A Vital New Source of Global Geospatial Intelligence
In December 2007, MacDonald, Dettwiler and Associates Ltd. (MDA) launched RADARSAT-2, which provides the world's most advanced commercially available C-band radar imagery. MDA is a key supplier of high-value conventional and operational small satellite missions for public and private customers around the world and innovative solutions for multiple geospatial intelligence applications. The company integrates commercial satellite data into defense and intelligence systems, from strategic command applications to in-theatre support for the warfighter.
The company's heritage as a space mission prime contractor has involved the development of several world firsts, including Anik-C, the first direct broadcast satellite; MSAT, the first mobile communications satellite; and RADARSAT-1, the first commercial remote sensing synthetic aperture radar (SAR) satellite. MDA also launched five small satellites, RapidEye, in August 2008. See story.
RADARSAT-2 is a multi-polarized commercial C-Band SAR satellite serving a follow-on mission to RADARSAT-1. RADARSAT-2 is a powerful tool for collecting global geospatial imagery through cloud cover and darkness. With more than 50 imaging modes, polarimetric options, and huge data volume collection capacity, the near-real-time mission is operationally scalable, with a ground segment that fits into the existing U.S. government infrastructure requirements. See Figure 1.
The Canadian Space Agency and MDA developed a unique public-private partnership to create the RADARSAT-2 mission. MDA designed and built the satellite and ground segment and is responsible for the overall operation of the seven-year mission. The Space Agency's investment in the program will be recovered through the guaranteed delivery of data products for a wide range of Canadian government agencies.
RADARSAT-2 ensures the continuity of all RADARSAT-1 imaging modes. It has an extensive range of new features that improve resolution, polarization sel-ection, tasking and data delivery. Significant improvements include a state-of-the-art phased array SAR antenna composed of hundreds of miniature transmit-receive modules. The antenna can be steered elect-ronically over the full range of a swath and switched instantaneously between operating modes. See Figure 2.
Figure 2. RADARSAT-2 imaging modes and ground resolution.
RADARSAT-2 is an important new data source of global geospatial intelligence. It offers very specific capabilities, the advantages of multi-polarized SAR, and applications of its specialized image products for defense and intelligence communities.
Polarimetry: Increasing the Density and Accuracy of Geospatial Information
Figure 3. The east coast of Greenland and the northern end of the Sermilik fjord are shown here from December 18, 2007, in the first RADARSAT-2 Standard Quad-Pol image, four days after launch. It is a composite of the three radar data channels (HH, VV, HV) displayed in a red-green-blue colour scheme. The scene is ~ 25km x 50km, with 25m nominal resolution.
The Fenrisgletscher glacier—a large, slow moving valley glacier that feeds into the Sermilik fjord—is visible in the upper right corner of the image. Glaciers in this area produce large volumes of icebergs that flow out to sea. In the fjord, variations in colour represent different types of sea ice and leads (open water). The use of polarimetric data greatly improves ice edge detection and the identification of ice types as well as increasing ice topography and structural information. The information provided can be used for ship navigation, and land/sea ice studies such as the position of glacier termini to support environmental monitoring.
SAR polarization refers to the or-ientation of the radar beam relative to the Earth's surface. RADARSAT-2 can send and receive radar waves in both Horizontal (H) and Vertical (V) polarizations to produce co-polarized signals (HH and VV) and cross-polarized signals (HV and VH).
RADARSAT-2 is the first commercial high-resolution SAR satellite to offer quadrature polarization (Quad-Pol) capabilities, effectively four different polarization channels per image, to produce fully polarimetric datasets (HH, HV, VV and VH). Quad-Pol data retains both the amp-litude and phase information of the radar waves, and the relative phase between the channels is also measured. RADARSAT-2 can image with Selective Polarization (HH and HV) or (VH and VV), Single Polarization (HH), Quad-Polarization (HH, VV, HV, VH), or Selective Single Polarization (HH, HV, VH, VV). Figure 3 shows the first Standard Quad-Pol image from the satellite, four days after launch. The information in a Quad-Pol dataset greatly improves the ability to characterize physical properties of objects and to retrieve bio- or geophysical properties of the Earth's surface.
Faster Tasking, More Beam Modes
Improvements in tasking, collection, and dissemination make RADARSAT-2 a powerful surveillance tool. RADARSAT-1 tasking lead time for data acquisition was measured in days; with RADARSAT-2, it is measured in hours. Optimized space and ground systems focused on responsiveness to users places RADARSAT-2 at the forefront of commercial mission TCPED (Tasking, Collection, Processing, Exploitation and Dissemination) levels.
The left- and right-looking capability of the satellite increases its revisit time for Wide Area Surveillance, and the new high-resolution and polarimetric beam modes can provide an effective countermeasure to traditional denial and deception (D&D) techniques, such as camouflage or decoys.
Actionable Geospatial Intelligence for Defense
RADARSAT-2 can play a vital role in multi-sensor surveillance programs for defense and intelligence applications. Its ability to perform regardless of weather conditions or time of day makes it a reliable source of geospatial intelligence for defense applications. Decision makers can receive actionable intelligence products within hours of downlink. The rapid revisit schedule and responsiveness to time-sensitive operations are also important.
The U.S. government has been using data from the RADARSAT family of satellites for 13 years. In that time, RADARSAT missions have established themselves as a trusted and proven source of powerful near-real-time surveillance products.
RADARSAT-2 is an exciting new source of geospatial intelligence for defense users. It offers a broad suite of applications, utility, and flexibility that can be readily integrated into existing U.S. government infrastructure. As the prime contractor for the mission ground segment and the supplier of the U.S. Air Force Eagle Vision transportable multi-satellite ground station, MDA can rapidly enable delivery of RADARSAT-2 imagery to all levels of the American defense and intelligence communities.
The recent successful completion of the U.S. Air Force/MDA space radar Tandem Mission Demonstration Program conclusively demonstrated RADAR-SAT-2's operational responsiveness, inter-operability, and warfighter utility for a broad range of Department of Defense and intelligence community users. During the first half of 2008, MDA provided roughly 5,000 RADARSAT-2 data products in support of a broad range of terrestrial and maritime applications across both the intelligence and warfighter communities. These included PGM (Precision Guided Munitions) targeting, Indications and Warning, broad area Coherence Change Detection, and Maritime Domain Awareness.
Advanced Geospatial Intelligence Products
RADARSAT-2 data can be delivered as raw imagery or as an Advanced Geospatial Intelligence (AGI) product. AGIs are derived from a single SAR image or multiple SAR images that can be single, dual, or quad-polarized, across the range of available resolutions. The information content of the image comes from computer-based algorithms that usually require some form of operator intervention. An AGI product may be considered as a tactical decision aid if the TCPED cycle occurs within hours. In contrast, if the TCPED cycle occurs within days, the AGI product would be a strategic decision aid.
An AGI product may entail quantitative information derived from the image or may be an annotated product containing end-user relevant features and targets. Examples of AGI products for selected defense and intelligence end users include:
- Air Force: Target product showing precise target locations; digital elevation models to support mission planning
- Navy: Ocean features product for operational oceanograph
- Army: Terrain mobility product depicting land classes; coherence change detection or polarimetric change detection for situational awareness
- Marine Corps: Coastal-zone product to support amphibious operations
Expanding on these applications, here are several detailed examples of RADARSAT-2 utility:
Surface Moving Target Indicator
RADARSAT-2 has Surface Moving Target Indicator (SMTI) capability that uses along-track interferometry techniques to estimate the range-direction speed of moving objects. The SMTI information product indicates the estimated speed of detected targets in both terrestrial and maritime environments.
Open Ocean Surveillance
The Open Ocean Surveillance (OOS) value-added product is for ship detection, providing accurate estimates of ship length and direction. Ship class may also be estimated depending on the RADARSAT-2 image mode and resolution. Powerful algorithms automate the production of ship detection information products, requiring limited operator intervention. Rapid production and accuracy create domain awareness in support of naval operations.
Maritime Domain Awareness
RADARSAT-2 data has significant potential to play a key role in support of international Maritime Domain Awareness. Drug transport corridors and illegal vessels typically transit open ocean, avoiding areas that are known to be regularly and accurately monitored by traditional methods and sensors. Detection and interdiction of illegal vessels relies heavily on a wide range of sensors and platforms used in an effort to track suspected targets from their point of origin to their destination.
SAR imagery from RADARSAT-1 has advanced the ability to monitor the world's oceans, particularly in the areas of ship detection, oil spill monitoring, and ocean wave surveillance, as it provides a direct measurement of the surface wave field.
The two basic approaches used for ship detection are detection of the wake signature, and detection of the ship target itself. RADARSAT-2 not only provides continuity to RADARSAT-1, but also offers specific improvements for ship detection applications such as the dual polarization modes that are available in all RADARSAT-2 beam modes.
Figure 4. Ships in a busy port are readily detected and classified in this RADARSAT-2 image.
Figure 5. Thunder Bay, Ontario, Canada, RADARSAT-2 ScanSAR Narrow B with dual polarization (Transmit VV; Receive VH; R:VH G:VH B:VV), taken March 3, 2008.
Widespread ice that has formed on the western edge of Lake Superior can be seen in this colour composite view of the RADARSAT-2 data. ScanSAR Narrow B is well suited to the detection and classification of ice and is used operationally to monitor ice formation and movement in the great lakes due to its large footprint (300 km in width - can cover several hundreds of kms along track) with very good resolution (50m) and frequent revisit (1-2 days at this latitude). This image also appears on the cover of the Fall 2008 issue.
This improvement expands on research done using RADARSAT-1 (C-HH) and ERS (C-VV) SAR data. Results showed that ship-sea contrast is higher for HH polarization, making RADARSAT-1 suitable for target detection. The results also demonstrated that VV polarization provides more information about the sea state for improved detection of ship wakes.
RADARSAT-2's cross-polarized component (VH or HV) enables target detection at smaller incidence angles. The HH/HV combination provides optimized target detection over a greater range of incidence angles than RADARSAT-1, and the VV/VH combination provides both target detection (VH) and the ship wake analysis (VV).
RADARSAT-2's Ultra-Fine beam mode (3-m resolution) improves ship detection and, in combination with fully polarimetric (Quad-Pol) data, offers the potential for ship classification. Figure 4 shows a port scene with ship detection and classification. Polarimetric data are not available on SCANSAR beam modes, which are best suited to ship tracking or to surveillance of regions with limited spatial extent such as small bays and harbors.
RADARSAT-2 complements existing shore-based radar and airborne approaches to monitoring for detecting ships, as well as existing homeland defense and law enforcement doctrine.
A multitude of unmanned aerial vehicles (UAVs), manned aircraft, and opt-ical space sensors would be needed to cover the RADARSAT-2 satellite transit area. The Wide Area Surveillance coverage capability of RADARSAT-2 is an ideal complement to existing persistent surveillance programs employing conventional platforms and sensors. See Figure 5 showing Wide Area Surveillance coverage of Thunder Bay.
RADARSAT-2 is well suited to collecting imagery for detailed change detection. Whether coherence, amplitude, or subsidence change detection, the millimeter elevation accuracy of RADARSAT-2 interferometry provides analysts with access to even the most subtle of environmental changes.
Land Target Detection and Classification
RADARSAT-2's active sensor and multiple beam modes are well suited to target detection and classification. Combined with the superior change detection capabilities and high revisit cycle, an unparalleled volume of current, accurate information of global activities is now accessible to defense and intelligence users.
Global HRTI-3 DEM Potential
SAR imagery has some significant advantages over conventional optical satellite imagery, because the active sensor can image in darkness and through heavy cloud cover. It is also well suited to rapidly collecting and deriving detailed terrain information on a global level for the creation of high-resolution digital elevation models (DEMs).
MDA has been working with the U.S. Air Force on a rigorous evaluation of RADARSAT-2 imagery for the purpose of creating a global DEM to HRTI-3. Previously thought to be little more than an objective for the future, the results have shown that a tandem mission combining RADARSAT-2 and a quick-to-launch clone satellite are more than capable of such a feat, with quality and accuracy levels far exceeding the current baseline SRTM (Shuttle Radar Topography Mission) dataset. See Figure 6 for contrast between SRTM data and RADARSAT-2.
Figure 6. This image illustrates the difference between RADARSAT-2 and SRTM interferometry.
To date, MDA has supplied more than 5,000 RADARSAT-2 images to the U.S. Air Force, where it has been evaluated for interferometric potential (DEM creation), wide-area surveillance, change and target detection, intelligence, mapping, and subsidence. Results and user feedback have been very positive.
RADARSAT-2 was developed with input from operational defense users, and as a result, it has an exceptionally responsive TCPED cycle—a critical factor to consider when merging commercial imagery into defense and intelligence workflow. The mission's flexibility, access, capacity, and imaging capabilities point to the creation of a next-generation global DEM that raises the level of our ability to understand and model the entire planet in the digital domain.
RADARSAT-2 is the world's most advanced commercial SAR mission. It has been designed expressly for high-throughput operational geospatial intelligence users. Its staggering data collection capacity, flexible imaging modes, information-rich data, and unmatched TCPED cycle position it at the forefront of commercial satellite missions for modern defense and intelligence applications. MDA's space and ground segment experience, and its ongoing work to meet changing requirements of defense and intelligence communities, are advancing the level of sensors, algorithms, infrastructure, and applications for next-generation maritime surveillance, target detection, tracking, classification, and change detection.
Credit for all images: RADARSAT-2 Data and Products © MacDonald, Dettwiler and Associates Ltd. (2008) - All Rights Reserved. RADARSAT is an official mark of the Canadian Space Agency.