When sunlight illuminates a body, a tiny pressure is exerted upon its surface due to the photons impacting on it. Such a principle forms the basis of solar sailing, in which the solar radiation pressure is used to accelerate highly reflective lightweight structures called solar sails. Similarly, a laser-enhanced solar sail is a solar sail in which also an external laser beam pointed towards the sail is exploited to generate thrust. In this way an additional laser radiation pressure is exerted onto the sail, hence conferring higher propulsive and steering capabilities, and leading to an increased maneuverability of the sailcraft. The main purpose of this thesis project is to provide a model of the laser-enhanced solar sail dynamics and to establish the advantages of laser-enhanced solar sailing as compared to "traditional" solar sailing. The analysis has been pursued focusing on interplanetary missions and considering ideal sails, i.e. sails able to perfectly reflect the impinging radiation. Normally, for low-thrust interplanetary missions the propellant consumption and time of flight required for the transfers to take place play a crucial role. However, since solar sails do not exploit any propellant, the traditional and laser-enhanced sailcraft performances have been compared by analyzing their flight-time optimal trajectories, focusing on three different mission scenarios: a Mercury orbit rendezvous, Mars orbit rendezvous and Neptune flyby. These trajectories have been computed by taking advantage of an evolutionary neurocontrol optimizer, in which newly added functionalities have been implemented with the purpose of optimizing laser-enhanced solar sail trajectories. The trajectory analysis results have shown that, if laser-enhanced sailcraft are used instead of traditional sailcraft, flight time gains in the order of 8-11% can be achieved for the missions to Mercury and Mars orbits, while a smaller 2.5% gain is achieved for the flyby mission to Neptune.

Among its results, the ReDSHIFT project has developed a software tool for spacecraft operators, space agencies and research institutions to design the end-of-life of Earth-based missions and to study the interaction with the space debris environment. As part of this, the “Disposal Mapping” module, presented in this paper in its structure and algorithm, computes the end-of-life disposal strategy for missions whose operational orbit is in the orbital region from Low-Earth orbit to Geostationary Earth orbit. Given the initial orbit, the available ?v on board and the spacecraft characteristics in terms of cross area and mass, the options for end-of-life disposal are given and compared; namely, end-of-life disposal via one or a sequence of impulsive manoeuvres, end-of-life disposal through the use of a solar/drag sail or end-of-life through a hybrid sail plus an impulsive manoeuvre.@en

Among its results, the ReDSHIFT project has developed a software tool for spacecraft operators, space agencies and research institutions to design the end-of-life of Earth-based missions and to study the interaction with the space debris environment. As part of this, the “Disposal Mapping” module, presented in this paper in its structure and algorithm, computes the end-of-life disposal strategy for missions whose operational orbit is in the orbital region from Low-Earth orbit to Geostationary Earth orbit. Given the initial orbit, the available ?v on board and the spacecraft characteristics in terms of cross area and mass, the options for end-of-life disposal are given and compared; namely, end-of-life disposal via one or a sequence of impulsive manoeuvres, end-of-life disposal through the use of a solar/drag sail or end-of-life through a hybrid sail plus an impulsive manoeuvre.@en