Mission requirements are tailored to respond to the needs identified by government users and to cover the Canadian and international areas of interest.
The following points list the main areas where the RADARSAT Constellation system will be different from RADARSAT-2:
- Conflicts between main users can be resolved in advance.
Main Operational Modes
The system is designed as a medium resolution mission primarily dedicated to regular monitoring of broad geographic areas. This provides a 'big picture' overview of Canada's land mass and proximate water areas. Combined with higher resolution imagery, the data are expected to dramatically enhance Canada's ability to manage resources and the environment, and to improve security by providing an operational surveillance system. The system also includes high resolution modes at 1 m x 3 m, 3 m and 5 m, primarily designed for disaster management.
rng x az
|HH, VV, HV or VH||VV or HH +HV||HH+VVFootnote 1||Compact||HH+VV+
|Low Resolution 100 m||100||8x1||500 (500)||-22||Yes||Yes||Yes||Yes|
|Medium Resolution 50 m||50||4x1||350 (600)Footnote 2||-22||Yes||Yes||Yes||Yes|
|Medium Resolution 30 m||30||2x2||125 (350)||-24||Yes||Yes||Yes||Yes|
|Medium Resolution 16 m||16||1x4||30 (350)||-25||Yes||Yes||Yes||Yes|
|High Resolution 5 m||5||1||30 (500)||-19||Yes||Yes||Yes||Yes|
|Very High Resolution 3 m||3@35o||1||20 (500)||-17||Yes||Yes||Yes||Yes|
|Low Noise||100||4x2||350 (600)Footnote 2||-25||Yes||Yes||Yes|
|Ship Detection||var.||5x1||350 (350)||variable||Yes||Yes||Yes|
|Spotlight||1 x 3@35o||1||20 (350)
[5 km in az]
|Quad-PolarizationFootnote 4||9||1||20 (250)||-24||Yes|
(Credit: Canadian Space Agency)
The three-satellite configuration will provide on average daily coverage of Canada's maritime approaches and frequent coverage of Canada's land, as well as daily access to 90% of the world to Canadian and international users. The satellites will be equally spaced, 32 minutes apart within 100 m radius orbit maintenance at a 600 km low earth orbit.
One of the most important project objectives is to increase data availability to the main operational users of SAR data in Canada. The system will be available as soon as all the satellites are in orbit and declared operational. The mission will provide data continuity to RADARSAT-1 and RADARSAT-2 users, but the system is not designed to be identical. The mission focuses on core applications and products and the provision of best value for money for the government of Canada. Some advanced features, such as RADARSAT-2's Ground Moving Target Indication (GMTI) mode, are not included. The system performance requirements and data quality (radiometric accuracy) specified for RADARSAT-1 and 2 are maintained. Some aspects of the data quality that were not originally specified for RADARSAT (like ScanSAR beam discontinuities) are now specified based on experience gained through the RADARSAT mission.
For the main system users, the operations should be simplified. Most of the acquisitions in Canada should be pre-planned and data made available to the users in near real-time. In some cases users will process the data; in other cases, specific products will be made available to user organizations.
Coverage, Access and Imaging Time
The mission is designed to respond to core needs at the highest level which can be summarized as:
- Regular coverage of Canada's land mass and inland waters, up to several times weekly in critical periods, for resource and ecosystem monitoring.
The RADARSAT Constellation will provide on average 15 minutes of imaging time per orbit per satellite, with peak imaging of 25 minutes per orbit per satellite outside the eclipse season.
Revisit and Re-look
The RADARSAT Constellation will provide a four-day exact revisit, allowing coherent change detection using an InSAR mode. It will also provide an average daily global re-look capability for several imaging modes. Most of the applications considered require re-look at least daily and an exact revisit once to twice weekly (interferometric change detection applications). Very frequent re-look capability is critical to certain disaster management applications.
Timeliness and Data Latency
The timelines and data latency requirement is highly variable according to the application area. For many ecosystem monitoring applications, data delivered several days or in some cases several weeks later may be sufficient. However, maritime surveillance and disaster monitoring have much more demanding timeliness requirements. For ship detection in Canadian and adjacent waters within Canadian ground station masks, RADARSAT Constellation will provide 10 minute data latency from acquisition to delivery of data, and 30 minutes for other maritime surveillance applications. For global and Canadian disaster management applications, the Constellation will provide 2 hour data latency from downlink to data delivery, and for ecosystem monitoring applications, 24 hour data latency from downlink to data delivery will be provided.
- Footnote 1
Some performance parameters will be degraded for the HH+VV polarization: swath width is reduced by half for the Low Resolution 100 m and Medium Resolution 50 m modes; number of looks in azimuth is reduced by half for the Medium Resolution 30 m and 16 m modes; azimuth resolution is degraded for the High Resolution 5 m and Very High Resolution 3 m modes.
- Footnote 2
For Medium Resolution 50 m and Low Noise modes, there is possibly degraded performance for the last 100 km of the accessible swath.
- Footnote 3
Spotlight mode, there is possibly slightly degraded performance in NESZ for the last 20 km swath.
- Footnote 4
There are no performance requirements for the quad-polarization mode: expected performance is shown.
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