The European Space Agency's (ESA) BIOMASS mission is a pioneering Earth observation satellite mission launched on April 29, 2025. Utilizing a P-band synthetic aperture radar (SAR), the objective of BIOMASS is to deliver estimates of above-ground forest biomass, forest height (FH), and forest disturbance (FD), with unprecedented accuracy. The mission's primary scientific goal is to quantify the distribution and changes in forest biomass, thereby reducing uncertainties in carbon flux estimates and informing climate models. The satellite's advanced instrumentation and innovative approach allow it to penetrate dense forest canopies, capturing data even in challenging environments. The mission will operate in two distinct phases: the tomographic phase and the interferometric phase, which will support polarimetric interferometric SAR (Pol-InSAR) and tomographic SAR (TomoSAR) processing. Additionally, BIOMASS will provide valuable observational data for ice sheets, deserts, the ionosphere, below canopy topography, and other domains.

The Copernicus program, and particularly Sentinel-1, are among the largest Earth Observation SAR data providers, serving an ever-increasing number of services, users, and applications. A key aspect of the program is the constant provision of quality data, which requires long term engagement to carefully monitor, preserve, and even improve the system performances. These tasks are mainly carried out within the SAR Mission Performance Cluster (SAR-MPC), an international consortium of SAR experts in charge of the continuous monitoring of the Sentinel-1 instruments status and of the L1 and L2 products quality. This paper provides an update on the monitoring and the actions implemented by the SAR-MPC during 2022 and 2023. The analysis regards the monitoring of the instrument status, the evaluation of the instrument radiometric and geometric accuracy, and the updates of the S-1 Instrument Processing Facility.

The Extended Timing Annotation Dataset (ETAD) product provides timing corrections for Sentinel-1 (S-1) single-look complex (SLC) data for improved geometric accuracy. Given the close relationship between path delay and radar signal phase, it also has the potential to serve as the basis for phase corrections in SAR interferometry (InSAR) applications with Sentinel-1. The provided timing corrections may be converted to phase offsets, which can be used to derive interferometric phase screens between pairs of repeat-pass acquisitions. In this work we explore the capabilities and limitations of ETAD to provide accurate interferometric phase corrections and introduce new features currently under investigation in the context of S1-ETAD scientific evolution study.

This paper introduces the extended timing annotation dataset (ETAD) product for Sentinel-1 (S-1) which was developed in a joint effort of German Aerospace Center (DLR) and the European Space Agency (ESA). It allows to correct range and azimuth timing of S-1 images for geophysical effects as well as for inaccuracies in synthetic aperture radar (SAR) image focusing. In combination with the precise orbit solution, these effects determine the absolute geolocation accuracy of S-1 SAR images and the relative collocation accuracy of repeat pass image stacks. ETAD contains the gridded timing corrections for the tropospheric and ionospheric path delays, the tidal-based surface displacements, and the SAR processing effects, all of which are computed for each data take using standard models from geodesy and auxiliary atmospheric data. The ETAD product helps S-1 users to significantly improve the geolocation accuracy of the S-1 SAR products to better than 0.2 m and offers a potential solution for correcting large scale interferometric phase variations. The product layout and the product generation are described schematically. The paper also reports first results for different SAR techniques: first, the improvement in geolocation accuracy down to a few centimeters by verification of accurately surveyed corner reflector positions in the range-azimuth plane; second, the well-established offset-tracking technique, that is used for systematic ice velocity monitoring of ice sheets and glaciers, where ETAD can reduce velocity biases down to sub-centimetric values; and third, the correction of atmospheric phase contributions in wide-area interferograms used for national and European ground motion services. These early results proof the added value of the ETAD corrections and that the product design is well suited to be integrated into the processing flows of established SAR applications such as absolute ranging of targets, speckle/feature tracking and interferometry.

This paper presents a Synthetic Aperture Radar (SAR) simulator designed to assess the performance of bi-static SAR missions. It is a modular software able to simulate realistic SAR data (including injection of the system non-idealities), to estimate the SAR performance at radiometric and interferometric level. In order to ensure accurate measures of the bi-static performance, it simulates raw data exploiting a time-domain approach, without assumptions on the acquisition geometry. This feature makes the simulator a useful tool for the design of new SAR mission concepts. We also report sample results considering the SAOCOM-CS mission case as an example of application of the simulator.

The increasing interest in bistatic SAR missions and in the new opportunities they can create has led to the development during time of a new set of processing solutions, as wide as the possible configurations assumed by the involved satellites and the corresponding applications.

The on-going European Space Agency (ESA) Sentinel-1 mission has introduced an important change in the management of SAR data, freely opening the archives of the generated Level-0 and Level-1 products to the scientific community. This change has provided to the users a huge amount of data to support their applications and the need for an adequate set of processing tools has become mandatory. This paper is aimed at presenting a new concept of SAR data processing called FreeSAR, aimed at supporting the community with a complete SAR processing chain through a user-friendly web interface.

Nowadays designing a SAR Instruments is getting more and more complex. On one hand the requirements on resolution are always shrinking, leading to an increase of complexity in all the system, on the other the introduction of digital SW-reconfigurable architectures increased the number of functions and modes allocated to the same HW (mixed SAR modes, GMTI, etc.). Another important requirement that recently appeared is the real-time focusing capability especially for Airborne and UAV systems. For this reasons the designers are always looking for simulation platforms that allow to improve the verification & validation coverage and possibly they use it at earliest stage of the developments. In this paper, we present the GSS-RT an Aresys toolkit for laboratory-validation of a complex SAR Radar.

The paper provides the description of a flexible frequency domain background clutter simulator for GMTI applications. The clutter module is able to simulate different acquisition geometries, including very high squint cases, and accounts for scene temporal decorrelation. The clutter simulator operates in frequency domain allowing good computational performance. Details on the simulation algorithm and an overview of the simulator results are provided.