Our team and mission

This position is based at the European Space Research and Technology Centre (ESTEC) - Noordwijk, Netherlands

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.

The goal of Sentinel-1NG is to provide a 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 a 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. It is mostly visible in SAR images containing homogeneous targets (e.g. Rainforest) and/or areas of low backscatter (e.g. calm ocean).

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.

Please find more information regarding Sentimel-1 at the following link: https://sentinel.esa.int/web/sentinel/missions/sentinel-1

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

You will carry out the following activities:

• You will familiarize yourself with the principle of Synthetic Aperture Radar (SAR) remote sensing and learn about future concepts for multichannel SAR systems, such as foreseen for the ESA mission Sentinel-1 Next Generation;
• You will familiarize yourself with scalloping effects in SAR data and known mitigation techniques;
• You will learn how to analyse Envisat and Radarsat Constellation Mission (RCM) data by implementing Python tools;
• Using the Envisat and RCM data, you will gain a better understanding of scalloping, as well as its correction and residual impact on the SAR image;
• The work can then be extended to predict the impact of residual scalloping on Sentinel-1 Next Generation and recommend potential mitigation strategies.

Depending on the duration of the internship and the interests of the selected candidate, further activities related to the advantages of multichannel systems for the estimation of radial velocities and ocean surface currents could be performed.

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 in your final or second-to-last year of a university course at Master’s level and you need to remain 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 Member State language would be an asset.

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.