Search

Synchronizing the local oscillators in multibeam satellites with the objective of coherent communications is still an open challenge. It has to be addressed to implement full-frequency reuse approaches, such as precoding techniques using the already deployed multibeam satellites. This article addresses the required phase synchronization to enable precoding techniques in multibeam satellite systems. It contains the detailed design of a frequency and phase compensation loop based on the proportional-integral controller, which deals with the phase drift introduced by the hardware components. Specifically, the phase noise of the local oscillators used for up and down conversion at each system element (gateway, satellite, and user terminals). The implementation of the two-state phase noise model used to emulate this phase drift is included in the article. Besides, a comparative analysis of several methods to combine the frequency and phase measurements obtained from the user terminals is also included. Finally, the performance of the proposed closed-loop synchronization method is validated through simulations using our in-house developed MIMO end-to-end satellite emulator based on SDR platforms., This research was funded by the Luxembourg National Research Fund (FNR) under the CORE project COHESAT: Cognitive Cohesive Networks of Distributed Units for Active and Passive Space Applications, grant reference [FNR11689919] and the project DISBuS: Dynamic Beam Forming and In-band Signalling for Next Generation Satellite Systems, grant reference [FNR13778945]. For the purpose of open access, the author has applied a Creative Commons Attribution 4.0 International (CCBY4.0) license to any Author Accepted Manuscript version arising from this submission. Additionally, this work has been supported by the European Space Agency under project number 4000122451/18/NL/NR ”Live Satellite Precoding Demonstration - CCN: MEO case (LiveSatPreDem).”, Peer Reviewed, Postprint (published version)

The Global Navigation Satellite Systems (GNSS), including the US’s GPS, China’s BDS, the European Union’s Galileo, and Russia’s GLONASS, offer real-time, all-weather, any-time, anywhere and high precision observations by transmitting L band signals continuously, which have been widely used for positioning, navigation and timing. With the development of GNSS technology, it has been found that GNSS-reflected signals can be used to detect Earth’s surface characteristics together with other signals of opportunity. In this paper, the current status and latest advances are presented on Global Navigation Satellite System-Reflectometry (GNSS-R) in theory, methods, techniques and observations. New developments and progresses in GNSS-R instruments, theoretical modeling, and signal processing, ground and space-/air-borne experiments, parameters retrieval (e.g. wind speed, sea surface height, soil moisture, ice thickness), sea surface altimetry and applications in the atmosphere, oceans, land, vegetation, and cryosphere are given and reviewed in details. Meanwhile, the challenges in the GNSS-R development of each field are also given. Finally, the future applications and prospects of GNSS-R are discussed, including multi-GNSS reflectometry, new GNSS-R receivers, GNSS-R missions, and emerging applications, such as mesoscale ocean eddies, ocean phytoplankton blooms, microplastics detection, target recognition, river flow, desert studies, natural hazards and landslides monitoring., This work was supported by the Henan International Science and Technology Cooperation Key Project (Grant No. 241111520700) and Strategic Priority Research Program Project of the Chinese Academy of Sciences (Grant No. XDA23040100)., Peer Reviewed, Postprint (published version)

This document is the partial result of an ongoing satellite research activity carried out by Universitat Politècnica de Catalunya NanoSat Lab and i2CAT Foundation, submitted to the Horizon Europe Program in 2022., Thousands of rockets, spaceships, and satellites have been launched, resulting in a steady increase in the number of space debris notably in Low Earth Orbit (LEO) and Geostationary Orbit (GEO). Among the objects comprising space debris, defunct satellites are commonly found, which may have been abandoned in space due to various anomalies. While these satellite failures may not be catastrophic, certain subsystems could still be repurposed for alternative uses beyond their initial design. This study aims to assess the feasibility of “recycling” partially failed satellites, also known as “Zombie Satellites”, by statistically evaluating the severity of their anomalies and quantifying their remaining capabilities and limitations. By conducting a comprehensive statistical analysis, the anomalies have been categorized based on subsystem, orbit type, occurrence date during the satellite’s lifespan, and severity. Additionally, an analysis is presented to identify failed satellites from some of the current large constellations., This work was sponsored in part by the I+D+i project of UPC GENESIS project PID 2021-1264360B-C21 financed by MCIN/AEI. Additionally, this work was supported by the Spanish Ministry of Economic Affairs and Digital Transformation and the European Union–NextGeneration EU , in the framework of the Recovery Plan, Transformation and Resilience (PRTR) (Call UNICO I+D 5G 2021, ref. number TSI-063000-2021-8-6GSatNet-SeS)., Peer Reviewed, Postprint (published version)

Monitoring vegetation moisture conditions is paramount to better understand and assess drought impacts on vegetation, enhance crop yield predictions, and improve ecosystem models. Passive microwave remote sensing allows retrievals of the vegetation optical depth (VOD; [unitless]), which is directly proportional to the vegetation water content (VWC; in units of water mass per unit area [kg/m2]). However, VWC is largely dependent on the dry biomass and structure imprints on the VOD signal. Previously, statistical models have been used to isolate the water component from the biomass and structure components. Physically-based approaches have not yet been proposed for this goal. In this study, we present a multi-sensor semi-physical approach to retrieve the vegetation moisture from the VOD and express it as Live Fuel Moisture Content (LFMC [%]; the percentage of water mass per dry biomass unit). The study is performed in the western United States for the period April 2015 – December 2018. There, in situ LFMC samples are available for assessment. We rely on a VOD model based on vegetation height data from GEDI/Sentinel-2 and radar backscatter from Sentinel-1, which account for the biomass and structure components. Vegetation moisture is retrieved at L-, X- and Ku-bands by minimizing the difference between the modeled VOD and the VOD estimates from SMAP (L-band) and AMSR-2 (X- and Ku-band) satellites. Results show that the LFMC retrievals are independent of canopy height, land cover, and radar backscatter, demonstrating the capability of the proposed algorithm to separate water dynamics from the biomass/structure component in VOD. LFMC estimates at X- and Ku-bands reproduce well the expected spatio-temporal dynamics of in situ LFMC. Results show good agreement with in situ at a regional scale, with Pearson's correlations (r) between in situ LFMC samples and LFMC estimates of 0.64 (Ku-band), 0.60 (X-band) and 0.47 (L-band). Similar results are obtained independently for shr, The work of D. Chaparro was supported by the XXXIII Ramón Areces Postdoctoral Fellowship and by MIT and the “la Caixa” Foundation (ID 100010434) under Grant LCF/ PR/MIT19/51840001 (MIT-Spain Seed Fund; D. Entekhabi, D. Chaparro). M. Piles thanks the support of Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital through the project AI4CS CIPROM/2021/56. M. Vall-llossera acknowledges funding from the Grant PID2020-114623RB-C32, funded by MCIN/AEI/10.13039/ 501100011033, and from the ERDF under Grant RTI2018-096765-A- 100. Also, the authors are grateful to MIT for supporting this research with the MIT-Germany Seed Fund (D. Entekhabi, T. Jagdhuber) and with the MIT-Belgium Seed Fund (D. Entekhabi, F. Jonard). A.F. Feldman was supported by both the ECOSTRESS science team and by a NASA Terrestrial Ecology scoping study for a dryland field campaign., Peer Reviewed, Postprint (author's final draft)

This project is the continuation of two previous TFGs about the mechanical design and mechanisms of a Fresnel Zone Plate Antenna developed in the NanoSat Lab. An in-house developed antenna that wants to test and prove the viability of an innovative design for CubeSats deployable antennas. This work tackles two main topics from the design process of this deployable antenna. The first is some of the design changes of the antenna and the reasoning behind them as well as the design of the deployment mechanism. The second one is the structural analysis of the 3Cat8 6U structure with the required changes to host the antenna as well as the antenna¿s structural simulation, Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura

The Lithosphere- Atmosphere-Ionosphere coupling models have been widely studied and applied to earthquakes and their precursors. Recently, evidence has been found that electromagnetic phenomena related to earthquakes might produce ionospheric anomalies even before their occurrence. This thesis aims to analyze the correlation between ionospheric scintillation and seismic events such as earthquake precursors, with the hypothesis that there is a positive correlation. Among all the ionospheric indicators, this study analyzes the S4 scintillation index from COSMIC-2 GNSS Radio Occultation (GNSS-RO), to estimate the ionospheric perturbation and identify anomalies. Case studies of earthquakes happening in 2022, as well as a statistical analysis centered on the Coral Sea area, are presented showing positive correlation. In some of the case studies are seen anomalies up to one week before the earthquake. Moreover, in the statistical analysis it is shown a correlation with anomalies happening between 3 and 6 days before the earthquakes and the earthquake itself. A probability of detection of 35.7% and a false alarm rate of 7.1% are obtained. This leads to the conclusion of ionospheric scintillation and seismic activity having a small positive correlation., Outgoing, Objectius de Desenvolupament Sostenible::13 - Acció per al Clima, Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura

Due to an increasing entry barrier to both universities and researchers in conventional small satellites initiatives, there has been an emergence of smaller and cheaper spacecrafts like PocketQubes, a much more affordable option for public entities. Considering all that, this thesis has been developed as part of a project undertaken by the UPC NanoSat Lab which started as an IEEE GRSS initiative named PoCat. The objective of the PoCat project is to design, develop and test three single unit picosatellites with each featuring the following different payloads, a Video Graphics Array (VGA) camera, a Radio Frequency Interference (RFI) monitoring system at L-band and an RFI monitoring system at K-Band. The three satellites, however, contain the same avionics core composed of the On-Board Computer (OBC), Communication System (COMMS), Attitude Determination and Control System (ADCS) and Electrical Power Supply System (EPS). Given this scenario, the purpose of this report is to give insights regarding the on-board software development for PocketQubes, which as of writing this report there is still room for debate concerning their standardization. Conceptually, the OBC system acts as the brain of the satellite. As for the technology, the OBC is build upon the STM32L476 microcontroller due to its memory storage, power efficiency and processing power. Performing the power management as well as giving response to events are the main objectives of the OBC. In order to do the latter, the flight software is based on a Real-Time Operating System (RTOS) called FreeRTOS which has been selected above other Operating System (OS) due to its predictability, compliance with the required deadlines, support, available documentation, compatibility with previous projects, licensing costs, and certifications. According to FreeRTOS, the program is structured into independent tasks where each one features a priority in line with their criticality. Then, the project is constituted by eight tasks

Existing climatological ionosphere models, for example, GISM, SCIONAV, WBMOD, and STIPEE, have known limitations that prevent their wide use. In the framework of ESA study “Radio Climatology Models of the Ionosphere: Status and Way Forward” their performance was assessed using experimental observations of ionospheric scintillation collected over the past years to evaluate their ability to properly support future missions, and eventually indicate their weaknesses for future improvements. Model limitations are more important in terms of the intensity scintillation parameter (S4). To improve them, the COSMIC model has been fit (scaling factor and offset) to the measured data, and it became the one better predicting the intensity scintillation in a statistical sense., This research was funded by the project “Radio Climatology Models of the Ionosphere: Status and Way Forward,” ESA/ESTEC, grant number 4000120868/17/NL/AF [https://nebula.esa.int/content/radio-climatology-models-ionosphere-status-and-way-forward]. Article processing charges were funded by the project “GENESIS: GNSS Environmental and Societal Missions – Subproject UPC,” AEI Grant PID2021-126436OB-C21., Peer Reviewed, Postprint (published version)

This end-of-degree project focuses on the software development of a pico-satellite Attitude Determination and Control System, using MATLAB, as well as its subsequent integration in C. The software carried out will be implemented in a 5 cm sided pico-satellite, called PocketQube. The research project will form part of the IEEE Open PocketQube Kit mission developed in the NanoSat laboratory belonging to the UPC. The pico-satellite attitude system can be broken down into two distinct branches, attitude determination and attitude control. Attitude determination involves the process of determining the orientation of the satellite using the measurements acquired by its sensors (they include photodiodes, gyroscopes, and magnetometers). On the other hand, attitude control is the process by which the orientation of the pico-satellite is controlled using specific control algorithms (such as detumbling and nadir pointing) and actuators, (such as magnetorquers). To analyse and understand the attitude of the pico-satellite, a model is developed that allows simulating the environment in which the satellite is located. This model encompasses pico-satellite dynamics, a model that describes orbital dynamics, and another that represents the various perturbation forces that affect the pico-satellite. In this way, it is possible to describe the orbit followed by the pico-satellite, including its position, speed and the external forces that influence and affect its behaviour during the orbital flight. Once the modelling of the simulation environment is complete, the determination and control algorithms are implemented, as well as the mathematical models that describe the behaviour of the sensors and actuators. These algorithms and models are designed with the aim of meeting the requirements established for the Determination and Control System. Subsequently, an exhaustive analysis of the results obtained during the simulation is carried out. The purpose of this analysis is to verify if t

The FMPL-2 payload on board the 3Cat-5/A 6 Unit CubeSat, part of the FSSCat CubeSat mission, includes a dual L-Band Microwave Radiometer and a Global Navigation Satellite System Reflectometer, in one instrument, implemented in a Software Defined Radio. One of the design challenges of this payload was its Nadir looking Antenna, which had to be directive (> 12 dB), dual-band at 1400–1427 MHz and 1575.42 MHz, left-hand circularly polarized, and with important envelope restrictions, notably with a low profile. After a trade-off analysis, the best design solution appeared to be an array of six elements each of them being a stacked dual-band patch antenna, with diagonal feed to create the circular polarization, and a six to one stripline combiner. The design process of the elementary antennas first includes a theoretical analysis, to obtain the approximate dimensions. Then, by means of numerical simulations, prototyping, and adjusting the results in the simulations, the manufacturing errors and dielectric constant tolerances, to which patch antennas are very sensitive, can be characterized. A similar approach is taken with the combiner. This article includes the theoretical analysis, simulations, and prototype results, including the Flight Model assembly and characterization, This work was by the Programa Estatal para Impulsar la Investigación Científico-Técnica y su Transferencia, del Plan Estatal de Investigación Científica, Técnica y de Innovación 2021-2023 (Spain) and in part by the European Social Fund (ESF). It is also funded in part by the Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya 2017 SGR 376 and 2017 SGR 219. This work has also been founded by the grant PID2019-106808RA-I00 funded by MCIN/AEI/10.13039/501100011033. Finally, this research was possible thanks to the FI-2019 grant from AGAUR-Generalitat de Catalunya, Spain., Peer Reviewed, Postprint (published version)

Spacecraft entering a planetary atmosphere are surrounded by a plasma layer containing high levels of ionization, due to the extreme temperatures in the shock layer. The high electron number densities cause attenuation of the electromagnetic waves emitted by the on-board antennas, leading to communication blackout for several minutes. This work presents experimental measurements of signal propagation through an ionized plasma flow. The measurements are conducted at the VKI plasma wind tunnel (Plasmatron) using conical horn antennas transmitting in the Ka-band, between 33 and 40 GHz. Testing conditions at 15, 50 and 100 mbar, and powers between 100 and 600 kW cover a broad range of the testing envelope of the Plasmatron as well as a broad range of atmospheric entry conditions. The transmitting antenna is characterized at the UPC anechoic chamber, obtaining the radiation patterns, beamwidth, and gain at the boresight direction; and an optical ray tracing technique is used to describe the electromagnetic waves propagation in the plasma flowfield inside of the Plasmatron chamber. The signal propagation measurements show clear attenuation when the signal is propagating through the plasma, varying between 2 and 15 dB depending on the testing conditions. This attenuation increases with electron number densities, which are driven by the Plasmatron power and pressure settings. Preliminary evidence of Faraday rotation effects caused by the plasma is also observed., Diana Luís research is funded by a doctoral fellowship (2021.04930.BD) granted by Fundação para a Ciência e Tecnologia (FCT Portugal). The research of Vincent Fitzgerald Giangaspero is supported by SB PhD fellowship 1SA8219N of the Research Foundation - Flanders (FWO). The resources and services used for the BORAT simulations were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation - Flanders (FWO) and the Flemish Government. The MEESST project is funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 899298., Peer Reviewed, Postprint (published version)

In the last decades, the number of wireless devices has notably increased, and improper RF filtering has resulted in an increase in Radio Frequency Interference (RFI). At L-band this is due to a plethora of reasons: from VHF/UHF harmonics, higher frequency band (e.g. WiFi boosters) emissions, or even intentional RFI created by Personal Privacy Devices (PPD), all these have resulted in a degradation of both Active and Passive Microwave Remote Sensing [1], [2]. Almost simultaneously, there has been an explosion of smallsats, notably following the CubeSat and PocketQube [3] form factors, both being excellent hands-on project topics for introducing students into the aerospace domain [4].In these circumstances, the IEEE Geoscience and Remote Sensing (GRSS) Open PocketQube Kit [5] initiative was started. The goal is to develop a set of flight ready Picosatellites with Earth Observation payloads complete with assembly, integration and testing tutorials and video tutorials. Each of these PocketQubes, while identical in all other regards, will house different Remote Sensing oriented payloads. One of them, and the focus of this work, is a L-band (1-2 GHz) Radio Frequency Interference Monitor, notably for the L1, L2 and L5-bands of GNSS [6] systems, and the 1400-1427 Mhz band reserved for passive observations., This payload has been developed as part of the IEEE Geoscience and Remote Sensing Society ”Open PocketQube Kit” educational initiative and it will be openly distributed when completed. Additionally, it was part of the project ”GENESIS: GNSS Environmental and Societal Missions – Subproject UPC”, Grant PID2021-126436OB-C21 funded by the Ministerio de Ciencia e Investigación (MCIN)/Agencia Estatal de Investigación (AEI)/10.13039/501100011033 and EU FEDER “Una manera de hacer Europa”., Peer Reviewed, Postprint (author's final draft)

Vegetation optical depth (VOD) depends on the water, structure, and biomass of vegetation. Here, we propose a multi-sensor approach to isolate the water component from the VOD and to retrieve gravimetric vegetation moisture (m g ) in the western United States. The approach estimates VOD from radar and LiDAR data and minimizes the differences between these estimates and SMAP/AMSR2 VOD observations. This minimization allows to obtain the best fitting value of m g with help of a dielectric model. Results are consistent both in space (drier vegetation in arid areas) and time (drier vegetation in drier months). The mg estimates are in the same range than in situ mg data, with some underestimation (bias ~ -0.07 kg/kg). Statistical results are reasonable (r ~ 0.45, RMSE =0.10 kg/kg), yet the different spatial and temporal representation of in situ and remote measurements have an impact in the direct comparisons. Our results highlight the potential for developing new vegetation moisture datasets based on VOD decomposition., The work of D. Chaparro was supported by the XXXIII Ramón Areces Postdoctoral Fellowship, and by “la Caixa” Foundation (ID 100010434) under Grant LCF/PR/MIT19/51840001 (MIT-Spain Seed Fund). This research was supported also by the Spanish Ministry of Science and Innovation (MCIN/AEI /10.13039/501100011 033), through the coordinated project INTERACT PID2020-114623RB-C32. M. Piles thanks the support of Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital through the project AI4CS CIPROM/2021/56., Peer Reviewed, Postprint (author's final draft)

Due to the recent licensing of the 26 GHz 5G communications bands, the passive microeaves Remote Sensing community is concerned that spurious out-of-band emissions could interfere with the measurements acquired in the 23.8 GHz water vapor resonance band. For this reason, the Frequency Allocations in Remote Sensing (FARS) Technical Committee from the IEEE Geoscience and Remote Sensing Society (GRSS) has procured the development of a RFI monitoring payload to detect possible interferences in the 24 to 25 GHz band. This payload is compatible with the PocketQubes being developed in the framework of the "IEEE GRSS Open PocketQube Kit" educational initiative, and it will be used to measure and determine the occurrence of possible interferences close to the 23.8 GHz water vapor band. This work presents the design, implementation and testing of the 24 to 25 GHz RFI monitoring payload designed for a 1P PocketQube., This work was sponsored by the Frequency Allocations in Remote Sensing (FARS) Technical Committee of the IEEE Geoscience and Remote Sensing Society (GRSS). This project was also sposored in part by the project ”GENESIS: GNSS Environmental and Societal Missions – Subproject UPC”, Grant PID2021-126436OB-C21 funded by the Ministerio de Ciencia e Investigación (MCIN)/Agencia Estatal de Investigación (AEI)/10.13039/501100011033 and EU FEDER “Una manera de hacer Europa”., Peer Reviewed, Postprint (author's final draft)

The Remote sensing and Interference detector with radiome-Try and vegetation Analysis (RITA Payload) [1] is a development of the UPC NanoSat Lab, aimed at Earth Observation (EO). It is one of the winners of the Second IEEE GRSS Student Grand Challenge, and will fly on-board AlainSat-1, a 3U CubeSat developed by the National Space Science and Technology Center (NSSTC) of the United Arab Emirates.RITA hosts three experiments. An L-band microwave radiometer (MWR) will gather data of soil moisture and sea ice thickness and concentration, aided with a Radio-frequency Interference (RFI) detection algorithm. A LoRa transceiver will perform on-demand execution of the EO experiments [2]. Finally, a Near-Infrared (NIR) Hyperspectral Camera will gather data for vegetation monitoring, agriculture applications, hydrology and coastal and inland waters mapping, among others [3].This work is focused on the calibration and validation of the Hyperspectral imager, at optical, electronic and spectral levels, as well as in the verification of its performance to measure Normalized Difference Vegetation Index (NDVI)., This project is supported and funded by the IEEE Geoscience and Remote Sensing Society (GRSS), as one of the winners of the 2nd IEEE GRSS Student Grand Challenge. It is also part of the project ”GENESIS: GNSS Environmental and Societal Missions – Subproject UPC”, Grant PID2021-126436OB-C21 funded by the Ministerio de Ciencia e Investigación (MCIN) / Agencia Estatal de Investigación (AEI) / 10.13039/501100011033 and EU FEDER “Una manera de hacer Europa., Peer Reviewed, Postprint (author's final draft)

The project developed in this thesis consists of the assembly, integration, verification and testing of the different subsystems of a PocketQube (Electrical Power Supply, Altitude Determination and Control System, On-Board Computer and Communications System). In this thesis, after a soldering training, the different PCBs of the PocketQube have been assembled.Subsequently, different tests have been designed and executed in order to verify the correct behaviour of the PCB, first electrically and then functionally. Lastly, the payloads had been integrated and tested as a whole in an Electrical Ground Support Equipment., El proyecto desarrollado en este trabajo de fin de grado consiste en el ensamblaje, integración, verificación y prueba de los diferentes subsistemas de un PocketQube (Electrical Power Supply, Altitude Determination and Control System, On-Board Computer and Communications System). En este trabajo de fin de grado, después de realizar un entrenamiento de soldadura, se han ensamblado las diferentes PCB del PocketQube. Posteriormente, se diseñaron y llevaron a cabo diferentes tests para verificar el correcto funcionamiento de las PCB, primero a nivel eléctrico y luego funcional. Por último, se integraron y probaron las placas como un todo utilizando el "Electrical Ground Support Equipment", El projecte desenvolupat en aquest treball de fi de grau consisteix en l’assemblatge, integració, verificació i prova dels diferents subsistemes d’un PocketQube (Electrical Power Supply, Altitude Determination and Control System, On-Board Computer and Communications System). En aquest treball de fi de grau, després de realitzar un entrenament de soldadura, s’han soldat les diferents PCB del PocketQube. Posteriorment, s’han dissenyat i executat diferents tests per verificar el correcte funcionament de la PCB, primer a nivell elèctric i després funcional. Finalment, s’han integrat i provat les places com a un tot en un ‘Electrical Ground Support Equipment’

Detection of marine litter is an urgent task given the large amount of plastics that end up in all water systems. This manuscript provides the description and results obtained from a ground-based Global Navigation Satellite System - Reflectometry (GNSS-R) system built in a controlled indoor environment intended to test the capabilities of GNSS-R techniques for marine litter detection, when different wave conditions and plastic litter were used. Results show that it may be possible to detect the damping of waves produced by the accumulations of some types of plastic., This article was part of the project ”GENESIS: GNSS Environmental and Societal Missions – Subproject UPC”, Grant PID2021-126436OB-C21 funded by the Ministerio de Ciencia e Investigación (MCIN)/Agencia Estatal de Investigación (AEI)/10.13039/501100011033 and EU FEDER “Una manera de hacer Europa”. Amadeu Gonga (FI2022/809) and Adrian Perez-Portero (FISDUR2020/105) were supported by grants for recruitment of early-stage research funded by the Agencia Gestió d’Ajuts Universitaris i de Recerca (AGAUR) Generalitat de Catalunya, Spain., Peer Reviewed, Postprint (author's final draft)

In recent timeps, SLR (Satellite Laser Ranging) is being used lately for orbit determination in many satellite constellations. It improves the accuracy of traditional radiofrequency systems by using laser transmitters, but the short-wavelength signals that are used in the lasers make them very weak against the atmospheric effects between the ground station and the satellite. In this thesis, the study on how the clouds affect the contact plan of the SLR stations will be done. For this, LEO, MEO and GEO constellations will be considered, as well as three ground station scenarios: cloudless, cloudy and hybrid. The contact plan for each ground station scenario with each satellite constellation will be executed to analyze the results, and draw conclusions.

In this TFG, the following tasks will be conducted: 1- Interfacing payload and other sensors with an STM32 microprocessor acting as On Board Computer (OBC) of a PocketQube 2- Environmental Tests of the payload (Thermal and Vaccuum Chamber and Shake table test) 3- Electrical and functional haracterization of payload wrt different types of radio frequency interfences., En este TFG, se llevarán a cabo las siguientes tareas: 1- Interconectar la carga útil y otros sensores con un microprocesador STM32 que actúa como Computadora a Bordo (OBC) de un PocketQube. 2- Realizar pruebas ambientales de la carga útil (pruebas de temperatura y vacío en una cámara y pruebas en una mesa de vibraciones). 3- Caracterizar eléctrica y funcionalmente la carga útil con respecto a diferentes tipos de interferencias de radiofrecuencia., En aquest TFG, es duran a terme les següents tasques: 1- Interconnectar la càrrega útil i altres sensors amb un microprocessador STM32 que actua com a Computadora a Bord (OBC) d'un PocketQube. 2- Realitzar proves ambientals de la càrrega útil (proves de temperatura i buit en una cambra i proves en una taula de vibracions). 3- Caracteritzar elèctrica i funcionalment la càrrega útil respecte a diferents tipus d'interferències de radiofreqüència.

Over 14 million tons of plastic end up yearly in the ocean, originating from polluted waterways such as rivers, sewers, or storm waters, or from industrial and nautical activities with improper garbage disposal methods. Due to its long decomposition time, and the presence of currents and gyres, most of plastic debris freely floating in the ocean end up forming large extensions of marine litter known as garbage patches. An example is the Great Pacific garbage patch located in the central North Pacific Ocean covering an area larger than 1.6 million squared kilometers. Some works have recently reported the potential of GNSS-Reflectometry to detect marine plastic litter from space. This study presents the results of a controlled field experiment conducted under the auspices of ESA at the "Atlantic Basin" at the Deltares research institute (Delft, The Netherlands)., Research funded by ESA project GLobal MonItoring of MicroPlastics using GNSS-Reflectometry (GLIMPS) 40001324 88/20/NL/GLC through a subcontract with Deimos Space UK Ltd “GLIMPS Subcontract DMU-UPC Ref. DMU-CP51 no. 2021-015; project “GENESIS: GNSS Environmental and Societal Missions—Subproject UPC”, Grant PID2021-126436OB-C21, sponsored by MCIN/AEI/10.13039/501100 011033/ and EU ERDF “A way to do Europe”, and grant for recruitment of early stage research staff of Agència Gestió d’Ajuts Universitaris i de Recerca (AGAUR) Generalitat de Catalunya, Spain (FISDUR2020/105 and FI2022/809)., Peer Reviewed, Postprint (author's final draft)

A modification of the Barcelona Expert Center (BEC) algorithm to downscale the Soil Moisture and Ocean Salinity (SMOS) soil moisture (SM) to 300 m spatial resolution is presented. It maintains the same functional relationship as the currently implemented version but employs the following inputs: SMOS brightness temperature (TB) and SM (25 km), European Center for Medium Weather Forecast (ECMWF) skin temperature (9 km), and Sentinel 3 Normalized Difference Vegetation Index (NDVI, 300 m).The performance of the downscaled SMOS SM at 300 m is analyzed by means of a temporal validation with in-situ observations from the Soil Moisture Measurements Stations Network of the University of Salamanca (REMEDHUS) and the Continuous Soil Moisture and Temperature Ground-based Observation Network (RSMN) during the year 2021. No significant differences in correlation, unbiased root mean square difference (ubRMSD) and bias are obtained over both networks compared to the 25 km and 1 km SM products, suggesting the BEC downscaling algorithm could work at hundreds of meters and result in a similar SM accuracy., This work was supported by the Spanish Ministry of Science and Innovation (MCIN/AEI/10.13039/501100011033) through the projects INTERACT (PID2020-114623RB-C32 and PID2020-114623RB-C31), ERDF funds, the Institute of Space Studies of Catalonia (IECC), the ICM-CSIC Severo Ochoa Excellence Award (CEX2019-000928-S), and the CSIC Interdisciplinary Thematic Platform (PTI) TELEDETECT., Peer Reviewed, Postprint (author's final draft)

In the work a random forest model has been implemented as an interpretable machine learning tool in the effort to estimate the burned areas caused by fire outbreaks in India, Pakistan, and Myanmar in April and May 2022. The proposed model combines environmental and atmospheric (including upper tropospheric) factors suggested to drive patterns of burned areas, and determines the weight of each factor on the propagation of fires. Results demonstrate that the model mimics the actual burned area by considering a combination of vegetation, atmosphere, and human-related variables and improves accuracy by approximately 7% after adding jet stream features. This approach could lead to implement a semi-operational forecast system that may be tested in multiple demonstration sites., The project that gave rise to these results received the support of a fellowship from the ”la Caixa” Foundation (ID 100010434), with fellowship code LCF/BQ/DI21/11860028. This work was also supported by Project PID2020-114623RB-C32 funded by MCIN/ AEI /10.13039/501100011033. In addition, D. Chaparro has received funding from the XXXIII Ramón Areces Postdoctoral grant., Peer Reviewed, Postprint (author's final draft)

AlainSat-1 is an educational and scientific nanosatellite project that was initiated in late 2019 by the IEEE Geoscience and Remote Sensing Society (GRSS) along with National Space Science and Technology Center (NSSTC) of UAE University in the frame of the 2nd Student Grand Challenge [1]. The project involves close collaboration between four international universities to design, build, test and launch a remote sensing CubeSat.The spacecraft is a 3U CubeSat that has a mass of around 4 Kgs. The spacecraft has an active 3-axis control system capable of attitude determination and control to less than one degree. Two communications systems will be used on-board: a UHF System and an S-Band System. The project has passed the Critical Design Review (CDR) stage and is currently in the assembly and integration phase. The satellite is currently planned for launch to a sun-synchronous orbit on-board a Falcon 9 rocket in the second quarter of 2024., Peer Reviewed, Postprint (author's final draft)

Aquest treball s’ha realitzat al laboratori NanoSat Lab de la Universitat Politècnica de Catalunya (UPC) i es centra en l'optimització i el desenvolupament del mecanisme de desplegament d'una Antena Fresnel Zone Plate (FZPA). El nom del nano-satèl·lit que conté l’antena és 3CAT-8. A aquest desenvolupament hi han contribuït investigacions prèvies i idees d'altres estudiants. També s'ha estudiat la viabilitat dels components en condicions espacials i s'ha desenvolupat el mecanisme de desplegament de l'antena mitjançant investigació, simulació i proves. S'han dissenyat i provat diverses parts del nano satèl·lit 3CAT-8 per garantir-ne el funcionament correcte en l'espai. En tractar-se d’un nano satèl·lit en format CubeSat, se cenyeix a unes dimensions estandarditzades per al llançament correcte a l'espai. Per a l'optimització de l'antena desplegable i els mecanismes relacionats es van tenir en compte molts aspectes, com ara les propietats mecàniques de les peces triades, els efectes potencials dels canvis en altres parts del nano satèl·lit, l'optimització i el cost. Els diferents aspectes del nano satèl·lit es van desenvolupar i resoldre en paral·lel durant l'estada al laboratori, des de la fase d'idea fins al disseny, la fabricació i les proves. El desenvolupament de parts del 3CAT-8 es va dividir entre diversos membres de l’equip, i la col·laboració va ser essencial, ja que les decisions de cada membre afecten les dels altres., Este trabajo se ha llevado a cabo en el NanoSat Lab de la Universitat Politècnica de Catalunya (UPC) y se centra en la optimización y desarrollo del mecanismo de despliegue de una antena Fresnel Zone Plate (FZPA). El nombre del nanosatélite que contiene la antena es 3CAT-8. A este desarrollo han contribuido investigaciones previas e ideas de otros estudiantes. También se ha estudiado la viabilidad de los componentes en condiciones espaciales y se ha avanzado en el mecanismo de despliegue de la antena mediante investigación, simulación y pruebas. Se han diseñado y probado varias partes del nanosatélite 3CAT-8 para garantizar su correcto funcionamiento en el espacio. Al tratarse de un nanosatélite tipo CubeSat, se ciñe a unas dimensiones estandarizadas para su correcto lanzamiento al espacio. Para la optimización de la antena desplegable y los mecanismos relacionados se tuvieron en cuenta muchos aspectos, como las propiedades mecánicas de las piezas elegidas, los efectos potenciales de los cambios en otras partes del nanosatélite, la optimización y el coste. Los distintos aspectos del nanosatélite se desarrollaron y resolvieron en paralelo durante la estancia en el laboratorio, desde la fase de idea hasta el diseño, la fabricación y las pruebas. El desarrollo del 3CAT-8 se dividió entre varios miembros del equipo, y la colaboración fue esencial, ya que las decisiones de los miembros afectan a la de los demás., This work has been conducted at the NanoSat Lab of the Universitat Politècnica de Catalunya (UPC) and it’s focused on the optimization and development of the deployment mechanism of a Fresnel Zone Plate antenna (FZPA). The name of the nanosatellite that contains the antenna is 3CAT-8. Previous research and ideas from other students have contributed to this development. The feasibility of the components in space conditions has also been studied, and progress has been made in the deployment mechanism of the antenna through research, simulation, and testing. Several parts of the 3CAT-8 nanosatellite were designed and tested to ensure proper space functioning. As a nanosatellite in CubeSat format, it adheres to standardized dimensions for proper launch into space. Many aspects were considered for the optimization of the deployable antenna and related mechanisms, including the mechanical properties of the chosen parts, the potential effects of changes in other parts of the nanosatellite, optimization, and cost. Different aspects of the nanosatellite were developed and solved in parallel during the stay at the lab, from the idea stage to design, fabrication, and testing. The development of parts of the 3CAT-8 was divided among various team members, and collaboration was essential as each member's decisions affects other’s decisions.

Spacecraft entering a planetary atmosphere are surrounded by a plasma layer containing high levels of ionization due to the high temperatures on the shock layer. The high electron number densities cause attenuation and rotation of the emitted signal, leading to communication blackout. This work presents experimental measurements of radio signal attenuation and Faraday rotation due to an ionized plasma flow. These measurements are conducted at the VKI Plasmatron using circularly polarized directive horn lens antennas with a waveguide orthomode transducer. Clear attenuations are observed when the signal is propagating through the plasma, and Faraday rotation measurements show a good agreement with the theoretical estimation., Diana Luıs research is funded by a doctoral fellowship (2021.04930.BD) granted by Fundaçao para a Ciencia e Tecnologia (FCT Portugal). The MEESST project is funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 899298., Postprint (author's final draft)

Every year, earthquakes cause thousands of casualties and high economic losses. For example, in the time frame from 1998 to 2018, the total number of casualties due to earthquakes was larger than 846 thousand people, and the recorded economic losses were about USD 661 billion. At present, there are no earthquake precursors that can be used to trigger a warning. However, some studies have analyzed land surface temperature (LST) anomalies as a potential earthquake precursor. In this study, a large database of global LST data from the Geostationary Operational Environmental Satellite (GOES) and AQUA satellites during the whole year 2020 has been used to study the LST anomalies in the areas affected by earthquakes. A total of 1350 earthquakes with a magnitude larger than M4 were analyzed. Two methods widely used in the literature have been used to detect LST anomalies in the detrended LST time series: the interquartile (IQT) method and the standard deviation (STD). To the authors’ knowledge, it is the first time that the confusion matrix (CM), the receiver operating characteristic curve (ROC), and some other figures of merit (FoM) are used to assess and optimize the performance of the methods, and to select the optimum combination that could be used as a proxy for their occurrence. A positive anomaly was found a few days before the studied earthquakes, followed by the LST decrease after the event. Further studies over larger regions and more extended periods will be needed to consolidate these encouraging results., This work was sponsored by project “GENESIS: GNSS Environmental and Societal Missions—Subproject UPC”, Grant PID2021-126436OB-C21, sponsored by MCIN/AEI/10.13039/501100011033/ and EU ERDF “A way to do Europe”. Badr-Eddine Boudriki Semlali received support in the form of an FI grant: 2021 FI_B 00471 from Generalitat de Catalunya—FI AGAUR 2021., Peer Reviewed, Postprint (published version)

Due to the recent licensing of the bands for the new 26 GHz 5G communications band, which ranges from 24.25 GHz up to 25.25 GHz, there is a rising concern that spurious emissions from the 5G communications could interfere with passive Earth Observation measurements in the 23.8 GHz water vapor resonance band, degrading meteorological forecasts capabilities, and affecting climate change monitoring. The Frequency Allocations in Remote Sensing (FARS) Technical Committee from IEEE-GRSS has procured the development of a RFI monitoring payload to detect possible interferences in this band that might be caused by 5G communications. This work shows the design and verification of the RFI monitoring payload, that is compatible with the PocketQube?s being developed in the framework of the "IEEE GRSS Open PocketQube Kit" educational initiative.

This final degree thesis describes the development and implementation of an ADCS simulator for the 3Cat-8 mission of the UPC NanoSat Lab, which enables the calculation of the actuators and controller variables. Additionally, based on the ADCS simulator, specially focuses on the ATHENA ionic thruster control analysis ensuring the proper ADCS actuators sizing of the spacecraft. The control is solely achieved by magnetic actuators. It is shown that the satellite can maintain the desired orientation with low angular rates, required during the orbital raising maneuver. A new configuration of the control stability with linear attitude dynamics for satellite thruster, based on a control algorithm using attitude quaternion and angular velocity feedback is also described. To conclude, the presented numerical results prove the efficiency of the applied method based on initial theoretical considerations and the design measurements of the satellite and the thruster.

Vegetation optical depth (VOD) has contributed to monitor vegetation dynamics and carbon stocks at different microwave frequencies. Nevertheless, there is a need to determine which are the appropriate frequencies to monitor different vegetation types. Also, as only a few VOD-related studies use multi-frequency approaches, it is needed to evaluate their applicability. Here, we analyze the sensitivity of VOD at three frequencies (L-, C- and X-bands) to different vegetation covers by applying a global-scale unsupervised classification of VOD. A combination of these frequencies (LCX-VOD) is also studied. Two land cover datasets are used as benchmarks and, conceptually, serve as proxies of vegetation density. Results confirm that L-VOD is appropriate for monitoring the densest canopies but, in contrast, there is a higher sensitivity of X-, C- and LCX-VOD to the vegetation cover in savannahs, shrublands and grasslands. In particular, the multi-frequency combination is the most suited to sense vegetation in savannahs. Also, our study shows a vegetation-frequency relationship which is consistent with theory: the same canopies (e.g., savannahs and some boreal forests) are classified as lighter ones at L-band due to its higher penetration (e.g., as shrublands), but labeled as denser ones at C- and X-bands due their saturation (e.g., boreal forests are labeled as tropical forests). This study complements quantitative approaches investigating the link between VOD and vegetation, extends them to different frequencies, and provides hints on which frequencies are suitable for vegetation monitoring depending on the land cover. Conclusions are informative for upcoming multi-frequency missions, such as the Copernicus Multi-frequency Image Radiometer (CIMR)., This work has been funded by the Spanish Ministry of Science, Innovation and Universities and the European Regional Development Fund (ERDF, EU) through projects ESP2017-89463-C3-2-R, RTI2018-096765-A-100 and MDM-2016-0600, and by the project PID2020-114623RB-C32, funded by MCIN/ AEI /10.13039/501100011033. D. Chaparro has also received funding from “la Caixa” Foundation (ID 100010434), under agreement LCF/PR/MIT19/51840001 (MIT-Spain “La Caixa” Foundation Seed Fund), and from the XXXIII Ramón Areces Postdoctoral Fellowship., Peer Reviewed, Postprint (published version)

Currently, eight million metric tons of plastic end up in the oceans every year, and microplastics in different forms are present in almost all water systems in the world: streams, rivers, lakes, or oceans, and even in our blood. Detection of marine litter is an urgent task. Some works have recently reported the potential of GNSS-Reflectometry to detect marine plastic litter from space. This study presents the results of a controlled field experiment conducted under the auspices of ESA at the “Atlantic Basin” at the Deltares research institute (Delft, The Netherlands). Several types of wave conditions were created: sinusoidal and with JONSWAP spectrum, with different significant wave heights, and with different types of plastics and marine litter collected from the Dutch coast. Experimental results show the difficulty in detecting marine plastic litter based on a change of the reflected power. However, a statistical analysis of the GNSS-R estimated reflectivities (amplitude and phase) computed with very short integration times (coherent integration time Tcoh = 1 ms, and no incoherent averaging: Nincoh = 1) show that it may be possible to detect large accumulations of some types of marine litter that dampen the water waves, such as nets, bottles in a net, food wraps, and bags., This research was funded by ESA project GLobal MonItoring of MicroPlastics using GNSS- Reflectometry (GLIMPS) 4000132488/20/NL/GLC through a subcontract with Deimos Space UK Ltd “GLIMPS Subcontract DMU-UPC Ref. DMU-CP51 no. 2021-015; and project “GENESIS: GNSS Environmental and Societal Missions—Subproject UPC”, Grant PID2021-126436OB-C21, sponsored by MCIN/AEI/10.13039/501100011033/ and EU ERDF “A way to do Europe”., Postprint (published version)

From 1998 to 2022, Earthquakes have caused more than 850 thousand deaths and US$ 700 billion in economic losses. At this time, there is no reliable precursor to predict them. Many studies have attempted to link Land Surface Temperature (LST) anomalies to earthquake occurrence. This study uses long-term datasets from FengYun-2F/VISSR (Visible and Infrared Spin Scan Radiometer) sensors [1] between 2014 and 2022 to analyze the extent of LST anomalies and their potential link to earthquakes. More than 14,000 land and coastal earthquakes of magnitude higher than M4 have been studied between [+40°, +140°] longitude. Three methods frequently used in the literature, the Standard Deviation (STD), the Interquartile (IQT), and the Z-Score techniques have been implemented to detect LST anomalies on temporal series. Other parameters, such as the confusion matrix and the Receiver Operating Curves (ROC), have also been computed to assess and improve their performance and select the optimum correlation threshold. A positive LST anomaly is typically found before the earthquakes, followed by an LST decrease after the event., This study was supported by project GENESIS. Badr Eddine Boudriki Semlali was granted the FI grant:2021 FI_B 00471 from FI AGAUR 2021., Peer Reviewed, Postprint (author's final draft)

CubeSats are now serving a wide range of applications beyond their original educational intent. Private companies are deploying large constellations for Earth observation and machine–to–machine communications. Their growing popularity and increased performance have raised the demand for reliability and costs. Today, it is becoming increasingly difficult to find subsystems providers, and the trend is to find fully integrated platforms on the market. Therefore, paradoxically, CubeSats are becoming less accessible to universities and research institutions than a few years ago. To overcome these problems, the PocketQube concept was invented. PocketQubes measure 50 × 50 × 50 mm³ and offer a cost-effective option, notably for education. These picosatellites can perform simple missions like Internet of Things communications or upper-atmosphere observations, ionosphere studies, or signal integrity tasks, while students face design challenges similar to larger satellites. This article presents the IEEE Geoscience and Remote Sensing Society (GRSS) “Open PocketQube Kit” educational initiative. Developed by the NanoSat Lab at the Polytechnic University of Catalonia (UPC), it is an affordable open source educational kit featuring a complete PocketQube structure with all the subsystems: an electrical power supply (EPS), attitude determination and control system (ADCS), an STM32-based onboard computer (OBC), long-range (LoRa) communications, and payload. Three different PocketQube models have been developed: Po Cat-1, with a video graphics array (VGA) camera, and Po Cat-2 and Po Cat-3 for monitoring radio-frequency interference (RFI) at the L-band (1–2 GHz) and K-band (24–25 GHz) to track 5G spectrum emissions., This work was sponsored by the GRSS Directorate of Education and FARS Technical Committee., Peer Reviewed, Postprint (published version)

This M. Eng. is devoted to the study of the effects produced during the propagation of electromagnetic waves through an ionized medium, the ionosphere, in the presence of a magnetic field. For this purpose, a review of the ionosphere, electromagnetic propagation, and the state-of-the-art atmospheric models. The main challenge addressed by this thesis is the development of an ionospheric Matlab simulator to assess the propagation of the electromagnetic waves through the ionosphere. The main novelty of this work is the introduction of the current atmospheric and ionospheric models, as well as the latest version of the international geomagnetic reference field. As a result of this project, a very powerful tool never developed before with these characteristics has been generated in the framework of an ESA project. In addition, an SDR-based receiver of satellite opportunity signals has been developed and deployed in the D3 building to measure scintillation effects.

Incidence angle diversity of space-borne radiometer and radar systems operating at low microwave frequencies needs to be taken into consideration to accurately estimate soil moisture (SM) across spatial scales. In this study, the single channel algorithm (SCA) is first applied to Soil Moisture and Ocean Salinity (SMOS) brightness temperatures at vertical polarization ( TBV ) to estimate SM at coarse resolution (25 km) and develop a land cover-specific and incidence angle (32.5°, 42.5°, and 52.5°)-adaptive calibration of single scattering albedo ( ¿ ) and soil roughness ( hs ) parameters. These effective parameters are used together with fine-scale multiangular Sentinel-1 backscatter in a single-pass active–passive downscaling approach to estimate TBV at fine scale (1 km) for each SMOS incidence angle. These TBVs are finally inverted to obtain the corresponding high-resolution SM maps. Results over the Iberian Peninsula for year 2018 show an increasing trend of ¿ and a decreasing trend of hs with SMOS incidence angle, with almost no variability of ¿ across land cover types. The active–passive covariation parameter is shown to increase with SMOS incidence angle and decrease with Sentinel-1 incidence angle. Coarse and fine TBV maps from the three SMOS incidence angles show similar distributions (mean differences below 0.38 K). Resulting high-resolution SM maps have maximum differences in mean and standard deviation of 0.016 and 0.015 m 3 /m 3 , respectively, and compare well with in situ measurements. Our results indicate that model-based microwave approaches to estimate SM can be adequately adapted to account for the incidence angle diversity of planned missions, such as Copernicus Microwave Imaging Radiometer (CIMR), Radar Observing System for Europe in L-band (ROSE-L), and Sentinel-1 next generation., This work was supported in part by Ministeriode Ciencia e Innovación (MCIN)/Agencia Estatalde Investigación (AEI)/10.13039/501100011033 under Project PID2020-114623RB-C32; in part by the Spanish Ministry of Science, Innovation and Universities, through the coordinated project L-Band [MCIU/AEI/Fondo Europeo de Desarrollo Regional (FEDER), Unión Europea (UE)]: Sobre la continuidad de las misiones satelitales de banda L. Nuevos paradigmas en productos y aplicaciones, under Grant ESP2017-89463-C3-2-R (UPC part) and Grant ESP2017- 89463-C3-1-R (ICM part); and in part by the Unidad de Excelencia María de Maeztu under Grant MDM-2016-0600. The work of María Piles was supported by project LEAVES under Grant RTI2018-096765-A-100 funded by MCIN/AEI/10.13039/501100011033 and by the European Regional Development Fund (ERDF, EU), Peer Reviewed, Postprint (author's final draft)

Annually, earthquakes cause human and material losses. For instance, between 1998 and 2018, 846 thousand deaths and about US$ 661 billion of economic losses were recorded due to earthquakes. Currently, there is no clear precursor to forecast earthquakes. However, numerous investigations have attempted to find precursor proxies based on Land Surface Temperature (LST) anomalies. In this study, a big database collected from GOES/ABI instrument during the full year 2020 has been used to calculate the LST anomalies in the earthquakes zones. A total of 1350 earthquakes of Mw = 4 were studied in 2020. Two methods commonly used in the literature, the interquartile method, and the standard deviation of the time series, have been applied to detect LST anomalies. The confusion matrix, some figures of merit, and the receiver operating characteristic curve have been used to evaluate and enhance the performance of the methods and choose the optimum decision threshold. A positive anomaly is usually found before the earthquakes, followed by an LST decrease after the event., This work was supported by project SPOT: Sensing with Pioneering Opportunistic Techniques grant RTI2018- 099008-B-C21/AEI/10.13039/501100011033. Badr-Eddine Boudriki Semlali received support in an FI grant:2021 FI_B 00471 from FI AGAUR 2021., Peer Reviewed, Postprint (published version)

We live in a era where science increasingly requires to push the limits of human technology, and space exploration is of course not an exemption. Many objects in the universe are simply not observable in the optical band, others, although some of their faint light in the optical band may arrive to us, other parts of their electromagnetic spectrum may reveal a huge amount of potentially useful information. This is the reason why so many efforts in today's Astronomy focus on developing and improving superconducting photon detectors that, unlike conventional photon detectors, can provide counting, imaging and energy resolution in different bands of the electromagnetic spectrum. Transition-Edge Sensors (TES) are one of such detectors. TES detectors are in essence a superconducting film, biased at its critical temperature, whose huge sensitive allows it to act as a particle detector in the infrared region. TES arrays with thousands of pixels are increasingly used nowadays, and will be even more essential for achieving the science objectives of future far-infrared astronomical telescopes. However, the read out of such large arrays represents a challenge in terms of power consumption and thermal loading on the coldest cryogenic stages of those instruments. This thesis describes the design, development and preliminary results of a proof of concept for a novel modular readout solution called Modular Adaptive Transition Edge Sensor SQUID Electronics (MATESSE) that was conceived at the NASA GSFC Astrophysics Division and that is expected to serve as the necessary step towards the adaptation of the TDM readout technology to an space-proven system.

Significant Wave Height (SWH) is a key parameter to characterize waves, which is typically used in sea state monitoring such as wave forecast to ensure ocean navigation safety. Satellite radar altimeter is probably the primary tool to obtain SWH information. However, it cannot be used for large-scale sea state monitoring unless many of theses satellites are deployed. In this article, we aim to study the potential of Global Navigation Satellite System (GNSS)-Reflectometry (GNSS-R) in SWH measurement based on spaceborne Delay-Doppler Maps (DDMs) data. First, 3 observables (i.e., Delay-Doppler Map Average (DDMA), leading edge slope (LES) of normalized integrated delay waveform (NIDW) (LES-NIDW), and trailing edge slope (TES) of NIDW (TES-NIDW) derived from the DDMs are introduced for SWH estimation. Then, an empirical SWH retrieval model is proposed based on three observables. Subsequently, ERA5 SWH is used as reference data to verify the performance of the proposed model. The experimental results show that the Root Mean Square Error (RMSE) and Correlation Coefficient (CC) estimated by SWH of the three observables are better than 0.54 m and 0.88 m, respectively. Among them, the estimation performance based on DDMA observable is the best, with RMSE and CC of 0.49 m and 0.89 m. This study shows the potential of spaceborne GNSS-R in SWH retrieval. © 2022 IEEE., This work was supported by the Grant RYC-2016-20918 financed by MCIN/AEI /10.13039 /501100011033 and by ESF Investing in your future., Peer Reviewed, Postprint (published version)

Recent studies have shown possible signatures or precursors of seismic activity in the ionosphere. Our group is focusing on ionospheric scintillation associated with seismic activity. By the time this study was conducted, the sudden volcanic eruption in the Spanish La Palma island, starting on September 19th, opened a possibility to study the impact of this exceptional, well time-defined seismic event on the iono-sphere and the radio-wave propagation through it. A complete study measuring scintillation on GNSS signals and its correlation to seismic activity is presented in this extended abstract. In particular, scintillation data from two ground stations in the Canary Islands, NASA CYGNSS GNSS-Reflectometry and Spire GNSS Radio-Occultation measurements have been used. A linear correlation analysis has been conducted between S4, and the earthquakes generated energy in 6 h intervals. Small, and slightly positive regression coefficients have been found with almost all methods. © 2022 IEEE., was supported by the Spanish Ministry of Science, Innovation and Universities and EFRD, ”Sensing with Pioneering Opportunistic Techniques” SPOT, grant RTI2018-099008- BC21/AEI/10.13039/501100011033, and by the Unidad de Excelencia Maria de Maeztu MDM-2016-0600., Peer Reviewed, Postprint (published version)

Passive microwave remote sensing encompasses techniques well suited for use in systems with limited power budget, due to the low consumption linked to reception-only operation. Some examples of these techniques include Microwave Radiometry (MWR), Global Navigation Satellite Systems Reflectometry (GNSS-R), and Radio-Frequency Interference (RFI) detection algorithms. Small satellite missions including these instruments, such as FSSCat, have proven the value of passive remote sensing techniques with high revisit times due to the low orbits, and the possibility to horizontally scale the mission with more satellites. The Flexible Microwave Payload (FMPL) used in the FSSCat mission has continued development within the RITA Payload project, and it is now being used in Drone-based platforms to provide in-situ data using space-proven acquisition algorithms. In this work, the development of a drone-based FMPL will be presented. © 2022 IEEE., This work was supported by the projects of Spanish Ministerio de Ciencia, Innovacion y Universidades and EU ´ ERDF project ref. RTI2018-099008-B-C21/AEI/10.13039/501100011033 ”SENSING WITH PIONEERING OPPORTUNISTIC TECHNIQUES”, and Adrian Perez-Portero (FISDUR2020/105) and Amadeu Gonga (FI2022/809) were supported by grants for recruitment of early-stage research staff of the Agencia de Gesti ` o d’Ajuts Universitaris i de Recerca (AGAUR) Generalitat de Catalunya, Spain, and the Grant RYC-2016-20918 financed by MCIN/AEI /10.13039/501100011033 and by ESF Investing in your future., Peer Reviewed, Postprint (published version)

GNSS-R (Global Navigation Satellite Systems Reflectometry) can be understood as a multi-static radar with as many transmitters as navigation satellites and in view and can be tracked. GNSS-Reflectometers can process the reflected signals as a scatterometer, as an altimeter, or as an unfocused synthetic aperture radar. GNSS-R has demonstrated its potential to infer numerous geophysical variables over land (soil moisture, vegetation height, detecting freeze-thaw states... ), over the ocean (wind speed and direction, significant wave height, sea surface altimetry... ), over sea ice (extent, depth, type... ). Even a marine plastics litter product has been recently released by NASA, and some have suggested that sea surface salinity could also be inferred. In scatterometric applications the most widely used GNSS-R observable is the peak of the Delay Doppler Map (DDM), and many efforts have been directed towards an accurate instrument calibration. However, many geophysical parameter retrievals have neglected some variations of the DDM linked to the observation geometry, as well as the sensitivity to other geophysical variables. In this study we present analyze some of these effects and present a sensitivity analysis for the ocean case, notably the impact of the wind direction (WD), the 10 m height wind speed (mathrm{U}-{10}), which is routinely obtained today from GNSS-R observables, the sea surface temperature (SST) and sea surface salinity (SSS), and the presence of oil slicks. This quantitative study illustrates the challenges presented to retrieve some of these variables, the required corrections and their accuracy., This work was (partially) sponsored by project SPOT: Sensing with Pioneering Opportunistic Techniques grant RTI2018-099008-B-C21/AEI/10.13039/501100011033., Peer Reviewed, Postprint (author's final draft)

Ionospheric disturbances induced by seismic activity have been studied in the last years by many authors, showing an impact both before and after the occurrence of earthquakes. In this study, the ionospheric scintillation produced by the 2021 La Palma volcano eruption is analyzed. The "Cumbre Vieja" volcano was active from September 19th to December 13th, 2021, and many magnitude 3–4 earthquakes were recorded, with some of them reaching magnitude 5. In this study the three methods: GNSS reference monitoring, GNSS Reflectometry (GNSS-R) from NASA CYGNSS, and GNSS Radio Occultation (GNSS-RO) from COSMIC and Spire constellations, are used, allowing us to compare and evaluate their performance in the same conditions. To compare the seismic activity with ionospheric scintillation, earthquakes’ generated energy, and percentile 95 % of the intensity scintillation parameter (S4), measurements have been computed every 6 h intervals for the whole duration of the volcanic eruption. GNSS-RO has shown the best correlation between earthquakes’ energy and S4, with values up to 0.09 when the perturbations occur around 18 h after the seismic activity. GNSS reference monitoring stations data also shows some correlation 18 h after and 7–8 days after. As expected, GNSS-R is the one that shows the smallest correlation, as the ionospheric signatures get masked by the signature of the surface where the reflection is taking place. Additionally, as expected as well, the three methods show a smaller correlation during the week before earthquakes., This work was supported in part by the grant PID2021-126436OB-C21 from the Programa Estatal para Impulsar la Investigación Científico-Técnica y su Transferencia, del Plan Estatal de Investigación Científica, Técnica y de Innovación 2021-2023 (Spain) and in part by the European Social Fund (ESF). GNSS-RO Spire data has been provided by the European Space Agency through the ESA TPM SPIRE project id 67176., Preprint

The project developed in this thesis consists of creating a PocketQube payload in charge of monitoring the 24 to 25 GHz band to enforce that the emissions of the 5G communications band are within limit. In this thesis, the design of the main RF circuit has been carried out. It has been divided in different sub-systems, for each of which, a PCB has been created to be able to test and characterize them. From those tests, information has been taken and was used to design the low frequency circuit, which includes the power supply and the inputs and outputs interface of the main RF circuit., El proyecto desarrollado en este trabajo de fin de grado consiste en la creación de una carga útil de un PocketQube destinada a monitorizar la banda de los 24 a los 25 GHz con tal de controlar que las emisiones de la banda de comunicaciones de 5G se encuentran dentro de los límites. En este trabajo de fin de grado, se ha realizado el diseño del circuito principal de RF. Éste ha sido dividido en diferentes sub-sistemas, para cada uno de los cuales, una PCB ha sido creada para testearlos y caracterizarlos. De estos tests, información ha sido extraída y usada para diseñar el circuito de baja frecuencia, el cual incluye la alimentación y la interfaz de entradas y salidas del circuito de RF principal., El projecte desenvolupat en aquesta treball de fi de grau consisteix en crear una càrrega útil per a un PocketQube encarregada de monitorar la banda dels 24 als 25 GHz per a controlar que les emissions de la banda de comunicació de 5G es troben dins dels límits. En aquest treball de fi de grau, s’ha portat a terme el disseny del circuit principal de RF. Aquest ha estat dividit en diferents sub-sistemes, per a cadascun d’aquests, s’ha creat una PCB per a poder testejar-los i caracteritzar-los. D’aquests tests, s’ha extret informació que s’ha utilitzat per dissenyar el circuit de baixa freqüència, que inclou l’alimentació i la interfície de les entrades i sortides del circuit principal.

In 2019, the IEEE 2nd GRSS Student Grand Challenge selected the Remote sensing and Interference detector with radiomeTry and vegetation Analysis (RITA) payload to fly on board of AlainSat-1, a 3U CubeSat from the United Arab Emirates' National Space Science and Technology Center (NSSTC). The RITA payload is equipped with a Commercial Off-The-Shelf (COTS) Software Defined Radio (SDR) for the RF signal conditioning and a System on a Chip (SoC) processor in charge of controlling the execution and processing of each experiment that conforms the payload. RITA includes an L-band microwave radiometer (MWR), a Radio Frequency Interference (RFI) detector, a LoRa transceiver, and a hyper-spectral camera. A multi-level acquisition strategy joining several sensors for the aforementioned experiments' allows this payload retrieve parameters such as: soil moisture derived from the MWR, Normalized Difference Vegetation Index (NVDI) obtained from the hyper-spectral camera, improved acquisition of vegetation-related measurements through the LoRa transceiver, or even the compilation of worldwide interference maps. This manuscript will focus on the design, implementation, verification, and testing of the MWR on board the RITA payload, a successor of previous CubeSat missions such as FSSCat, which carried the FMPL-2 payload, or 3Cat-4 carrying FMPL-1 payload. © 2022 IEEE., Peer Reviewed, Postprint (published version)