Intern in the Earth Observation Projects Department, SAR Analyst in the Sentinel-1 Project

Internship Opportunity in the Earth Observation Projects Department: SAR Analyst in the Sentinel-1 Project

Our team and mission

The Sentinel-1 Project is responsible for the development of the Sentinel-1 Next Generation (NG) mission concept, the spacecraft, and the Synthetic Aperture Radar (SAR) and Automatic Identification System (AIS) payloads. The team also oversees the satellite launch and in-orbit commissioning, ensuring end-to-end system performance and calibration. This includes the development of prototype SAR and SAR interferometry (InSAR) data processors and the Calibration and Performance Analysis Facility (CPAF).

Sentinel-1NG is the successor of the Earth Observation Copernicus Sentinel-1 SAR mission. Copernicus is the most ambitious Earth observation programme to date and a cornerstone of Europe’s efforts to monitor the planet and its ecosystems. Sentinel-1 enables instantaneous mapping of wide-area surface deformation, such as that caused by tectonic processes or ground subsidence, and supports the monitoring of ice sheet and glacier dynamics.

The goal of Sentinel-1NG is to provide enhanced long-term continuity of C-band SAR observations beyond the next decade (2030) in support of operational Copernicus services that routinely use Sentinel-1 data. The enhanced capabilities of Sentinel-1NG, compared to Sentinel-1, along with novel imaging features, will enable further development and improvement of operational applications.

Improvements in Sentinel-1NG imaging capabilities—including better spatial resolution, shorter revisit time, longer orbital SAR duty cycle, improved radar sensitivity, and a shorter repeat-pass orbit interval for SAR interferometry—are made possible by a new multi-channel SAR architecture. This enables novel techniques such as SCORE (Scan On Receive) and MAPS (Multiple Azimuth Phases), combined with a ScanSAR mode. Systems with multiple channels in azimuth also provide inherent Along Track Interferometry (ATI) capability, which can be used for accurate velocity estimation of ocean surface currents and vessels.

Sentinel-1NG is expected to enable efficient maritime surveillance, including the detection of vessels of different sizes, due to its wide-area coverage and all-weather monitoring capability. Information on the characteristics of ocean-going vessels—such as location, dimensions, heading, and velocity—is required for coastal security, maritime safety, and fisheries and environmental enforcement. The importance of ship detection and identification has increased significantly due to rising incidents of piracy, smuggling, and the need for accountability of polluting tankers causing oil spills.

Conventional ship detection relies on identifying bright point-like target signatures against radar sea clutter noise in SAR intensity images. A Constant False Alarm Rate (CFAR) is typically specified, setting a detection threshold based on local radar sea clutter statistics. This method works well for large ships but becomes unreliable for small ships in heavy sea states, where sea clutter intensity approaches that of the ship. CFAR detection is based on statistical models of sea surface signal intensity, with the K-distribution being the most commonly used, though it has limitations. Recently, the 3MD model, developed by a Canadian team from DRDC-Ottawa, has shown improved performance under challenging, heterogeneous sea state conditions.

Alternatively, the Displaced Phase Centre Antenna (DPCA) method effectively suppresses interfering clutter signals (clutter cancellation), significantly improving vessel detection probability under challenging sea states. Phase-based Along-Track Interferometry (ATI) provides additional information about vessel velocity.

Internship Opportunity: Ship Detection using Multi-Channel SAR Systems in support of Sentinel-1 Next Generation

Field(s) of activity for the internship

• Become familiar with the principles of Synthetic Aperture Radar (SAR) remote sensing for both current conventional SAR systems and future multichannel SAR systems, such as Sentinel-1 Next Generation (S1NG).
• Study the fundamentals of Along Track Interferometry (ATI) and its applications to maritime surveillance, with emphasis on vessel detection and velocity estimation.
• Implement and validate ship detection algorithms based on different sea clutter models (K-distribution and 3MD) using Sentinel-1 SAR data, considering different sea states and vessel sizes, and systematically compare results with AIS ground truth to evaluate detection performance and limitations.
• Analyze results and extrapolate how S1NG’s enhanced capabilities, particularly its multi-channel azimuth system, could improve ship detection through DPCA clutter suppression, velocity estimation, and overall performance.
• Propose strategies or recommendations for optimizing ship detection algorithms to fully utilize the advantages offered by S1NG’s advanced sensor characteristics.

Behavioural competencies

• Result Orientation
• Operational Efficiency
• Fostering Cooperation
• Relationship Management
• Continuous Improvement
• Forward Thinking

Education

You must be a university student, preferably at master’s level, and able to prove enrollment at your university for the entire duration of the internship.

Additional requirements

• A good knowledge of English or French (the Agency’s working languages) is required. Knowledge of another ESA Member State language is an asset.
• Your motivation for applying to this role will be explored during the interview.
• Specific competence in one of the following disciplines is considered an asset: signal processing, geophysics, electromagnetics, remote sensing; familiarity with development of data analysis tools using, e.g., Python or MATLAB.

Important Information and Disclaimer

During the recruitment process, the Agency may request applicants to undergo selection tests. The information published on ESA’s careers website regarding internship conditions is correct at the time of publication. It is not intended to be exhaustive and may not address all questions you may have.

Nationality

Applications are only considered from nationals of one of the following States: Austria, Belgium, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, and the United Kingdom.