Giovanni Mengali

University of Pisa | UNIPI · Department of Civil and Industrial Engineering

A refractive sail is a special type of solar sail concept, whose membrane exposed to the Sun’s rays is covered with an advanced engineered film made of micro-prisms. Unlike the well-known reflective solar sail, an ideally flat refractive sail is able to generate a nonzero thrust component along the sail’s nominal plane even when the Sun’s rays stri...

An E-sail is a propellantless propulsion system that generates thrust in the interplanetary space by extracting momentum from the stream of solar wind ions by means of a number of long, electrically charged tethers. In its usual configuration, the E-sail consists of a series of radially deployed tethers that belong to a fundamental plane, typically...

In this paper, a spacecraft formation control framework is presented aimed at guaranteeing a long-term bounded relative motion in the asteroid's uncertain dynamical environment. The mean-orbital-elements-based invariant boundedness conditions via an approximate gravitational field are adopted to develop a nominal steering control strategy, while a...

The Electric Solar Wind Sail (E-sail) is a propellantless propulsion system that converts solar wind dynamic pressure into a deep-space thrust through a grid of long conducting tethers. The first flight test, needed to experience the true potential of the E-sail concept, is likely to be carried out using a single spinning cable deployed from a smal...

Solar sails are propellantless propulsion systems that extract momentum from solar radiation pressure. They consist of a large ultrathin membrane, typically aluminized, that reflects incident photons from the Sun to generate thrust for space navigation. The purpose of this study is to investigate the optimal performance of a solar sail-based spacec...

This study analyzes the optimal transfer trajectory of a spacecraft propelled by a spin-stabilized electric solar wind sail (E-sail) with a single conducting tether and a spin axis with a fixed direction in an inertial (heliocentric) reference frame. The approach proposed in this study is useful for rapidly analyzing the optimal transfer trajectori...

This paper discusses a space debris removal mission in low Earth orbit in which, for a preliminary design, a solar sail is used as a chaser satellite to reach, capture and de-orbit a debris object. The sail, which exploits the solar radiation pressure as its main source of thrust, is subject to the effects of aerodynamic forces, Earth’s oblateness...

Large truss structures have many potential applications in space, such as antennas, telescopes and space solar power plants. In this scenario, a natural concern is the susceptibility of these lightweight structures to be damaged during their operational life, due to impacts, transient thermal states and fatigue phenomena. The inclusion of active el...

Recent literature indicates that the diffractive sail concept is an interesting alternative to the more conventional reflective solar sail, which converts solar radiation pressure into a (deep space) thrust using a thin, lightweight highly reflective membrane, usually metalized. In particular, a diffractive sail, which uses a metamaterial-based mem...

The electric solar wind sail, or E-sail, is a propellantless interplanetary propulsion system concept. By deflecting solar wind particles off their original course, it can generate a propulsive effect with nothing more than an electric charge. The high-voltage charge is applied to one or multiple centrifugally deployed hair-thin tethers, around whi...

Orbits that are frozen in an averaged model, including the effect of a disturbing body laying on the equatorial plane of the primary body and the influence of the oblateness of the primary body, have been applied to probes orbiting the Moon. In this scenario, the main disturbing body is represented by the Earth, which is characterized by a certain...

The growing amount of space debris in geocentricorbit poses a significant threat to the future of space operations. To mitigate this problem, current international guidelines state that a satellite should be able to deorbit or insert into a graveyard orbit within 25 years from the end of its operational life. In this context, drag-enhancing devices...

The solar sail thrust vector depends on the orientation of the sail nominal plane relative to the Sun-spacecraft line. In an ideal force model, when that plane is perpendicular (or parallel) to the Sun-spacecraft line, the thrust vector magnitude is maximum (or zero) and its direction is purely radial in a heliocentric reference frame. This Sun-fac...

This paper analyzes the possibility of maintaining a circular displaced non-Keplerian orbit around the Sun by means of a Sun-facing diffractive sail. With the goal of monitoring the Earth’s high-latitude regions, the spacecraft is required to track its displaced orbit at an angular velocity equal to the mean motion of the planet. In doing so, the s...

The aim of this paper is to analyze the performance of a state-feedback guidance law, which is obtained through a classical sliding mode control approach, in a two-dimensional circle-to-circle orbit transfer of a spacecraft equipped with a continuous-thrust propulsion system. The paper shows that such an inherently robust control technique can be e...

This paper analyzes the rapid rendezvous trajectory of a spacecraft equipped with an advanced solar electric propulsion system towards asteroid 4660 Nereus. In this context, a set of possible minimum-time orbit-to-orbit transfer trajectories is calculated by modeling the propulsion system performance characteristics on those of NASA’s Evolutionary...

An Electric Solar Wind Sail (E-sail) is a propellantless propulsion concept that extracts momentum from the high-speed solar wind stream to generate thrust. This paper investigates the performance of such a propulsion system in obtaining the transition from a prograde to a retrograde motion. The spacecraft is assumed to initially trace a circular h...

The electric solar wind sail, or E-sail, is a novel deep space propulsion concept which has not been demonstrated in space yet. While the solar wind is the authentic operational environment of the electric sail, its fundamentals can be demonstrated in the ionosphere where the E-sail can be used as a plasma brake for deorbiting. Two missions to be l...

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 maint...

The aim of this paper is to analyze the transfer performance of a spacecraft whose primary propulsion system is a diffractive solar sail with active, switchable panels. The spacecraft uses a propellantless thruster that converts the solar radiation pressure into propulsive acceleration by taking advantage of the diffractive property of an electro-o...

This paper proposes a preliminary design for a space debris removal mission in low Earth orbit that makes use of a solar sail as a chaser satellite to reach, capture and de-orbit a debris object. The sail employs solar radiation pressure as the main source of thrust, and it is also subjected to the effects of the aerodynamic forces, the oblateness...

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 homo...

According to the classical two-body Keplerian model, the orbital parameters of a spacecraft are constant during a mission. However, real-life spacecraft motion is different from a classical Keplerian model due to the presence of perturbing forces, whose effects are usually undesirable, especially for observation and communication spacecraft that re...

A displaced non-Keplerian orbit is a trajectory whose orbital plane does not contain the center of mass of the primary body, so that its orbital maintenance requires the application of a suitable continuous thrust. Although the latter could be provided, in principle, by a low-thrust electric propulsion system, innovative propellantless propulsive t...

In recent decades, growing interest has arisen within the scientific community in asteroids, in particular near-Earth objects (NEOs), which are asteroids or comets characterized by a semimajor axis close to that of the Earth. Interest in these objects is motivated not only by their capability of providing answers to important questions concerning t...

The recent discovery of Earth’s second Trojan asteroid (2020 XL5), which will remain in the vicinity of the Sun–[Earth+Moon] triangular Lagrangian point L4 for at least 4000 years, has attracted the attention of the scientific community as a remarkable example of those elusive objects that are the witnesses of the first phase of our Solar System. T...

A close observation of the near-Sun region, with in situ measurements, requires that a scientific probe be placed in a heliocentric orbit with a perihelion distance on the order of a few solar radii only. This is the solution adopted by the Parker Solar Probe (PSP), whose mission design uses a very complex transfer trajectory with seven Venus gravi...

The Solar Wind Ion Focusing Thruster (SWIFT) is a highly-innovative propellantless propulsion concept, recently proposed by Gemmer and Mazzoleni. In its nominal configuration, a SWIFT consists of a conically-shaped mesh of positively-charged conducting tethers, with its vertex linked to the spacecraft and its axis oriented towards the Sun. The SWIF...

The aim of this paper is to investigate the performance of a robotic spacecraft, whose primary propulsion system is an electric solar wind sail (E-sail), in a mission to a heliostationary point (HP)—that is, a static equilibrium point in a heliocentric and inertial reference frame. A spacecraft placed at a given HP with zero inertial velocity maint...

Propellantless propulsive systems such as Electric Solar Wind Sails are capable of accelerating a deep-space probe, only requiring a small amount of propellant for attitude and spin-rate control. However, the generated thrust magnitude is usually small when compared with the local Sun’s gravitational attraction. Therefore, the total velocity change...

The presence of a number of space debris in low Earth orbits poses a serious threat for current spacecraft operations and future space missions. To mitigate this critical problem, international guidelines suggest that an artificial satellite should decay (or be transferred to a graveyard orbit) within a time interval of 25 years after the end of it...

In the preliminary design of low-thrust trajectories with multiple gravity-assist phases, the selection of the celestial bodies to be considered and the sequence of optimal maneuvers have a significant impact on the overall mission performance. This aspect makes the preliminary transfer trajectory analysis a very complex task. This Short Communicat...

The transfer between two coplanar Keplerian orbits of a spacecraft with a continuous-thrust propulsion system is a classical problem of astrodynamics, in which a numerical procedure is usually employed to find the transfer trajectory that optimizes (i.e., maximizes or minimizes) a given performance index such as, for example, the delivered payload...

The plasma brake is a propellantless device conceived for de-orbiting purposes. It consists of an electrically charged thin tether that generates a Coulomb drag by interacting with the ionosphere. In essence, a plasma brake may be used to decelerate an out-of-service satellite and to ensure its atmospheric re-entry within the time limits establishe...

In a formation-flying mission where multiple spacecraft must cooperate and maintain a prescribed relative separation, the early detection of possible anomalies is a primary requirement. This is possible, for example, by employing an inspector spacecraft whose aim is to monitor the condition of the formation members with an on-orbit inspection. This...

The aim of this paper is to analyze the performance of a radially-accelerated spacecraft in a capture mission scenario, in which a space vehicle transfers from a parabolic approaching trajectory of assigned semilatus rectum to a target circular orbit around a generic celestial body. The radial propulsive acceleration provided by the spacecraft prop...

The utilization of V∞ leveraging maneuvers in deep space missions is able to mitigate the mission requirements on launch energy, as the spacecraft propulsive acceleration is used to increase the hyperbolic excess velocity at the starting planet. Usually, such a maneuver is studied in the context of multiple impulsive velocity changes, whereas a few...

A heliogyro is a particular solar sail configuration whose reflective surface is divided into a number of long and slender blades, which are stiffened by a suitable spin-induced centrifugal force. The reflective blades can rotate around their longitudinal axes to change (either collectively or cyclically) the pitch angles and allow the spacecraft a...

A challenging problem from a technological viewpoint is to send a spacecraft at a distance of about 600 au from the Sun, comparable with that of the Sun’s gravitational focus (that is, the general relativistic focusing of light rays, whose minimum solar distance is obtained when the light rays are assumed to graze the Sun’s surface), and reach it i...

The recent successes of demonstration missions based on solar sail technology have paved the way for designing new mission scenarios with propellantless propulsion systems. In this context, the Italian Space Agency has been supporting a preliminary study of Helianthus, an innovative concept of deep-space mission, which is designed to use a solar sa...

The aim of this work is to investigate the performance of a solar sail-based spacecraft in an optimal apse line rotation maneuver. Considering a heliocentric two-body motion and a low-performance solar sail with an ideal force model, this study derives the optimal steering law that maximizes the final rotation angle of the osculating orbit apse lin...

This study made use of a shape-based method to analyze the orbital dynamics of a spacecraft subject to a continuous propulsive acceleration acting along the circumferential direction. Under the assumption of a logarithmic spiral trajectory, an exact solution to the equations of motion exists, which allows the spacecraft state variables and flight t...

The aim of this paper is to analyze the performance of a solar sail-based spacecraft in a heliocentric V∞ leveraging maneuver. Assuming a circular restricted three-body framework, and using an optical force model for the description of the propulsive acceleration vector, this work quantifies the solar sail performance with an optimal approach, that...

The Electric Solar Wind Sail (E-sail) is an innovative propellantless propulsion system conceived by Pekka Janhunen in 2004 for use in interplanetary space. An E-sail consists of a network of electrically charged tethers maintained at a high voltage level by an electron emitter. The electrostatic field surrounding the E-sail extracts momentum from...

In this paper, the closed-form along-track boundedness condition for spacecraft relative motion around a slowly rotating asteroid is presented. As opposed to the previously proposed criteria where three necessary constraints must be satisfied, the current approach only requires to enforce one constraint to suppress the along-track drift, thus allow...

The aim of this Correspondence is to analyze the performance of a solar sail-based spacecraft in a two-impulse orbit transfer between circular and coplanar heliocentric orbits of assigned radii. In particular, assuming a transfer trajectory with a sweep angle and a flight time equal to those of a classical Hohmann orbit, the sail propulsive acceler...

This Short Communication analyzes the motion of a spacecraft whose primary propulsion system generates an inward, radial propulsive acceleration of constant magnitude. Starting from the classical literature results regarding the more common outward radial-thrust case, the proposed mathematical model uses a set of modified non-singular orbital eleme...

The aim of this article is to analyze the two-dimensional heliocentric trajectory of a solar sail with constant attitude in presence of reflective film optical degradation. The proposed procedure starts from the results obtained for a non-degrading flat sail and, taking into account the film optical degradation, obtains an analytical (although appr...

The propellantless working principle of a solar sail requires the total flight time to be minimized when looking for the optimal trajectory to reach a given target state. In this work the solar sail steering law is found by applying a Q-law algorithm, which aims at driving the spacecraft toward the final (target) orbit by decreasing the distance be...

The aim of this paper is to investigate the heliocentric motion of a passively actuated solar balloon placed at a distance of about one astronomical unit from the Sun. The analysis exploits a recent thrust model, according to which a solar balloon undergoes a passive control of its lightness number (that is, the ratio of the generated thrust to the...

Propellantless propulsion systems allow innovative mission scenarios to be envisaged, including the generation and the stabilization of artificial equilibrium points in the circular restricted three-body problem. This paper discusses the generation of collinear, L1-type, artificial equilibrium points in the Sun-[Earth+Moon] system, using a (photoni...

The aim of this paper is to analyze optimal trajectories of a solar sail-based spacecraft in missions towards the outer Solar System region. The paper proposes a simplified approach able to estimate the minimum flight time required to reach a given (sufficiently high) heliocentric distance. In particular, the effect of a set of solar photonic assis...

A heliogyro is a rotating solar sail with the reflecting surface divided into a number of long and slender blades, which are stiffened by a spin-induced centrifugal force. Each blade can rotate around its own longitudinal axis so as to change the pitch angle and allow the thrust vector to be effectively controlled. The aim of this paper is to analy...

This paper investigates approximate solutions to the two-dimensional equations of motion of a generalized sail-based spacecraft. A generalized sail is a propellantless propulsion system that produces a continuous thrust the magnitude of which varies with the heliocentric distance as 1/rη, where η is a positive real number that characterizes the pro...

We address the heliocentric in-orbit repositioning problem of an E-sail-based spacecraft that covers a circular parking orbit of given radius, with the assumption that the propulsive acceleration is directed along the Sun-spacecraft line. According to the recent literature, the analysis exploits the possibility of reducing the mathematical problem...

In this study, new analytical solutions to the equations of motion of a propelled spacecraft are investigated using a shape-based approach. There is an assumption that the spacecraft travels a two-dimensional spiral trajectory in which the orbital radius is proportional to an assigned power of the spacecraft angular coordinate. The exact solution t...

The analysis of the optimal control law that steers a solar sail-based spacecraft from a given initial condition toward a final target state is typically carried out using either indirect or direct approaches. Both these methods are usually time-consuming and require good initial guesses of costates or state vector. This paper presents a procedure...

A solar sail generates thrust without consuming any propellant, so it constitutes a promising option for mission scenarios requiring a continuous propulsive acceleration, such as the maintenance of a (collinear) L1-type artificial equilibrium point in the Sun-[Earth+Moon] circular restricted three-body problem. The usefulness of a spacecraft placed...

The aim of this paper is to evaluate the effect of a maximum admissible value of the sail cone angle on the transfer performance of a solar sail-based spacecraft in an interplanetary mission scenario. The proposed approach models the possible constraint on the maximum Sun angle of the solar panels, when thin film solar cells are attached to the fla...

The optimization of a solar sail-based orbital transfer amounts to searching for the control law that minimizes the flight time. In this context, the optimal trajectory is usually determined assuming constant solar properties. However, the total solar irradiance undergoes both long-term (solar cycles) and short-term variations, and recent analyses...

The propulsive characteristics of an Electric Solar Wind Sail are usually evaluated using a simplified model in which all the sail tethers are coplanar and form a sort of rigid disk. However, the three-dimensional arrangement of the tethers is fundamental information in the study of the spacecraft performance, and must be accounted for in refined m...

This article discusses the maintenance of an L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> -type artificial equilibrium point in the Sun-[Earth+Moon] circular restricted three-body problem by means of an electric solar wind sail. The reference configuration instability is compensated for wi...

The heliocentric orbital dynamics of a spacecraft propelled by a solar sail is affected by some uncertainty sources, including possible inaccuracies in the measurement of the sail film optical properties. Moreover, the solar radiation pressure, which is responsible for the solar sail propulsive acceleration generation, is not time-constant and is s...

The aim of this work is to investigate heliocentric phasing maneuvers performed by a spacecraft propelled by an Electric Solar Wind Sail, that is, an innovative propellantless propulsion system that consists of a spinning grid of charged tethers that uses solar wind momentum to produce thrust. It is assumed that the Electric Solar Wind Sail may be...

This paper deals with the problem of determining an analytical control law capable of maintaining highly elliptical heliosynchronous polar orbits around Venus. The problem is addressed using the Smart Dust concept, a propellantless propulsion system that extracts momentum from the solar radiation pressure using a reflective coating. The modulation...

This paper analyzes reachable domains of spacecraft using a single impulsive maneuver. In particular, compact expressions are obtained of the envelopes of spacecraft trajectories in closed form, in both cases of either radial or tangential impulse. Suitable bounds are enforced on the magnitude of the velocity variation to obtain an elliptic transfe...

This paper discusses the linearized relative motion and control of Electric Solar Wind Sails (E-sails) operating in formation flight around a heliocentric displaced orbit. An E-sail is constituted by thin and centrifugally stretched tethers, and generates a propulsion by momentum interaction with the charged particles from the solar wind. Feasible...

The heliocentric transfer of a solar sail-based spacecraft is usually studied from an optimal perspective, by looking for the control law that minimizes the total flight time. The optimal control problem can be solved either with an indirect approach, whose solution is difficult to obtain due to its sensitivity to an initial guess of the costates,...

An Electric Solar Wind Sail is a propellantless propulsion system that gains thrust from the interaction of solar wind particles with a grid of long and charged tethers, which are deployed by spinning the spacecraft about its symmetry axis. In an ideal arrangement, the tethers are all stretched out and the sail takes the shape of a spoked wheel. Ac...