Alessandro Morselli

Politecnico di Milano | Polimi · Department of Aerospace Engineering

Convex optimization for low-thrust trajectory generation guarantees high levels of reliability while keeping the computational time low. However, it is affected by one major disadvantage: constraints are only imposed and respected at the collocation points. Outside of these points, the control commands must be interpolated. Physical constraints on...

As the number of interplanetary space missions keeps increasing thanks to the reduction of spacecraft development and integration costs, there is the urge of avoiding the saturation of the ground infrastructure required to operate satellites. The aim of the EXTREMA project, which has received fundings from the European Research Council, is to solve...

A new space era is fast approaching. In this decade, CubeSats have granted affordable access to space due to their reduced manufacturing costs compared to traditional missions. Although most of miniaturized spacecraft has thus far been deployed into near-Earth orbits, soon a multitude of CubeSats will be employed for deep-space missions as well. By...

This paper presents a survey of past and new results of the application of advanced sampling techniques for orbital conjunction analysis and Near Earth Objects impact probability computation. The theoretical background of the methods is presented, along with the results of their applications and a critical discussion of the benefits introduced .

This paper is aimed at presenting a new tool developed by Dinamica, with the support of ESA, for the efficient non-linear propagation of uncertainties in space dynamics. The newly implemented software is based on Differential Algebra, which provides a method to easily extend the existing linearization techniques and allows the implementation of eff...

In this chapter, a method to assess the occurrence of impacts between objects (either spacecraft or space debris) orbiting around the Earth is presented. The method is based on the computation of the minimum distance between two evolving orbits by means of a rigorous global optimizer. Analytical solutions of artificial satellite motion are utilized...

As the amount of space debris orbiting the earth is continuously increasing, it is becoming essential to monitor and predict the debris' trajectories in order to avoid collision that could threaten space missions, i.e. operative satellites or manned spacecraft. An innovative bistatic radar system, that couples multi-beaming and ranging techniques,...

Three methods for the computation of the probability of collision between two space objects are presented. These methods are based on the high order Taylor expansion of the time of closest approach (TCA) and distance of closest approach (DCA) of the two orbiting objects with respect to their initial conditions. The identification of close approache...

Optimal feedback control is classically based on linear approximations, whose accuracy drops off rapidly in highly nonlinear dynamics. Several nonlinear optimal feedback control strategies have appeared in recent years. Among them, differential algebraic techniques have been used to tackle nonlinearities by expanding the solution of the optimal con...

The possibility of having collision between a satellite and a space debris or another satellite is becoming frequent. The amount of propellant is directly related to a satellite’s operational lifetime and revenue. Thus, collision avoidance maneuvers should be performed in the most efficient and effective manner possible. In this work the problem is...

A high order method to quickly assess the effect that uncertainties produce on orbital conjunctions through a numerical high-fidelity propagator is presented. In particular, the dependency of time and distance of closest approach to initial uncertainties on position and velocity of both objects involved in a conjunction is studied. The approach rel...

The manuscript addresses the problem of computing conjunctions either between Near Earth Objects and our planet or space debris and operative spacecraft. The problem is formulated as a global optimization problem, solved rigorously using Taylor models. With this technique, narrow bounds of the objective function are computed on sub-portions of the...

A method for the computation of the probability of collision between two space object is pre- sent.ed. The method is based on the Taylor expansion of the time of close approach (TCA) and distance of close approach (DCA) of the two orbiting objects. These quantities are computed during the conjunction detection phase by means of a global optimizer b...

Optimal feedback control is classically based on linear approximations, whose accuracy drops off rapidly in highly nonlinear dynamics. Several nonlinear optimal feedback control strategies have appeared in recent years. Among them, differential algebraic techniques have already been used to tackle nonlinearities by expanding the solution of the opt...

The study of orbital conjunctions between space bodies is of fundamental importance in space situational awareness programs. The identification of potentially dangerous conjunctions, either between Near Earth Objects and our planet, or space debris and operative spacecraft, is most commonly done by looking at the distance between the objects in a g...

A method intended to assess the occurrence of impacts between satellites and space debris is presented. The method is based on the computation of the minimum orbit intersection Distance (MOID) between two perturbed orbits. The MOID is obtained by means of a global optimization, using a global optimizer based on Taylor models. The position of the or...