RADARSAT: Canada’s Eye in the Sky

Successful and Enduring Contributions

The RADARSAT program represents one of the Canadian Space Agency’s (CSA) most successful and enduring contributions to science and technology. It’s a series of advanced Earth observation satellites designed to monitor the environment, manage resources, and support a wide range of government, scientific, and commercial activities. Unlike satellites that capture images using visible light, like a standard camera, the RADARSAT family uses a powerful technology called Synthetic Aperture Radar (SAR).

SAR is an active sensing system. It doesn’t rely on the sun for illumination. Instead, the satellite transmits its own microwave energy pulse – like a camera’s flash – down to the Earth’s surface. It then records the “echo” that bounces back. Because it provides its own light, SAR can “see” in total darkness, such as during the long polar night. Its microwave signals also penetrate clouds, fog, smoke, and haze, which means it can acquire reliable imagery regardless of the weather.

This all-weather, day-or-night capability is especially important for a country like Canada. With the world’s longest coastline, a vast and often ice-choked Arctic territory, and huge expanses of remote, sparsely populated land, the ability to monitor conditions reliably is a matter of economic prosperity, environmental stewardship, and national sovereignty. The RADARSAT program has evolved over three decades, from a single pioneering satellite, RADARSAT-1, to a sophisticated commercial successor, RADARSAT-2, and finally to the high-frequency RADARSAT Constellation Mission (RCM) that operates today.

The Origins of Canadian Radar Expertise

Canada’s legacy in space began long before the first RADARSAT. On September 29, 1962, the launch of Alouette 1 made Canada the third nation in space, after the Soviet Union and the United States. This satellite, designed to study the ionosphere, was built by the Defence Research Telecommunications Establishment (DRTE), which is now part of the Communications Research Centre Canada. The Alouette program proved that Canada had the scientific and engineering skill to build complex, reliable spacecraft.

The specific idea for a Canadian radar satellite was sparked by another nation’s mission. In 1978, NASA launched SEASAT, the first satellite designed for oceanography and the first to carry a civilian SARinstrument. SEASAT operated for only 106 days, but the data it collected was revolutionary.

Scientists at the Canada Centre for Remote Sensing (CCRS) were among the first to process SEASAT’s SAR data. They were astonished by its clarity and its ability to distinguish different types of sea ice in the Arctic. At the time, navigating these waters was hazardous and relied on sparse reports and aerial reconnaissance. The SEASAT data showed the immense potential of using space-based radar for ice monitoring.

This experience highlighted a strategic need. While data from foreign satellites was useful, Canada couldn’t rely on it for its own operational needs, like safe shipping in the Northwest Passage. The data had to be available when and where Canada needed it. This realization was the seed from which the RADARSAT program grew, leading to a formal project approval in 1980.

RADARSAT-1: A New Vision for Earth Observation

The Mandate and the Mission

The development of RADARSAT-1 was driven by clear economic and sovereign imperatives. Monitoring sea ice for navigation in the Arctic and the Gulf of Saint Lawrence was the top priority. This would support seasonal shipping, resource exploration, and safety. Existing optical satellites, like the American Landsat program, were often defeated by the Arctic’s persistent cloud cover and long winter darkness. A radar satellite would solve both problems.

The program was led by the newly formed Canadian Space Agency (CSA). It was a complex partnership. The CSA managed the project and would operate the satellite. The United States, through NASA, agreed to provide the launch on a Delta II rocket in exchange for a share of the satellite’s data. Canadian provinces also contributed funding, anticipating benefits for their own resource management.

The private sector was essential. The prime contractor for the satellite was Spar Aerospace, the company famous for building the Canadarm for the Space Shuttle. This project would leverage that hard-won expertise in space robotics and engineering and transition it to the new field of Earth observation.

Building the Satellite

The heart of RADARSAT-1 was its C-band SAR instrument. C-band is a microwave frequency that provides a good balance between penetration (it’s not easily stopped by rain) and resolution. The satellite bus, its main body, was based on a design from Ball Aerospace.

What made RADARSAT-1 truly innovative was its flexibility. Unlike SEASAT’s fixed-beam radar, RADARSAT-1’s antenna could be electronically steered to “look” at the Earth from different viewing angles, ranging from 20 to 50 degrees to the side.

This steerable beam enabled multiple “beam modes,” allowing operators to make a trade-off between the detail of the image (resolution) and the size of the area captured (swath width).

Standard Mode: A balance of 30-meter resolution and a 100-kilometer swath. This was the workhorse mode for general mapping.
Fine Mode: A high-resolution 10-meter mode over a smaller 50-kilometer swath, useful for detailed analysis of specific targets like cities or bridges.
Wide Mode: A lower-resolution (100-meter) mode that covered a 150-kilometer swath, good for large-area monitoring.
ScanSAR: This was the most important mode for ice monitoring. By electronically combining beams, it could image an enormous 500-kilometer-wide swath. While the resolution was lower (50 meters), it allowed the satellite to map the entire Arctic every few days.

Most imaging satellites are designed to look to the right of their flight path. RADARSAT-1 was built this way, which unfortunately made it difficult to combine its data with images from the European Space Agency’s ERS-1satellite, which looked to the left.

Launch and a Long-Lived Mission

RADARSAT-1 was launched on November 4, 1995, from Vandenberg Air Force Base in California. It was placed in a sun-synchronous orbit, which is standard for Earth observation satellites. However, it used a unique “dawn-dusk” orbit. It crossed the equator at 6 AM (on the descending, or south-bound, pass) and 6 PM (on the ascending, north-bound, pass).

This orbit was a clever engineering choice. The satellite was almost constantly in sunlight, with its solar panels perpetually angled toward the sun. This minimized the need to use its batteries, reducing wear and tear and dramatically extending its life.

The original design life for RADARSAT-1 was five years. It surpassed that expectation by a massive margin. The satellite operated almost flawlessly for over 17 years, more than triple its design life. It was a testament to the quality of its design and construction. In March 2013, after a long and productive career, RADARSAT-1 suffered a technical failure and the mission was declared over. It remains in orbit as a piece of space debris.

What RADARSAT-1 Gave the World

The impact of RADARSAT-1’s data was immediate and far-reaching.

Ice Monitoring: This was its main job, and it performed brilliantly. The Canadian Ice Service used its ScanSAR imagery daily. For the first time, they could produce reliable, near-real-time ice charts for ships navigating the Arctic and Canada’s East Coast of Canada. This made shipping far safer and more efficient, saving millions of dollars in fuel and time, and preventing accidents.

Disaster Management: SAR’s all-weather capability makes it a powerful tool for responding to natural disasters.

Floods: Water surfaces are very smooth and act like a mirror to the radar, bouncing the signal away from the satellite. This makes rivers and flooded areas appear black in a SAR image, standing out clearly against the brighter, rougher land. RADARSAT-1 was used to map devastating floods around the world, including the 1997 Red River flood in Manitoba.
Earthquakes and Volcanoes: The data could be used for interferometry, a technique to map ground movement, helping scientists understand the impact of earthquakes and monitor swelling ground near active volcanoes.
Landslides: Its images helped identify unstable slopes and map the extent of landslide damage.

Maritime Surveillance:

Ship Detection: On the dark, smooth surface of the ocean, the metal structure of a ship acts as a “corner reflector,” bouncing the radar signal directly back to the satellite. This makes ships appear as intensely bright spots, easily detectable. This data was used for fisheries enforcement (spotting illegal fishing boats), customs, and general maritime security.
Oil Spill Detection: Oil on the water’s surface calms the small waves, creating a smooth patch. Just like a calm lake, this oil-covered patch appears dark in a SAR image, allowing for rapid detection and monitoring of oil spills.

Mapping:

Antarctic Mapping Mission (AMM): Perhaps its most celebrated scientific achievement. In 1997, satellite controllers performed a complex maneuver to rotate RADARSAT-1, making it “look” to its left instead of its right. In this new orientation, it was able to image Antarctica, which was unreachable from its normal viewing angle. This mission produced the first-ever high-resolution, complete radar map of the entire Antarctic continent, a landmark achievement for glaciology and Earth science. A second, even better map was produced in 2000.
Agriculture and Forestry: The data was used to monitor crop health, soil moisture, and harvest readiness. It was also able to track deforestation in tropical regions, where constant cloud cover blinds optical satellites.
Geology: Geologists used the imagery to map rock formations and structures, aiding in the exploration for minerals and oil and gas.

The Business of RADARSAT

RADARSAT-1 pioneered a hybrid public-private model. While the Government of Canada was the primary user, a private company, Radarsat International (RSI), was formed to market and sell RADARSAT-1 data commercially around the world. RSI, which was a predecessor to MDA Geospatial Services, successfully created a global market for SAR data. This model, where the government secured its own data needs and the private sector commercialized the excess capacity, became a template for future missions.

RADARSAT-2: The Commercial Successor

Building on a Legacy

As RADARSAT-1 aged, its government and commercial users needed a guarantee of data continuity. This led to the development of RADARSAT-2, but with a new business model. This time, it would be a fully commercial mission.

The Canadian Space Agency (CSA) entered into a partnership with MacDonald, Dettwiler and Associates (MDA), the company that had acquired Spar Aerospace. The CSA provided a significant portion of the funding. In return, MDA would build, own, and operate the satellite, and the Government of Canada would receive a data allocation to meet its needs (ice monitoring, surveillance, etc.) for the life of the mission. MDA would own the satellite and the rights to sell all other data commercially on the global market.

A Leap in Technology

RADARSAT-2 wasn’t just a copy of its predecessor; it was a major technological leap forward. It incorporated all the lessons learned from RADARSAT-1 and added capabilities that were, at the time, at the absolute cutting edge.

High-Resolution Modes: RADARSAT-2 introduced an “Ultra-Fine” mode with 3-meter resolution. This was a significant improvement, moving from simply detecting objects to identifying them. For example, a 3-meter image could help an analyst distinguish between a fishing boat and a container ship. Later in the mission, an even higher-resolution 1-meter “Spotlight” mode was activated.
Full Polarization (Quad-Pol): This was arguably its most important new feature. RADARSAT-1 used a single polarization (it sent a horizontal pulse and received the horizontal echo, called HH). RADARSAT-2 was “quad-pol,” meaning it could send and receive in both horizontal (H) and vertical (V) polarizations. It could collect data in all four combinations: HH, VV, HV, and VH.
- This is like the difference between seeing in black and white versus full color. Different polarizations provide much more information about the physical properties of a target, like its shape, texture, and material. This unlocked a new level of scientific analysis, especially for classifying crop types, identifying different kinds of ice (hazardous multi-year ice versus thinner first-year ice), and understanding land cover.
Left and Right-Looking: The satellite was built with the ability to image on either side of its flight path. This made it far more flexible, doubled its accessible imaging area, and made it an ideal platform for interferometry.
Enhanced Agility: It could switch between its different imaging modes much faster and re-point its beam more quickly.
On-Board Data Recorder: It was equipped with a large solid-state recorder. This allowed it to image any location on Earth – even far from a ground station – store the data, and then download it later when it passed over a friendly station, like the ones in Canada.

Launch and Operations

RADARSAT-2 was launched on December 14, 2007, from the Baikonur Cosmodrome in Kazakhstan aboard a Soyuz-FG rocket.

It was placed in the exact same “dawn-dusk” sun-synchronous orbit as RADARSAT-1. This was a deliberate choice to ensure data continuity. Scientists and commercial users could easily compare new RADARSAT-2 images with the existing archive of RADARSAT-1 data, creating a long-term record of change.

With a design life of seven years, RADARSAT-2 has proven to be another incredibly durable workhorse. As of late 2025, it is still fully operational, continuing to provide high-quality data to the Government of Canada and MDA’s commercial customers worldwide, well over a decade past its launch.

The RADARSAT-2 Data Market

MDA (whose geospatial data business was for a time part of Maxar Technologies before being re-established as a standalone Canadian company MDA Ltd.) successfully built upon the market created by RSI. RADARSAT-2 became a premier source of SAR data globally.

Key customers included governments (for defense, intelligence, and maritime security), oil and gas companies (for monitoring drilling platforms and navigating ice-filled waters), the shipping industry, mining companies (for monitoring ground subsidence), insurance agencies (for assessing flood damage), and the agriculture sector.

A major selling point was the “near-real-time” (NRT) delivery. Data could be acquired, downlinked, processed, and delivered to a user – like the Canadian Ice Service or a maritime security center – in under an hour, allowing for immediate action.

The RADARSAT Constellation Mission (RCM)

A New Paradigm: From One to Many

Even with RADARSAT-2’s flexibility, a single satellite has inherent limitations. The main limitation is revisit time. For RADARSAT-2 to image the exact same spot from the exact same viewing angle (which is necessary for interferometry), it has a 24-day repeat cycle. While it can image near any spot in Canada within a day or two by steering its beam, this isn’t good enough for monitoring truly dynamic events like floods, oil spills, or fast-moving ships.

The solution was to move from one large, complex satellite to a constellation of smaller, identical ones. This is the RADARSAT Constellation Mission (RCM), Canada’s third-generation system. Instead of one satellite, it is three.

Mission Design and Objectives

RCM is a Canadian Space Agency (CSA) project, with the satellites again built by MDA. Unlike the commercial RADARSAT-2, the RCM is owned and operated by the Government of Canada.

The three identical satellites (nicknamed Bolt, Pounce, and Arrow) fly in the same 600-kilometer sun-synchronous orbit, evenly spaced 30 minutes apart. This “train” formation is the key to the mission’s power. It provides:

Rapid Revisit: The three satellites working together can image most of Canada every single day. They can revisit any specific point on Earth (at the same viewing angle) every four days, a massive improvement from RADARSAT-2’s 24 days. This is a game-changer for monitoring fast-evolving situations.
High-Capacity: Three satellites collect three times the data, allowing for comprehensive national mapping programs that were not possible with a single satellite.
Near-Real-Time Delivery: The system is designed for rapid tasking and data delivery to support operational government users.

New Capabilities

While the RCM satellites are smaller than RADARSAT-2, they are highly advanced. They provide C-band data, ensuring continuity with the previous missions and the 40-plus-year data archive. They also introduced a new, powerful capability:

Automatic Identification System (AIS): Each RCM satellite carries a secondary receiver for the Automatic Identification System (AIS). AIS is a radio system that large ships are required to use to broadcast their identity, position, course, and speed.
“Dark Vessel” Detection: This is the RCM’s killer application. In near-real-time, the system can overlay the AIS data (showing cooperative ships) on top of the SAR image (which sees all ships). Any bright spot on the radar image that does not have a corresponding AIS signal is a “dark vessel.”
- This dark vessel could be a ship in distress with a broken transmitter. It could also be a ship engaged in illegal activity – such as smuggling, illicit fishing, or violating sanctions – that has deliberately turned off its transponder. This provides an unprecedented tool for Canadian (and international) maritime security and sovereignty enforcement.

Launch and Current Status

The three RCM satellites were launched together on a SpaceX Falcon 9 rocket from Vandenberg Air Force Base on June 12, 2019.

The constellation is fully operational and serves as the Government of Canada’s primary source of Earth observation data. The data supports the core needs of government departments like Environment and Climate Change Canada (for ice and pollution monitoring), Natural Resources Canada (for mapping and hazard assessment), and the Department of National Defence (DND) (for maritime surveillance). Data is also made available to scientific, public, and, to some extent, commercial users.

The Science and Applications of RADARSAT Data

To fully appreciate the RADARSAT program, it’s helpful to understand what a radar image actually shows and the advanced scientific techniques used to analyze the data.

Understanding a Radar Image

A SAR image is not an intuitive photograph. It’s a map of the microwave “brightness” of the surface. This brightness is determined by two main factors: surface roughness and the “corner reflector” effect.

Bright Surfaces: Rough surfaces, like a forest canopy, a field of crops, or a choppy sea, scatter the radar signal in all directions, including back to the satellite. These appear bright.
Dark Surfaces: Smooth surfaces, like a calm lake, an airport runway, or a patch of smooth, new ice, act like a mirror. They reflect the radar signal away from the satellite, so very little energy returns. These areas appear dark or black.
The Corner Reflector Effect: This is what makes SAR so good at spotting man-made objects. When a radar signal hits a 90-degree corner (like the side of a building meeting the ground, or the deck of a ship meeting its superstructure), it bounces off both surfaces and is reflected directly back to the satellite. This creates an intensely bright return signal. Cities, bridges, towers, and ships all appear extremely bright in SAR images.
Radar Shadow: Just like a flashlight, the side-looking radar beam can’t see “behind” tall objects. A steep mountain will have a bright, forward-facing slope and a completely black “shadow” on its back slope where no radar signal reached.
Speckle: All SAR images have a grainy, “salt-and-pepper” look. This is called speckle. It’s a natural side effect of the way coherent microwave signals interfere with each other. A great deal of processing goes into “despeckling” the images to make them clearer.

The Power of Interferometry (InSAR)

One of the most powerful techniques using SAR data is Interferometric Synthetic Aperture Radar (InSAR). This technique uses two radar images of the same location taken from slightly different positions. By comparing the phase of the returning waves – essentially, how the wave “crests” line up in each image – scientists can measure tiny changes in distance.

Digital Elevation Models (DEMs): If two images are taken at the same time (for example, by two satellites flying in formation, or by the Space Shuttle Radar Topography Mission), InSAR can be used to create highly accurate 3D maps of the Earth’s surface.
Differential InSAR (DInSAR): This is where the real magic happens. By comparing two images taken at different times (e.g., two RADARSAT-2 images taken 24 days apart), scientists can create a map of how the ground moved in the time between the images. This technique is sensitive enough to detect changes of just millimeters.
- Applications of DInSAR:
  - Earthquakes: It can map the “slip” on a fault after an earthquake, showing exactly where and how much the ground moved.
  - Volcanoes: It’s a primary tool for monitoring volcanoes. Scientists can see the ground “inflate” or swell as magma moves underneath, a key warning sign of a potential eruption.
  - Subsidence: It can measure the slow sinking of ground in cities (due to groundwater extraction) or in mining areas (due to operations or unstable tailings ponds).
  - Infrastructure: It can be used to monitor the structural health of dams, bridges, and large buildings by detecting tiny, imperceptible movements.
  - Glacier Movement: It tracks the flow of glaciers and ice sheets, providing essential data for climate change science.

The Science of Polarimetry

The quad-pol capability of RADARSAT-2 opened up a new field of analysis. By looking at how an object scatters different polarizations of light, scientists can learn much more about its physical nature.

Agriculture: This is a classic example. A signal sent with horizontal polarization (HH) might reflect off the horizontal ground surface. A vertical (VV) signal might reflect strongly off the vertical stalks of corn or wheat. A cross-polarized signal (HV, sending horizontal and receiving vertical) might show “volume scattering” from a leafy crop canopy. By combining these channels like an RGB image, an algorithm can automatically classify fields: “This is corn,” “This is soy,” “This is a fallow field.” This is very powerful for organizations like The United States Department of Agriculture (USDA) tracking global food security.
Ice Typing: Thick, old, multi-year sea ice (a major hazard to shipping) scatters radar very differently than thin, smooth, first-year ice. Polarimetry makes the classification of these ice types much more accurate.
Shipping: The complex, metallic, 90-degree-angle-filled structure of a ship scatters all polarizations very strongly, making it “pop” in a quad-pol image, allowing for easier detection and even classification.

The RADARSAT Ground Segment

The satellites in orbit are only one half of the system. A vast “ground segment” of antennas, data hubs, and processing centers is required to control the satellites and turn their raw data into usable products.

The CSA’s primary satellite control center is at the John H. Chapman Space Centre in Longueuil, Quebec. From here, operators command the satellites and monitor their health.

The data itself is downlinked to large receiving antennas. The primary Government of Canada stations are in Gatineau, Quebec, and Prince Albert, Saskatchewan.

A third station in Inuvik, Northwest Territories, is especially important. Its high-latitude location means it is within sight of a polar-orbiting satellite (like RADARSAT) on almost every one of its 15 daily orbits. This allows for extremely frequent and rapid data downlinks, which is essential for the near-real-time delivery of data for ice monitoring and maritime surveillance.

Once on the ground, the raw data is sent to processing hubs. The Canada Centre for Remote Sensing (CCRS)is a key government center for processing and archiving the data. From there, it’s distributed to end-users like the Canadian Ice Service (who turn it into ice maps) and the Department of National Defence (who use it for the Polar Epsilon maritime surveillance project). MDA operates its own parallel ground segment for its commercial operations.

The Future of RADARSAT

The RADARSAT Constellation Mission is still in the prime of its life, but the CSA and Canadian industry are already looking ahead to what comes next. The world of Earth observation is changing rapidly.

Trends in SAR:

Different Frequencies: Canada has mastered C-band. Other frequencies offer different advantages. X-band (used by Germany’s TerraSAR-X) provides extremely high resolution. L-band (used by Japan’s ALOS-2 and the joint NASA–ISRO NISAR mission) has a longer wavelength that can penetrate deeper into forest canopies and even into dry soil, making it useful for biomass estimation and archaeology.
The Global Context: RADARSAT no longer operates in a vacuum. The European Union’s Copernicus Programme offers its Sentinel-1 C-band SAR data for free to the entire world. This has changed the market, moving it away from raw data sales and toward value-added analysis services.
Commercial Competition: The “NewSpace” revolution has produced a flurry of commercial SAR companies. ICEYE (from Finland) and US companies like Capella Space and Umbra Lab are launching large constellations of small, X-band satellites. They offer extremely high revisit times (multiple times per day) and very high resolution.

Canada’s future will likely involve a hybrid approach. It will continue to leverage its deep, world-leading expertise in C-band radar, which remains the best tool for its core sovereign need: ice monitoring. A follow-on to RCM is likely. This core government system may be supplemented by data purchased from commercial partners (both Canadian and international) to gain access to different frequencies and even higher revisit rates.

Summary

The RADARSAT program is a cornerstone of Canada’s technological identity. The journey began with the inspiration drawn from SEASAT and the proven capability of Alouette 1. It matured with RADARSAT-1, a pioneering satellite that operated for 17 years, created the first complete map of Antarctica, and made Arctic shipping safe and efficient.

The program then evolved with RADARSAT-2, a powerful commercial workhorse that introduced advanced technologies like quad-polarization and became a global success. Today, the RADARSAT Constellation Mission (RCM) continues this legacy, using a trio of satellites to provide daily, comprehensive monitoring of Canada’s land, coasts, and Arctic, and providing new tools like “dark vessel” detection.

At the heart of it all is Synthetic Aperture Radar (SAR), the all-weather, day-and-night technology that makes this monitoring possible. The RADARSAT program has not only provided essential services for Canadian security, sovereignty, and economic prosperity but has also delivered invaluable data for disaster management and climate change science around the globe. It stands as one of Canada’s most significant scientific and engineering achievements, a true eye in the sky.