Optimal interplanetary trajectories for Sun-facing ideal diffractive sails

A diffractive sail is a solar sail whose exposed surface is covered by an advanced diffractive metamaterial film with engineered optical properties. This study examines the optimal performance of a diffractive solar sail with a Sun-facing attitude in a typical orbit-to-orbit heliocentric transfer. A Sun-facing attitude, which can be passively maintained through the suitable design of the sail shape, is obtained when the sail nominal plane is perpendicular to the Sun–spacecraft line. Unlike an ideal reflective sail, a Sun-facing diffractive sail generates a large transverse thrust component that can be effectively exploited to change the orbital angular momentum. Using a recent thrust model, this study determines the optimal control law of a Sun-facing ideal diffractive sail and simulates the minimum transfer times for a set of interplanetary mission scenarios. It also quantifies the performance difference between Sun-facing diffractive sail and reflective sail. A case study presents the results of a potential mission to the asteroid 16 Psyche.

Application of homotopy perturbation method to the radial thrust problem

The dynamics of a spacecraft propelled by a continuous radial thrust resembles that of a nonlinear oscillator.This is analyzed in this work with a novel method that combines the definition of a suitable homotopy with a classical perturbation approach,in which the low thrust is assumed to be a perturbation of the nominal Keplerian motion.The homotopy perturbation method provides the analytical(approximate)solution of the dynamical equations in polar form to estimate the corresponding spacecraft propelled trajectory with a short computational time.The accuracy of the analytical results was tested in an orbital-targeting mission scenario.

Smart dust option for geomagnetic tail exploration

In-situ measurements are necessary for a long-term analysis of the spatial structure of the geomagnetic tail.This type of mission requires the use of a propellantless propulsion system,such as a classical solar sail,to continuously rotate the design orbit apse line such that it remains parallel to the Sun-Earth direction.To reduce the mission costs,this paper suggests the employment of Sun-pointing smart dusts,which are here investigated in terms of propulsive acceleration level necessary to guarantee a mission’s feasibility.A Sun-pointing smart dust can be thought of as a millimeter-scale solar sail,whose geometric configuration allows it to passively maintain an alignment with the Sun-spacecraft line.The smart dust external surface is coated with an electrochromic reflective film in such a way that it may change,within some limits,its propulsive acceleration magnitude.A suitable control law is necessary for the smart dust to enable an artificial precession of its Earth-centred orbit,similar to what happens in the GeoSail mission.This paper analyzes the required control law using an optimal approach.In particular,the proposed mathematical model provides a set of approximate equations that allow a simple and effective tradeoff analysis between the propulsive requirements,in terms of the smart dust acceleration,and the characteristics of the design orbit.