Kevin Rokosh ’s world-leading spaceborne radars give The Engineer’s Copywriter Maria Rey Space Strategies Consulting Ltd. planners and decision makers a unique capability Director General of Defence Research and Development Canada, Lab. (retired) to monitor our ocean territories, aid in resource David G. Michelson University of British Columbia development and assess humanitarian needs.

nytime, ground, the quality and utility of the azimuthal or such images suffer greatly. “along-track” res- anywhere – Radars provide their own olution of SAR illumination and operate at images is indepen- Earth Imaging using wavelengths that easily penetrate dent of range, yield- Spaceborne Radar clouds, fog and smoke, but con- ing the possibility of Since the dawn of the space age, ventional side looking radars creating photograph- orbiting have provided lack the resolution required to like images with high Azimuth planners and decision makers generate useful radar images of resolution. with a unique vantage point the Earth’s surface from orbit. Range from which to routinely observe Canada has made the Earth and gather informa- The advent of Synthetic Aperture significant contribu- tion for applications as diverse Radars mounted on fast moving tions to SAR research, In Synthetic Aperture Radar (SAR), resolution in the as weather forecasting, crop airborne platforms introduced development and azimuth direction is independent of range. SAR was assessment, strategic surveil- the first practical way to generate application during the first developed for airborne application. lance, and geology. Until the high resolution two-dimensional past 40 years includ- late 1970s, however, virtually radar images of the land below.1 ing development of fundamen- international customers. Since all Earth observation from As in conventional radar images, tal SAR image processing tech- the advent of Canada’s space was based on optical the intensity of individual pixels niques and providing SAR program in the mid 1990s, images produced from reflected corresponds to the radar reflec- image processors and systems Canada has played a leading role light in the visible and infrared. tivity of the scene. Unlike con- engineering expertise to major in demonstrating the routine use ventional radar images, however, U.S., European, Asian and other of SAR imagery in both public While optical imagery from and private sector applications. space has proven to be extremely 1 Polarimetric and interferometric SARs go a step beyond conventional SARs and allow special types useful, producing it requires of multi-channel or multi-image SAR data to be processed to yield image products useful in the Today, Canadian decision mak- both adequate illumination and identification of targets, interpretation of target structure, observation of fine ground movement and ers benefit from a wide range of clear skies. At night, or when production of terrain elevation maps. In this manner, the utility of advanced SAR imagery can Canadian-produced SAR image clouds, fog or smoke obscure the fundamentally surpass (and complement) conventional optical imagery. products. Marine surveillance and

10 Spring / Printemps 2016 ice-mapping have become routine width using simple beam- SAR MAKES SPACEBORNE RADAR POSSIBLE applications. Geotechnical map- forming techniques is not suffi- ping and environmental monitor- cient. A simple geometric con- ing are becoming increasingly struction reveals that the width important. Humanitarian disaster of the pixels in the radar image relief is a less common applica- will increase linearly with the A long tion — thankfully — but is of range to the target. antenna is Effective immense benefit when needed. orbits increase that range to synthesized by recording the antenna hundreds of kilometres and reflected pulses lengths of fatally degrade the azimuth received by the SAR several kilo- The “Magic” of SAR as it moves along its metres are resolution. A new approach is possible in this required. orbital track, and (Synthetic Aperture Radar) combining the result using way, required due appropriate techniques. to satellite altitudes. The linear path traversed by the Synthetic aperture radar is simplest form of SAR as it moves based upon the observation that along the scene is called the the energy from a given point track. Resolution in range or the target is spread in both range cross track direction – the direc- and azimuth. In SAR image SAR creates photograph-like images tion in which the radar antenna reconstruction, this dispersed points – is determined by the energy is collected or focused ake Superior is easily rec- ered. The SAR was operating effective duration of the radar into a single pixel in the output Lognized in this RADARSAT-1 in ScanSAR Wide mode, giving pulse. In this respect, SAR func- image using advanced signal image. Taken in late winter, the a swath width of 500 km. tions in the same manner as con- processing techniques. The lake is almost entirely ice cov- ventional radar and conventional underlying principle also forms pulse compression techniques can the basis for the well known be used to improve resolution. A medical diagnostic tool com- monostatic SAR uses the same monly called CAT Scan, short antenna for transmission and for Computer Aided reception and is sensitive to the Tomography, that yields high diffuse waves reflected back resolution images of the body from the target (backscatter using low power X-rays. In radar response). In bistatic SARs, the application, the result is also a transmitting and receiving anten- high-resolution image. But RADARSAT Data © RADARSAT (CSA) 1997 nas are separate.2 unlike conventional side-look- n enlargement of the north ing radar, the azimuth resolu- shore near the east end of Resolution in the azimuthal or tion is independent of range. A along track direction is determined the lake. RADARSAT-1 operated by the radar antenna’s length. It is Such fine and uniform resolu- at an altitude of about 800 km. In well known that an antenna’s tion in both the azimuth and ScanSAR wide mode, the reso- beamwidth becomes finer as the range directions means that a lution of pixels in the azimuth antenna lengthens. There are limits SAR can create photograph-like direction was about 100 m. to how long a physical antenna can images of the landscape, as seen satellite equipped with be realized given the many in the RADARSAT-1 image in Aconventional real aperature constraints imposed upon satellite the sidebar to the right. This is radar operating at the same alti- payloads. However, it is possible the magic of SAR. However, tude would yield a resolution in to synthesize an arbitrarily long because the location of a point the azimuth direction in excess antenna by recording the signal target in a SAR image is based of 5 km. Very little useful infor- received by the SAR as it moves upon the time of flight, not the mation would be obtainable. along its orbital track and line of sight as in an optical combining the result using image, SAR images suffer from rocessing of the appropriate techniques. a characteristic distortion in PRADARSAT-1 image using which higher terrain appears to calibration software and a However, a side-looking radar be folded towards the observer. library of backscatter signatures that simply synthesizes a large This is apparent in SAR allows classification of ice antenna with a very fine beam- images of mountainous terrain. coverage. Image created by George Leshkevich and Son 2 They may even be carried by different platforms, either to permit characterization of forward scatter Nghiem, 2007 [REF: 1] from the target, to allow a secondary receiver to take advantage of existing transmitter in a parasitic Consolidated ice flows Brash ice Stratified ice Calm water mode of operation, or to make it difficult for a third party to detect the receiver.

Spring / Printemps 2016 11 RADARSAT Operating Modes

Stripmap Mode ScanSAR Mode Spotlight Mode he basic SAR configuration modes in order to enhance certain than is possible in conventional In Spotlight SAR, the radar antenna in which the radar antenna is aspects of SAR performance. SAR systems. Canada’s is electronically steered in order to T pointed broadside to the RADARSAT-2 ScanSAR uses two keep the target in view for a longer direction of travel permits formation In ScanSAR, as orginally developed, or more physical beams operated period. Because this extends the of a continuous image of the ground. the radar antenna is electronically sequentially, each producing size of the synthetic aperture, it This is called Stripmap SAR. steered to different angles in order separate image blocks that are increases the azimuthal resolution Synthetic aperture radars can be to illuminate multiple swaths. This then electronically merged of the image but at the expense of configured to operate in other permits a wider area to be imaged together. spatial coverage.

A Brief History of SAR Communications Research early 1990s. The total develop- Centre (CRC) and The Defence RADARSAT ment contract was about $620 The synthetic antenna concept Research Establishment Ottawa In 1990 Canada created the million (almost $1 billion in was first successfully applied to (now DRDC Ottawa). These Canadian Space Agency (CSA) today’s dollars), and the CSA radar by Carl Wiley at the algorithms were shared with within the Department of owned and operated the final Goodyear Aircraft Corp. in 1953. Canadian industry in keeping Industry. The RADARSAT-1 system. The major Canadian He used an aircraft for the mov- with the commercialization man- project was not only its first industrial team members who ing antenna platform and a stor- date of the CRC dating back to major project, but also the designed and built RADARSAT-1 age tube display that was config- its creation in 1969.3 world’s first operational civil- for the CSA included ured to mimic a conventional ian SAR satellite mission. • Plan Position Indicator to present In 1978, a Canadian startup Launched in 1995, the space- (prime contractor, now part the radar returns. SAR literally company, MacDonald, Dettwiler craft lasted nearly 18 years and of MDA Corp.) took flight. [REF: 2] and Associates, won the race to fundamentally changed the • MacDonald, Dettwiler & demonstrate that the general- nature of Canada’s Earth obser- Associates Early data storage and process- purpose minicomputers avail- vation program. • COM DEV International Ltd. ing was only practical using able at the time could be used to • CAL Corporation (now part of Fourier optics. By the mid 1970s, reconstruct a viable SAR image Building on lessons learned, COM DEV International Ltd.) minicomputers with sufficient from data collected by NASA’s Canada developed RADAR- • SED Systems processing power to process SEASAT spaceborne SAR (see SAT-2 and launched it in 2007. • Fleet Industries (now SAR imagery digitally became IEEE Milestone article in the Continuing Canada’s world-lead- Magellan Aerospace Corp.) available. The earliest computer previous issue). In 1979, a CRC- ing role in operational SAR solu- • IMP Group algorithms in this area processed designed processor yielded the tions, we will be launching the • FRE Composites data from airborne SAR, first full-resolution SAR images new three-satellite RADARSAT developed by researchers at the from SEASAT. Constellation Mission (RCM) in In exchange for access to SAR 2018. [REF: 3, 4, 5, 6] data, the National and Space Administration (NASA) 3 Historically, the vast majority of SAR image reconstruction has been conducted using frequency supplied the Delta II rocket used domain processing where computationally intensive convolution operations are replaced by much RADARSAT-1 to launch RADARSAT-1. simpler multiplications in the frequency domain after application of a Fast Fourier Transform. The Canadian spaceborne SAR Canadian SAR researchers played key roles in the development of three of the four common SAR story began with RADARSAT-1, RADARSAT-1 followed a dusk- processing algorithms in use today: Range-Doppler, Chirp Scaling, and SPECAN. A fourth, Omega-K, was developed at Politecnico di Milano in Italy. In recent years, advances in computing launched in 1995. The CSA man- to-dawn sun-synchronous polar technology have made it possible to reconstruct SAR images using direct methods such as back aged the RADARSAT-1 project orbit with an altitude of about projection and thereby avoid the need to satisfy some of the simplifying assumptions inherent to as a key component of the 800km. It always passed over frequency domain approaches. Canadian space program in the the same Earth location at the

12 Spring / Printemps 2016 In 1990 Canada created its Canadian Space Agency (CSA); RADARSAT-2RADARSAT 2 RADARSAT-2 SAR does a bet- the RADARSAT-1 project was its first major crown project. The follow-on CSA project, ter job of discriminating differ- RADARSAT-2 was a direct des- ent surface types and can clas- cendent of the lessons learned sify terrain more accurately. It is same time of day, which was spacecraft. It would revisit its from RADARSAT-1. It was a particularly useful for detecting important for consistent imaging orbital path every 28 days. unique Public-Private Partnership returns from artificial objects, through time and comparison However, it could provide daily (P3) project between CSA and such as ships at sea. Artificial with visible light imagery pro- coverage of the Arctic. This was MDA, with MDA owning and objects tend to incorporate duced by other platforms. It also important, because at the time operating the final system. The right-angled corners and, as a meant downlink ground sta- Canadian Ice Services needed a development contract was consequence, generate strong tions had a consistent window better method to monitor sea ice. approved in 2004 for a total of radar reflections with distinct- of time to receive data sets. RADARSAT-1 had its basic $528.8 million (about $641 mil- ive polarimetric features. [See Being sun-synchronous also operating parameters (C-Band, lion today) – slightly more than sidebar on page 18] meant the satellite’s solar pan- HH polarization) optimized for half the cost of RADARSAT-1. els were almost always in sun- ice mapping. And using one of The Government of Canada RADARSAT-2 also added rou- light, ensuring that RADARSAT-1 its wider but lower resolution contributed $437.1 million to tine look-left or look-right ran primarily from solar rather beam modes, the SAR could the project. Though it had no capabilities. This meant that than battery power. view almost any part of Canada ownership interest in from the same orbital path as within three days, and places RADARSAT-2, the government RADARSAT-1 it could re-visit The on-board SAR payload had near the equator every six days. did receive about $446 million the same Earth locations more the following specifications: in data product credits from often. More frequent image • Frequency band: C-Band, CSA planners had projected a MDA. capture increased the change • Centre frequency 5.3 GHz 5-year lifespan for RADARSAT-1. detection capabilities of the • Bandwidth 30 MHz So when it eventually failed in One limitation of RADARSAT-1 RADARSAT-2 data products. • Polarization HH (Horizontal late March 2013, RADARSAT-1 was its single polarimetry mode transmit, Horizontal receive) had outlived all expectations. It of Horizontal Transmit / While RADARSAT-1 relied • Polarization isolation > 20 dB delivered data products to more Horizontal Receive (HH). mostly on analog tape record- • Aperture length 15 m than 60 countries. But more Previous work had shown that ers, RADARSAT-2 employed • Aperture width 1.5 m important was its legacy as a much more information about solid-state memory devices for • Mass 679 kg civilian-based research tool, the nature of the target can be data storage. With solid-state working hard to advance SAR extracted from radar pulse memory came higher reliability RADARSAT-1 had seven beam Earth observation technologies. returns when a system can oper- and faster access to data. operating modes, with resolu- Though inoperable today, ate with multiple polarizations tions from 8m to 100m RADARSAT-1 still follows its in both transmit (TX) and Finally, RADARSAT-2 could use (depending on the mode) but dusk-to-dawn orbit — one more receive (RX). With flexible GPS to geo-locate itself to +/- could only look-right from the piece of space junk now. polarimetry modes, 60m on orbit in real-time.

RADARSAT-1RADARSAT-1 RADARSAT-2 (Inoperablenoperable as of 2013)2013) (2007JPresent)esent)

• Left or right looking • 17 Beam modes • Selective H and V • 7 Beam modes polarization on • 1 Beam polarization (H) transmit and receive • 8mJ100m resolution • 1mJ100m resolution

Spring / Printemps 2016 13 RADARSAT CONSTELLATION MISSION (Expectedected launch 2018)2018)

• 3 identical satellites • Right looking only (multiple satellites eliminate left looking requirement) • 10 Beam modes • Selective H and V polarization on transmit and receive • 1mJ100m resolution • On-board AIS

The constellation as a whole improves the time- availability of image updates. Conceivably, the constellationation could bbee expanded to six satellites. They will pass over the Northwest Passage anddth the rest t of fC Canada d several lti times per dday.

RADARSAT-2’s SAR has the launches that could compete with Defence (DND) that SAR is a The constellation will also fol- following specifications: their own interests – commercial real solution to help monitor low a sun-synchronous polar • Frequency band: C-Band and security. A launch contract Canada’s marine traffic, all the orbit, but at 586km – lower than • Centre frequency 5.405 GHz was instead awarded to the way out to 2,000 nautical miles. RADARSAT-2. Space Explor- • Bandwidth 100 MHz Russians, and RADARSAT-2 was ation Technologies (more com- • TX/RX Polarization HH, VV, delivered into orbit on a Soyuz Over about five years, begin- monly known as SpaceX) has HV, VH FG rocket. ning in 2005, the Government been awarded the contract to • Polarization isolation > 25 dB of Canada spent $216 million launch all three RCM satellites • Aperture length 15 m RADARSAT Constellation on RCM concept studies with on one Falcon 9 launch vehicle. • Aperture width 1.37 m MDA Corp. In 2013, the gov- • Mass 750 kg Mission (RCM) ernment entered a $706 million As a constellation, there’s no For about five years, both fixed-price contract with MDA longer a need to have both left- The SAR has 17 beam modes that RADARSAT-1 and RADAR- Corp. to complete operational and right-looking SAR features. achieve resolutions from 100m SAT-2 co-existed. This provided development of the RCM. The constellation as a whole down to 1m. It can look left or an opportunity to combine SAR improves the time-availability right from the spacecraft (but not data from two separate satellites RCM will initially launch three of image updates. If required, both sides simultaneously). and made it easier to collect identical SAR satellites in 2018. the constellation could later be interferometric data sets (see The final system will be owned expanded to six satellites. Designed to last seven years, sidebar on pg 17 for explanation and operated by the CSA. The RADARSAT-2 has already of InSAR) to be used in the cre- major Canadian contractors Each RCM satellite will have exceeded its lifespan. It was ation of geophysical elevation delivering the space project are: the following specifications: launched in 2007, but not after data for monitoring land struc- • MDA Corporation • Frequency band: C-Band some push-back from U.S. gov- tural stabilities. The results • COM DEV International Ltd. • Centre frequency 5.405 GHz ernment policy. The original showed the value of having a • Magellan Aerospace Corp. • Bandwidth 100 MHz plan was to utilize another constellation of SAR satellites • Polarization HH, VV, HV, VH, NASA-led Delta II rocket working cooperatively to image Working as a constellation, Compact Polarimetry launch. the Earth. these satellites will monitor the (Circular TX, H&V RX) Arctic with four overhead pass- • Polarization isolation > 30 dB But at the time, U.S. government But moreover, the ship detection es daily, and will pass over the • Aperture length 6.75 m policy evolved to frown upon capabilities of SAR proved to Northwest Passage and the rest • Aperture width 1.38 m supporting foreign technology the Department of National of Canada several times per day. • Mass ~400 kg

14 Spring / Printemps 2016 Each satellite will have 10 beam modes with resolutions from 100m down to 1m. Its ship Automatic Identification System (AIS) detection mode should be able to detect vessels down to at least utomatic Identification System tion of satellite surveillance, a more It allows maritime operations control- 25m in size. To support the (AIS) is a ship-to-ship and complete picture of maritime traffic lers like the DND to quickly discern DND’s operational objectives Aship-to-shore transponder flow and control can be achieved. known vessel traffic from unknown, for marine surveillance, the based system of identifying marine perhaps rogue vessels. RCM will also have an vessels. AIS-equipped ships broad- The rules of the International Automatic Identification cast identification, heading, ship size Maritime Organization mandate that exactEarth Ltd. (jointly owned by COM System (AIS) payload. [See and type, and hazardous cargo infor- most ships greater than 300 gross DEV International Ltd. and HISDESAT sidebar to the right]. The SAR mation. Other ships use this to aid in tonnage operate AIS transponders. Strategic Services, S.A) has a com- and AIS systems can be used in collision avoidance and shore sys- Today, more than 60,000 ships world- mercially operating constellation of 7 synergy to improve ship tems use the data to manage mari- wide carry AIS transponders. The AIS satellites providing global ship detection. SAR can image time control. AIS signals can also be data AIS provides is valuable to detection capability. Since 2012 they vessels whose transponder received by satellite, and RCM will accurately tag and identify vessel have been under contract to provide signals are not detected by AIS, have an on-board AIS. With the addi- traffic identified by space borne SAR. data to the CSA and DND. [REF: 8] and vice-versa.

The later introduction of differ- potentially locate productive SAR Data Marine Surveillance ently polarized radar pulses fishing grounds. Construction of Canadian expertise in this par- greatly enhances SAR vessel new islands in disputed waters Applications ticular application of SAR recognition capability (see can be detected. Canada has three primary inter- actually began emerging in the sidebar on pg. 18 for polariza- ests in using SAR imagery: late 1970s. Defence Research tion techniques). Reflected • Maritime surveillance and Development Canada cross-polarized backscatters Marine Wind (ice, surface wind, oil pollution (DRDC), the Science and provide well-correlated sea- Monitoring and ship monitoring) Technology arm of the state wind speeds. The ocean • Ecosystem monitoring Department of National Defence, surface appears fuzzy, and ship From hurricane monitoring to (agriculture, wetlands, forestry had been developing high-reso- returns stand out clearly. The wind farm site selections, SAR and coastal change monitoring) lution airborne SAR signal pro- resulting picture can be used data can be used to build ocean • Disaster management cessing algorithms for military for monitoring ocean traffic. surface wind-speed images. (mitigation, warning, response coastal surveillance applications. and recovery) In June 1978, NASA’s Jet The DND has integrated SAR The radar cross-section (the Each RADARSAT mission has Propulsion Laboratory launched imaging into their Polar Epsilon effective area that an object pre- included project objectives to Seasat, the first Earth-orbiting maritime surveillance system. sents to a normally incident meet these application demands. SAR-equipped satellite designed Ground stations use satellite radar pulse) of ocean wave sur- And RCM will continue to sup- for remote sensing of the Earth’s SAR data to aid the DND with faces correlates well with wind port these objectives. RCM also oceans. Although it functioned monitoring naval traffic around speeds. The intensity of the continues the research oppor- for only about three months, all of Canada’s coastal waters, ocean surface returns tends to tunity to expand the scope of Seasat produced a wealth of east, west and north. When increase with the wind-state of applications through further ocean imagery. combined with AIS ship data, the ocean. Cross-polarized SAR operating mode analysis pro- positive maritime ship tracking, returns can be used to further jects in Canada and around the Applying their expertise in air- of both friendly and rogue ves- refine estimates of the wind world. [REF: 7] borne SAR surveillance, DRDC sels, becomes possible. In fact, state of the sea. The SAR data scientists were able to exploit the DND’s next generation can be used to build wind maps Coast-to-Coast-to-Coast – the vast number of Seasat Polar Epsilon-2 project will to help identify the best sea- images made available, includ- employ the RCM for this very based locations for wind farms Keeping an Eye on ing many of ships and their purpose, using the co-located – often a better option than pla- Our Oceans wakes, imaged in varying ocean AIS system on board each sat- cing them on land. [REF: 12] Continuous monitoring of conditions. With colleagues ellite to enhance the system’s Canada’s vast ocean frontiers from Natural Resources Canada capabilities. [REF: 9, 10, 11] Useful for disaster prediction would be a tedious, time-con- (NRCan) and the Canadian and response, though, are the suming impracticality if we did Coast Guard, they began evalu- Since SAR imaging produces hurricane maps that can be it all at the Earth’s surface. With ating the use of space-based detailed land maps, the world’s built. Optically, we rely on map- space-based SAR data, even SAR for monitoring ship traffic coastal areas can be monitored ping the change in cloud cover from the first generation off Canada’s coasts. So when for changes over time too. to predict a hurricane’s trajec- RADARSAT-1 system, Canada RADARSAT-1 was being Observers can routinely map and tory. But if wind speed can be enhanced its overview of off- designed, its benefit in this area compare coastal erosion, mon- correctly extracted from the shore interests. was well understood. itor aquaculture activities and data within the SAR return

Spring / Printemps 2016 15 image, then forecasters can routes and aid supply trips to Making comparative maps of growth and use, agricultural land more accurately monitor and offshore exploration, research polar ice over months and years use, and wetland growth or ero- predict a hurricane’s destructive and drilling operations. also allows us to measure and sion. These types of SAR images path. SAR can see through the report the changing effects of can also be used to monitor land swirling cloud cover down to “RADARSAT data has proven to global warming. The breadth and use threats to wildlife, including the ocean surface, and provide a be a very cost-effective way of depth of our ice will help us know Polar Bears around Hudson Bay, dimension to hurricane analysis monitoring ice conditions where we stand on the global or Grizzlies in the National that has not been previously throughout Canadian waters and temperature continuum. From the Parks. Officials can make better available using optical imagery. has enabled us to expand our beginning of our SAR story, informed land management service and reduce the Canadian Canada has supported these decisions to protect our wildlife Ice Services budgets by about $6 global interests. In 1997, we habitats and their biodiversity. Ice Mapping million dollars a year in terms of helped to produce the first seam- With our large polar ice areas, data acquisition.” - B. Ramsay, less image of Antarctica using Combining SAR images with shrouded in darkness through- Canadian Ice Services [REF: 13] RADARSAT-1 data. [REF: 16] optical satellite imagery vastly out the winter, SAR imaging increases the utility of the data. provides detailed ice mapping Processing the intensity of the During Manitoba’s “Flood of the capabilities. RADARSAT-1’s SAR return data creates ice Oil Spill Monitoring Century” in 1997, RADARSAT-1 design was optimized for this. maps that ships can use to safely Like ice, oil also displays an image data was overlaid on maps Experience has confirmed the navigate our waters. Sea ice easily detectable SAR reflection of the Winnipeg area. The practicality of using radar data reflections are far more coherent characteristic. Detailed map- Canadian Forces were able to see to produce daily ice maps than returns from ocean water. ping and tracking of oil spills washed-out roads and bridges throughout the year and use Different ice types themselves allows accurate deployment of that couldn’t be used. They them to chart safe shipping display measureable reflection marine clean-up efforts, saving directed their relief efforts characteristics too, time and possibly saving sensi- around the obstacles and quickly especially if cross- tive coastal areas from environ- got aid on the ground to where polarized backscatter mental disasters. people needed it. [REF: 17] returns are available. [REF: 14] The Compact Land and Environmental Frequent satellite overpasses of Polarimetry mode of Monitoring Lead to a particular location also allow the RCM provides a detailed image building. promising tool to map Disaster Relief Interferometric SAR (InSAR) large ice-area SAR Poor ambient light, clouds, and can be accomplished using one swaths with very use- difficult physical access create SAR satellite operating in so- ful ice-type content. barriers to detailed land map- called Spotlight mode: taking [REF: 15] ping. None of these stand in the many localized snapshots of a way of SAR. Radar backscatter smaller area during the satel- returns can be correlated to vari- lite’s overhead tracking time. ous land matter, like forests, grasslands, lakes, mountains and But results are more efficiently urban development. obtained — with higher resolu- tion possibilities — if SAR data Land Monitoring and can be combined from more than one satellite passing over- Cartography head in a small time window. The polarization response of a From this data a stereographic target is sensitive to the struc- 3-D image can be built. This ture and spatial arrangement of produces a detailed Digital surface and vegetation features, Elevation Model (DEM) that like forests, grasslands and wet- can be used to prepare engineer- lands. Radar scattering proper- ing site drawings and opens the ties can be used to retrieve geo- possibility to remotely monitor physical and biophysical param- site integrity. eters such as soil dielectric con- stants, ground surface rough- K. Mattar and J. Secker at ness, slope as well as forest Defence R&D Canada looked at Upper Image: Red River Floodway, spring 2007. Photo Credit: Natural Resources Canada 2012, courtesy of height and biomass. the feasibility of using the Geological Survey of Canada (Photo 2000-118 by G.R. Brooks) RADARSAT Spotlight Mode Lower Image: RADARSAT-1; dark areas represent flooding. The Floodway was able to provide protection for the city of Winnipeg; a ring dike around the town of Morris keeps the waters at bay. Photo Credit: The resulting geophysical and InSAR data to monitor the land- RADARSAT Data © Canadian Space Agency (CSA) 1997 ; data enhancement and interpretation by Canada biophysical SAR images can be fill integrity at four of Canada’s Centre for Remote Sensing used to better manage forestry decommissioned Distant Early

16 Spring / Printemps 2016 Warning (DEW) Line radar Along the same lines, pipeline Already mentioned was the sup- program jointly sponsored by sites. These remote sites are corridors can be monitored port SAR provided in response NASA and the Indian Space strung across the Canadian with SAR images. Geological to the 1997 Manitoba “Flood of Research Organization (ISRO) — Arctic from Alaska to shifts that might indicate the Century.” Earlier, though, dubbed NISAR — is a good Greenland. To maintain unstable slopes or similar RADARSAT-1 images were used example. With broad capability Canada’s stewardship of the instabilities before a ground to support humanitarian relief to measure changes to the earth’s North, we need to monitor these team needs to be dispatched. assistance during the 1994-1996 surface through polarimetric sites for landfill changes like Remote oil pipeline breaks Rwandan “Great Lakes Refugee InSAR, it will assess the extent surface slides, soil depressions, might be seen earlier if sam- Crisis.” Millions of Hutu refu- and severity of damage in nat- water ponding, frost-induced pled with the appropriate beam gees massed in the Great Lakes ural disasters, and will have a changes and even human altera- mode. region of Africa. Comparing host of other humanitarian tions. [REF: 18] before and after RADARSAT-1 applications. A launch date by Wildfire mapping, hurricane images, ground picture changes 2021 has been suggested by the Mattar and Secker found the monitoring, catastrophic flood- were easily seen. This allowed ISRO. [REF: 19, 20] concept is feasible, though it ing – if we can’t predict the pin-point determination of refu- really needs a better coherent disaster we can use SAR gee encampments and even repeat imaging cycle than the imaging data to support our showed new obstacles on nearby Spaceborne Earth 24-day cycle offered by relief efforts. Pre- and post- airstrips, likely making them Observation — RADARSAT-2. The upcoming tsunami SAR images were unusable to support delivery of launch of the RCM will address used to assess coastline dam- humanitarian shipments. Canada’s Legacy this shortcoming with its four- ages and to help direct aid and day coherent repeat visit interval. rescue efforts after the South SAR continues to be a key tech- The capability for monitoring Asian ocean tsunamis of nology for the relief of human of Canada’s natural resources Also, Mattar and Secker pro- December 26, 2004. suffering. A new SAR satellite from space began with the cre- pose a method to aid surface ation in 1971 of the federal deformation monitoring in the government’s Canada Centre for future: place radar corner Interferometric SAR (InSAR) Remote Sensing (CCRS), reflectors at key geographic recently renamed the Canada measurement points to “ampli- A technique for taking Centre for Mapping and Earth fy” the return. From such a SAR samples of the Observation (CCMEO). This reflector, a SAR signal return same area from slightly coincided with the advent of would have an expected con- A different overhead earth observation satellites such stant amplitude and site-sur- 1 as ERTS (Earth Resources tracking paths and veyed location. Over time, it θ Technology Satellite, later would be possible to build a estimating terrain elevation renamed Landsat), which could centimetre-accurate SAR from differences in the phase return high-resolution imagery image of the reflector’s loca- component of the radar returns. of the ground in several differ- tion – opening the possibility r(t2) Uses one SAR Satellite in ent optical wavelengths or spec- to detect minor surface move- r(t1) tral bands. Spotlight Mode, or two ments before they become h major catastrophes. SAR Satellites with Through the CCRS, the newly well-planned available data products could be successive Disaster Management z(t2) reliably obtained by policy and Humanitarian Relief passes. makers, decision makers and Surface deformation the general public. Monitoring Using InSAR, key geographic and managing of Canada’s zz(t(t1) locations around the globe can natural resources were be monitored for disaster fundamentally changed. Over O y response. Minute changes in the the next few decades, optical height of terrain in the vicinity Earth observation satellites of volcanic structures can be Civil Engineering InSAR Applications proved their value and steadily measured, enhanced if necessary increased in number, ble to detect changes in ele- sections, and monitoring the stabil- with corner-reflector markers. sophistication and capability. vation in the order of a centi- ity of slopes in roads, reservoirs, etc. The results can be used by A metre or less, InSAR is becoming The increased frequency of InSAR authorities to alert the nearby Beginning with the RADARSAT-1 increasingly important in ensur- data to be available with RCM will population of an impending project, the Canadian govern- ing the safety of large civil reinforce this trend. Development of eruption. Similar InSAR ment has had a specific policy engineering installations. Appli- such commercially viable data prod- mapping can be applied to aid objective to produce and operate cations include monitoring move- ucts is key to supporting ongoing prediction of flash floods and the most advanced SAR-based ment of bridge footings and pipeline remote sensing research. landslides. earth observation satellites in the

Spring / Printemps 2016 17 world. We were the first to mar- The sidebar to the right lists the the Canadian land and ocean THE TOP ket with an operational civilian Canadian Government organiz- scape. This list implies how Canadian spaceborne SAR in 1995, and ations that use RADARSAT-2 valuable SAR Earth observation are continuing to lead into the data. Each has a mandate that has become to our national Government future with RCM. covers wide remote swaths of interests. Of particular note, organizations Canada today is the global fore- that use runner in space-based Maritime Domain Awareness; although RADARSAT-2 data* are: Horizontal-Vertical-Circular government led, integral to this success is the strong participa- 5 EM Wave Polarization tion of industry and academia. • Canadian Ice Services •Department of National Defence lectromagnetic (EM) fixed point in space. Often, the CSA’s RADARSAT-2 Project •Natural Resources Canada waves are polarized in one polarization state divides into was a Public-Private Partnership. E of three basic senses: hori- randomly polarized or /unpolar- At the project conclusion MDA •Canadian Space Agency zontal, vertical or elliptical/circu- ized/ and fixed or /fully polarized became the owner and operator •Canadian Coast Guard lar. The amplitude of each polar- components. The fully polarized of RADARSAT-2. This put MDA (Department of Fisheries and Oceans) into the business of selling SAR ized EM field vector (E) will oscil- component is completely speci- (*as of 2009) late with respect to the normal fied by a 2 x 2 complex-valued ground station equipment and [REF: 5] image data nationally and inter- pointing direction of the antenna. polarization scattering matrix nationally. However, it’s been a An antenna tuned to transmit in referred to orthogonally polarized business of first educating the UTIAS-SFL built and launched one polarized sense will likewise bases, e.g., horizontal and verti- users. It is one thing to identify the twin nanosatellite mission be tuned to receive that sense. cal, right and left circular, etc. By usable SAR data. It’s another CANX-4 and CANX-5. It suc- Earth reflections (ground struc- comparing the polarization states thing to develop actual user read- cessfully proved that two satel- tures, vegetation, ice, ships, vary- of the incident and reflected iness to put that data to work. lites can orbit in close proximity ing soil moisture, etc.) provide waves, much can be inferred The market development con- and even maneuver around each unique radar reflections based on about the geometry and sym- tinues to evolve. For example, other at the same time. Perhaps the incident polarized EM waves. metry of the radar target. MDA has SAR product contracts this points in the direction of with the oil industry, European Canada’s next generation space- The polarization state of an elec- Thus, polarization response sup- agencies and the US Department based SAR constellation. tromagnetic wave describes the ports both identification and clas- of Defence. Canadian SAR behaviour of the electric field sification of targets seen in SAR expertise has become an inter- In March 2015, Magellan vector over time as observed at a imagery. national export product. Aerospace and the University of Manitoba (U of M) launched The RADARSAT family of their new Advanced Satellite Polarization Scheme CSA space missions have Integration Facility (ASIF) Vertical fostered the development of the inside Magellan’s Winnipeg Polarization Canadian aerospace industry. buildings. The ASIF can sup- The legacy is wide and deep. port all three RCM satellites in Canadian universities like 6,000 square feet of ISO Class 8 University of Toronto, cleanroom space. Magellan will University of Manitoba and use the ASIF to assemble and E Circularrc University of British Columbia test the RCM satellites. And it Polarizationlaa have industry-partnered positions the company to win research and development more national and international programs that feed engineering satellite assembly projects. and science talent into the Canadian aerospace industry. Magellan went beyond provid- E ing real estate for the ASIF. The University of Toronto They also used $625,000 to cre- Institute for Aerospace Studies ate an Industrial Research Chair Horizontal – Space Flight Laboratory in satellite development at U of Polarization (UTIAS-SFL) has been doing M’s Faculty of Engineering. exciting work on micro/nano- Together, the ASIF and the satellite spacecraft. These satel- Chair give faculty and students lites are about half the size of a opportunities for world-class E typical bar fridge, whereas research and hands-on experi- RADARSAT spacecraft are ences in satellite technology more the scale of a small car. development.

18 Spring / Printemps 2016 The RADARSAT family of CSA space missions have fostered the development of the Canadian aerospace industry. The legacy is wide and deep.

The University of British Moving west, the prairies are Columbia has a long history of home to Saskatoon-based SED Application GeographicGeographic SAR End Use collaborating with MDA in the Systems, a major supplier of Coverage PolarizatioPolarizationn areas of SAR image reconstruc- satellite ground stations to the ModeMode tion and image interpretation. . In B.C., From 1992-2007, MDA spon- 3V Geomatics of Vancouver pro- Ice and iceberg Great Lakes, Coastal Dual co-cross Ice Charts sored an NSERC Industrial vides InSAR data analysis servi- monitoring zones (3 oceans), Research Chair in Radar Remote ces in support of the oil and gas, Shipping lanes Sensing that was held by SAR mining, infrastructure manage- pioneer Ian G. Cumming. Many ment, and offshore sectors. Also MMarinearine winds G Greatreat Lakes, CCoastaloastal n/a Weathe Weatherr of the graduate students trained in Vancouver, UrtheCast Corp., zones (2 oceans) forecasts under the Chair went on to which has announced plans to become MDA employees. More build, launch and operate the recently, MDA has begun to col- world’s first fully-integrated, Oil pollution Shipping lanes, Dual co-cross Integrated Satellite laborate with the UBC Radio multispectral optical and SAR Coastal zones Tracking of Pollution Science Lab to develop more commercial constellation of Earth (ISTOP), sophisticated models of radar tar- Observation satellites, to be Spill response gets in both terrestrial and mari- deployed over multiple launches time environments. expected in 2019 and 2020. ShipShip detection 1200nm Dual co-cross DomainDomain aawarenesswareness (above 42° N) product Numerous other universities have also participated in satellite or Continuing Our Forestry Forest areas of Quad State of the forest interplanetary missions includ- Proud Heritage of Canada report ing: Alberta (U. of), Athabasca, Calgary (U. of), Dalhousie, Innovation Protected Parks and Quad Chan Changege mamapp Guelph (U. of), Lethbridge (U. aareasreas aandnd se sensitivensitive aareasreas of), McMaster, Montréal (U. de), Canadian government agencies, wilwildlifedlife hhabitatabitat New Brunswick (U. of), Québec universities and industry have à Montréal (U. du), Royal been playing a world-leading Agriculture Cultivated land in Quad Crop classification, Military College, Saint Mary’s, role in advancing Earth Canada crop yield products, Saskatchewan (U. of), Simon observation using SAR. For our tillage practice Fraser, Victoria (U. of), Waterloo small population, we have the product (U. of), Western Ontario (U. of), second biggest country in the and York. world to keep watch over. By WWetlandsetlands Wetlands in CCanadaanada Q Quaduad C Changehange mamapp building a space-based observation While MDA Corp. plays a lead- system like RADARSAT to help Coastal change Coastlines 3% TBD Change map ing role in the industry side of keep an eye on it all, we’ve highly sensitive Canada’s SAR efforts, many leveraged some of the best other Canadian companies are engineering talents our country DiDisastersaster CanadianCanadian urbaurbann Variable Risk mapsmaps playing important roles in SAR has ever produced. mitimitigationgation areasareas, TransportTransport anandd and in other satellite-related enerenergygy corridorcorridorss technologies. Examples include: We are well positioned to take Array Systems Computing, Inc advantage of recent trends in Disaster River basins, Variable Warning bulletins of Toronto, which provides spaceborne remote sensing. warning Geohazard risk areas technical investigations and With further electronics mini- software engineering support aturization and faster process- services to develop signal pro- ing speeds, there will be more Disaster Global Variable SSituationalituational cessing and display software for “small” SAR-equipped satel- rresponseesponse awareness; damagedamage SAR and related fields; PCI lites (500 kg or less). A whole assessment Geomatics, based in Toronto host of microsatellites are also and Gatineau, which provides under development—less Disaster Global Dual co-cross Maps specialized tools for processing capable, yes, but less expensive recovery or Quad SAR data in a standard remote as well. These will complement sensing or GIS environment. traditional large satellites. [ Information in table extracted from REF: 7 ]

Spring / Printemps 2016 19 At the same time, the techno- [3] Canadian Space Agency, “Earth“Earth [11][[11] NationalNational DefenceDefence andand thethe CanadianCanadi [16]Canadian Space Agency, “Antarctic Observation Satellites,” [Online], Armed Forces, Polar Epsilon 2, Mapping Mission (AMM), logical advances mentioned http://www.asc-csa.gc.ca/eng/ [Online], http://www.forces.gc.ca/ [Online], http://www.asc-csa. above are opening up new possi- satellites/default-eo.asp en/business-defence-acquisition- gc.ca/eng/satellites/radarsat1/ guide-2015/joint-and-other- antarctic.asp bilities for satellites in time-sensi- [4] Treasury Board of Canada Secretariat, systems-19.page tive applications such as Maritime “Status Report on Major Crown [17] S. Simonovic and T. Birkenstock, Domain Awareness. Until now, Projects,” [Online], https://www.tbs- [12] P.W. Vachon and J. Wolfe, “C-Band Database Subgroup Co-Chairs, raw data has been transmitted to sct.gc.ca/dprrmr/2007-2008/inst/csa/ Cross-Polarization Wind Speed “Red River Flooding Final Report,” ground stations in a relatively st-ts04-eng.asp Retrieval,” IEEE Geoscience and International Red River Basin Task Remote Sensing Letters, vol. 8, no. Force of The International Joint [5] Public Works and Government slow process, given the volume of 3, pp. 456-459, May 2011 Commission, May 2000 data. Onboard processing of SAR Services Canada, “Evaluation of the RADARSAT-2 Major Crown [13] Canadian Space Agency, “Maritime [18] K. Mattar and J. Secker, “Coherent data will mean that immediately Project,” Project Number: 570-2782- Surveillance,” [Online], http:// Stacks of RADARSAT-2 Spotlight useful information can be sent 3, September 2009, [Online], http:// www.asc-csa.gc.ca/eng/satellites/ Mode Interferometry Data for directly to decision makers, rath- www.asc-csa.gc.ca/pdf/eng/ radarsat/maritime.asp Monitoring Arctic DEW Line Clean- publications/er-5702-7823.pdf Up,” IEEE Geoscience and Remote er than waiting for ground sta- A. Kaur and S.S. Kang, “Sea Ice [14] Sensing Symposium 2015, Milan, [6] The Canadian Press, “Controversial Detection using Synthetic Aperture tions to first construct the Italy, pp. 1519-1522, [Online], http:// Canadian satellite mission to Radar Algorithm in Image imagery. cradpdf.drdc-rddc.gc.ca/PDFS/ proceed,” [Online], http://www. Processing,” International Journal unc195/p801998_A1b.pdf cbc.ca/news/politics/controversial- of Computer Applications, vol. 121, Future articles will explore a canadian-satellite-mission-to- no. 13, July 2015 [19] NASA, “NASA-ISRO SAR Mission proceed-1.1341208 (NISAR),” [Online], http://nisar.jpl. range of novel satellite trends, M. Dabboor and T. Geldsetzer, “On [15] .gov/ including the capabilities of [7] Canadian Space Agency, “The The Classification Of Sea Ice Types upcoming Canadian nanosatel- RADARSAT Constellation Mission,” Using Simulated RADARSAT 20] Geospatial Media and April 18, 2013 [Online] http://www. lites (weighing one kilogram or Constellation Mission (RCM) Communications, “NISAR will set asc-csa.gc.ca/pdf/eng/publications/ Compact Polarimetric SAR standards for future collaborations less) and the combining of SAR radarsat-constellation-eng.pdf Parameters,” American Society for between NASA and ISRO says Dr. data with that of other remote [8] H. Ball, Satellite AIS for Dummies, Photogrammetry & Remote Sensing Paul Rosen,” April 15, 2016, sensing technologies. ■ Special Edition, John Wiley & Sons 2014 Annual Conference, [Online] https://www.youtube.com/ Canada, Ltd., 2013. Louisville, Kentucky. watch?v=WFXV5HMoKIE ■ [9] P. W. Vachon and R. Quinn, References “Operational Ship Detection in [1] G. A. Leshkevich and S. V. Canada using RADARSAT,” IEEE Nghiem, “Satellite SAR Remote Geoscience and Remote Sensing N.Ed. A five-part series on radar remote sensing was published Sensing of Great Lakes Ice Cover, Symposium 2014, Québec City, in the IEEE Canadian Revieww in issues #19 to #23 inclusive Part 2. Ice Classification and Québec, pp. 998-1001, [Online], (Spring 1994 to Fall 1995). The topics included the latest Mapping,” J. Great Lakes Res., http://cradpdf.drdc-rddc.gc.ca/ commercial and government-operated airborne SAR systems, vol. 33, pp. 736–750, 2007 PDFS/unc197/p802388_A1b.pdf DND’s Spotlight SAR project, and the design and capabilities of [2] C. A Wiley, “Synthetic Aperture [10] National Defence and the Canadian the then yet-to-be launched RADARSAT-1 satellite. Those Radars – A Paradigm for Technology Armed Forces, “Polar Epsilon Project,” Evolution,” IEEE Trans. Aerosp. [Online], http://www.forces.gc.ca/en/ interested in the background to Canada’s current leadership in Electron. Syst., vol. AES-21, pp. 440- news/article.page?doc=polar-epsilon- remote sensing will find these articles a most worthwhile read. 443, May 1985 project/hnps1uo5

About the Authors

Kevin Rokosh is Maria Rey is the David Michelson Maria Rey bio a freelance writ- former Director is with the ...continued er who helps General of Def- University of detection off Canada’s coasts. engineering and ence Research British Colum- She retired from DRDC in technology com- and Development bia, Department 2014 and is now Vice President panies with their writing pro- Canada, Ottawa Laboratory. of Electrical and Computer and Chief Science Advisor jects. He received his BSc in First joining Defence Research Engineering in Vancouver, with Space Strategies Electrical Engineering from Establishment Ottawa (DREO) where he leads the Radio Consulting Limited in Ottawa; the University of Alberta in in 1984, her early work was in Science Laboratory. He cur- contact: [email protected] 1988 and has been an IEEE the area of SAR signal and rently serves as the Canadian member for more than 25 image processing with an Representative for Com- years. He spent his engineer- emphasis on RADARSAT 1 mission F (Radio Wave David Michelson bio ing career working on air traf- and other space-based and air- Propagation and Remote ...continued fic control radar systems for borne imaging radars. In 1995, Sensing) of the International Governors of both the IEEE Transport Canada and Nav she founded the Radar Data Union of Radio Science Communications and Veh- Canada. He’s also an accom- Exploitation group, leading (URSI) and is Editor of the icular Technology Societies. plished road and track cyclist the development of SAR Wiley/IEEE Press Series on He is immediate past chair of and cycling coach. He can be imagery analysis, including Vehicular Technology. He is a IEEE Canada’s Industry reached at: copy@Kevin automatic ship and wake Member of the Boards of Relations Committee; contact: Rokosh.com (continued in 4th column...) (continued in 4th column...) [email protected]

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