Giacomo Curzi

In designing the trajectory for a multiple flyby mission to asteroids the choice of the targets is the most challenging problem. This dissertation faces this problem in the framework of the recently issued medium-size mission call (M5) from ESA: CASTAway. Starting from the preliminary work done in [6], this thesis develops a methodology for sequencing the potential targets in a multiple flyby mission. In order to reduce the computational time, the complete database of known small bodies is firstly pruned on the base of heuristic considerations. Using the assumption of small manoeuvres, a chief orbit concept could be used. Thus, two heuristic thresholds are defined in order to exclude non-promising targets given a chief orbit. The sequencing process takes chief orbit and promising targets as inputs and gives a set of candidate sequences. The results of such a process are analysed in the CASTAway framework and the best feasible sequence studied in details

In questo lavoro di tesi è stata validata una interfaccia grafica in ambiente Windows capace di impostare i parametri della camera Tau 320 FLIR, usata a bordo del satellite ESEO come sensore di terra. L'impostazione dei parametri passa, inoltre, attraverso l'hardware Discovery F4 e per questo è stato sviluppato e validato anche uno script in linguaggio C per la Discovery che fa comunicare il PC con la camera

Since 2003, the Microsatellite and Space Microsystems Lab at the University of Bologna (UniBo) has extended his research activities to the design of a ground segment for small satellites missions. In the framework of the European Student Earth Orbiter (ESEO), an ESA Education Office project for the development of a microsatellite mission, with SITAEL S.p.A. as the Industrial System Prime Contractor, the first-generation GS has been upgraded to support ESEO operations. UniBo was in charge for the design and development of the Mission Control Centre (MCC), the implementation of the primary ground station for telemetry and telecommand operations, and of the secondary one for the downlink of payloads data. ESEO was launched on December 3rd, 2018. Soon after launch, the activities planned for the Launch and Early Orbit Phase (LEOP) were forced to be held back due to the lack of success in commanding the spacecraft. After weeks of coordinated efforts among spacecraft operators, spacecraft engineers and ESA technical staff, LEOP activities could be resumed, thanks to the support of the radio amateur community and of ES5PC ground station in Tartu. Since then, new challenges are coming, which need to be faced for ESEO mission to advance further: this paper provides a thorough perspective of the achievements and lessons learnt during these months of operations.

As space traffic increases, Space Situational Awareness (SSA) is becoming fundamental for safe spaceflight operations. Cost-driven missions based on small satellite platforms would benefit from the availability of alternative tools providing preliminary SSA from publicly available information, such as two-line elements. In this work, we propose an orbit prediction and uncertainty evaluation method based on the well-established TLE differencing technique aided by a machine learning corrector. By designing a Recurrent Neural Network with carefully chosen input parameters, the TLE prediction accuracy is significantly improved, when tested against precise orbital data of real satellites. The prediction error is reduced, on average, by 45% across a prediction window of 16 days which may include manoeuvres. We further show that in combination with a statistical test for equality between error distributions, the differencing technique applied to the corrected TLE allows a reliable variance...

Since 2003, the Microsatellite and Space Microsystems Lab at the University of Bologna (UniBo) has extended his research activities to the design of a ground segment for small satellites missions. In the framework of the European Student Earth Orbiter (ESEO), an ESA Education Office project for the development of a microsatellite mission, with SITAEL S.p.A. as the Industrial System Prime Contractor, the first-generation GS has been upgraded to support ESEO operations. UniBo was in charge for the design and development of the Mission Control Centre (MCC), the implementation of the primary ground station for telemetry and telecommand operations, and of the secondary one for the downlink of payloads data. ESEO was launched on December 3rd, 2018. Soon after launch, the activities planned for the Launch and Early Orbit Phase (LEOP) were forced to be held back due to the lack of success in commanding the spacecraft. After weeks of coordinated efforts among spacecraft operators, spacecraft...

To enable a reliable verification of attitude determination and control systems for nanosatellites, the environment of low Earth orbits with almost disturbance-free rotational dynamics must be simulated. This work describes the design solutions adopted for developing a dynamic nanosatellite attitude simulator testbed at the University of Bologna. The facility integrates several subsystems, including: (i) an air-bearing three degree of freedom platform, with automatic balancing system, (ii) a Helmholtz cage for geomagnetic field simulation, (iii) a Sun simulator, and (iv) a metrology vision system for ground-truth attitude generation. Apart from the commercial off-the-shelf Helmholtz cage, the other subsystems required substantial development efforts. The main purpose of this manuscript is to offer some cost-effective solutions for their in-house development, and to show through experimental verification that adequate performances can be achieved. The proposed approach may thus be pr...

Since 2003, the Microsatellite and Space Microsystems Lab at the University of Bologna (UniBo) has extended his research activities to the design of a ground segment for small satellites missions. In the framework of the European Student Earth Orbiter (ESEO), an ESA Education Office project for the development of a microsatellite mission, with SITAEL S.p.A. as the Industrial System Prime Contractor, the firstgeneration GS has been upgraded to support ESEO operations. UniBo was in charge for the design and development of the Mission Control Centre (MCC), the implementation of the primary ground station for telemetry and telecommand operations, and of the secondary one for the downlink of payloads data. ESEO was launched on December 3rd, 2018. Soon after launch, the activities planned for the Launch and Early Orbit Phase (LEOP) were forced to be held back due to the lack of success in commanding the spacecraft. After weeks of coordinated efforts among spacecraft operators, spacecraft ...

As space traffic increases, Space Situational Awareness (SSA) is becoming fundamental for safe spaceflight operations. Cost-driven missions based on small satellite platforms would benefit from the availability of alternative tools providing preliminary SSA from publicly available information, such as two-line elements. In this work, we propose an orbit prediction and uncertainty evaluation method based on the well-established TLE differencing technique aided by a machine learning corrector. By designing a Recurrent Neural Network with carefully chosen input parameters, the TLE prediction accuracy is significantly improved, when tested against precise orbital data of real satellites. The prediction error is reduced, on average, by 45% across a prediction window of 16 days which may include manoeuvres. We further show that in combination with a statistical test for equality between error distributions, the differencing technique applied to the corrected TLE allows a reliable variance estimate in most situations. Limitation of the work is the training of a dedicated neural network corrector for each specific space object, which will be deposed as part of our ongoing efforts.

To enable a reliable verification of attitude determination and control systems for nanosatellites, the environment of low Earth orbits with almost disturbance-free rotational dynamics must be simulated. This work describes the design solutions adopted for developing a dynamic nanosatellite attitude simulator testbed at the University of Bologna. The facility integrates several subsystems, including: (i) an air-bearing three degree of freedom platform, with automatic balancing system, (ii) a Helmholtz cage for geomagnetic field simulation, (iii) a Sun simulator, and (iv) a metrology vision system for ground-truth attitude generation. Apart from the commercial off-the-shelf Helmholtz cage, the other subsystems required substantial development efforts. The main purpose of this manuscript is to offer some cost-effective solutions for their in-house development, and to show through experimental verification that adequate performances can be achieved. The proposed approach may thus be pr...

We propose a simple and relatively inexpensive method for determining the center of gravity (CoG) of a small spacecraft. This method, which can be ascribed to the class of suspension techniques, is based on dual-axis inclinometer readings. By performing two consecutive suspensions from two different points, the CoG is determined, ideally, as the intersection between two lines which are uniquely defined by the respective rotations. We performed an experimental campaign to verify the method and assess its accuracy. Thanks to a quantitative error budget, we obtained an error distribution with simulations, which we verified through experimental tests. The retrieved experimental error distribution agrees well with the results predicted through simulations, which in turn lead to a CoG error norm smaller than 2 mm with 95% confidence level.

Constellations of satellites are being proposed in large numbers; most of them are expected to be in orbit within the next decade. They will provide communication to unserved and underserved communities, enable global monitoring of Earth and enhance space observation. Mostly enabled by technology miniaturization, satellite constellations require a coordinated effort to face the technological limits in spacecraft operations and space traffic. At the moment in fact, no cost-effective infrastructure is available to withstand coordinated flight of large fleets of satellites. In order for large constellations to be sustainable, there is the need to efficiently integrate and use them in the current space framework. This review paper provides an overview of the available experience in constellation operations and statistical trends about upcoming constellations at the moment of writing. It highlights also the tools most often proposed in the analyzed works to overcome constellation managem...