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Smart hinges for self-deployable solar sails have been prototyped by using shape memory polymer composites (SMPCs). During hinge lamination, a shape memory (SM) epoxy resin is deposited between carbon fiber reinforced (CFR) plies, and consolidation is obtained by an out-of-autoclave (OOA) process. The smart hinges have been assembled with CFR booms to prototype a small self-deployable square sail. Polymeric supports, made by fused deposition modelling (FDM), have been added for correct assembly and to drive the recovery of the SMPC hinges. Flexible heaters have been used as heating elements for SMPC hinge activation. The sail consisted of a polyimide membrane which was connected with the composite booms by flexible joints. The solar sail prototype size has been limited to 260 × 260 mm2 for on-Earth testing, with 4 hinges at the middle length of the composite booms. Recovery tests have shown the ability of the smart hinges to overcome the sail weight and additional friction forces, and the small sail has been successfully deployed in laboratory. Full recovery has been achieved in less than 3 min under different configurations. [ABSTRACT FROM AUTHOR]

Propellantless propulsion systems, such as the well-known photonic solar sails that provide thrust by exploiting the solar radiation pressure, theoretically allow for extremely complex space missions that require a high value of velocity variation to be carried out. Such challenging space missions typically need the application of continuous thrust for a very long period of time, compared to the classic operational life of a space vehicle equipped with a more conventional propulsion system as, for example, an electric thruster. In this context, an interesting application of this propellantless thruster consists of using the solar sail-induced acceleration to artificially precess the apse line of a planetocentric elliptic orbit. This specific mission application was thoroughly investigated about twenty years ago in the context of the GeoSail Technology Reference Study, which analyzed the potential use of a spacecraft equipped with a small solar sail to perform an in situ study of the Earth's upper magnetosphere. Taking inspiration from the GeoSail concept, this study analyzes the performance of a solar sail-based spacecraft in (artificially) precessing the apse line of a high elliptic orbit around Venus with the aim of exploring the planet's induced magnetotail. In particular, during flight, the solar sail orientation is assumed to be Sun-facing, and the required thruster's performance is evaluated as a function of the elliptic orbit's characteristics by using both a simplified mathematical model of the spacecraft's planetocentric dynamics and an approximate analytical approach. Numerical results show that a medium–low-performance sail is able to artificially precess the apse line of a Venus-centered orbit in order to ensure the long-term sensing of the planet's induced magnetotail. [ABSTRACT FROM AUTHOR]

The objective of this research is to forecast the impact of alternating non-uniform temperature distributions on the deformation and internal stress within the thin film of a solar photon sail, as well as to assess how stress variations affect the sail's characteristics. To maintain the internal stress amplitude within the film during extreme temperature fluctuations, the solar sail employs an innovative pre-tensioning technique utilizing shape memory alloy (SMA) springs. A thermal-structural model is formulated specifically for a hexagonal solar sail. Subsequently, thermal-structural analyses are conducted to quantify deformations and stresses within the sail during its operation on the Earth-Moon L1 halo orbit. Incorporating the prestress factor, the out-of-plane deflection of the film under solar pressure is computed. Furthermore, prestressed modal analyses are performed to determine mode shapes and natural frequencies, taking into account both the prestress and the solar pressure acting on the film. Finally, numerical results are used to compare the performance of the solar sail in hot and cold environments. [ABSTRACT FROM AUTHOR]

Refractive and diffractive solar sails have been cited to yield benefits in both performance and utility over reflective sails, but their range of viable flight regimes and future applications have not been fully explored. In this paper, a flight model is developed to test and compare these transmissive sail designs under realistic conditions. Raw performance is translated into tangible flight characteristics within a range of flight regimes, such as rate change of orbital energy and minimum operational altitude, and used to make comparison with reflective sails and contemporary thrusters. Additionally, the sensitivity of these flight characteristics to certain orbital parameters is explored when operating under either a locally optimal or simplified Sun-pointing steering law. The developed flight model focuses on solar radiation pressure, atmospheric drag and the effects of eclipse and orbital precession; locally optimal steering laws are numerically generated for every flight regime using a ray tracing-derived performance sensitivity profile. Relative to an idealised reflective sail, the sensitivity of transmissive sail performance is found to be lower for altitude, but higher for orbital inclination. High performance transmissive sail designs are found to outperform idealised reflective ones in every flight regime nonetheless. Meanwhile, only certain lower performance designs demonstrate this trait; others retain advantage only within high inclination, low altitude orbits. 36 m 2 transmissive sails performing an orbit-raising manoeuvre from low Earth orbit are shown to generate transit times comparable to mid-range electric thrusters. In light of these findings, potential applications for transmissive sails are discussed, as well as several practical considerations and potential limitations. • Solar sail performance and operational flexibility improved by transmissive membranes. • Non-meta transmissive sails find advantage at low altitude and/or high inclination. • Transmissive metasails find advantage in every flight regime. • Transmissive sails may fulfil contemporary thruster roles in low Earth orbit. • Transmissive sails may provide feasible space debris mitigation strategy. [ABSTRACT FROM AUTHOR]

A solar sail is a propellantless propulsion system that allows a spacecraft to use solar radiation pressure as a propulsive source for planetary and deep space missions that would be difficult, or even unfeasible, to accomplish with more conventional thrusters, either chemical or electric. A challenging application for these fascinating propulsion systems is a heliocentric mission that requires a displaced non-Keplerian orbit (DNKO), that is, a solar sail-induced closed trajectory in which the orbital plane does not contain the Sun's center of mass. In fact, thanks to the pioneering work of McInnes, it is known that a solar sail is able to reach and maintain a family of heliocentric DNKOs of given characteristics. The aim of this paper is to analyze the properties of Mars-synchronous circular DNKOs, which have an orbital period matching that of the planet for remote sensing applications. In fact, those specific displaced orbits allow a scientific probe to continuously observe the high-latitude regions of Mars from a quasi-stationary position relative to the planet. In this context, this paper also analyzes the optimal (i.e., the minimum-time) heliocentric transfer trajectory from the Earth to circular DNKOs in two special mission scenarios taken as a reference. [ABSTRACT FROM AUTHOR]

The motion properties of the infinitesimal body is studied under the forces due to kerr-like oblate heterogeneous primary, continuation fractional potential for secondary, solar sail, three-body interactions, Coriolis and centrifugal forces in the circular restricted three-body problem. The equations of motion of infinitesimal body are evaluated under the above-said perturbations. Using these equations of motion, we illustrate the locations of equilibrium points, their stability, the periodic orbits and Poincaré surfaces of section. This study will applicable on the motion of the artificial satellite. [ABSTRACT FROM AUTHOR]

The paper considers the possibility of cargo relocation without fuel costs along a tether connecting two heavy space stations by a spacecraft with a controlled solar sail. The spacecraft's relative motion dynamics is studied within the context of a model problem that assumes that the stations describe one heliocentric orbit, the solar sail is a perfect reflective flat panel, and the tether realizes an ideal unilateral handrail constraint that restricts the spacecraft relative motion to an ellipsoid. It is noted that, if the distance between stations is sufficiently small and the ratio of the sail area to the spacecraft mass is on the same order of magnitude as in already-implemented space missions, solar radiation is the main factor that influences the spacecraft's motion in the orbital frame of reference. The problem of searching a set of pairs of points, between which relocation with a permanently oriented sail is possible, is solved for the pairs that belong to the intersection of the ellipsoid boundary and the plane of the stations' orbit. The duration of the spacecraft relocation between the ellipsoid poles is estimated for the case of the sail oriented orthogonally to the solar rays. Also, the duration of the fastest relocation between poles is computed using special sail orientation control laws, including the case of zero initial and final velocities. [ABSTRACT FROM AUTHOR]

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Liquid crystal diffractive sails can generate controllable tangential radiation pressures, which have advantages in the Solar Polar Imager mission (SPI). This paper proposes a composite diffractive sail design consisting of an ideal passive diffraction grating sail and liquid crystal polarization gratings (LCPGs). The main diffractive grating sail generates thrust for orbital transfer with a sun-facing attitude. An optimal 3.8-year transfer trajectory is obtained by an improved direct method. Small-area LCPGs distributed around the edge are used for three-axis attitude control. The LCPGs can continuously modulate the force and torque by controlling the applied voltage based on the electro-optical characteristic of liquid crystal materials. A control strategy, including an adaptive attitude-tracking PD controller and a control allocation method, is designed to track the attitude profile generated by the transfer trajectory. Finally, the attitude-orbit coupling dynamics are used to simulate the whole process, and the results show that orbital insertion errors are minor. • A combined diffractive solar sail model using liquid crystal polarization gratings. • Independent and controllable three-axis attitude control of diffractive solar sails. • Optimizing transfer trajectory for solar polar mission based on the proposed sail. • An adaptive attitude-tracking PD controller and a control allocation method. [ABSTRACT FROM AUTHOR]

A solar sail presents a flat low areal density membrane and is an example of propellant-less propulsion system for the future space exploration. To date, the study of sail membrane deployment strategies is of considerable importance. In this work we present a general theoretical approach to deployment of solar sail of circular shape. We consider a system of a circular membrane attached to a toroidal rim under a force uniformly distributed along the rim's circumference. The stress and strain of the system required for the successful deployment and mechanical stability of the sail are considered in deployed static configuration. Three examples of the deployment force of different nature are presented: magnetic, electric, and the pressurized gas. We give limitations for the solar sail radius for each considered force. [ABSTRACT FROM AUTHOR]

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 and eclipse occurrence. Locally-optimal laws are used to control the transfer with the aim of maximizing (or minimizing) the rate of change of a specific orbital element or a suitable combination of them, depending on the transfer phase. When blended control laws are used to target the debris, the optimal weighting factors are calculated with a genetic algorithm to assess the relative importance of each orbital element. Numerical simulations show the effectiveness of locally-optimal laws in driving the sail towards the target even in the presence of the above-mentioned orbital perturbations. In a test-case scenario, a solar sail with a characteristic acceleration of 0.1 mm/s2, departing from 550 km of altitude, is able to reach the debris orbit at 1200 km of height in less than 200 days with a good accuracy level. The same analysis has been repeated for a solar sail with performance characteristics similar to those of NASA's planned Advanced Composite Solar Sail System (ACS3) mission. [ABSTRACT FROM AUTHOR]

This article presents a study on design and testing of space sails using Al-polyurethane Shape memory polymer. The properties of the polymer are simulated and tested in the design phase, and the results are compared with the fabricated sail, which is considered nominal. The efficiency of the polyurethane sail is found to be approximately 86.5%. The controllability of the sail is enhanced using a heating system that uses light rays to heat the polymer at specific control spots. The relative deflection at these spots causes a deviation in solar momentum, resulting in a controlled displacement of the sail. This control system is found to be 42% more efficient than conventional vane-type deflection systems. The paper also presents the fabrication of a ground testing apparatus designed to test the sail specimen in laboratory conditions. The apparatus is capable of producing a vacuum chamber pressure up to −400 mm/Hg and includes a magnetic levitation platform with strong permanent magnets to neglect local gravitational effects. The platform provides support for fixing the solar sail frame made from carbon fiber composite material. The testing apparatus consists of a 1000-W halogen light source with intensity ranges of approximately 200,000 lux. Sail material with a reflective surface is exposed to controlled luminance under vacuum conditions to measure the deflection of the sail. Deflection values are recorded by means of a resistance type strain gauge and strain indicator arrangement. Plotting deflections with time period gives the acceleration of the sail inside the test apparatus. A coolant chamber with a ceramic base is also provided to reduce temperature effects inside the vacuum chamber. In conclusion, this study presents a promising approach for the design and testing of solar sails using shape memory polymer and a ground testing apparatus. The results of this research can contribute to the development of more efficient and versatile solar sail technology for fuel-free aerospace propulsion. • A solar sail can travel to stars and planets without carrying fuel. • AI-polyurethane shape memory polymer is used for testing the space soils. • The ground-based testing is used to predict sail movement accurately. • A coolant chamber reduces the temperature within the vacuum chamber during testing. • Simulates and compares the properties of the polymer with the fabricated sail. [ABSTRACT FROM AUTHOR]

Propellantless propulsion systems, such as the well-known photonic solar sails that provide thrust by exploiting the solar radiation pressure, theoretically allow for extremely complex space missions that require a high value of velocity variation to be carried out. Such challenging space missions typically need the application of continuous thrust for a very long period of time, compared to the classic operational life of a space vehicle equipped with a more conventional propulsion system as, for example, an electric thruster. In this context, an interesting application of this propellantless thruster consists of using the solar sail-induced acceleration to artificially precess the apse line of a planetocentric elliptic orbit. This specific mission application was thoroughly investigated about twenty years ago in the context of the GeoSail Technology Reference Study, which analyzed the potential use of a spacecraft equipped with a small solar sail to perform an in situ study of the Earth’s upper magnetosphere. Taking inspiration from the GeoSail concept, this study analyzes the performance of a solar sail-based spacecraft in (artificially) precessing the apse line of a high elliptic orbit around Venus with the aim of exploring the planet’s induced magnetotail. In particular, during flight, the solar sail orientation is assumed to be Sun-facing, and the required thruster’s performance is evaluated as a function of the elliptic orbit’s characteristics by using both a simplified mathematical model of the spacecraft’s planetocentric dynamics and an approximate analytical approach. Numerical results show that a medium–low-performance sail is able to artificially precess the apse line of a Venus-centered orbit in order to ensure the long-term sensing of the planet’s induced magnetotail.

Photonic solar sails are a class of advanced propellantless propulsion systems that use thin, large, lightweight membranes to convert the momentum of light from the Sun into thrust for space navigation. The conceptually simple nature of such a fascinating propulsion system requires, however, advances in materials, packaging, deployment, and control of a very large space structure. In this context, the finite element method (FEM), implemented in a robust and flexible software such as the commercial software Abaqus, represents a fundamental instrument to progress with the practical study of this promising propulsion system concept. In particular, in a typical (medium-size) square solar sail design process, the FEM-based analyses are used to better understand fundamental aspects of structural design, such as, for example, membrane pre-tensioning, deformations induced by Solar Radiation Pressure (SRP), and the buckling of reinforcing booms. The aim of this study is to describe an effective procedure to model a classical square solar sail structure into a typical commercial software for finite element analysis, such as the well-known suite Abaqus. In particular, we compare various membrane pre-tensioning techniques (useful for increasing the membrane's bending stiffness) and describe possible approaches to applying the SRP-induced load in a realistic way. Additionally, the flexibility of the structure under the solar sail loads and the criticality of section shape and boom size are taken into account, with particular regard to the problem of structural instability. In this context, performance and critical issues of different structural solutions are discussed and compared, allowing an improvement in the preliminary design phase of solar sails to be obtained. [ABSTRACT FROM AUTHOR]

In this work, off-nominal trajectory design options for NASA's sail-based Solar Cruiser mission are examined. A novel method for constructing bounded trajectories about a periodic reference orbit is used to parameterize insertion into the target sub- L 1 halo orbit. The nominal mission plan of reaching the sub- L 1 halo orbit under purely sail power is then examined for a range of projected launch vehicle dispersions. Results indicate that cold (underburn) injections less than −0.2 m/s are incapable of arriving at the nominal sub- L 1 mission orbit. However, hot (overburn) injections are shown to be much more robust to the nominal mission plan than the low-energy trajectories. The resilience of the overburn cases compared to the underburn cases reveals that the mission would significantly benefit from additional launch vehicle hyperbolic excess energy to ensure mission requirements are satisfied. • Nominal Solar Cruiser transfer design for three deployment dates. • Novel method for bounded motion generation in ephemeris dynamics. • Effects of high and low-energy deployments on Solar Cruiser transfer. [ABSTRACT FROM AUTHOR]

Solar sails are an attractive technology for propellant-free propulsion, especially in small satellites with tight power and mass budgets. Several recent missions have shown promising applications of solar sails for nanosatellite orbital control in low Earth orbit (LEO). They enable easier access to and removal from high-altitude orbits. Since solar radiation pressure produces torques in addition to forces, a solar sail can also be used for low-power attitude control. Few missions have exploited this effect. In response, this paper proposes a new nanosatellite mission concept, only achievable by combined orbit-attitude control via solar sail: the sunflower mission, for high-altitude wide-area Earth observation. A realistic sail design meeting the mission requirements is obtained via parametric analysis and comprehensive review of past missions. A pyramid-shaped sail is proposed for the mission, and its advantages and drawbacks are analysed. The dynamics are evaluated using a high-fidelity numerical simulator with all relevant physical perturbations in LEO. The imaging objectives are successfully achieved over a multi-year duration. The sail also provides propellant-free orbit insertion from a low-altitude launch orbit, and fast de-orbit at end-of-life. It uses less power and has a smaller stowed size than several competitor technologies for orbit-attitude control of LEO nanosatellites. [Display omitted] • Sunflower mission proposed for wide-area small satellite Earth observation in LEO. • A pyramid-shaped solar sail provides low-power orbit and attitude control. • Propellant-free orbit raising from a low deployment altitude reduces launch cost. • Passive Sun pointing enables low-power attitude control for remote sensing. • Propellant-free orbit lowering enables quick de-orbit at end-of-life. [ABSTRACT FROM AUTHOR]

Composite booms for solar sails have been prototyped by using innovative smart materials. Shape memory polymer composites (SMPCs) have been manufactured by interposing SMP layers between carbon-fiber-reinforced (CFR) plies. A polyimide membrane has been embedded into the CFR-SMPC frame of the sail during lamination. The sail's size has been limited to 250 × 250 mm2 to allow its testing on Earth. The feasibility of large sail deployments has been shown by prototyping small CFR-SMPC elements to insert only in the folding zones. Numerical simulation by finite element modeling allowed for predicting the presence of wrinkles close to the frame's vertexes in the cases of large sails under solar radiation pressures. Nevertheless, the frame's configuration, with SMPC booms at all the edges of the sail membrane, seems to be suitable for drag sails instead of propulsion. On-Earth recovery tests have been performed on 180° folded sails by using flexible heaters. After an initial induction time, the maximum rate was reached with a following drop. In the case of two heaters per folding zone, the angular recovery rate reached the maximum value of about 30 deg/s at the power of 34 W, and full recovery was made in 20 s. [ABSTRACT FROM AUTHOR]

A solar sail is a propellantless propulsion system that allows a spacecraft to use solar radiation pressure as a propulsive source for planetary and deep space missions that would be difficult, or even unfeasible, to accomplish with more conventional thrusters, either chemical or electric. A challenging application for these fascinating propulsion systems is a heliocentric mission that requires a displaced non-Keplerian orbit (DNKO), that is, a solar sail-induced closed trajectory in which the orbital plane does not contain the Sun’s center of mass. In fact, thanks to the pioneering work of McInnes, it is known that a solar sail is able to reach and maintain a family of heliocentric DNKOs of given characteristics. The aim of this paper is to analyze the properties of Mars-synchronous circular DNKOs, which have an orbital period matching that of the planet for remote sensing applications. In fact, those specific displaced orbits allow a scientific probe to continuously observe the high-latitude regions of Mars from a quasi-stationary position relative to the planet. In this context, this paper also analyzes the optimal (i.e., the minimum-time) heliocentric transfer trajectory from the Earth to circular DNKOs in two special mission scenarios taken as a reference.

Electromagnetic wideband absorption is still perceived as a critical and formidable challenge to address with an unambiguous photonic absorber. Subwavelength metamaterial (MM) unit cells with unique and controlled features have recently gained considerable interest. However, meta‐atoms, generated using a quantum‐inspired pattern distribution, are underwhelming in existing literature to design photonic absorbers and their potential application to manufacture solar sails is still quite uncommon. In this article, to create a flexible, polarization‐insensitive, ultrathin, and broadband MM absorber, quantum interference pattern‐inspired design is utilized. Herein, a novel approach to fabricating solar sails for the space exploration incorporates the proposed broadband photonic absorber rather than conventional reflectors. The quantum‐inspired meta‐absorber (QIMA) exhibits an absorption of over 91% for the visible domain, i.e., 380–800 nm under a conventional plane‐polarized source. It is shown in the study that broadband absorbers are almost equivalent to excellent reflectors to design the solar sails in terms of the time‐averaged force calculated by utilizing the Maxwell stress tensor method. Thus, the QIMA has the potential to be a viable alternative to reflectors in the design of futuristic solar sails for space exploration. The interference theory model is also utilized to assure the dependability of calculated data, and additionally, the standard AM1.5 solar spectrum is utilized to demonstrate the QIMA's solar‐harvesting potentiality. [ABSTRACT FROM AUTHOR]

Building upon the recent development of solar sailing primer vector theory and its successful applications, we propose a new formulation for indirect solar-sail trajectory optimization, which minimizes solar angle (cone angle between the sail normal and sunlight vectors) over a trajectory. The minimum solar-angle objective is introduced to address a typical demand in mission design: having the ability to design trajectories with fixed time-of-flight, which is especially crucial when the mission involves time-sensitive events, such as scientific observations with specific lighting conditions, gravity assists at specific epochs, to name a few. We derive an analytical optimal control law for minimum solar-angle sail transfers by applying Pontryagin's optimality principle. Our theoretical results illuminate that a quantity termed solar sailing primer vector characterizes the optimal solar-sail control law for both minimum-time and minimum solar-angle transfers, as is the case in Lawden's primer vector theory for conventional low-thrust transfers. We numerically demonstrate these theoretical results by applying them to asteroid rendezvous transfers for NASA's NEA Scout mission. The numerical examples also reveal the numerical advantage of using the minimum solar-angle objective over the minimum-time one for solar-sail trajectory design because of the smoother optimal control profile. Solar sailing primer vector theory provides a tool to characterize the optimal control law independent of particular state representations or solution methods, enabling mission designers to combine it with a wealth of techniques developed for low-thrust trajectory optimization. • Propose an indirect trajectory optimization formulation based on solar sail primer vector theory. • The formulation minimizes the solar angle over a transfer with fixed time-of-flight. • The formulation derives an analytical optimal control law via Pontryagin's minimum principle. • Numerical examples demonstrate the analytical results in a NASA's NEA Scout exploration scenario. [ABSTRACT FROM AUTHOR]

The orbital motion of a spacecraft with a solar sail in the vicinity of the Sun–Earth collinear libration point is studied. The study is carried out within the Hill approximation of the circular restricted three-body problem. The collinear libration point is unstable, but instability can be a positive factor in the tasks of maneuvering in interplanetary space. This is because a small change in velocity near an unstable libration point can lead to a significant change in orbital motion. This property can be used in the development of projects to counteract the comet–asteroid hazard. A scheme for constructing the trajectories of interception of a spacecraft with a potentially hazardous object is proposed. One of the stages of this scheme, an optimal escape from the vicinity of the libration point using light pressure forces, is considered. The results of numerical simulations are presented. [ABSTRACT FROM AUTHOR]

The goal of this paper is to analyze the optimal transfer towards the periodic comet 29P/Schwassmann–Wachmann 1 of a solar sail-based spacecraft. This periodic and active comet is an interesting and still unexplored small body that has been regarded as an object of the Centaurs group. In this work, a classical (heliocentric) orbit-to-orbit transfer is studied from an optimal viewpoint, by finding the spacecraft trajectories that minimize the flight time for a given value of the solar sail characteristic acceleration, that is, the typical performance parameter of a photonic sail. In particular, the optimal Earth–comet transfer is studied both in a typical three-dimensional mission scenario and with a simplified two-dimensional approach, whose aim is to rapidly obtain an accurate estimation of the minimum flight time with a reduced computation cost. The numerical simulations illustrate the mission performance, in terms of the characteristics of the rapid transfer trajectory, as a function of the typical propulsive parameter and the solar sail thrust model. [ABSTRACT FROM AUTHOR]

Abstract Large-scale solar sails can provide power to spacecraft for deep space exploration. A new type of telescopic tubular mast (TTM) driven by a bistable carbon fiber-reinforced polymer tube was designed in this study to solve the problem of contact between the sail membrane and the spacecraft under light pressure. Compared with the traditional TTM, it has a small size, light weight, high extension ratio, and simple structure. The anti-blossoming and self-unlocking structure of the proposed TTM was described. We aimed to simplify the TTM with a complex structure into a beam model with equal linear mass density, and the simulation results showed good consistency. The dynamic equation was derived based on the equivalent model, and the effects of different factors on the vibration characteristics of the TTM were analyzed. The performance parameters were optimized based on a multiobjective genetic algorithm, and prototype production and load experiments were conducted. The results show that the advantages of the new TTM can complete the deployment of large-scale solar sails, which is valuable for future deep space exploration.

In this paper, we have investigated the dependence of characteristic acceleration and design sensitivity function of solar sail on mass and area of solar sail by solving the dynamics of solar sails using electromagnetic treatment of Maxwell's and quantum mechanics of Einstein's theories. It is found that the solar sail with large area A, fewer payloads mass m p and sail loading σ would be best for distribution in space to meet the new avenues of space science. It has also been observed that higher relative characteristic acceleration procured by using sail of large area with low density sail film as much as possible, which is our requirement for mission of solar sail. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of coupled orbit-attitude control for solar sail formation flying where the leader follows a solar-sail resonant halo orbit in the Earth-Moon system, whereas the follower is controlled to track a predefined reference relative trajectory around the leader. Taking the reflectivity control devices (RCDs) as joined orbit and attitude control actuators, their force and torque models are first established for a spinning solar sail. In particular, the saturation and coupling of the control variables for the coupled orbit-attitude control are focused. Then the orbit and attitude dynamics of the spinning solar sail are discussed and the equations of relative orbit-attitude motion are given. Furthermore, constraints on the relative attitude angles between the sails and their rates of change are considered for the attitude control. Together with the optimal switch regulations of RCDs, the problem addressed in this paper is essentially a problem of constrained optimal coupled orbit-attitude control. Therefore, the framework of model predictive control (MPC) technique is applied to deal with this problem by solving a convex quadratic programming problem subject to linear constraints. Finally, illustrative scenarios are simulated to show the effectiveness and controllability of the proposed coupled orbit-attitude controller. [ABSTRACT FROM AUTHOR]

The solar sail, a new type of spacecraft that uses only the Solar Radiation Pressure (SRP) for its propulsion, has great application prospect in the pole-sitter mission and deep space exploration. However, because of the large surface-to-mass ratio and the coupling effect of attitude and structure vibration, the study of dynamics and control of solar sail is challenging. This paper investigates the attitude control of a class of solar sails through control boom, and proposes a new vibration control strategy of the solar sail using self-contained cable actuators on the sail surface. Firstly, a rigid-flexible coupling dynamic model of the solar sail system is established by using the velocity variational principle considering the membrane tensioning stress. Then, an attitude tracking controller is designed utilizing the backstepping method, and by using the tensioning cables as actuators controller is designed to suppress the vibration of the sail surface. Finally, numerical simulations are conducted to verify the effectiveness of the methods presented in this paper. Research results show that the dynamic model developed in this paper can describe the dynamic behavior of the solar sail system precisely, and the designed controllers can have the solar sail following the desired attitude trajectory accurately and suppress the vibration of the sail surface significantly. [ABSTRACT FROM AUTHOR]

The purpose of this work is to determine the influence of the optical characteristics of a thin multilayer solar sail on its orbital motion. First of all, the influence of the coefficients of reflection, scattering and absorption is investigated. These coefficients are computed on the basis of a mathematical model of the optical characteristics of a multilayer epitaxial thin film which is a solar sail itself. The paper considers the effect of temperature changes and sail surface degradation on its optical properties. Modeling of changes in optical characteristics is carried out drawing on an example of heliocentric flight from the Earth to Mercury applying locally optimal control laws. Applying the transfer matrix method and considering the distribution of solar spectral radiation optical parameters for two distinct constructions of a solar sail were obtained (aluminum and silver front coating).

Interstellar Objects (ISOs) offer a unique opportunity to answer fundamental questions about the nature of objects that originate outside our Solar System. Only two members of this new class of mission target have been identified: asteroid 1I/'Oumuamua in 2017 and comet 2I/Borisov in 2019. Many more are expected to be found with the introduction of the Vera C. Rubin Observatory motivating the formulation of mission concepts to investigate future ISOs. While fast flyby missions are technically feasible today, rendezvous missions that orbit or even land offer the only means for literal ground truth into the nature of these objects. Mission design and propulsion capability are current challenges due to the brevity of ISO paths through the Solar System. These challenges may be overcome with a trade space of detection capabilities, launch vehicles, trajectory designs, and near-term spacecraft technology development. In particular, the combination of Jupiter gravity assist and nuclear electric propulsion provides the highest likelihood of delivering a spacecraft to match the orbit of an ISO. • Orbital rendezvous with interstellar objects is possible using near-term technology. • A broad search of trajectories to a synthetic population reveals preferred strategies. • Falcon Heavy launcher and nuclear electric propulsion reach 25% of comet-like objects. • Space Launch System and chemical propulsion reach 25% of comet-like objects. • Detections by the Rubin Observatory would enable rendezvous with up to six objects. [ABSTRACT FROM AUTHOR]

A new solar sail model that can be controlled passively using gravity stabilization and black-coating was designed. In this paper, a long boom with a tip-mass was used to realize gravity-gradient stabilization when a solar radiation pressure (SRP) was applied. The solar sail does not require extra controllers or fuel sources to maintain proper attitude for orbit raising schemes. In an orbit mission, attitude dynamics and control analysis of a solar sail are critical issues for successful performance. This paper investigated analytically and numerically the stability of 1-dof pitch motion of the solar sail model. Ignoring the SRP and conducting analytic interpretation, among the four equilibrium points of the solar sail, the solar sail was marginally stable in the standing attitude aligned along the direction of gravity or in the standing attitude upside down. The computation, including an SRP, showed that the state near two of the four equilibrium points (standing attitude and standing attitude upside down) were oscillating within a certain boundary if the perturbation was small and stable. The validation was verified by checking the phase portrait and the power spectral density. The simulation of 3-dof orbit demonstration mission of the presented model with translation motions shows the result of increased orbital altitude change, implying the feasibility of mission performance. [ABSTRACT FROM AUTHOR]

The recent discovery of Earth's second Trojan asteroid (2020 XL 5 ), which will remain in the vicinity of the Sun–[Earth+Moon] triangular Lagrangian point L 4 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. The possibility that an Earth's Trojan asteroid (ETa) may represent a pristine record of the initial conditions of the Solar System formation makes these small objects an interesting target for a robotic exploration mission. This paper analyzes orbit-to-orbit Earth–ETa transfer trajectories of an interplanetary spacecraft propelled by a solar sail. In the last decade, some pioneering space missions have confirmed the feasibility and potentiality of the solar sail concept as a propellantless propulsion system able to convert the solar radiation pressure in a continuous thrust by means of a large, lightweight and highly reflective surface. Using the state-of-the-art level of solar sail technology, this paper studies the performance of a solar-sail-based transfer trajectory toward an ETa from an optimal viewpoint and with a parametric approach. [ABSTRACT FROM AUTHOR]

Large-scale solar sails can provide power to spacecraft for deep space exploration. A new type of telescopic tubular mast (TTM) driven by a bistable carbon fiber-reinforced polymer tube was designed in this study to solve the problem of contact between the sail membrane and the spacecraft under light pressure. Compared with the traditional TTM, it has a small size, light weight, high extension ratio, and simple structure. The anti-blossoming and self-unlocking structure of the proposed TTM was described. We aimed to simplify the TTM with a complex structure into a beam model with equal linear mass density, and the simulation results showed good consistency. The dynamic equation was derived based on the equivalent model, and the effects of different factors on the vibration characteristics of the TTM were analyzed. The performance parameters were optimized based on a multiobjective genetic algorithm, and prototype production and load experiments were conducted. The results show that the advantages of the new TTM can complete the deployment of large-scale solar sails, which is valuable for future deep space exploration. [ABSTRACT FROM AUTHOR]

Photonic solar sails are a class of advanced propellantless propulsion systems that use thin, large, lightweight membranes to convert the momentum of light from the Sun into thrust for space navigation. The conceptually simple nature of such a fascinating propulsion system requires, however, advances in materials, packaging, deployment, and control of a very large space structure. In this context, the finite element method (FEM), implemented in a robust and flexible software such as the commercial software Abaqus, represents a fundamental instrument to progress with the practical study of this promising propulsion system concept. In particular, in a typical (medium-size) square solar sail design process, the FEM-based analyses are used to better understand fundamental aspects of structural design, such as, for example, membrane pre-tensioning, deformations induced by Solar Radiation Pressure (SRP), and the buckling of reinforcing booms. The aim of this study is to describe an effective procedure to model a classical square solar sail structure into a typical commercial software for finite element analysis, such as the well-known suite Abaqus. In particular, we compare various membrane pre-tensioning techniques (useful for increasing the membrane’s bending stiffness) and describe possible approaches to applying the SRP-induced load in a realistic way. Additionally, the flexibility of the structure under the solar sail loads and the criticality of section shape and boom size are taken into account, with particular regard to the problem of structural instability. In this context, performance and critical issues of different structural solutions are discussed and compared, allowing an improvement in the preliminary design phase of solar sails to be obtained.

In the framework of a strict mathematical approach based on classical theory of elasticity we present an idea of the deployment and stretching of the circular solar sail attached to the inflatable toroidal shell. It is predicted that by introducing the gas into the inflatable toroidal shell one can deploy and stretch a large size circular solar sail membrane. The formulas for the toroidal shell and sail membrane stresses and strains caused by the gas pressure in the shell are derived. The analytical expressions can be applied to a wide range of solar sail sizes. Numerical calculations for the sail of radii up to 100 m made of CP1 membrane and attached to the toroidal shell with the varied cross-section radius are presented. The normal transverse vibration modes of the sail membrane under tension caused by gas pressure in the shell are calculated. The feasibility of deployment and stretching of a solar sail with a large size circular membrane attached to the inflatable toroidal shell is demonstrated. • Deployment of large circular membrane by an inflatable toroidal shell. • Stress and strain in a thin circular membrane. • Stress and strain in an inflatable toroidal shell. • Stress in membrane attached to toroidal shell. • Feasibility of deployment and stretching of a large size circular solar sail. [ABSTRACT FROM AUTHOR]

The idea of solar sail is used to investigate the motion properties of the test particle which is varying its mass according to the Jeans law and moving under the gravitational forces of the primaries, the Coriolis and centrifugal forces in the circular restricted three-body system (CRTBS). The equations of motion of the test particle are determined under the above said perturbations. And hence, the dynamical properties like the locations of equilibrium points, their stability, periodic orbits, Poincar´e surfaces of section and basins of attracting domain are investigated. This problem will help those researchers who are interested in studying the problem related to solar sail for space missions. [ABSTRACT FROM AUTHOR]

This paper focuses on the optimization of two-dimensional transfer trajectories for solar sails using analytical approximation and modified analytical approximation methods. Instead of assuming circular orbits [ 29-31 , 37 ], the proposed approach allows for the analysis of solar sails launched from general heliocentric elliptical orbits. By employing linear perturbation theory, analytical propelled trajectories with fixed pitch angles are derived, where the perturbation coefficient serves as the reference lightness coefficient. To obtain the optimal transfer orbit between general heliocentric elliptical orbits, the analytical segments corresponding to different pitch angles are spliced together. A nonlinear optimization algorithm is then utilized to optimize the multi-segment trajectory, aiming to achieve the optimal performance index while satisfying boundary and intermediate constraints. Remarkably, this method requires the optimization of only the pitch angle for each segment, resulting in a small number of optimization variables and significantly improved efficiency in transfer orbit optimization. Additionally, the analytical approximation approach offers substantial time savings compared to numerical integration, particularly when repeated calculations are involved. Furthermore, the modified approximate trajectory exhibits high accuracy, with the optimal analytical transfer trajectory closely approximating the optimal actual trajectory acquired through the shooting method. This paper extensively validates and analyzes the precision of the proposed analytical transfer orbit through numerical verification. Additionally, when contrasted with actual transfer orbit, the suggested analytical approach can significantly decrease the computation time for multi-object challenges by a minimum of 80%. This makes the proposed method highly suitable for rapid design of optimal transfer orbits in multi-target mission scenarios for solar sail-based probes. [ABSTRACT FROM AUTHOR]

Composite booms for solar sails have been prototyped by using innovative smart materials. Shape memory polymer composites (SMPCs) have been manufactured by interposing SMP layers between carbon-fiber-reinforced (CFR) plies. A polyimide membrane has been embedded into the CFR-SMPC frame of the sail during lamination. The sail’s size has been limited to 250 × 250 mm2 to allow its testing on Earth. The feasibility of large sail deployments has been shown by prototyping small CFR-SMPC elements to insert only in the folding zones. Numerical simulation by finite element modeling allowed for predicting the presence of wrinkles close to the frame’s vertexes in the cases of large sails under solar radiation pressures. Nevertheless, the frame’s configuration, with SMPC booms at all the edges of the sail membrane, seems to be suitable for drag sails instead of propulsion. On-Earth recovery tests have been performed on 180° folded sails by using flexible heaters. After an initial induction time, the maximum rate was reached with a following drop. In the case of two heaters per folding zone, the angular recovery rate reached the maximum value of about 30 deg/s at the power of 34 W, and full recovery was made in 20 s.

Interstellar objects are a category of comets and asteroids that offer a unique scientific opportunity to answer fundamental scientific questions about the origin of solar system volatiles, the compositions of exo-solar systems, and the transfer rates of material between solar systems. However, they are also difficult to reach due to their high energy and the minimal lead time afforded by current detection infrastructure. This investigation presents the stationary satellite, or statite, concept as a method to enable rendezvous missions with extended stays at these important targets of study. Through the use of a high-performance solar sail, the statite spacecraft is able to maintain a stationary position with respect to the Sun, thus maintaining a state with a high potential energy. Upon detection, it reorients its sail and enters into a controlled fall towards the Sun, by which it obtains a high velocity to match the trajectory of the target. The applicability of this approach is assessed on rendezvous missions to the two known interstellar objects: 'Oumuamua and Borisov. Counter examples based upon electrically propelled spacecraft characterize the potential improvement in response time and mission duration offered by the statite concept. Based on the expected population of detectable objects, conclusions are drawn regarding flight times to the target population. The analysis includes trajectories that transfer the statite from the Earth to strategic locations to await interstellar targets. • Statites are solar sails with performance equivalent to the Sun's gravity. • Interstellar objects are fast-moving, high-energy targets with great scientific value. • The energy needed for rendezvous is obtained by departing from a stationary state. • Expensive plane changes are eliminated by starting from the target's orbital plane. • Full coverage of possible targets may be achieved with a widespread constellation. [ABSTRACT FROM AUTHOR]

One of the important applications of the space tethered system is formation flying. To satisfy the requirement for interferometry of ground targets by remote-sensing satellites, a new type of tethered solar sail spacecraft has been proposed in recent research. The replacement of subsatellites of conventional tethered satellite systems with solar sail spacecraft allows for a special formation configuration in which the main satellite is in sun-synchronous orbit and the subsolar sail is in displaced orbit. If the solar sail is at the appropriate attitude, the main satellite and the solar sail spacecraft connected by metal tethers could move side by side, hence this formation system is called transverse formation. The relative baseline of this transverse formation system is perpendicular to the ground trajectory of the satellite, effectively solving the problem that the relative baseline of conventional orbital formations varies in a trigonometric cycle. Researchers on the past ignored the mass and elasticity of the tether, and considered the tether just a constraint in the model system. Since the solar sail is generally quite light compared to the other components of the system, the model inaccuracy caused by ignoring the mass of the tether on the dynamic model and control is extremely obvious. This paper investigates the relative dynamics and control of a proposed system during the deployment process with the mass of the tether. Two precise models of satellite-sail systems are established. One is based on the dumbbell model with the mass tether for the tethered satellite system, and the other is on the basis of the beads model of a tethered satellite system. The rigid one is for control design and the flexible one is for dynamic simulation. It is concluded that the length of the tether and attitude angle of the transverse formation configuration can be decoupled and controlled separately. On the basis of the models, a length rate and LQR control law is developed and the control of the deployment and retrieval process of the tethered solar sail system is investigated. Numerical simulations are performed to verify the accuracy of the conclusions. [ABSTRACT FROM AUTHOR]

Due to small magnitude of solar radiation pressure (SRP), the area-mass ratio of the solar sail should be large enough to obtain adequate thrust acceleration. Therefore, the membrane structure is usually adopted for solar sails. However, the membrane barely has out-of-plane stiffness; thus, it is necessary to apply in-plane tension on the membrane for maintaining the plane, which may result in wrinkles. The wrinkle will influence SRP force of solar sails. On the one hand, wrinkled regions of the sail are no longer flat, so the angle between the normal vector of the surface in wrinkled regions and the direction of sunlight differ from a flat sail. On the other hand, wrinkles may cause shadow when the solar sail is almost parallel to sunlight and the shadow region cannot generate SRP force. In this paper, the nonlinear buckling theory is used to propose a numerical calculation method to solve the problem of wrinkling analysis of solar sails with complex boundary. Then, a high-precision method for calculating SRP force of wrinkled solar sails is proposed, consisting of two parts: the infinitesimal element SRP force model and the wrinkle shading model. Numerical simulation result verifies the effectiveness of the wrinkling analysis method and the SRP force calculation method. Furthermore, according to calculation result, wrinkles have a certain influence on the SRP force of the solar sail, which will become significant when the solar sail gets parallel to sunlight. [ABSTRACT FROM AUTHOR]