Spacecraft Rendezvous and Docking Using Electromagnetic Interactions

On-orbit operations such as refuelling, payload updating, inspection, maintenance, material and crew transfer, modular structures assemblies and in general all those processes requiring the participation of two or more collaborative vehicles are acquiring growing importance in the space-related field, since they allow the development of longer-lifetime missions. To successfully accomplish all these on-orbit servicing operations, the ability to approach and mate with another vehicle is fundamental. Rendezvous strategies, proximity procedures and docking manoeuvres between spacecraft are of utmost importance and new, effective, standard and reliable solutions are needed to ensure further technological developments. Presently, the possibility to create low-cost clusters of vehicles able to share their resources may be exploited thanks to the broadening advent of CubeSat-sized spacecraft, which are conditioning the space market nowadays. In this context, this thesis aims at presenting viable strategies for spacecraft RendezVous and Docking (RVD) manoeuvres exploiting electro-magnetic interactions. Two perspective concepts have been investigated and developed, linked together by the use of CubeSat-size testing platforms. The idea behind the first one, PACMAN (Position and Attitude Control with MAgnetic Navigation) experiment, is to actively exploit magnetic interactions for relative position and attitude control during rendezvous and proximity operations between small-scale spacecraft. PACMAN experiment has been developed within ESA Education Fly Your Thesis! 2017 programme and has been tested in low-gravity conditions during the 68th ESA Parabolic Flight Campaign (PFC) in December 2017. The experiment validation has been accomplished by launching a miniature spacecraft mock-up (1 U CubeSat, the CUBE) and a Free-Floating Target (1 U CubeSat, the FFT) that generates a static magnetic fields towards each other; a set of actively-controlled magnetic coils on board the CUBE, assisted by dedicated localization sensors, are used to control the CUBE attitude and relative position, assuring in this way the accomplishment of the soft-docking manoeuvre. The second one, TED (Tethered Electromagnetic Docking), concerns a novel docking strategy in which a tethered electromagnetic probe is expected to be ejected by a chaser toward a receiving electromagnetic interface mounted on a target spacecraft. The generated magnetic field drives the probe to the target and realizes an automatic alignment between the two interfaces, thus reducing control requirements for close approach manoeuvres as well as the fuel consumption necessary for them. After that, hard-docking can be accomplished by retracting the tether and bringing the two spacecraft in contact

REGULUS CubeSat Propulsion System: In-Orbit Operations

A robust, versatile, and cost-effective propulsion system to provide wide mobility to small satellite platforms and nanosatellite deployers. A Plug&Play propulsion system designed to be easily integrated into different satellite platforms and to match customer\u27s requirements, with minimal customization efforts and costs

REGULUS Iodine Electric Propulsion System Integration in CubeSats’ Platforms and Testing

REGULUS is an electric propulsion (EP) system for CubeSats at TRL8 and now waiting for the IoD flight in late 2020. REGULUS system is provided for integration with all electronics, fluidic line, iodine tank and structures for total mass below 3 kg. Thanks in particular to the Magnetically Enhanced RF Plasma Thruster (MEPT) technology and the use of iodine propellant, the system can provide 3000Ns of total impulse in a 93.8 x 95.0 x 150.0 mm volume performance, fitting in a 1.5U Cubesat. REGULUS includes the whole propulsion package for integration in CubeSats and MicroSats as well as small CubeSat carriers. The system is composed by the thruster, the electronics (PPUs and PCU) the fluidic line and the tank. The main features of REGULUS are the presence of a simple architecture, a thruster with no neutralizer and grids, no high DC-voltage PPU and the use of solid iodine as propellant, that can be substituted with Xenon fluidic line and tank when required. Its first mission will be onboard of Unisat-7 by GAUSS. The flight will take place in late 2020 in a Soyuz flight. During the mission, REGULUS will allow Unisat-7 to perform an orbit descending maneuver, drag compensation in VLEO and decommissioning

Brain activation in Highly Superior Autobiographical Memory: The role of the precuneus in the autobiographical memory retrieval network

This is the first study to examine functional brain activation in a single case of Highly Superior Autobiographical Memory (HSAM) who shows no sign of OCD. While previous work has documented the existence of HSAM, information about brain areas involved in this exceptional form of memory for personal events relies on structural and resting state connectivity data, with mixed results so far. In this first task-based fMRI study of a normal individual with HSAM, dates were presented as cues and two phases were assessed during memory retrieval, initial access and later elaboration. Results showed that initial access was very fast, did not activate the hippocampus, and involved activation of predominantly posterior visual areas, including the praecuneus. These areas typically become active during later stages of elaboration of personal memories rather than during initial access. Elaboration involved a balanced bilateral activation of most of the autobiographical network areas, rather than the more typical shifts observed in people without HSAM. Overall, the pattern of brain activations, which rests on repeated observations in a single individual, highlights a strong involvement of the praecuneus and an idiosyncratic initial access to personal memory representations. Implications for the nature of personal memories in HSAM are discussed

Spacecraft Rendezvous and Docking Using Electromagnetic Interactions

On-orbit operations such as refuelling, payload updating, inspection, maintenance, material and crew transfer, modular structures assemblies and in general all those processes requiring the participation of two or more collaborative vehicles are acquiring growing importance in the space-related field, since they allow the development of longer-lifetime missions. To successfully accomplish all these on-orbit servicing operations, the ability to approach and mate with another vehicle is fundamental. Rendezvous strategies, proximity procedures and docking manoeuvres between spacecraft are of utmost importance and new, effective, standard and reliable solutions are needed to ensure further technological developments. Presently, the possibility to create low-cost clusters of vehicles able to share their resources may be exploited thanks to the broadening advent of CubeSat-sized spacecraft, which are conditioning the space market nowadays. In this context, this thesis aims at presenting viable strategies for spacecraft RendezVous and Docking (RVD) manoeuvres exploiting electro-magnetic interactions. Two perspective concepts have been investigated and developed, linked together by the use of CubeSat-size testing platforms. The idea behind the first one, PACMAN (Position and Attitude Control with MAgnetic Navigation) experiment, is to actively exploit magnetic interactions for relative position and attitude control during rendezvous and proximity operations between small-scale spacecraft. PACMAN experiment has been developed within ESA Education Fly Your Thesis! 2017 programme and has been tested in low-gravity conditions during the 68th ESA Parabolic Flight Campaign (PFC) in December 2017. The experiment validation has been accomplished by launching a miniature spacecraft mock-up (1 U CubeSat, the CUBE) and a Free-Floating Target (1 U CubeSat, the FFT) that generates a static magnetic fields towards each other; a set of actively-controlled magnetic coils on board the CUBE, assisted by dedicated localization sensors, are used to control the CUBE attitude and relative position, assuring in this way the accomplishment of the soft-docking manoeuvre. The second one, TED (Tethered Electromagnetic Docking), concerns a novel docking strategy in which a tethered electromagnetic probe is expected to be ejected by a chaser toward a receiving electromagnetic interface mounted on a target spacecraft. The generated magnetic field drives the probe to the target and realizes an automatic alignment between the two interfaces, thus reducing control requirements for close approach manoeuvres as well as the fuel consumption necessary for them. After that, hard-docking can be accomplished by retracting the tether and bringing the two spacecraft in contact.La capacità di eseguire operazioni di servizio su veicoli in orbita ha riscontrato, negli ultimi anni, un’enorme interesse da parte delle maggiori compagnie e agenzie spaziali internazionali. La necessità di ridurre i costi di produzione, assieme alla possibilità di ottenere sistemi complessi più affidabili e duraturi, ha indirizzato marcatamente il mercato dell’ingegneria aerospaziale verso lo studio di soluzioni innovative per eseguire in orbita operazioni quali rifornimento, aggiornamento e manutenzione di sottositemi, riparazioni di componenti non funzionanti e ispezioni. Le nuove idee e tecnologie in via di sviluppo per eseguire queste operazioni sono percepite come estremamente funzionali e efficienti in termini di costo, in grado di estendere la vita operativa di un satellite e diminuire i costi connessi alla sua completa sostituzione. Attualmente, il tassello mancante per poter procedere efficacemente con questo tipo di procedure, è un sistema automatico di docking che possa costituire un nuovo standard semplice ed affidabile. Gli odierni sistemi di docking, infatti, sono caratterizzati da elevati requisiti di puntamento e necessitano dell’attuazione di precise azioni sul controllo d’assetto in modo da garantire un aggancio sicuro tra i due veicoli coinvolti nella manovra. Questo è dovuto al fatto che tali sistemi di aggancio sono stati progettati quasi unicamente per il trasferimento di equipaggio o di materiali mentre nessuna progettazione, finora, è mai stata prevista per i satelliti commerciali e scientifici. Recentemente, l’avvento dei CubeSat ha fortemente incoraggiato aziende e agenzie del settore aerospaziale ad investire nello sviluppo di dimostratori tecnologici e payload scientifici, grazie alla notevole riduzione nel costo necessario per lanciare in orbita tali veicoli. Lo svantaggio nell’utilizzare questo tipo di piattaforme è principalmente legato ai limiti tecnici intrinseci degli stessi, rappresentati dalle ridotte risorse a disposizione. Ciononostante, gran parte di queste limitazioni sono state superate grazie alla possibilità di scalare i risultati ottenuti ed applicarli a sistemi più grandi. Numerose tecnologie sono già state testate e caratterizzate nello spazio usando moduli CubeSat, ma solo esperimenti marginali sono stati condotti sino ad oggi su sistemi di docking, anche se si sta percependo un cambio di tendenza. Tali sistemi, infatti, permetterebbero l’esecuzione di operazioni di aggancio e sgancio, ampliando enormemente i possibili scenari di missione: sistemi modulari formati da molteplici unità CubeSat potrebbero interagire tra loro creando agglomerati più grandi in grado di condividere le risorse più efficacemente, riorganizzarsi e aggiornarsi autonomamente. Lo scopo di questa ricerca è quello di proporre un nuovo sistema di soft-docking caratterizzato da requisiti meno stringenti per quanto concerne l’accuratezza nel puntamento e nel controllo d’assetto rispetto ai sistemi esistenti. L’idea innovativa alla base dello studio è quella di sfruttare la capacità di auto-allineamento e reciproca attrazione garantita dall’interazione magnetica che si instaura tra due interfacce elettromagnetiche, in modo da facilitare le manovre di prossimità ed aggancio. La trattazione è suddivisa in due parti principali. Nella prima parte viene presentato l’esperimento PACMAN (Position and Attitude Control with MAgnetic Navigation) il quale rappresenta un dimostratore tecnologico di un sistema di docking per piccoli satelliti basato su attuatori magnetici. Tale sistema, sviluppato all'interno del programma ESA Education Fly Your Thesis! 2017, è stato testato in gravità ridotta durante la 68th campagna di voli parabolici ESA a dicembre. La seconda parte si focalizza invece su un nuovo concept, TED (Tethered Electromagnetic Docking), secondo il quale le manovre di close-range rendezvous e docking possono essere realizzate lanciando una sonda elettromagnetica collegata ad un filo da un satellite chaser verso un’interfaccia elettromagnetica montata su di un satellite target. Stabilito il collegamento, tramite il recupero del filo, i due veicoli sono connessi rigidamente concludendo la manovra

Aerodynamic analysis of morphing airfoils in dynamic stall using the ONERA model

La tesi presenta un modello unificato per determinare i carichi dinamici agenti sui profili. Tale modello è composto da tre parti principali:\n1) la teoria di Johnson/Peters sui profili flessibili per la descrizione di un qualsiasi profilo;\n2) un modello di flusso indotto per valutare l'effetto scia;\n3) modello di stallo dinamico di ONERA per descrivere tale fenomeno