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The capability to establish the magnitudo, time and place of a forthcoming earthquake is still far from having a reliable and accurate prevision of practical interest. Different precursory phenomena of forthcoming earthquakes have been experimentally observed; they are mostly linked to a microfracturation of the rock due to stress accumulation during the pre-seismic phase in the hypocentral zone of an earthquake. The microcracks in the rocks can be considered seismic sources able to generate electromagnetic emissions, in particular in ULF-ELF bands (0-3000 Hz). The electromagnetic waves spread through the lithosphere to the ionosphere and the magnetosphere and they produce irregularities (Earth magnetic field variations, ionospheric plasma parameters disturbances and particles precipitation from Van Allen belts). In addition, the shallow earthquakes are capable to produce gravity oscillations, propagating upwards and coupling with neutral atmosphere and, eventually, with ionospheric layers. Significant variations of the total electron content in the ionosphere have been measured through GPS receivers. A space mission seems to be an affordable way to achieve in-situ observations, overall the Earth. A plasma diagnostic system suitable to be hosted on board LEO satellites to investigate the presence of ionosphere disturbances has been designed, manufactured and tested. The system is an electrostatic probe, specifically a Triple Probe System (TPS), which allows the local plasma density and electron temperature determination through acquisition of instantaneous voltage and current measurements. A prototype has been arranged to be hosted on board UNISAT-4, a low-cost university satellite built by GAUSS (Gruppo di Astrodinamica – Università degli Studi di Roma “La Sapienza”), scheduled to be launched on December 2005. The paper deals with the TPS basic concepts and some preliminary results, obtained in a test campaign carried out in a climatic room from -40°C to +60°C, are depicted.

Monitoring of bridges and viaducts has become a priority for asset owners due to progressive infrastructure ageing and its impact on safety and management costs. Advancement in data processing and interpretation methods and the accessibility of Synthetic Aperture Radar (SAR) datasets from different satellite missions have contributed to raise interest for use of near-real-time bridge assessment methods. In this context, the Multi-temporal Interferometric Synthetic Aperture Radar (MT-InSAR) space-borne monitoring technique has proven to be effective for detection of cumulative surface displacements with a millimetre accuracy [1-3].This research aims to investigate the viability of using satellite remote sensing for structural assessment of the Rochester Bridge in Rochester, Kent, UK. To this purpose, high-resolution SAR datasets are used as the reference information and complemented by additional data from different sensing technologies (e.g., medium-resolution SAR datasets and ground-based (GB) non-destructive testing (NDT)). In detail, high-resolution SAR products of the COSMO-SkyMed (CSK) mission (2017-2019) provided by the Italian Space Agency (ASI) in the framework of the Project “Motib - ID 742”, approved by ASI, are processed using a MT-InSAR approach.The method allowed to identify several Persistent Scatterers (PSs) – which have been associated to different structural elements (e.g., the bridges piers) over the four main bridge decks – and monitor bridge displacements during the observation time. The outcomes of this study demonstrate that information from the use of high-resolution InSAR data can be successfully integrated to datasets of different resolution, scale and source technology. Compared to stand-alone technologies, a main advantage of the proposed approach is in the provision of a fully-comprehensive (i.e., surface and subsurface) and dense array of information with a larger spatial coverage and a higher time acquisition frequency. This results in a more effective identification and monitoring of decays at reduced costs, paving the way for implementation into next generation Bridge Management Systems (BMSs).Acknowledgements: This research is supported by the Italian Ministry of Education, University and Research under the National Project “EXTRA TN”, PRIN2017, Prot. 20179BP4SM. Funding from MIUR, in the frame of the“Departments of Excellence Initiative 2018–2022”,attributed to the Department of Engineering of Roma Tre University, is acknowledged.Authors would also like to acknowledge the Rochester Bridge Trust for supporting research discussed in this paper. The COSMO-SkyMed (CSK) products - ©ASI- are provided by the Italian Space Agency (ASI) under a license to use in the framework of the Project “ASI Open-Call - Motib (ID 742)” approved by ASI.References[1] Gagliardi V., Bianchini Ciampoli L., D'Amico F., Alani A. M., Tosti F., Battagliere M. L., Benedetto A., “Bridge monitoring and assessment by high-resolution satellite remote sensing technologies”, Proc. SPIE 11525, SPIE Future Sensing Technologies. 2020. doi: 1117/12.2579700[2] Jung, J.; Kim, D.-j.; Palanisamy Vadivel, S.K.; Yun, S.-H. "Long-Term Deflection Monitoring for Bridges Using X and C-Band Time-Series SAR Interferometry". Remote Sens. 2019[3] Gagliardi V., Bianchini Ciampoli L., D'Amico F., Tosti F., Alani A. and Benedetto A. “A Novel Geo-Statistical Approach for Transport Infrastructure Network Monitoring by Persistent Scatterer Interferometry (PSI)”. In: 2020 IEEE Radar Conference, Florence, Italy, 2020, pp. 1-6, doi: 10.1109/RadarConf2043947.2020.9266336

In recent years, successful applications of the Synthetic Aperture Radar Interferometry (InSAR) for the monitoring of subsidence and deformations in transport infrastructures have been reported in the literature. The main advantage of this technique compared to other non-destructive surveying methodologies is in the possibility to perform fast network-level surveys as well as the provision of time-series of the displacements by multi-temporal data acquisitions. Given the medium ground resolution, C-band imagery are usually not employed for transport infrastructure monitoring as it is considered unlikely to obtain sufficiently accurate information. However, the use of medium resolution SAR data has not been thoroughly investigated until now and is still an open challenge. This study presents a novel approach for transport assets monitoring, based on the synergistic use of medium resolution (C-Band) and high resolution (X-Band) SAR imagery. To this effect, a multi-temporal SAR Interferometry analysis of high and medium-resolution datasets is performed on a runway of the Leonardo Da Vinci Airport in Rome, Italy. The data were acquired by the Sentinel-1A and the COSMO-SkyMed missions, respectively. A comparison between the results from medium and high-resolution datasets demonstrates the viability of using multi-frequency SAR imagery, and pave the way to the development of new methodologies for the monitoring of transport infrastructures. © 2021 IEEE

Satellite Remote-Sensing has been successfully applied for detection of natural-hazards, (e.g. seismic events, landslides and subsidence) and transport infrastructure monitoring over the last few years. Persistent Scatterer SAR Interferometry (PSI), is a satellite remote sensing technique able to measure ground displacements over the time. More specifically, the PSI technique is an evolution of the DInSAR technique and it is based on a statistical multi-temporal differential interferogram analysis. This allows to determine coherent stable-pixels over a data-stack of SAR images, in order to identify potential ground displacements. This study aims at demonstrating the potential of the PSI technique as an innovative health-monitoring methodology for the structural integrity of bridges. For this purpose, X‐Band COSMO‐SkyMed images provided by the Italian Space Agency (ASI) were acquired and processed in order to detect structural displacements of the Rochester Bridge in Rochester, UK. Outcomes of this investigation outlined the presence of various PSs over the inspected bridge, which were proven useful to achieve a more comprehensive monitoring methodology and to assess the structural integrity of the bridge. This research paves the way for the development of a novel interpretation approach relying on the integration between remote-sensing technologies and on-site surveys to improve upon current maintenance strategies for bridges and transport assets.