Since World War II, the far northern approaches to North America have been central to national defense—strategically vital, yet persistently difficult to monitor. Vast distances, sparse infrastructure, and a violently unstable radio environment have long limited the effectiveness of traditional radar systems across the Arctic.
Now, as melting sea ice opens new shipping lanes and global competition increasingly shifts toward the Arctic, the Defense Advanced Research Projects Agency (DARPA) believes it is time to take a fundamentally different approach to protecting the far north.
Recently, DARPA unveiled “FROSTY,” a new program aimed at rethinking how radar sensing operates in one of the most hostile electromagnetic environments on Earth.
Rather than fighting the Arctic’s turbulent ionosphere, FROSTY aims to exploit it, using noise-like radio signals and advanced signal processing to detect low-flying aircraft and slow-moving maritime vessels far beyond the reach of conventional systems.
According to program solicitation documents reviewed by The Debrief, DARPA frames FROSTY as a response to both environmental reality and strategic necessity.
“The Frosty program will develop sensing modes to improve our awareness of activities in the northern latitudes as the Arctic opens to shipping and other uses,” the agency’s documents read. “Particularly, the United States and allies would benefit from new ways to detect, track, and identify low-flying air vehicles or maritime vessels in Arctic regions.”
Why the Arctic Is Becoming a Defense Priority
The Arctic is no longer a frozen buffer zone. Climate-driven ice retreat has opened the region to growing commercial traffic, resource exploration, and military activity.
The region’s importance has been underscored lately by controversial efforts from President Donald Trump to acquire Greenland as a U.S. territory. While the rationale has been the subject of debate, the President has said the idea is intended to address the High North’s growing strategic significance.
At the same time, Russia has expanded its Arctic basing and radar infrastructure, and China has declared itself a “near-Arctic state.” These developments have prompted the United States and its NATO allies to reassess the security of their northern defenses.
Overshadowed by the geopolitical drama are the formidable technical challenges of defending the frigid far north.
The Arctic remains uniquely difficult to monitor. Ground-based microwave radars, such as those that underpin the current North Warning System, are limited by the curvature of the Earth. The joint U.S.-Canadian early-warning radar network is effective against high-altitude aircraft. However, these same systems struggle to detect low-flying platforms that remain below the radar horizon.
Space-based sensors and traditional over-the-horizon radars offer potential alternatives. However, both suffer significant performance degradation at high latitudes, where the ionosphere is in constant flux due to solar activity.
DARPA explicitly acknowledges these limitations in its FROSTY program documents. “Because of how the Earth’s upper atmosphere interacts with solar wind, the Arctic is often a hostile radio propagation environment that degrades both of these two approaches,” the agency writes.
Rather than trying to impose order on that polar chaos, FROSTY’s core idea is to extract useful information from it.
FROSTY Aims To Turn Noise Into a Sensor
At the heart of FROSTY is a counterintuitive concept: radar does not necessarily need clean, coherent signals to work. When radio waves pass through the auroral ionosphere, they become distorted, randomized, and noise-like. Traditional radar processing treats this as a problem to be minimized. However, FROSTY aims to treat this as raw material.
The program envisions using stand-off high-power transmitters—such as the High-frequency Active Auroral Research Program (HAARP) facility in Alaska—along with naturally occurring ambient radio noise to illuminate targets indirectly. The resulting signals, though scrambled by ionospheric turbulence, still contain subtle correlations that advanced algorithms may be able to extract.
“The Frosty program seeks to develop methods to utilize sources that are subject to severe, random modulations by a disturbed ionosphere for radar functions,” DARPA’s solicitation documents explain.
The approach draws on ideas from passive sensing techniques already used in fields like ocean acoustics and astronomy, where researchers detect objects by correlating noise rather than transmitting clean pulses.
In the far north, radio signals behave in unusual ways—spreading out, bending, and changing unpredictably as they move through the atmosphere. Those effects make the signals harder to interpret, creating challenges that existing sensing techniques were never designed to handle.
Correcting those distortions—without knowing in advance how the ionosphere will behave—is the central technical challenge FROSTY hopes to solve.
DARPA graphic depicting how sensors developed in the FROSTY program might work. (Image Source: DARPA)
From Raw Data to Reliable Tracks
Unlike many DARPA programs that focus on hardware breakthroughs, FROSTY is primarily a signal-processing effort. Phase 1 of the program, spanning 18 months, will focus on developing algorithms that can convert raw radio-frequency data into reliable target tracks.
According to the solicitation, a successful Phase 1 system must demonstrate a detection range of at least 47 miles (75 km), achieve a probability of detection greater than 90%, and form target tracks using no more than 90 seconds of collected data.
These metrics will be evaluated using government-furnished datasets collected from Arctic test sites, including high-frequency receiver arrays with roughly two dozen antenna elements.
The targets themselves will be deliberately challenging. They include commercial aircraft flying at altitude, small aircraft flying at low altitude, and maritime vessels operating in icy waters. Illumination will come from both controlled transmitters and ambient environmental noise, ensuring that algorithms must work under realistic, often unfavorable conditions.
By the end of Phase 1, performers are expected to deliver a complete software processing chain—from baseband receiver samples to target tracks—along with a conceptual design for a future deployable system.
However, testing will not be confined to simulations. DARPA’s proposers’ materials indicate that data collection will take place in central and northern Alaska, including locations under the auroral oval where ionospheric disturbances are strongest
Sites such as Point Barrow and the Poker Flat Research Range are expected to play key roles, offering both maritime access and intense space-weather effects.
FROSTY Program materials make it clear that DARPA will deliberately expose performers to imperfect data. Calibration errors, land and sea clutter, meteor trails, and unpredictable ionospheric behavior are all expected. “Approaches should be resilient in the face of calibration errors,” DARPA notes.
This emphasis on realism reflects a broader shift in defense research. Rather than designing idealized systems that struggle outside controlled conditions, DARPA increasingly wants technologies that work despite uncertainty, degradation, and incomplete information.
DARPA’s History of Arctic Experiments
The FROSTY program does not emerge in isolation. DARPA’s program materials trace its intellectual roots to earlier efforts such as the Assured Arctic Awareness program and the ongoing Defense Applications of Innovative Remote Sensing (DAIRS) initiative. Both programs demonstrated that noise-like illumination could, in principle, support detection. However, they also revealed limitations tied to anisotropy, clutter, and insufficient processing gain.
What has changed is computational capability and algorithmic sophistication. Advances in array processing, statistical inference, and high-performance computing now make it plausible to attempt corrections that were previously out of reach.
In that sense, FROSTY is less about inventing a new sensor than about extracting new value from signals that were once discarded as unusable.
FROSTY’s Strategic Implications Beyond the Arctic
While FROSTY is explicitly framed as an Arctic sensing program, its implications could extend far beyond the Arctic. Techniques for detecting and tracking targets using distorted, noise-like signals could be applied in other contested or degraded environments, including regions subject to jamming, spectrum congestion, or deliberate interference.
Moreover, the program reflects a growing recognition that future surveillance will not rely on single exquisite sensors, but on distributed, resilient systems that fuse weak signals across space and time.
DARPA is careful not to overpromise. Phase 1 is exploratory, while Phase 2 will be focused on system integration and field deployment. Both phases are intended to be completed separately. But the agency’s intent is clear.
Nevertheless, with the launch of FROSTY, the Pentagon is signaling that, as the Arctic shifts from a frozen frontier to a navigable, increasingly contested domain, maintaining situational awareness is no longer optional.
Ultimately, FROSTY represents a bet by DARPA that the physics that once obscured the Arctic can be turned into an advantage. And that in an era of shifting climate and geopolitics, seeing through the noise may matter more than ever.
“As the Arctic becomes more accessible for shipping and other activities, the need for a reliable, long-range sensing method that can overcome these limitations has become critical for national security,” DARPA’s solicitation reads
“The Frosty program will pioneer innovative signal processing techniques to use these distorted signals,” the solicitation documents add, “and even the ambient background noise of the environment, to create a functional radar system capable of seeing over the horizon.”
Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan. Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com