Sentinel-1
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| Sentinel-1 | |
|---|---|
 Rama · CC BY-SA 2.0 fr · source | |
| Name | Sentinel-1 |
| Mission type | Earth observation |
| Operator | European Space Agency |
| Manufacturer | Thales Alenia Space, Airbus Defence and Space |
| Launch mass | 2300 kg |
| Power | 5.9 kW |
| Instruments | C-band Synthetic Aperture Radar (SAR) |
| Orbit | Sun-synchronous orbit |
| Programme | Copernicus Programme |
Sentinel-1 is a series of polar-orbiting radar imaging satellites developed under the Copernicus Programme and coordinated by the European Commission with major implementation and operations by the European Space Agency and the European Organisation for the Exploitation of Meteorological Satellites. The constellation provides day-and-night, all-weather surface imaging using C-band Synthetic Aperture Radar to support environmental monitoring, maritime surveillance, disaster response, and scientific research. Sentinel-1 underpins numerous operational services delivered by the Copernicus Services and has been integrated into workflows of institutions such as the European Centre for Medium-Range Weather Forecasts, the European Environment Agency, and national agencies across Europe.
Overview
The programme was conceived within the framework of the Copernicus Programme to provide continuity with legacy missions including ERS-1, ERS-2, and ENVISAT. Design objectives emphasized systematic, routine interferometric and wide-swath imaging to enable Interferometric Synthetic Aperture Radar time series, sea ice monitoring, and rapid response to events like floods and oil spills. The baseline architecture envisages a multi-satellite constellation to ensure short revisit times and geometric baselines suitable for Synthetic Aperture Radar interferometry, supporting applications developed by organisations such as European Space Research and Technology Centre and national mapping agencies including the United Kingdom Hydrographic Office.
Spacecraft and Instruments
Each spacecraft bus, built by industrial teams including Thales Alenia Space and Airbus Defence and Space, carries a C-band SAR instrument derived from technologies proven on ERS and RADARSAT programmes. The radar operates in multiple modes—Interferometric Wide (IW), Extra Wide (EW), Stripmap (SM), and Wave (WV)—to trade spatial resolution and swath width for applications ranging from sea state analysis to high-resolution land monitoring used by agencies like the French Space Agency (CNES) and the German Aerospace Center (DLR). Onboard systems include precise timing and attitude control subsystems developed in collaboration with suppliers such as OHB SE and payload electronics teams with heritage from the Landsat and COSMO-SkyMed programmes. The SAR instrument supports polarimetric and interferometric acquisitions used in deformation mapping with techniques adopted by research groups at institutions like ETH Zurich and Delft University of Technology.
Mission Operations and Ground Segment
Mission operations are conducted from ESA facilities including the ESOC mission control and coordinated with the Svalbard Satellite Station and the Kiruna Ground Station for data acquisition. The ground segment incorporates elements of the Copernicus Ground Segment, relying on processing centres such as the European Space Operations Centre and national data hubs to deliver near-real-time products to users including the European Maritime Safety Agency and civil protection authorities in countries like Italy and Greece. Flight scheduling and collision avoidance procedures interact with international entities such as US Space Command for conjunction assessments, while calibration and validation campaigns engage research infrastructures like the Integrated Carbon Observation System.
Data Products and Processing
Sentinel-1 delivers a range of calibrated SAR products distributed via the Copernicus Open Access Hub and national mirror sites operated by institutions such as ESA ESRIN and the Norwegian Polar Institute. Standard product levels include Level-0 raw data, Level-1 Single Look Complex and Ground Range Detected products, and Level-2 thematic outputs like Ocean and Land Interferometric products used by organisations including the European Flood Awareness System and the Global Monitoring for Environment and Security initiative. Processing chains implement algorithms from the European Space Agency and research groups at University of Cambridge and University of Bonn for radiometric calibration, speckle filtering, and geocoding; advanced processors support persistent scatterer interferometry workflows pioneered by teams at Politecnico di Milano and Delft University of Technology.
Applications and Use Cases
Operational applications span maritime surveillance for illegal fishing and marine pollution tracked by the European Maritime Safety Agency, ice mapping for polar navigation used by operators such as Arctic Council member agencies, and land deformation monitoring supporting infrastructure managers and utilities in countries like Norway and Spain. Emergency response agencies rely on rapid change detection to map earthquake and landslide impacts, while researchers use time-series interferometry to study glacial dynamics at institutes including University of Oslo and University of Iceland. Environmental monitoring activities integrate Sentinel-1 data with optical missions such as Sentinel-2 and microwave datasets from SMAP and GPM for multi-sensor analyses by bodies like the European Environment Agency.
Development, Launches, and Constellation Status
The Sentinel-1 programme launched Sentinel-1A and Sentinel-1B aboard Soyuz and Rockot vehicles respectively, with subsequent replenishment and expansion managed through ESA procurement involving contractors like ArianeGroup and launch services coordinated with providers such as Arianespace. Sentinel-1A entered service following an initial checkout phase; Sentinel-1B experienced an on-orbit anomaly leading to operations adjustments coordinated among ESA, the European Commission, and national stakeholders. The constellation roadmap foresees additional units to ensure continuity and enhance revisit capabilities, aligning with long-term strategies articulated by the European Commission and the Copernicus Programme Office to meet the evolving needs of users across Europe and beyond.