Intern in the Earth Observation Projects Department, Sentinel-1 Next Generation

Internship Opportunity in the Earth Observation Projects Department: Sentinel-1 Next Generation

Our team and mission

The Sentinel-1 Project, based at ESTEC, 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 manages 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 program to date and is 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 the monitoring of ice sheet and glacier dynamics.

Mission Goals

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 capabilities, enable further development and improvement of operational applications. Improvements include better spatial resolution, shorter revisit time, longer orbital SAR duty cycle, better radar sensitivity, and a shorter repeat-pass orbit interval for SAR interferometry. These are enabled by a new multi-channel SAR architecture, supporting techniques such as SCORE (Scan On Receive) and MAPS (Multiple Azimuth Phases), combined with a ScanSAR mode. Another advantage of systems with multiple channels in azimuth is the inherent Along Track Interferometry (ATI) capability, which can be used for accurate velocity estimation of ocean surface currents and vessels.

Technical Challenges

A challenge when operating a SAR in a ScanSAR mode is that each target is observed by a different portion of the azimuth antenna pattern. This effect, along with antenna beam mispointing, causes a periodic modulation of the image radiometry and a variation of the noise floor in azimuth direction referred to as Scalloping. It is mostly visible in SAR intensity images containing homogeneous targets (e.g. rainforest) and/or areas of low backscatter (e.g. calm ocean). In addition, this Scalloping effect could affect the SAR interferometry performance, especially the interferometric phase and coherence. Having perfect pointing and/or Doppler estimation accuracy would minimize the radiometric Scalloping. Another mitigation strategy is the use of multiple-azimuth looks (look balancing), which was implemented for ScanSAR missions such as ENVISAT/ASAR, RADARSAT-2, RADARSAT Constellation Mission (RCM), and ALOS-2/4.

Field(s) of activity for the internship

Topic of the internship: Analysis of Scalloping Effects in Synthetic Aperture Radar (SAR) Interferometry in support of Sentinel-1 Next Generation

Your activities will center on investigating the phenomenon of scalloping in Synthetic Aperture Radar (SAR) data, with a view toward understanding its implications for SAR interferometry. The primary objective will be to analyse the nature and causes of scalloping artifacts in InSAR imagery, evaluate their effects on the interferometric phase and coherence, and develop strategies to mitigate these issues. Furthermore, you will be tasked with making informed predictions regarding how Sentinel-1 Next Generation (S1NG) interferograms may be influenced by the presence and impact of scalloping.

As part of your tasks, you will:

• Develop a solid understanding of the principles of SAR remote sensing, with a special focus on the origins of Scalloping artifacts in the ScanSAR mode.
• Study the fundamentals of SAR interferometry and explore how Scalloping can affect the InSAR phase and coherence, as well as the overall image quality and measurement accuracy.
• Analyse real SAR datasets to detect, characterize, and quantify Scalloping effects, employing both visual inspection and quantitative metrics tailored to InSAR applications, such as earthquake-related surface deformation.
• Assess the current mitigation techniques applied to reduce Scalloping, evaluating their effectiveness and identifying areas for improvement.
• Formulate predictions and recommendations on how S1NG SAR interferograms may be impacted by scalloping.
• Propose strategies or algorithmic improvements for future SAR systems to minimize scalloping effects, ensuring reliable and high-quality interferometric measurements.

Behavioural competencies

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

Education

You must be a university student, preferably studying at master’s level. In addition, you must be able to prove that you will be enrolled at your University for the entire duration of the internship.

Additional requirements

• The working languages of the Agency are English and French. A good knowledge of one of these is required. Knowledge of another ESA Member State language is an asset.
• Specific competence in one of the following disciplines is considered an asset: knowledge of signal processing, geophysics, electromagnetics, remote sensing; familiarity with development of data analysis tools using, e.g., Python or MATLAB.

During the interview, your motivation for applying to this role will be explored.

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 would have.

Nationality

Please note that 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.