This work was carried out during an eight months traineeship program, from May to December 2020, at the European Space Agency (ESA), in the European Space Operation Centre (ESOC) located in Darmstadt, Germany. ESOC is responsible for a wide range of activities, such as operation during the launch phase of satellites and probes and during the Low Earth Orbit Phase (LEOP) not only of ESA’s missions but also supporting other space agencies, flight dynamics control, ground systems engineering, software development and the development of all relevant instruments for the missions control. During the internship, the author has worked, in teleworking due to the Covid-19 pandemic, in the Ground Station Antennas section, taking part in the project called SNOWBEAR (Svalbard grouNd statiOn for Wide Band Earth obsErvation dAta Reception), which is commissioned by the EPS-SG mission (EUMETSAT Polar System – Second Generation), in the ESA’s Earth observation program, in order to de-risk the introduction of the new band for the downlink at 26 GHz. The general goal of the SNOWBEAR program is to build, integrate and validate all the prototypes that constitute the receiving chain of a ground station, installed in the Svalbard archipelago, for the frequency band between 25.5 GHz and 27 GHz, by performing a two years long measuring campaign. Over this period, the data are collected thanks to the so-called shadow-tracking of the NASA (National Aeronautics and Space Administration) JPSS-1 satellite (Joint Polar Satellite System 1), renamed NOAA-20 after le LEOP campaign. In particular, the SNOWBEAR project is useful to check and validate the current atmospheric attenuation and propagation models are also suitable for polar environment applications that exploit the, above mentioned, new frequency band. In order to understand if they can be used for the development of future missions such as next generation Sentinel satellites, part of the Copernicus program, and the Metop-SG (EUMETSAT), the new generation of polar orbiting satellites for Earth observation. Another important outcome is to gain experience not only with the ground station design process but also with the validation phase itself of ground station working at 26 GHz and equipped with a radome in order to protect the antennas from the harsh environment conditions. This work studies and gives a first description and modelling of the effects caused by the presence of snow layers on the radome that incorporate the antenna under analysis. These effects are not only related to the absorption, due to the additional dielectric layer between the antenna and the spacecraft, but they also affect the pointing system of the ground terminal, leading to extra losses. Within this study, an “a posteriori” method to measure and correct systematic errors that affect the SNOWBEAR antenna pointing has been implemented and validated. This correction has been then successfully implemented as enhanced feature of the SNOWBEAR post processing tool. This is a python software, developed by UNIPV, which allows to compare theoretical and measured data and to produce statistical analyses of the link performances.
Analisi degli effetti dell'accumulo di neve su un radome di un’antenna di una stazione di terra alle frequenze in banda K. Questo lavoro è stato svolto durante un programma di internship della durata di otto mesi, da maggio a dicembre 2020, presso l’European Space Agency (ESA), allo European Space Operation Centre (ESOC) a Darmstadt, in Germania. ESOC è responsabile di svariate attività, come ad esempio delle operazioni di fase di lancio di satelliti e sonde e di Low Earth Orbit Phase (LEOP) di missioni, sia progettate da ESA che da altre agenzie, del controllo delle dinamiche di volo, dello sviluppo di stazioni di terra, dello sviluppo software e dello sviluppo di tutti gli strumenti utili per il controllo delle missioni. In questi mesi l’autore ha lavorato, da remoto a causa della pandemia di Covid-19, nella sezione Ground Station Antennas prendendo parte al progetto SNOWBEAR (Svalbard grouNd statiOn for Wide Band Earth obsErvation dAta Reception), finanziato dalla missione EPS-SG (EUMETSAT Polar System – Second Generation), all’interno del programma di osservazione della terra di ESA, al fine di introdurre la nuova banda di ricezione a 26 GHz. L’obiettivo generale del progetto è di costruire, integrare e validare tutti i prototipi che vanno a costituire la catena di ricezione di una stazione di terra installata alle isole Svalbard, per la banda di frequenze tra 25.5 GHz e 27 GHz, attraverso una campagna di misura della durata di due anni. Per l’intera durata di questo periodo, verranno raccolti e analizzati diversi dati grazie al così detto shadow-tracking del satellite JPSS-1 (Joint Polar Satellite System 1) della NASA (National Aeronautics and Space Administration), denominato NOAA-20 una volta completata la fase di LEOP. In particolare, il progetto SNOWBEAR serve per appurare se gli odierni modelli relativi all’attenuazione atmosferica e alla propagazione di segnale siano validi anche per applicazioni in ambiente polare che utilizzano la sopra citata nuova banda di frequenze, in modo tale da poter essere utilizzati per lo sviluppo di missioni future quali per esempio la nuova generazione dei satelliti Sentinel, parte del programma Copernicus, e Metop-SG, la nuova generazione di satellite polari per l’osservazione terrestre da parte di EUMETSAT. Un ulteriore obiettivo di SNOWBEAR è quello di acquisire esperienza sia per il processo di progettazione che per la fase di validazione di stazioni di terra a 26 GHz che utilizzano un radome per la protezione dell’antenna da fenomeni metereologici quali vento e pioggia. Nello specifico, questo lavoro di tesi nasce per studiare e fornire una prima descrizione e modellazione degli effetti causati dalla presenza di strati di neve sul radome che ingloba l’antenna in questione. Effetti che non sono solo relativi all’assorbimento di segnale, essendo la neve uno strato dielettrico addizionale tra l’antenna di terra e il satellite, ma affliggono anche il sistema di puntamento del terminale di terra, causando perdite aggiuntive. All’interno di questo percorso di studio è poi stato anche presentato e validato un metodo di correzione a posteriori per errori sistematici relativi al sistema di puntamento del di SNOWBEAR. Questa correzione è stata poi implementata con successo a miglioramento del tool di post-processing di SNOWBEAR. Si tratta di un software Python, sviluppato da UNIPV, che permette di confrontare i dati teorici con quelli misurati e di produrre analisi statistiche riguardo alle prestazioni del collegamento tra antenna e satellite.
Analysis of the effects of snow accumulation on a ground station antenna radome at K-Band frequencies
ARENARE, DAVIDE
2019/2020
Abstract
This work was carried out during an eight months traineeship program, from May to December 2020, at the European Space Agency (ESA), in the European Space Operation Centre (ESOC) located in Darmstadt, Germany. ESOC is responsible for a wide range of activities, such as operation during the launch phase of satellites and probes and during the Low Earth Orbit Phase (LEOP) not only of ESA’s missions but also supporting other space agencies, flight dynamics control, ground systems engineering, software development and the development of all relevant instruments for the missions control. During the internship, the author has worked, in teleworking due to the Covid-19 pandemic, in the Ground Station Antennas section, taking part in the project called SNOWBEAR (Svalbard grouNd statiOn for Wide Band Earth obsErvation dAta Reception), which is commissioned by the EPS-SG mission (EUMETSAT Polar System – Second Generation), in the ESA’s Earth observation program, in order to de-risk the introduction of the new band for the downlink at 26 GHz. The general goal of the SNOWBEAR program is to build, integrate and validate all the prototypes that constitute the receiving chain of a ground station, installed in the Svalbard archipelago, for the frequency band between 25.5 GHz and 27 GHz, by performing a two years long measuring campaign. Over this period, the data are collected thanks to the so-called shadow-tracking of the NASA (National Aeronautics and Space Administration) JPSS-1 satellite (Joint Polar Satellite System 1), renamed NOAA-20 after le LEOP campaign. In particular, the SNOWBEAR project is useful to check and validate the current atmospheric attenuation and propagation models are also suitable for polar environment applications that exploit the, above mentioned, new frequency band. In order to understand if they can be used for the development of future missions such as next generation Sentinel satellites, part of the Copernicus program, and the Metop-SG (EUMETSAT), the new generation of polar orbiting satellites for Earth observation. Another important outcome is to gain experience not only with the ground station design process but also with the validation phase itself of ground station working at 26 GHz and equipped with a radome in order to protect the antennas from the harsh environment conditions. This work studies and gives a first description and modelling of the effects caused by the presence of snow layers on the radome that incorporate the antenna under analysis. These effects are not only related to the absorption, due to the additional dielectric layer between the antenna and the spacecraft, but they also affect the pointing system of the ground terminal, leading to extra losses. Within this study, an “a posteriori” method to measure and correct systematic errors that affect the SNOWBEAR antenna pointing has been implemented and validated. This correction has been then successfully implemented as enhanced feature of the SNOWBEAR post processing tool. This is a python software, developed by UNIPV, which allows to compare theoretical and measured data and to produce statistical analyses of the link performances.È consentito all'utente scaricare e condividere i documenti disponibili a testo pieno in UNITESI UNIPV nel rispetto della licenza Creative Commons del tipo CC BY NC ND.
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https://hdl.handle.net/20.500.14239/12751