and SSNs must cover. The UK is short of hulls and submarines at the moment Russian undersea activity is rising, so that layer has obvious appeal. The C-Star has proven it can survive at sea. What it now has to prove is acoustic: detection and localization of quiet submarines, from the surface, in bad weather, with false-alarm rates operators can live with. REPMUS 2026 and Maritime Big Play should produce the first data. Navies should require that data to be made available for independent evaluation before judging how much of the promised efficiency is real.

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Verified Sources

Naval News Staff. "World's First Acoustic Picket Line at REPMUS26." Naval News, September 2026. https://www.navalnews.com/naval-news/2026/09/worlds-first-acoustic-picket-line-at-repmus26

"British Robot Sailboats Test Submarine Picket Line." UK Defence Journal, September 2026. https://ukdefencejournal.org.uk/british-robot-sailboats-test-submarine-picket-line/

"UK Firm Tests Robot Sailboats to Track Hidden Submarines." Defence Blog, September 2026. https://defence-blog.com/uk-firm-tests-robot-sailboats-to-track-hidden-submarines/

"Oshen Tests Distributed Acoustic Surveillance Network." Smart Maritime Network, September 21, 2026. https://smartmaritimenetwork.com/2026/09/21/oshen-tests-distributed-acoustic-surveillance-network/

"UK Tests Anti-Sub Technology." Australian Naval Institute, September 2026. https://navalinstitute.com.au/uk-tests-anti-sub-technology/

Giordano, Paolo. "Task Force X-Arctic Takes Its Next Step at REPMUS 2026." NATO Allied Command Transformation, September 24, 2026. https://www.act.nato.int/article/tfx-arctic-repmus/

"NATO Exercises 2026: The Complete Guide to Allied Readiness." Grosswald, 2026. https://www.grosswald.org/nato-exercises-2026/

"A MUSt DO: REPMUS Is Primary Means for NATO to Develop Maritime Uncrewed Capability." Seapower, March 23, 2026. https://seapowermagazine.org/a-must-do-repmus-is-primary-means-for-nato-to-develop-maritime-uncrewed-capability/

Royal Navy. "AUKUS Nations to Build on Last Year's Successes as They Look Ahead to 2026." February 6, 2026. https://www.royalnavy.mod.uk/news/2026/february/06/20260206-aukus-nations-look-ahead-to-2026

"AUKUS Navies Step Up Autonomous Warfare Push in 2026." UK Defence Journal, February 9, 2026. https://ukdefencejournal.org.uk/aukus-navies-step-up-autonomous-warfare-push-in-2026/

Australian Department of Defence. "Defence Tests Cutting-Edge Autonomous Capabilities during AUKUS Maritime Big Play." February 19, 2026. https://www.defence.gov.au/news-events/releases/2026-02-19/defence-tests-cutting-edge-autonomous-capabilities-during-aukus-maritime-big-play

Royal Navy. "New Royal Navy Undersea Warfare Technology Unveiled to Counter Threat from Russia." December 8, 2025. https://www.royalnavy.mod.uk/news/2025/december/08/20241208-atlantic-bastion

Royal Navy. "Royal Navy Works with Businesses on Enhancing Anti-Submarine Warfare Using Autonomous Tech." April 22, 2026. https://www.royalnavy.mod.uk/news/2026/april/22/20260422-underwater-battlespace-demos

"More Detail Emerges on Royal Navy Atlantic Bastion." UK Defence Journal, April 17, 2026. https://ukdefencejournal.org.uk/more-detail-emerges-on-royal-navy-atlantic-bastion/

"Underwater Surveillance Tech to the Fore as Royal Navy Forges Ahead with Atlantic Bastion." Navy Leaders, April 30, 2026. https://navyleaders.com/news/underwater-surveillance-tech-to-the-fore-as-royal-navy-forges-ahead-with-atlantic-bastion/

"Atlantic Bastion: How the UK Is Addressing the Undersea Threat." DSEI Gateway, April 2, 2026. https://dsei-gateway.com/en/insights/explainers/atlantic-bastion-how-the-uk-is-addressing-the-undersea-threat/

Royal Navy. "Royal Navy Steps Up Monitoring of Increased Russian Activity in UK Waters." August 8, 2026. https://www.royalnavy.mod.uk/news/2026/august/08/20260807-uk-armed-forces-step-up-monitoring-of-increased-russian-activity-in-uk-waters

"Royal Navy Reports 25 Percent Increase in Russian Activity in U.K., North Atlantic Waters." USNI News, August 11, 2026. https://news.usni.org/2026/08/11/royal-navy-reports-25-percent-increase-in-russian-activity-in-u-k-north-atlantic-waters

Cranny-Evans, Sam. "UK Operation to Counter Russian Submarine Activity." Calibre Defence, April 9, 2026. https://www.calibredefence.co.uk/uk-details-operation-to-counter-russian-submarine-activity-in-north-atlantic/

"Bolster Our Capability or Risk Seeing Russia Dominate GIUK Gap, Warns Former Submariner." Forces News, March 10, 2026. https://www.forcesnews.com/services/navy/bolster-our-capability-or-risk-seeing-russia-dominate-giuk-gap-warns-former

NOAA Atlantic Oceanographic and Meteorological Laboratory. "Ocean Robot First to Collect Data in Category 5 Storm." September 30, 2025. https://www.aoml.noaa.gov/mini-ocean-robot-collects-data-in-category-5-hurricane/

National Hurricane Center. Tropical Cyclone Report: Hurricane Humberto (AL082025). NOAA. https://www.nhc.noaa.gov/data/tcr/AL082025_Humberto.pdf

"Oshen Autonomous Vessel Completes First Unaided Atlantic Crossing." Smart Maritime Network, September 16, 2026. https://smartmaritimenetwork.com/2026/09/16/oshen-autonomous-vessel-completes-first-unaided-atlantic-crossing/

"Tiny Autonomous Boat Completes Historic Atlantic Crossing." Interesting Engineering, September 2026. https://interestingengineering.com/transportation/tiny-autonomous-boat-crosses-atlantic-microtransat

"The Microtransat Challenge." Wikipedia. https://en.wikipedia.org/wiki/The_Microtransat_Challenge

"Oshen Raises $5M to Scale Autonomous Ocean Robots for Defence Missions." Resilience Media, August 24, 2026. https://resiliencemedia.co/oshen-raises-5m-to-scale-autonomous-ocean-robots-for-defence-missions/

"Imperial College Grads' Oshen Raises $5M to Mass-Produce Hurricane-Tested Ocean Robots." Tech Funding News, August 21, 2026. https://techfundingnews.com/oshen-raises-5m-hurricane-tested-ocean-robots/

"Oshen's Sail-Powered Robots Prove Seabed-Mapping Capability in U.S. Navy Trial." Ocean News & Technology, August 5, 2026. https://oceannews.com/news/science-technology/oshen-c-star-robots-prove-seabed-mapping-capability-in-us-navy-trial

"Uncrewed Boat Launches Uncrewed Boats." Autonocion, August 2026. https://www.autonocion.com/us/uncrewed-boat-launches-uncrewed-boats/

Oshen Ltd. "Persistent, Wide-Area Ocean Intelligence" (corporate website). Accessed September 25, 2026. https://www.oshendata.com/

A few notes on sourcing. The Iceland 10-nautical-mile detection and the 1,000-hull picket figure come from Oshen's own website (which attributes them to Janes and The Telegraph), and I could not independently retrieve those originals. Reported REPMUS participation figures conflict across outlets, so I used NATO ACT's. The Engineering Reality Check section is analysis, not reported fact.

 

Light's Topology Shrugs Off Turbulence

Scientists Transmit Data via Magnetic Skyrmions in Laser Beams with 98% Fidelity Over Hundreds of Meters

A laser beam scrambled beyond recognition still carried its data intact across a 270-meter open-air link. The trick was to encode information not in the beam's shape, but in a topological invariant no amount of atmospheric churn can erase.

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BLUF (Bottom Line Up Front): A team from the University of the Witwatersrand (Wits) in Johannesburg and the University of Bordeaux has sent optical skyrmions—particle-like topological textures woven into a laser beam's polarization field—across a 270-meter free-space link on the Wits campus and recovered the encoded topological number with roughly 98 percent fidelity under most conditions, degrading to about 86 percent only in the harshest midday turbulence. Crucially, the recovery used no adaptive optics and no turbulence pre-measurement: a single-shot polarization-camera measurement reads the invariant directly. The result, reported in Science Advances, is a clean experimental confirmation that topological encoding survives real-world atmospheric distortion. Two cautions temper the excitement. First, this is a robustness proof-of-principle—it demonstrates that an encoded topological number survives the channel, not a high-throughput data link; the gigabit-to-terabit rates circulating in some secondary coverage are not part of the experiment. Second, and contrary to several popular write-ups, these are optical skyrmions (topological structures in light's electromagnetic field), not the magnetic skyrmions found in thin-film spintronics. The physics is real; the "magnetic laser beam" framing is not.

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The problem: turbulence eats structured light

Free-space optical (FSO) communication—laser links through open air rather than glass fiber—has an enduring appeal for last-mile connectivity, campus and rooftop hops, drone-to-ground links, and satellite-to-ground terminals. It offers fiber-class bandwidth with no trenching and no spectrum licensing. Its enemy is the atmosphere. Temperature gradients and turbulent eddies scramble the refractive index on millisecond timescales, distorting a beam's amplitude, phase, and polarization.

For engineers who came up through radar and coherent RF, the failure mode is familiar in a new guise. Conventional structured-light schemes buy extra channel capacity by multiplexing spatial modes—orbital angular momentum (OAM) states, for instance—but turbulence induces mode crosstalk that mixes those channels together, exactly as multipath and scintillation corrupt a spatial waveform. The usual countermeasure is adaptive optics: sense the wavefront error with a wavefront sensor, then correct it with a deformable mirror in a fast feedback loop. It works, but it adds cost, latency, and mechanical complexity, and it must keep up with the turbulence in real time.

The Wits–Bordeaux approach sidesteps that loop entirely. Instead of correcting the distortion, it encodes information in a quantity that the distortion cannot change.

What an optical skyrmion actually is

A skyrmion, borrowed originally from nuclear and condensed-matter physics, is a field configuration whose winding—how many times a field vector wraps around a sphere as you traverse the plane—is a topological invariant. That integer wrapping number can't change under smooth deformation; altering it requires a discontinuity, which is energetically forbidden for small perturbations.

An optical skyrmion realizes this in the electromagnetic field of a structured light beam rather than in the magnetization of a material. The Wits team builds one as a vector beam: a coherent superposition of spatial modes (Laguerre–Gaussian, carrying OAM) placed in orthogonal polarization states, so that the beam's polarization vector traces out a full skyrmionic texture across its cross-section. The encoded value is the skyrmion, or wrapping, number—an integer. Andrew Forbes, the Wits group leader and corresponding author, has offered the standard topologist's analogy: a coffee mug and a doughnut are "the same" because each has exactly one hole, and you can knead either shape without changing that count. Turbulence kneads the beam; the hole count survives.

That is the conceptual departure from OAM multiplexing. OAM encodes data in a mode index that turbulence smears through crosstalk. Skyrmion encoding places the data in a global topological property of the whole vector field, which is invariant to the local, continuous distortions turbulence imposes—provided the channel is (approximately) unitary, i.e., it reshuffles the field without destroying its coherence.

The experiment

The team generated skyrmion-bearing vector beams with standard structured-light optics—spatial light modulators and an interferometric combiner to co-align orthogonally polarized spatial modes—and launched them across a 270-meter horizontal path between two buildings on the Wits campus in central Johannesburg. The link was deliberately run across a full daily cycle, from calm, cool morning air to the violent seeing of midday heat, sampling a wide range of turbulence strengths in the wild rather than in a lab-simulated phase screen.

Recovery is where the engineering is cleanest. At the receiver, the beam—by then visibly mangled—passes through a 50:50 beam splitter and a quarter-wave plate onto a polarization-sensitive ("division-of-focal-plane") camera, which captures all the projections needed to reconstruct the four Stokes parameters across the beam in a single shot. From that spatially resolved Stokes map, the wrapping number is computed directly. There is no wavefront sensor, no deformable mirror, no iterative optimization, and—contrary to the uploaded secondary account—no machine-learning classifier trained on distorted skyrmions. The topology is simply measured.

The headline numbers: the wrapping number was recovered correctly with about 98 percent fidelity across most of the day's conditions, falling to roughly 86 percent only under the most extreme turbulence. The authors also probed the regime beyond the atmospheric coherence time τ₀—the interval over which the channel looks momentarily "frozen" to the beam—and showed that while the beam's degree of polarization decays as the medium fluctuates (a decoherence-like effect), the topological number remains stable. As a visual proof of concept, they encoded a small multi-value message by mapping symbols to distinct wrapping numbers and read it back across the link.

What it is—and isn't

For a working communications engineer, the honest framing matters. This experiment establishes channel robustness of a topological alphabet, not a demonstrated high-bit-rate link. The recovered quantity is a small integer per beam; the achievable throughput depends on how many distinguishable skyrmion states you can pack, how fast you can generate and measure them, and how they multiplex—none of which this paper set out to maximize. Claims of "several gigabits per second" scaling to "terabit" capacity, seen in some coverage, are extrapolation, not result.

What the work does deliver is a compelling systems argument: a passive, compute-light receiver that skips the adaptive-optics feedback loop entirely. In link-budget and latency terms, removing the deformable-mirror control loop is attractive for compact, pole-mounted, or airborne terminals where size, weight, and power are at a premium. It is also a natural fit for links to and from space, where the turbulence is concentrated in the ground-side boundary layer and a correction-free decoder is appealing.

The obvious limitations are the ones physics imposes. Topological protection assumes a roughly unitary, coherence-preserving channel. Fog, heavy rain, and snow scatter and absorb the light—non-unitary loss that no winding number can survive—so this is a clear-air technique. Generation still relies on bulky bench optics today, though integrated photonic skyrmion sources (metasurface fibers and on-chip generators) are advancing quickly. And the alphabet size and symbol rate that make this competitive with mature intensity/phase modulation remain to be demonstrated.

Where it sits in the field

This is not an isolated flash. The same Wits group had already shown, in 2023, that vectorial structured light retains recoverable structure across a real outdoor link, and in early 2026 a companion effort with Yijie Shen's group at Nanyang Technological University demonstrated topological resilience of both classical and quantum optical skyrmions through lab-controlled turbulence—finding that even as entanglement degrades, the topological character of quantum skyrmion states persists. Related lines of work include quantum "nonlocal" skyrmions as noise-resilient entangled states, topological protection of skyrmions through scattering media, the stability of optical knots in turbulence, and a decade of turbulence-resilient vector-beam communication going back to compensation-free SPDPSK links. The foundational demonstration of optical skyrmion lattices in evanescent fields dates only to 2018, which makes the jump to an outdoor communications link in under a decade a notably fast translation from exotic physics to field experiment.

On the intellectual-property and legal front: a targeted search of patent databases and dockets turned up an active FSO patent landscape—turbulence-mitigation methods, patterned-light demultiplexing with convolutional neural networks, non-mechanical beam steering for satellite links, and ultra-wideband FSO apparatus among them—but no litigation or court filings specific to optical-skyrmion communication, which remains squarely in the pre-commercial research phase. The primary "official release" is the Wits University news announcement accompanying the Science Advances publication; there is no standards activity yet defining interoperable skyrmion formats.

The takeaway

The elegant part is philosophical as much as technical: rather than fighting the channel, encode in a quantity the channel can't touch. That the invariant survived a Johannesburg summer afternoon, measured by a single camera frame with no correction loop, is a genuine milestone for turbulence-resilient FSO. Whether it becomes a deployed modulation format will hinge on the unglamorous engineering the paper leaves open—alphabet size, symbol rate, multiplexing, integrated sources, and honest link budgets against clear-air scatter. The physics has cleared its bar. The systems case is the next experiment.

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Verified sources

Primary research

1. C. Peters, V. Hakobyan, A. Drozdov, E. Brasselet, M. Cox, and A. Forbes, "Topological robustness of optical skyrmions through a real-world free-space link," Science Advances (2026). DOI: 10.1126/sciadv.aee2671 — https://doi.org/10.1126/sciadv.aee2671
2. Preprint of the above: arXiv:2602.04446 — https://arxiv.org/abs/2602.04446
3. Z. Guo, C. Peters, N. Mata-Cervera, A. N. Vetlugin, R. Guo, et al., "Topological robustness of classical and quantum optical skyrmions in atmospheric turbulence," Nature Communications (2026). DOI: 10.1038/s41467-026-68751-3 — https://doi.org/10.1038/s41467-026-68751-3

Official release

4. University of the Witwatersrand, "Wits researchers use light's topology to beat atmospheric distortion," Wits News, August 2026 — https://www.wits.ac.za/news/latest-news/research-news/2026/--2026-08/wits-researchers-use-lights-topology-to-beat-atmospheric-distortion.html

Key related literature

5. C. Peters, M. Cox, A. Drozdov, and A. Forbes, "The invariance and distortion of vectorial light across a real-world free-space link," Applied Physics Letters 123(2) (2023). DOI: 10.1063/5.0155203 — https://doi.org/10.1063/5.0155203
6. Y. Shen, et al., "Optical skyrmions and other topological quasiparticles of light," Nature Photonics 18, 15–25 (2024). DOI: 10.1038/s41566-023-01325-7 — https://doi.org/10.1038/s41566-023-01325-7
7. S. Tsesses, et al., "Optical skyrmion lattice in evanescent electromagnetic fields," Science 361, 993–996 (2018). DOI: 10.1126/science.aau0227 — https://doi.org/10.1126/science.aau0227
8. I. Nape, et al., "Revealing the invariance of vectorial structured light in complex media," Nature Photonics 16, 538–546 (2022). DOI: 10.1038/s41566-022-01023-w — https://doi.org/10.1038/s41566-022-01023-w
9. P. Ornelas, I. Nape, R. de Mello Koch, and A. Forbes, "Nonlocal skyrmions as topologically resilient quantum entangled states of light," Nature Photonics 18, 258–266 (2024). https://doi.org/10.1038/s41566-023-01360-4
10. P. Ornelas, I. Nape, R. de Mello Koch, and A. Forbes, "Topological rejection of noise by quantum skyrmions," Nature Communications 16, 2934 (2025). https://doi.org/10.1038/s41467-025-58208-4
11. A. A. Wang, et al., "Topological protection of optical skyrmions through complex media," Light: Science & Applications 13, 314 (2024). https://doi.org/10.1038/s41377-024-01679-9
12. L. Wang, et al., "The robustness of skyrmion numbers of structured optical fields in atmospheric turbulence," Optics Communications 579, 131568 (2025). arXiv:2410.05999 — https://arxiv.org/abs/2410.05999
13. G. Xie, et al. (Willner group), "Compensation-free high-dimensional free-space optical communication using turbulence-resilient vector beams," Nature Communications 12, 1666 (2021). https://doi.org/10.1038/s41467-021-21793-1
14. D. Pires, et al. (Litchinitser group), "Stability of optical knots in atmospheric turbulence," Nature Communications 16, 3001 (2025). https://doi.org/10.1038/s41467-025-58245-z
15. Optical skyrmion generation via integrated metafiber, Nature Communications (2024). DOI: 10.1038/s41467-024-54207-z — https://doi.org/10.1038/s41467-024-54207-z

Selected press coverage

16. Tech Xplore / Phys.org, "Information encoded in a beam of light can survive real-world atmospheric turbulence," August 2026 — https://techxplore.com/news/2026-08-encoded-survive-real-world-atmospheric.html
17. Interesting Engineering, "World-first test sends information through light beams without loss," August 2026 — https://interestingengineering.com/innovation/world-first-experiment-light-signals-chaotic-air
18. Photonics Online, "Wits researchers use light's topology to beat atmospheric distortion," August 2026 — https://www.photonicsonline.com/doc/wits-researchers-use-light-s-topology-beat-atmospheric-distortion-0001

Patent-landscape context (no skyrmion-specific litigation found)

19. T. Doster, et al., "Method for free space optical communication utilizing patterned light and convolutional neural networks," U.S. Patent 10,187,171 — https://patents.google.com/patent/US10187171
20. "System and method for transmitting signals in a free space optics communication system" (turbulence/interception mitigation), U.S. Prov. App. 63/813,253, filed May 2025 — https://patents.google.com/patent/US12457038

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Editor's note on the source article: the uploaded WebProNews/TechRadar write-up describes this work as encoding data in "magnetic skyrmions" generated by "magnetic thin-film emitters" and decoded by a machine-learning algorithm over 300 meters. Those specifics are incorrect. The experiment uses optical (electromagnetic-field) skyrmions in a vector laser beam, generated with spatial light modulators and an interferometer, decoded by direct single-shot Stokes polarimetry, over a 270-meter link. The ~98% / ~86% fidelity figures are approximately right; the gigabit/terabit data-rate and multiplexing claims are extrapolations not demonstrated in the paper.

 

The Instrumented Sea: When Land-Based Patrol Can't Reach the Fight

The Amphibious ASW Screen:

A feature in the style of U.S. Naval Institute Proceedings — reframed third installment in a series on the edge-AI acoustics convergence, August 2026

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Bottom Line Up Front

The Navy's post-2009 answer to organic anti-submarine warfare (ASW) — retire the carrier's S-3 Viking and let land-based maritime patrol aircraft cover the open ocean — collapses in the one theater that matters most. In a Western Pacific fight, the land-based patrol force (the P-8A Poseidon, successor to the P-3C Orion) cannot be relied upon to screen the carrier and amphibious groups, because the fixed airfields it flies from — Kadena, Andersen, and their like — sit inside China's anti-access/area-denial (A2/AD) missile envelope, and its large, non-stealthy aircraft cannot loiter forward in contested airspace. The strike group's own organic ASW, meanwhile, has been reduced to a single short-legged helicopter. The author contends that the answer is to make the sea base itself hunt: turn the big-deck amphibious ship — the America-class LHA and Wasp-class LHD — into a mobile ASW aviation base, flying persistent unmanned aircraft that lay and tend edge-AI sonobuoy fields and relay finished tracks to the force. Unlike a runway, a big deck moves, disperses, and hides in the clutter-free-but-vast ocean; unlike the crewed P-8, an attritable unmanned aircraft can be risked forward. The enabling technologies — the MQ-9B STOL that flies from a flat deck without catapult or arresting gear, and the milliwatt acoustic inference that makes a smart, expendable buoy affordable — already exist or have been demonstrated. What is missing is the decision to resource the amphibious force as an ASW sea base, the processing to host the screen, and the sonobuoy magazine to sustain it.

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The answer that doesn't survive contact with the theater

When the Navy retired the S-3B Viking, it did not so much replace the carrier air wing's ASW capability as redistribute it and bet on geography. Area ASW moved ashore to the P-3C and then the P-8A; close-in defense stayed with the embarked helicopter. The unstated assumption was that land-based maritime patrol, flying from established Pacific and allied airfields, would always be able to reach out and screen the fleet's operating areas. For three decades of uncontested access, that assumption held.

It does not hold against China. The People's Liberation Army built its A2/AD architecture precisely to keep U.S. airpower at arm's length in a fight over Taiwan or the South China Sea, and Chinese strategists identified the weak point plainly: America's forward air bases, and especially their runways, are vulnerable to missile attack. The open-source assessments are unsparing. Kadena Air Base in Okinawa is judged remarkably vulnerable to missile strike for want of hardening and active defense, and other regional bases are similarly unprepared to survive, defend against, or recover from such attacks. Guam — long treated as a sanctuary at roughly 3,000 kilometers from the Chinese coast — is moving inside the threat ring as the PLA fields longer-range cruise missiles on its bombers and deploys intermediate-range and anti-ship ballistic missiles such as the DF-26. A base that can be cratered, or whose fuel and maintenance can be disrupted, cannot generate the persistent maritime-patrol sorties the fleet's ASW plan silently depends on.

The aircraft itself compounds the problem. The P-8A is a superb sensor and weapons platform, but it is a large, non-stealthy militarized airliner that needs runways, tanking, and overflight permission, and the fleet is small and heavily tasked. Land-based patrol coverage exists where bases and clearances allow it — which, in the contested first and second island chains, may be exactly where and when it does not. There is a deeper asymmetry worth naming: reconnaissance and targeting work best against simple backgrounds, and the open sky and sea surface are far simpler backgrounds than cluttered land. That asymmetry favors the side hiding mobile missile launchers ashore against airborne and surface targets at sea — but it also rewards the side that keeps its own critical nodes moving rather than parked on a fixed, surveyed runway. A sea base exploits mobility; an airfield cannot.

The gap the fleet already carries

Layered on top of the A2/AD problem is the organic-ASW hole the carrier air wing has carried since 2009. With the Viking gone and no replacement fielded, the embarked helicopter — today the MH-60R — is the sole organic airborne ASW asset of the carrier and expeditionary strike groups, and it was never built for area search: it lacks the range, speed, and endurance to work the outer zone 150 to 200 nautical miles from the formation where a submarine launches its anti-ship missiles. The carrier can defend a small bubble organically and must otherwise borrow coverage from shore. In an uncontested sea that is an inconvenience. In a contested one, where the shore-based provider may itself be under attack or out of range, it is a war-losing dependency.

Put the two problems together and the conclusion writes itself: the fleet needs organic, sea-based, mobile ASW that does not depend on a runway anyone can hold at risk.

The big deck as the new ASW base

The platform to host it is already in the fleet, and it is not the aircraft carrier. It is the big-deck amphibious ship. GA-ASI designed the MQ-9B STOL — a short-takeoff-and-landing variant of the SeaGuardian, built with a Mojave-derived folding wing and enlarged tail — specifically to operate from America-class LHAs and Wasp-class LHDs without a catapult or a ski jump, launching over the bow and recovering on the same 250-odd-meter flat decks those ships already possess. It trades some range for that flexibility but retains roughly thirty hours of endurance, and — the essential point — it carries and dispenses the same sonobuoys as the land-based SeaGuardian. GA-ASI's own framing is that the STOL kit enables organic ASW and fleet defense without returning to a land-based airfield to refuel and rearm. That is the whole argument in one sentence.

This is not pure PowerPoint. A Mojave STOL demonstrator flew to and from the British carrier HMS Prince of Wales in November 2023 — the first remotely piloted aircraft of its size to operate from a carrier outside the United States — and repeated the feat from the Republic of Korea Navy's ROKS Dokdo in November 2024. And the amphibious force has already been reconceived as a flexible aviation base through the Marine Corps' "Lightning carrier" experiments, loading an America-class ship with F-35Bs to act as a distributed strike platform. Adding a persistent unmanned ASW screen to that repertoire extends a logic the Navy and Marine Corps are already exercising: the L-class ship as a distributable, multi-mission sea base rather than a single-purpose amphibious transport.

The operational picture that results is the distributed heir to the Viking's outer screen — but launched from a moving deck instead of a fixed runway. An amphibious ship, or several dispersed across the operating area, keeps one or more MQ-9B STOLs continuously aloft, seeding a volume of ocean with a multistatic sonobuoy field, monitoring it, and relaying finished contact tracks over datalink to the escorts, the helicopters, and any P-8 that can reach the fight. The sea base provides the persistence and the magazine; the escorts and helicopters prosecute; the whole screen moves with the force.

Why the intelligence has to live forward

This is where the reframed concept meets the thread that runs through the whole series. The sonobuoy field is only as survivable as the radio-frequency links that tie it together, and in a contested electromagnetic environment those links are the seam an adversary attacks first. Today the acoustic processing sits on the aircraft, and the buoy-to-air path carries conditioned acoustics; the aircraft-to-ship path carries the picture back to the sea base. Both are emitters, and the unmanned relay is a single, jammable node.

The commercial edge-AI revolution — the milliwatt, always-on neural inference that turned a consumer earbud into a regulated hearing aid — is what lets the Navy push classification forward, into the buoy and the pod, so the contested links carry a track or a classified contact rather than a firehose of raw hydrophone data. That collapses the required bandwidth, shrinks the field's emitting signature, and makes the whole screen more survivable and more scalable from a single sea base with finite datalink capacity. Multistatic geometry compounds the gain: an active source in a field of passive receivers covers more ocean with fewer buoys, and "fewer buoys, each smarter" is exactly what a magazine-limited amphibious ship needs. The affordable, partly autonomous, throwaway buoy exists only because consumer-driven "AI-per-watt" silicon drove the cost and power of onboard inference down to where an expendable can carry it.

The honest constraints

A reframing this ambitious owes the reader its qualifications, and there are several.

First, the flat-deck capability is demonstrated, not yet operational. The Prince of Wales and Dokdo events used a Mojave demonstrator, and the deck-length margins on U.S. amphibious ships are real; fielding a fully-loaded MQ-9B STOL with buoys and fuel from an LHA or LHD in Sea State and crosswind is an integration program, not a fait accompli.

Second, the amphibious ship is itself a high-value unit inside the same A2/AD envelope — threatened by the same anti-ship ballistic and cruise missiles — and it carries a primary amphibious mission and an embarked Marine air combat element. Deck spots, hangar volume, ordnance handling, and sortie generation are finite, and an ASW screen competes with all of it. There is a certain irony in a ship that needs its own ASW protection also serving as the ASW base; the answer is dispersion and teaming, not treating any single deck as indispensable.

Third, the L-class ships were not built to be aviation command nodes. The recurring Lightning-carrier critique — that the embarked aircraft are more capable than the ship's command, control, and data systems — applies double to a networked, machine-generated ASW picture. Hosting an edge-AI buoy field may require the processing and datalink fit that the more sophisticated LPD-class command systems, or a dedicated afloat processing suite, would supply.

Fourth, the magazine remains the binding constraint carried over from the wider concept: U.S. sonobuoy production has narrowed to a single domestic source, and a screen that consumes expendables across a wide area at wartime rates cannot rest on a sole-source base.

The clock, and four recommendations

The urgency is the peer competitor's undersea buildup in the very waters where U.S. land-based patrol is least able to help. The instrumented sea, launched from a mobile amphibious deck, is one of the few affordable ways to buy back organic outer-zone ASW for a force that can no longer count on the shore. To make it real:

Resource the big-deck amphib as an ASW sea base. Fund MQ-9B STOL integration on the LHA and LHD, and treat organic, sea-based ASW as a designed mission of the amphibious force — not a bolt-on to be improvised in crisis.

Give the sea base the brains. Push edge-AI classification forward into the buoy and aircraft so the contested links carry tracks, and fit the ship (or an afloat processing node) with the command-and-control to fuse a multistatic field. The picture must compose aboard a moving deck, under jamming, without a shore reachback.

Fix the magazine before scaling the screen. Fund surge capacity and a second sonobuoy source and drive down expendable cost. Mobility and autonomy are wasted if the buoy runs out.

Protect and disperse the base. Plan the amphibious ASW screen as a distributed set of decks, deconflicted with the amphibious and Marine-aviation mission, each protected and none indispensable — because the sea base is a target too.

The Navy spent the last thirty years assuming the land bases would always be there to hunt for the fleet. In the Western Pacific that assumption is gone. The hearing aid proved the silicon; the unmanned submarine proved the endurance; and the amphibious ship — mobile, distributable, and already in the fleet — is where the two can restore to the sea base the organic submarine-hunting capability it surrendered in 2009. It is a screen, not a silver bullet, and it will be only as good as the decks that fly it and the buoys that feed it. But it does not need a runway the enemy can crater — and in this theater, that is the whole point.

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Sources

The carrier ASW gap and the land-based dependency

1. National Security Journal. "The S-3 Viking Was Built To Kill Russian Submarines From Aircraft Carriers — And It Was Retired Just Before the U.S. Navy Needed It Again." 17 May 2026. https://nationalsecurityjournal.org/the-s-3-viking-was-built-to-kill-russian-submarines-from-aircraft-carriers-and-it-was-retired-just-before-the-u-s-navy-needed-it-again/

2. Center for International Maritime Security (CIMSEC). "Close the Gaps! Airborne ASW Yesterday and Tomorrow." 2 Jun 2021. https://cimsec.org/close-the-gaps-airborne-asw-yesterday-and-tomorrow/

3. The War Zone. "Reviving The Use Of Navy Tactical Jets As Submarine-Hunters." 23 Feb 2023. https://www.twz.com/reviving-the-use-of-navy-tactical-jets-as-submarine-hunters

Chinese A2/AD and the vulnerability of land bases

4. Stimson Center. "Cratering Effects: Chinese Missile Threats to US Air Bases in the Indo-Pacific." Dec 2024. https://www.stimson.org/2024/cratering-effects-chinese-missile-threats-to-us-air-bases-in-the-indo-pacific/

5. Mastro, O. S., & Easton, I. "Risk and Resiliency: China's Emerging Air Base Strike Threat." Project 2049 Institute. https://indopacificsecurity.org/wp-content/uploads/P2049_Mastro_Easton_China_Emerging_Airbase_Strike_Threat_110817.pdf

6. RAND Corporation. "Chinese Attacks on Air Bases in Asia" (research brief). https://www.rand.org/content/dam/rand/pubs/research_briefs/RB9800/RB9858z2/RAND_RB9858z2.pdf

7. Montgomery, E. B. "Future Warfare in the Western Pacific: Chinese Antiaccess/Area Denial…" International Security 41(1), 2016. https://direct.mit.edu/isec/article/41/1/7/12133/

8. Missile Defense Advocacy Alliance. "China's Anti-Access Area Denial." https://www.missiledefenseadvocacy.org/missile-threat-and-proliferation/todays-missile-threat/china/china-anti-access-area-denial/

The amphibious ship as ASW aviation base (MQ-9B STOL)

9. GA-ASI. "MQ-9B STOL" (organic ASW and fleet defense from big-deck amphibious vessels). https://www.ga-asi.com/remotely-piloted-aircraft/mq-9b-stol

10. Naval News. "General Atomics unveils MQ-9B STOL for small Flat Tops" (America-class LHA / Wasp-class LHD; ~30-hr endurance; sonobuoy dispensing). 10 May 2022. https://www.navalnews.com/event-news/indo-pacific-2022/2022/05/general-atomics-unveils-mq-9b-stol-for-small-flat-tops/

11. GA-ASI. "GA-ASI Demonstrates Short Takeoff/Landing of UAS on UK Carrier" (Mojave aboard HMS Prince of Wales, Nov 2023). 17 Nov 2023. https://www.ga.com/ga-asi-demonstrates-short-takeoff-landing-of-uas-on-uk-carrier

12. Naval News (via forum archive). "ROK Navy tests Mojave drone aboard ROKS Dokdo." 13 Nov 2024. https://www.navalnews.com/naval-news/2024/11/rok-navy-tests-mojave-drone-aboard-roks-dokdo/

13. The War Zone. "New Kit Will Allow MQ-9 Reaper To Fly From Navy Flattops." 11 May 2022. https://www.twz.com/new-kit-will-allow-mq-9-reaper-to-fly-from-navy-flattops

14. USNI News. "Marines Test 'Lightning Carrier' Concept, Control 13 F-35Bs from Multiple Amphibs." 23 Oct 2019. https://news.usni.org/2019/10/23/marines-test-lightning-carrier-concept-control-13-f-35bs-from-multiple-amphibs

Sonobuoy screen mechanics, multistatic buoys, and industrial base (see companion piece)

15. Army Recognition. "U.S. Navy Expands MQ-9B SeaGuardian Sonobuoy Payload…" 20 Jan 2026. https://www.armyrecognition.com/news/aerospace-news/2026/u-s-navy-expands-mq-9b-seaguardian-sonobuoy-payload-to-extend-unmanned-anti-submarine-warfare

16. The Aviationist. "MQ-9B SeaGuardian Becomes First UAV to Drop MAC Sonobuoys." 15 Jan 2026. https://theaviationist.com/2026/01/15/mq-9b-seaguardian-mac-sonobuoys/

17. The Defense News. "U.S. Navy Awards Ultra Maritime LRIP Contract for Next-Gen AN/SSQ-125B Sonobuoys." 7 Apr 2026. https://www.thedefensenews.com/news-details/US-Navy-Awards-Ultra-Maritime-LRIP-Contract-for-Next-Gen-ANSSQ-125B-Sonobuoys/

Edge-AI silicon baseline (documented fully in the companion articles)

18. Edge AI and Vision Alliance. "AI at the Edge: Low Power, High Stakes." 20 Nov 2025. https://www.edge-ai-vision.com/2025/11/ai-at-the-edge-low-power-high-stakes/

Editorial notes: (1) MQ-9B STOL flat-deck operation has been shown with Mojave demonstrators aboard HMS Prince of Wales and ROKS Dokdo; operational integration aboard U.S. America- and Wasp-class ships, with a full ASW load, remains a development effort, and deck-margin and environmental limits are real. (2) SeaGuardian sonobuoy capacity and onboard-processing figures are GA-ASI's stated specifications, not independently verified fleet performance. (3) "Court filings" are not implicated; the governing official record is Navy/NAVAIR release, procurement contracting, and think-tank and CRS analysis, cited above. (4) This is the reframed third installment of a series; the edge-AI silicon and undersea-autonomy arguments are documented more fully in the two companion pieces.