The paper provides and up-to-date overview of the science activities of the Spanish PAZ SAR mission. PAZ Science activities, coordinated by the Spanish National Institute of Aerospace Technology (INTA) has as purpose to strengthen the use and improvement of SAR technology in all its areas, from the specification of new SAR missions, SAR engineering, development of new algorithms and promotion of applications based on the use of SAR products and derived variables. In order to achieve these objectives and in addition to the activities carried out in INTA, the science PAZ program (called PAZCiencia) started in 2019, providing PAZ scientific products to research teams as basis and support to their SAR-related projects. Due to the commonalities of PAZ with the German TerraSAR-X and TanDEM-X missions, a specific call for their joint scientific use was launched in 2021, which is outlined in the paper.

PAZ is a Spanish SAR mission developed within the framework of the National Program of Earth Observation by Satellite and launched in February 22, 2018. Its main payload is an X-band SAR sensor that can operate at three imaging modes to generate products able to fulfil a broad range of application requirements for commercial, scientific and security/defence purposes.Entering its fifth year of operation, PAZ calibration and validation centre focuses the calibration activities on daily and long-term instrument monitoring and PAZ image performances verification by means of the analysis of instrument, antenna and complex image parameters.Current PAZ calibration status based on the updated values of these parameters is shown in this paper.

Earth Observation using satellites is a fundamental information source for most activities in the civil and military environment. Currently, the design of this kind of systems is moving from the traditional model of big satellites with multiple capacities requiring larger development times, elevated investment and a long operation to be profitable to a model based in small, low cost satellite constellations with shorter development times, faster replacements and taken advantage of latest technological innovations.This paper describes the SAR system currently being developed at INTA based in collaborative low cost satellites in order to provide products similar to traditional high performance satellites.

With the start of the Spanish PAZ system, another earth observation satellite has become available to the scientific community. Following the launch of the PAZ science phase, we performed a number of ground experiments using different modes of the satellite SAR instrument, measuring the transmitted radar signal as well as its ground reflections using the HITCHHIKER receiver. The data acquired in these experiments is analyzed and used in collaboration with the PAZ calibration team at Instituto Nacional De Técnica Aerospacial (INTA) to characterize the PAZ instrument, thus verifying the system calibration. Furthermore, we obtained bistatic radar images from the data of the HITCHHIKER ground receiver.

This paper analyzes the potential of the joint exploitation of the Spanish PAZ satellite and the two TerraSAR-X/TanDEM-X German satellites for interferometry. Since both platforms are almost identical and they were launched on the same orbital plane, similar images under the same geometry may be acquired by both missions. Several time series over different test sites with distinct land cover types in Germany and Spain that have been acquired by both missions are compared in order to evaluate the possibility of joint exploitation for interferometry. Results show no loss of performance on the in-terferograms obtained while combining satellites of both missions. This allows to effectively reduce the minimum revisit time from 11 days to 4 or 7 days.

A new compact fully Polarimetrie Ku band SAR system (SBK) is being developed by INTA radar Laboratory as an advanced payload for QUASAR project, which involves INTA new SAR developments for small platforms and UAV's. As an operative system, SBK shall allow precise calibration of the obtained data in order to achieve high products quality. The present paper shows SBK internal calibration concept focusing on internal calibration facility description, on ground characterization task overview and in flight calibration method. Furthermore, internal calibration accuracy estimation based on first prototypes measurements is also presented.

This paper describes the INTASAR Program of Spanish National Institute for Aerospace Technology (INTA) which goal is to research in Synthetic Aperture Radar technology area. INTASAR constitutes an INTA's long-term program, which basis is the development of airborne SAR prototypes, working presently in three complementary lines: SAR prototypes on-board CASA-212 platform, SAR developments in small platforms and participation in PAZ Program - Spanish radar satellite.

Since 1993 The National Institute of Aerospace Technology (INTA) has been working on the Synthetic Aperture Radar (SAR) program based on airborne SAR prototypes with increasing complexity development. In this frame, flexible data processing tools are needed as ground support, to allow the complete prototypes operation. This paper outlines the data processing framework of Radar laboratory. High level SAR processing environment is described. Different tasks and developments built in SAR data processing are introduced in several tools (data take campaigns design, performance assessment estimation, system configuration, product generation and data analysis). This group of tools performs the data processing core for the INTA SAR prototypes. New processing tools to cover specific needs for the new SAR prototypes developments in this laboratory are also introduced.

This paper will outline the objectives and mission, general features and roadmap and will give a brief description of the two main prototypes of QUASAR (Quicklook Unmanned Aerial SAR), the main project in Synthetic Aperture RADAR for small platforms carried out by the Spanish National Institute for Aerospace Technology. QUASAR is planned be released as a functional demonstrator in 2011 and as complete, operative and deliverable high resolution Ku-band SAR with ground segment station for mission planning, image formation and data exploitation system in 2013.