The number of space debris in orbit around the Earth is constantly increasing. For this reason, the scientific community is moving in the direction of safeguarding the space environment by monitoring the presence of space debris and trying to reduce their future creation. In this context, many methods have been devised for the active remove of inactive objects in orbit, but other passive mitigation actions are still necessary. These actions should lead to the debris' progressive decrease over time. In this regard, the use of solar sails for controlled satellite deorbitation is an attractive alternative, as it would allow satellites with high semi-major axis orbits to re-enter in atmosphere in a relatively short time. This thesis focuses in the first place on finding the minimum Area-To-Mass (ATM) ratio of a satellite equipped with a solar sail that allows direct or modulated deorbitating. The former method progressively increases the eccentricity of the orbit until it reaches the maximum value, that for a certain ATM ratio coincides with the critical eccentricity. The latter method would allow the use of solar sails with a lower area-to-mass ratio, increasing the practicability of deorbiting even for those cases that required too large sails with the previous method. Modulated deorbiting on the other hand generates a slower deorbiting. In this work Hamiltonian system theory is used, as the use of phase space facilitates the study of the orbit evolution by reducing the variables under analysis. The schemes used include both a simplified Hamiltonian (which consists of an analysis of an equatorial orbit without considering the tilt of the Earth's axis) and a 3D Hamiltonian, which allows the study of inclined orbits. For this second methodology a pseudo-algebraic expression for the minimum area-to-mass ratio to deorbit is found in this work. Only the perturbations due to the solar radiation pressure and the J2 of the Earth are considered. At the end of the thesis, an application section is also presented. This will consist in designing a quasi-rhombic pyramid-shaped sail that should be stored inside a single CubeSat unit. Different methods of sail folding will be proposed, starting from the most classic, up to those inspired by origami art. This thesis project is part of the project COMPASS which has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No 679086 - COMPASS).
Il numero di space debris in orbita attorno alla Terra è in continuo aumento, perciò la comunità scientifica si stà muovendo nella direzione di salvaguardare l'ambiente spaziale monitorando la presenza di spazzatura e cercando di ridurne la futura creazione. Sono stati ideati in questo contesto molti metodi per la raccolta in orbita di oggetti inutilizzati, ma è necessaria pure un'azione di mitigazione passiva che porti alla loro diminuzione progressiva nel tempo. A questo proposito, l'impiego di vele solari per una deorbitazione controllata del satellite risulta essere un'alternativa attraente, poichè permetterebbe a satelliti con orbite a semiasse maggiore elevato di rientrare in atmosfera in tempi relativamente brevi. Questa tesi si concentra soprattutto sul trovare il minimo rapporto area su massa del satellite disposto di vela solare che consenta la deorbitazione diretta (per aumento progressivo dell'eccentricità dell'orbita fino a raggiungere il massimo valore di eccentricità critica) o modulata. Quest'ultimo metodo consentirebbe l'utilizzo di vele solari con minore rapporto di area su massa, aumentando la praticabilità del deorbiting anche per orbite che con il primo metodo richiedevano vele troppo grandi. Il deorbiting modulato d'altro canto genera una caduta più lenta. Viene utilizzata la matematica Hamiltoniana, poichè l'uso dello spazio di fase facilita lo studio dell'evoluzione dell'orbita riducendo le variabili analizzate. Gli schemi utilizzati comprendono sia un Hamiltoniano semplificato (che consiste in un'analisi di un orbita equatoriale senza considerare il tilt dell'asse terrestre) sia un Hamiltoniano 3D, che consentirà lo studio di orbite inclinate. Per questa seconda metodologia viene inoltre trovata un'espressione pseudo-algebrica per il minimo rapporto di area su massa per deorbitare. Vengono prese in considerazione solo le perturbazioni dovute alla pressione solare e al J2 della Terra. A conclusione della tesi verrà inoltre presentata una parte applicativa, che consiste nel progettare una vela a forma piramidale in una singola unità di CubeSat. In questo frangente verranno presentati diversi metodi di piegatura delle vele, partendo dai più classici fino a quelli ispirati dall'arte origami. Questa tesi fa parte del progetto COMPASS che ha ricevuto finanziamenti dal Consiglio Europeo della Ricerca (ERC) nell'ambito del programma di ricerca e innovazione Horizon 2020 dell'Unione Europea (accordo di sovvenzione n. 679086 - COMPASS).
Solar sail strategies for satellite's direct and modulating deorbiting
GIOVANNINI, CECILIA
2020/2021
Abstract
The number of space debris in orbit around the Earth is constantly increasing. For this reason, the scientific community is moving in the direction of safeguarding the space environment by monitoring the presence of space debris and trying to reduce their future creation. In this context, many methods have been devised for the active remove of inactive objects in orbit, but other passive mitigation actions are still necessary. These actions should lead to the debris' progressive decrease over time. In this regard, the use of solar sails for controlled satellite deorbitation is an attractive alternative, as it would allow satellites with high semi-major axis orbits to re-enter in atmosphere in a relatively short time. This thesis focuses in the first place on finding the minimum Area-To-Mass (ATM) ratio of a satellite equipped with a solar sail that allows direct or modulated deorbitating. The former method progressively increases the eccentricity of the orbit until it reaches the maximum value, that for a certain ATM ratio coincides with the critical eccentricity. The latter method would allow the use of solar sails with a lower area-to-mass ratio, increasing the practicability of deorbiting even for those cases that required too large sails with the previous method. Modulated deorbiting on the other hand generates a slower deorbiting. In this work Hamiltonian system theory is used, as the use of phase space facilitates the study of the orbit evolution by reducing the variables under analysis. The schemes used include both a simplified Hamiltonian (which consists of an analysis of an equatorial orbit without considering the tilt of the Earth's axis) and a 3D Hamiltonian, which allows the study of inclined orbits. For this second methodology a pseudo-algebraic expression for the minimum area-to-mass ratio to deorbit is found in this work. Only the perturbations due to the solar radiation pressure and the J2 of the Earth are considered. At the end of the thesis, an application section is also presented. This will consist in designing a quasi-rhombic pyramid-shaped sail that should be stored inside a single CubeSat unit. Different methods of sail folding will be proposed, starting from the most classic, up to those inspired by origami art. This thesis project is part of the project COMPASS which has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No 679086 - COMPASS).| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/183320