Maritime Use Cases of SAR: What SAR can do for nations, private companies and NGOs

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We’ve already dived deep into the basics of SAR (Synthetic Aperture Radar) and its advantages for maritime surveillance. Mounting sophisticated antennas on Earth Observation Satellites gives humanity a literal eye in the sky. Using radio waves (specifically microwaves), SAR antennas capture satellite-based images with granular details of the Earth's surface.

Microwaves do not need visible light to capture images. They can penetrate clouds, smog, and pollution. They can work at night and penetrate the atmospheric barrier to capture the target surface. They are also sensitive to roughness, moisture, and other features of the target area.

So, we know what SAR is capable of doing. Now, let’s focus on what SAR can be used to accomplish in the real world. In this article, we’ll focus on the primary use cases of SAR for national governments, private organizations, and even NGOs focused on conservation, research, and education.

How does SAR work?

SAR creates images using radio waves, specifically microwaves with wavelengths ranging from a few centimeters to a few meters. These microwaves are transmitted from antennas mounted on airborne objects like drones, aircraft, or orbiting satellites. After hitting the Earth's surface, the microwaves are scattered in different directions. Some of these waves are reflected back to the sensor. The received signals are then processed to generate images of the region.

SAR antennae and sensors can be mounted on airplanes and other in-atmosphere aircraft, but satellite systems have a stable orbit due to low air resistance, and hence provide more reliable observations.

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Note: For the purpose of product relevance, we’ll be talking specifically about use cases related to marine surveillance by SAR satellites.

Real-world use-cases of SAR

Environmental Monitoring

SAR imagery is essential for monitoring changes in the oceanic surface, tracking changes in wave patterns, water levels, density, composition, and so on. They are also adept at imaging and studying glaciers, ice caps, and polar drifts on the surface of seas.

SAR imagery is especially important for tracking indicators of climate change (rising sea levels, coastal erosion, shore-line delineation, algal bloom, melting sea ice and glaciers, etc) as they impact oceans. This is integral to sustainability and conservation efforts.

SAR satellites are particularly useful for detecting oil spills on ocean surfaces.

“In 2024, six large spills (>700 tonnes) and four medium spills (7-700 tonnes) were recorded from tanker incidents. The total volume of oil lost to the environment from tanker spills in 2024 was approximately 10,000 tonnes.”

Source

A chart published by ITOPF indicates oil spills by tankers are declining despite an increasing volume of trade through the sea. That is good news.

But oil spills are typically self-reported, and usually, this is when there’s an accident involving a tanker. In other words, there are probably far more oil spills occurring than are reported.

However, technology such as SAR can identify and track oil spills on ocean surfaces from space. The oil on the surface leads to microwaves being reflected away from the sensor. Consequently, these regions appear darker in captured images – indicating an oil spill.

Additionally, using information on wind speed and direction, we can predict its trajectory and possible impact on sea and land masses.

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Disaster Management

The previous example of oil spill management can definitely go under this header, but we’re talking more closely about ocean-based natural occurrences such as tsunamis, tropical cyclones, heavy storms, and the like. SAR images can capture information on these phenomena before they become too destructive and devastate human life and resources.

To quote NASA

“Weather-related hazards, such as flash flooding and hurricane surges, are natural phenomena that can have devastating impacts on communities worldwide. As a result, disaster responders must react as quickly as possible to mitigate the impact on people and their homes. Synthetic Aperture Radar (SAR) – satellites that provide images of land on Earth – help monitor weather-related hazards with an ability to see an area day and night, rain or shine.”

In fact, SAR works so well in this regard that NASA offers a course on Disaster Assessment Using Synthetic Aperture Radar.

Marine Insurance

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We will be covering this topic in greater detail in an upcoming article focused on Marine Insurance. Stay tuned!

The conversation about piracy translates directly into SAR’s usability in marine insurance. Insurers often incur huge losses if the ships they insure engage in illegal activity or sail through piracy-prone regions.

To salvage these losses and prevent them in the future, they would have to know, for instance, if certain ships are stuck in a blockage, damaged by natural disasters, or collided with critical infrastructure (windmills, oil rigs, etc.)

Enter SAR.

SAR satellites can provide almost immediate information on sea events, such as oil spills, ships transporting oil in violation of sanctions, or natural disasters. Instead of waiting for hours or days to know what’s happening at sea, SAR provides insight into ground-level data at a speed and level of detail unmatched by any other technology.

These images, along with AIS data, provide a source of truth, transparency, and visibility — exactly what insurance companies need to understand and assess risk with the highest levels of accuracy. Companies can verify if any insured ships are known to sail through areas prone to piracy, collisions with other vessels or infrastructure, or were responsible for an environmental breach.

Alternative Data for Hedge Funds

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We will be covering this topic in greater detail in an upcoming article focused on Alternative Data for Hedge Funds. Stay tuned!

Believe it or not, hedge funds can actually make better stock picks from space.

Consider this example.

Your company invests heavily in global oil interests.

Russia, a highly sanctioned country, is prohibited from selling its oil and natural gas stores on the international market. However, dark ships still manage to carry sanctioned oil to buyers, undermining legal oil supplies and impacting market prices.

With traditional data, you do not know about any of these dark fleets or the volumes being transported, since these ships switch off their AIS transponders to go “dark” i.e., untraceable by legal authorities and monitoring bodies.

Over 80% of global trade happens via sea. Illegal movements of goods, commodities, and finished products can significantly impact market dynamics. Consequently, this information is highly valuable when making investment decisions.

Piersight’s marine surveillance satellites, however, can track these ships' movement by imaging entire swathes of the ocean from space. Ships are nearly impossible to conceal from SAR satellites, so you know exactly what occurs at sea in close to real-time.

In other words, hedge funds can get near-immediate information on global trade and commerce, risks due to piracy events or conflicts, operations and compliance of vessels, and other data that could help make better bets.

Managing and Minimizing Piracy

Remember all the breaking news around Somali piracy from 2009 to 2011? I remember seeing a new report every week, at one point.

Global governments did eventually get the crisis under control, as this video explains. But, they didn’t do it until the piracy became such a major issue that even a cruise ship was targeted. Somali pirates demanded and received millions of dollars in ransom, and stole cargo on top of that.

Once again, this is exactly the kind of problem SAR is built to solve. Navy ships and even aircraft cannot surveil large swathes of the ocean at once. For satellites, doing the same is much easier. With PierSight’s constellation of SAR & AIS satellites, situational awareness is a default.

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A service like PierSight, if it had existed at the time, would have been able to detect ships of questionable origin and identity in regions prone to piracy – putting legal ship liners on guard and enabling them to better protect their crew and cargo.

Preventing IUU (Illegal, Unreported, and Unregulated) Fishing

IUU fishing refers to activities that violate national laws or international obligations and undermine the sustainability of fish stocks. At a high level, it can involve some of the following:

Fishing without a valid license or permit

Fishing in prohibited areas like marine reserves

Using banned fishing gear or methods

Catching prohibited species

Failing to report or misreporting catches to relevant national or regional authorities.

Underreporting catches to avoid quotas or controls.

Fishing by vessels without nationality or flying a "flag of convenience."

Fishing in areas with no applicable conservation or management measures

Fishing in a manner inconsistent with responsible fishing practices

IUU fishing is estimated to result in (almost) a $36 billion annual loss to the global fishing industry. It also threatens species like Atlantic bluefin tuna (82% population loss since the 1970s).

SAR satellites can simultaneously scan large maritime areas – about 500 kilometers, easily. As a result, a wider range of vessels and activities can be detected across huge swaths of the ocean surface, expanding the surveillance scope. In other words, you can see illegal fishing vessels from space. There is almost zero chance of such boats concealing themselves and continuing to operate illegally.

Identifying embargoes and sanctions

The example in the previous point mentions a Russian ship selling oil in violation of global sanctions.

To operate undetected, many ships under sanctions or affected by embargoes, switch off their AIS transponder or spoof it to transmit inaccurate location data. These “dark ships” can fly under the radar and escape the consequences of sanctions and embargoes.

PierSight’s SAR satellites can spot these ships from space, rendering their concealment tactics useless. We can track these ships throughout their operations - from ports for loading & unloading, through to scenarios wherein there is a ship-to-ship transfer out at sea — regardless of their AIS signal.

This capability to extract real-time data can help law enforcement clamp down on crime at sea. It can also serve business interests depending on the lawful flow of people, goods, and services via oceans.

Defence and Counterterrorism

In 2008, India suffered one of the most heinous terrorist attacks of the modern era. Ten armed terrorists with automatic weapons and grenades entered Mumbai via the Arabian Sea.

The terrorists hijacked a fishing trawler - Kuber - off the coast of Gujarat. It's unclear if the trawler had AIS signals activated at the time of the hijacking.

SAR imaging is especially useful in this regard. By monitoring ocean waters in real-time, all above-surface objects over 10 meters in length can be immediately detected and tracked. In this case, PierSight's ML algorithm would have been able to flag an anomaly given that this is a trawler operating out of Gujarat that's taking a major deviation toward Mumbai.

A country’s size is usually inversely proportional to the security of its Exclusive Economic Zone (EEZ). Monitoring using conventional means is impossible for a country like India, with 2.3 million square kilometers of EEZ. Many countries also lack adequate resource allocation for monitoring and enforcement efforts along coastal borders.

To illustrate the point, take a look at the area of the Exclusive Economic Zone of US, India, and Indonesia. Alongside this, we compare the number of patrol craft - sea and air - available to each of the coastguards.

Country	Land Surface (sq. km)	Exclusive Economic Zone (sq. km)
United States	9,833,520	11,351,000
India	3,287,263	2,372,298
Indonesia	1,904,569	6,159,032

It’s very evident that the exercise of monitoring such vast areas with so few resources could be compared to finding a needle in a haystack. Coastguards have been inducting Unmanned Aerial Vehicles (UAVs) but it would barely make a dent.

With a constellation of SAR satellites, one could detect changes in near real-time in maritime environments. Mounting SAR on satellites, or working with startups excelling in SAR imaging (like PierSight) can provide intelligence that prevents large-scale loss of life.

Persistent Monitoring by SAR satellites can also keep a country’s coastline free of incursive vessels, by periodically photographing Economic Exclusive Zones from space.

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Limitations of SAR

In the interest of informed decision-making, one must take a moment to consider the limitations of SAR. Despite its incredible abilities and flexible usability, it does have a couple of gaps (as with all forms of technology in existence).

Speckle Noise and Image Quality

SAR systems use microwave signals to capture images. These microwaves naturally produce something called speckle noise. This “noise” produces a sort of grainy, salt-and-pepper impression in SAR images which, in some cases, can obscure finer details and complicate data interpretation.

Trade-off between Resolution and Swath

Generally, SAR satellites that cover large swathes of the Earth's surface will offer lower-resolution images. Higher-resolution imagery with SAR satellites is only possible if it is scanning a limited swath of land or sea. Essentially, you have to choose between image resolution and the expanse of area scanned.

Complex Data Processing and Interpretation

Data acquired by SAR signals is quite complex, as it carries not just the image but also amplitude and phase information. Interpreting this data – often requiring advanced methods like interferometry (InSAR) or polarimetry – needs the contribution of experts who understand these highly technical algorithms and mechanisms.

Temporal Resolution and Revisit Frequency

A SAR satellite’s revisit frequency – how often a sensor passes over a specific area to attempt to capture new imagery – depends on its specific orbit and the swath of area it covers. Depending on these parameters, particular SAR satellites may be unable to provide close to real-time data due to long revisit times.

This is a particular problem if SAR satellites are being used for disaster response.

Sensitivity to Surface Roughness and Material Properties

The strength of the microwaves returning to the SAR satellite sensor depends on the roughness and other physical properties of the target surface. Smooth surfaces (like calm seas) cause more radar waves to reflect away from the sensor, which results in weak returning signals and unclear images (with less data).

How PierSight makes SAR surveillance accessible to governments, businesses, and NGOs

Current Earth Observation solutions lack real-time situational awareness of our oceans. To address this gap, PierSight is building a constellation of miniaturized satellites, combining SAR and AIS technology for persistent maritime monitoring. These backpack-sized satellites, called CubeSats, offer a 30-minute revisit time and operate flawlessly at night and in all weather conditions.

With a constellation of 32 CubeSats orbiting Earth, PierSight offers access to real-time, persistent monitoring of the oceans. Developed by former ISRO engineers, PierSight provides businesses, governments, and nonprofits with an "eye in the sky" for the vast expanse of our planet's water surface.

Here’s what PierSight customers can expect to achieve with SAR imagery:

Real-time monitoring and situational awareness of maritime environments—essential for shipping companies, law enforcement, and conservation agencies.

Precise data on vessel activities.

Detection of illegal fishing vessels, oil spills, and dark ships.

Maritime Use Cases Of Synthetic Aperture Radar (SAR) Satellites