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

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. In addition, the Sentinel-1 team has responsibility for the satellite launch and in-orbit commissioning, i.e. end-to-end system performance and calibration. This also involves 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. It is a cornerstone of Europe’s efforts to monitor the planet and its many ecosystems. Sentinel-1 enables an instantaneous mapping of wide-area surface deformation, caused, e.g., by tectonic processes or ground subsidence, as well as the monitoring of ice sheet and glacier dynamics.

S1 Mission

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

This improvement of the Sentinel-1NG imaging capabilities (i.e. a better spatial resolution, a shorter revisit time, a longer orbital SAR duty cycle, a better radar sensitivity and a shorter repeat-pass orbit interval for SAR interferometry) over the performance currently achievable with Sentinel-1 is possible by employing an envisioned new multi-channel SAR architecture that enables novel 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.

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 an 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 a 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.

Candidates interested are encouraged to visit the ESA website: http://www.esa.int

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

The following tasks shall be performed during the internship considering your interest and experience.

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

For more information, please refer to ESA Core Behavioural Competencies guidebook

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.

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

Specific competence in one of the following disciplines shall be considered an asset:

• knowledge of signal processing, geophysics, electromagnetics, remote sensing;
• familiarity with development of data analysis tools using, e.g., Python or MATLAB.