Advances in Solar Sailing

Japan Aerospace Exploration Agency (JAXA) made world’s first Solar Sail mission, Ikaros in 2010 successfully. This mission was performed as a precursor and technology verification mission toward our goal of having Solar Power Sail mission to Trojan asteroids rendezvous. This paper overviews what Ikaros demonstrated and presents the future mission currently studied at JAXA. It includes some introduction on technology development programs.

Solar Sail Propulsion (SSP) is a high-priority new technology within The National Aeronautics and Space Administration (NASA), and several potential future space missions have been identified that will require SSP. Small and mid-sized technology demonstration missions using solar sails have flown or will soon fly in space. Multiple mission concept studies have been performed to determine the system level SSP requirements for their implementation and, subsequently, to drive the content of relevant technology programs. The status of SSP technology and potential future mission implementation within the United States (US) will be described.

The Japan Aerospace Exploration Agency (JAXA) makes the world’s first solar power sail demonstration of photon propulsion and thin film solar power generation during its interplanetary cruise by IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). It deployed and spans a membrane of 20 m in diameter taking the advantage of the spin centrifugal force. It accelerates and controls the orbit using solar radiation pressure successfully. This is the first actual solar sail flying an interplanetary voyage. This paper presents the summary of development and operation of IKAROS.

This paper discusses the attitude stability criteria for spinning spacecraft equipped with large flexible membrane, such as solar sail. One actual realization of such a configuration is IKAROS, which is the world-first interplanetary solar sail spacecraft launched by JAXA in 2010. The authors previously derived stability criteria for spinning sail craft. This paper revisits the stability criteria of spinning solar sail spacecraft, and shows how it has been applied to the practical design of the IKAROS spacecraft configuration. The validity of the stability criteria is then evaluated by some numerical simulations and flight data of IKAROS.

In the post operational phase of spin type solar sail “IKAROS”, a slow-spin operation and a reverse-spin operation were conducted to acquire basic knowledge of mechanics of sail membrane. The flight data indicates that the sail membrane kept its shape against the solar radiation pressure even with low centrifugal force.

The world’s first solar sail IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) which is operated by Japan Aerospace Exploration Agency (JAXA) lost communication with the ground station due to the power short-age on December 24, 2011. In order to acquire IKAROS again after the power comes back, we immediately initiated to predict the attitude and orbit for the spacecraft.

NanoSail-D unfurled January 20th, 2011 and successfully demonstrated the deployment and deorbit capability of a solar sail in low Earth orbit. The orbit was strongly perturbed by solar radiation pressure, aerodynamic drag, and oblate gravity which were modeled using STK HPOP. A comparison of the ballistic coefficient history to the orbit parameters exhibits a strong relationship between orbital lighting, the decay rate of the mean semi-major axis and mean eccentricity.

NASA’s newly minted Space Technology Mission Directorate (STMD) is supporting the fabrication of a sail of this design in preparation of a planned 2014 flight. This mission, dubbed Sunjammer, will further advance the potential of propellantless solar sails. The Sunjammer mission is being led by the private company L’Garde Inc. of Tustin, CA. Sunjammer is named after a short story written by Sir Arthur C. Clarke. This ambitious project aims to prove the efficacy of a versatile and scalable solar sail design.

Space Services Holdings, Inc. (SSHI) is the commercial infusion partner for the NASA Technology Demonstration Mission Sunjammer. In partnership with LGarde, Inc. and the U. S. National Oceanic and Atmospheric Administration (NOAA), SSHI will demonstrate the commercial market for solar sail missions, augment the capabilities of the Sunjammer mission, and produce innovative content about the mission for a global audience. This paper will explore commercial infusion activities associated with Sunjammer and outline the potential for follow on commercial solar sail missions enabled by the Sunjammer mission.

The aim of the GOSSAMER-1 mission is an in-orbit deployment of versatile ultra-lightweight deployable sail hardware as a feasibility demonstration. The presented work focuses on the design and manufacturing of the sail membrane for GOSSAMER-1. The work has reached a preliminary design status which shall be presented in this paper. It includes mechanical analysis as well as a description of manufacturing strategies at the department of System Conditioning at the DLR Institute of Space Systems in Bremen.

This paper presents an overview of the different gossamer sail flight projects being undertaken at the Surrey Space Centre. The missions consist of a 25 m

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solar sail to be launched in Q1 2014 (CubeSail), a gossamer deorbiter for future European space assets (DGOSS), a scalable sailcraft that will demonstrate satellite deorbiting in Low Earth Orbit (DeorbitSail), and a drag sail that uses inflatable and rigidizable technology to be flown as part of the QB50 mission (InflateSail). The key technologies currently being developed for each project will be summarized and the most relevant scientific results presented.

The paper is about heliogyro solar sail deployment experiment called BMSTU-Sail which is developed by Bauman Moscow State Technical University (BMSTU) students and this experiment’s main aim is the validation of heliogyro deployment technology. Small prototype of two bladed solar sail will be deployed from picosatellite which will be launched by cosmonaut during extravehicular activity on International Space Station. BMSTU-Sail experiment was included into Russian segment experiment list as an educational experiment in December 2012 and it is financed by Russian Federal Space Agency “Roscosmos”. It is planned to be performed in the end of 2014.

Structure in the solar wind magnetic field can cause space weather (e.g. geomagnetic storms) at Earth. The magnetic field must be measured in situ and to improve warning times, monitoring platforms operating further upstream of the Earth than existing satellites are ultimately needed. This can be accomplished by solar sail missions, but any instrumentation must be extremely light-weight. Here we describe the development of a highly miniaturized magnetometer (MAGIC), which as part of the Sunjammer payload will conduct scientific studies of the solar wind magnetic field and its evolution to better understand the fundamental sources and causes of space weather.

The Solar Wind Analyser (SWAN) is a miniaturised analyser to be delivered for NASA’s Sunjammer solar sail mission. The aim of the Sunjammer mission is to demonstrate the technology readiness of solar sails and the ability to carry out good measurements of the solar wind with in situ instrumentation. Such measurements are extremely valuable, particularly when available in real-time, for advanced space-weather warning systems, alerting satellite operators and utilities on Earth of potential hazards from geomagnetic storms caused by coronal mass ejections from the sun. SWAN combines an electrostatic analyser with an energetic particle detection system to provide a comprehensive measurement of the low to medium energy solar wind plasma. The electrostatic analyser, based on the Charged Particle Spectrometer (ChaPS) built for the TechDemoSat mission, is designed to measure energy distribution functions of proton and alpha particles and provide real-time data for future space weather operational missions. The energetic particle detection system on the other hand will extend the energy range to enable measurement of solar energetic particles. This paper will present instrument requirements for a solar wind space weather monitor, present technical details of ChaPS and SWAN and discuss the challenges of making plasma measurements in the presence of a large solar sail.

A technology reference study for a multiple near-Earth object (NEO) rendezvous mission with solar sailcraft is currently carried out by the authors of this paper. The investigated mission builds on previous concepts, but adopts a strong micro-spacecraft philosophy based on the DLR/ESA Gossamer technology. The main scientific objective of the mission is to explore the diversity of NEOs. After direct interplanetary insertion, the solar sailcraft should—within less than 10 years—rendezvous three NEOs that are not only scientifically interesting, but also from the point of human spaceight and planetary defense. In this paper, the objectives of the study are outlined and a preliminary potential mission profile is presented.

A technology reference study for a displaced Lagrange point space weather mission is presented. The mission builds on previous concepts, but adopts a strong micro-spacecraft philosophy to deliver a low mass platform and payload which can be accommodated on the DLR/ESA Gossamer-3 technology demonstration mission. A direct escape from Geostationary Transfer Orbit is assumed with the sail deployed after the escape burn. The use of a miniaturized, low mass platform and payload then allows the Gossamer-3 solar sail to potentially double the warning time of space weather events. The mission profile and mass budgets will be presented to achieve these ambitious goals.

A technology reference study for a solar polar mission is presented. The study uses novel analytical methods to quantify the mission design space including the required sail performance to achieve a given solar polar observation angle within a given timeframe and thus to derive mass allocations for the remaining spacecraft sub-systems, that is excluding the solar sail sub-system. A parametric, bottom-up, system mass budget analysis is then used to establish the required sail technology to deliver a range of science payloads, and to establish where such payloads can be delivered to within a given timeframe. It is found that a solar polar mission requires a solar sail of side-length 100–125 m to deliver a ‘sufficient value’ minimum science payload, and that a 2.5 μm sail film substrate is typically required, however the design is much less sensitive to the boom specific mass.

In this paper, we detail the scientific objectives and outline a strawman payload of the SOLAR sail Investigation of the Sun (SOLARIS). The science objectives are to study the 3D structure of the solar magnetic and velocity field, the variation of total solar irradiance with latitude, and the structure of the corona. We show how we can meet these science objective using solar-sail technologies currently under development. We provide a tentative mission profile considering several trade-off approaches. We also provide a tentative mass budget breakdown and a perspective for a programmatic implementation.

The Sun–Earth L

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Lagrange point is an ideal location for an operational space weather forecasting mission to provide early warning of Earth-directed solar storms (coronal mass ejections, shocks and associated solar energetic particles). Such storms can cause damage to power grids, spacecraft, communications systems and astronauts, but these effects can be mitigated if early warning is received. Space weather missions at L

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have been proposed using conventional spacecraft and chemical propulsion at costs of hundreds of millions of dollars. Here we describe a mission concept that could accomplish many of the goals at a much lower cost by dividing the payload among a cluster of interplanetary CubeSats that reach orbits around L

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using solar sails.

This paper provides a mission analysis and systems design of a pole-sitter mission, i.e. a spacecraft that is continuously above an Earth Pole, and can provide real-time, continuous and hemispherical coverage of the polar regions. Two different propulsion strategies are proposed: solar electric propulsion (SEP) and SEP hybridized with a solar sail. For both, minimum-propellant pole-sitter orbits and transfers are designed, assuming Soyuz and Ariane 5 launch options. A mass budget analysis allows for a trade-off between mission lifetime and payload mass capacity (up to 7 years for 100 kg), and candidate payloads for a range of applications are investigated.

Solar sails have the potential to provide mass and cost savings for spacecraft traveling within the inner solar system. Companies like L’Garde have demonstrated sail manufacturability and various in-space deployment methods. The purpose of this study was to evaluate a current Mars sample return architecture and to determine how cost and mass would be reduced by incorporating a solar sail propulsion system. The team validated the design proposed by L’Garde, and scaled the design based on a trajectory analysis. Using the solar sail design reduced the required mass, eliminating one of the three launches required in the original architecture.

The dynamics of solar sails with a variable surface reflectivity distribution are investigated. When changing the reflectivity across the sail film, solar radiation pressure forces and torques can be controlled without changing the attitude of the spacecraft relative to the Sun or using attitude control actuators. The reflectivity can in principle be modified using electro-chromic coatings, which are applied here as examples to counteract gravity-gradient torques in Earth orbit and to enable specific shape profiles of a flexible sail film. This ‘optical reconfiguration’ method introduces an adaptive solar sail as a multi-functional platform for novel mission applications.

The development of Gossamer sail structures for solar sails contributes to a large field of future space applications like thin film solar generators, membrane antennas and drag sails. The focus of this paper is the development of a drag sail based on solar sail technology that could contribute to a reduction of space debris in low Earth orbits. The drag sail design and its connections to solar sail development, a first test on a sounding rocket, as well as the ongoing integration of the drag sail into a triple CubeSat is presented.

Fast intercept trajectories are discussed to impact the dangerous Earth-crossing asteroids by using a solar sail spacecraft for the near to far-term missions. The heliocentric trajectory with a single solar photonic assist is considered to transfer the sail kinetic impactor from the Earth orbit to the collision point with the asteroid. Two options of such trajectories, i.e., the direct flyby and the angular momentum reversal trajectory, are compared via numerical simulations with respect to the transfer time and the relative collision velocity to determine which one is more suitable. The variation trend of the relative collision velocities are presented for different mission scenarios as a function of the sail lightness number. For a square flat ideally reflective sail with a given assembly loading, the determination of the impactor mass is studied to obtain the highest value of the net increment velocity of the asteroid.

Solar-photon sails have been proposed for decades-duration missions to the heliopause (~200 AU) and the Sun’s inner gravitational focus (~550 AU). A more advanced goal for space-manufactured sails capable of ~500 km/s interstellar cruise velocities is a search for weakly interacting massive particles (WIMPS), a suggested form of dark matter, within the solar vicinity. Newton’s Shell Theorem is applied, in which WIMPS within the sphere defined by the solar distance are treated as at the Sun’s center; those outside this sphere are ignored. A spherically symmetric near-Sun WIMP cloud will produce an anomalous spacecraft acceleration towards the Sun. Consideration of the Pioneer Anomaly demonstrated to be caused by differential spacecraft thermal emissions, reveals that WIMP mass within ~60 AU is <0.2 Earth masses. Increasing the published accuracy of Pioneer 10/11 acceleration measurements by a factor of 10X allows probe trajectory measurements at ~10,000 AU to confirm or falsify the existence of a ~3X star mass WIMP cloud in the Sun’s galactic vicinity. Various sail configurations, sail/space-environment interactions, and mission planning are discussed.

The solar light pressure exerted on a thin foil is the quantity that determines crucially the performance of a solar sail propulsion technology. Besides the distance from the sun and the relative position of the sail to the sun, the light pressure depends on the quality of the sail surface. The surface quality, especially the reflectivity, degrades by exposing the sail to particle and electromagnetic irradiation under space conditions. This process will be simulated by a test facility at DLR Bremen. By directly measuring the light pressure after exposing the foils to a certain dose yields a kind of integral quantity of the degradation effects. To this end a light pressure measurement facility based on a high precision balance has been developed, completed and tested at DLR Bremen.

Before a solar sail will be used as a primary propulsion system for a space flight mission, many technical areas must be developed further. One of these areas concerns understanding the propulsion performance of a realistic solar sail well enough so that solar sail orbits can be confidently predicted to meet defined mission requirements. This paper identifies major contributors to solar sail thrust uncertainty, and analyzes the most significant ones to provide a better understanding of thrust generation by a “realistic” solar sail. Performance of representative “realistic” sailcraft are compared to similar “ideal” and “non-ideal” sailcraft to illustrate the differences.

A measure of propulsive efficacy for the grooved L’Garde solar sail surface — the photonic thrust efficiency in the context of an equivalent smooth (i.e., not grooved) sheet — is numerically assessed for thrust in the surface normal direction, and the dependence of this metric on the illumination incidence angles (in the directions along and across the grooves) is found to have some remarkable counter-intuitive characteristics. The study is based on a simple but powerful reflectivity model which, despite being a straightforward approximation to the full optical formulation, has received little attention in the past. This model, referred to as “linear” thrust model, simplifies analysis at the cost of only a minor loss of detail shown to be insignificant in the context of other common approximations. A result of this simplification is rigorous proof that the L’Garde sail surface groove contour shapes well approximate the classic catenary curve — the hyperbolic cosine function. The insight here offered contributes both to a practical appreciation of photonic thrust models and to the better understanding of some of the thrust characteristics of the L’Garde solar sail.

A solar sail membrane that deforms under radiation pressure is numerically analyzed to determine the thrust efficiency at different attitudes. The deformable sail is compared to flat and other rigid structures. Our numerical model uses ray tracing and simulated annealing to calculate the force, torque, and steady-state contour of a loose-fitting, thin membrane adhered to a rigid support.

In this study, a solar sail is modeled as smooth curved surfaces and the total force and moment models for the deformed sails are investigated, and two different forms of the models, namely the tensor expressions and the parameterized expressions, are proposed. Both forms can describe the total force and moment off-line by using the constant coefficient tensors or coefficient matrix correspondingly. Besides, some other properties as a result of deformation such as the sail mass center are also discussed. Thus this work paves the way for sail craft’s precise navigation and control where exact forces are needed.

The Rayleigh-Rice Vector Scattering Theory is applied to the interaction between sunlight and sail’s reflective layer, thus going beyond the scalar scattering theory already applied to solar-photon sailing. Diffuse-reflectance sailcraft acceleration is not negligible in accurate sailcraft trajectory propagation. The related values amount to about 20–110 times those ones due to the total solar irradiance fluctuations. The resultant of the diffuse-reflectance photon momenta per unit time and unit area, as function of the sail surface properties and sunlight incidence angle, exhibits many meaningful properties not previously reported in the solar-photon sailing literature.

Introduced at ISSS 2010, the Solar Sail Materials (SSM) project conducted for ESA came to its end at the beginning of 2013 with interesting and practical results. The project, relying also on past major European solar sails design projects, aimed at developing and testing future sail technologies suitable for large solar sailcrafts featuring low Sail Film Areal Density σ

Film

. The proposed paper presents the project’s achievements, mainly in the fields of Sail film and coating materials, Sail-to-Structure Interfaces (SSIF) and, Correlation of ground sail tensioning strategies with 3D imaging and Finite Element Model (FEM) simulations.

Commercial metallized polyimide or polyester films and hand-assembly techniques are acceptable for small solar sail technology demonstrations, although scaling this approach to large sail areas is impractical. Opportunities now exist to use new polymeric materials specifically designed for solar sailing applications, and take advantage of integrated sail manufacturing to enable large-scale solar sail construction. This approach has, in part, been demonstrated on the JAXA IKAROS solar sail demonstrator, and NASA Langley Research Center is now developing capabilities to produce ultrathin membranes for solar sails by integrating resin synthesis with film forming and sail manufacturing processes. This paper will discuss the selection and development of polymer material systems for space, and these new processes for producing ultrathin high-performance solar sail membrane films.

The performance of solar sails is significantly affected by both the sail geometry and the physical properties of used materials which degrade under space conditions. Hence it is of utmost importance for a sail-mission to select such sail materials which degrade as little as possible in space. The Complex Irradiation Facility (CIF) is a new laboratory at DLR-Bremen to study the degradation behavior of materials under space conditions. The CIF allows the simultaneous irradiation with three light sources and with a dual beam irradiation system for the bombardment of materials with electrons and protons having energies up to 100 keV. It is eminently suitable to perform degradation investigations at solar sail foils.

H

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-blisters are metal bubbles filled with hydrogen molecular gas resulting from recombination processes of protons in metal lattice. Bubble formation depends on many physical parameters, for instance: proton energy, proton flux, or the temperature of an exposed sample. Up to now no metallic sample that has been exposed to conditions prevalent in the interplanetary medium has been returned to Earth. Therefore, a direct evidence that blistering appears in space is missing. However, blistering is certainly a candidate of degradation processes which may occur in space. It could play an important role in the solar sail technology, where the performance of the sail is significantly affected by both the sail geometry but especially by optical properties of sail materials. Thus, both theoretical and laboratory studies of the blistering process have to be performed. The here presented model simulates the growth of molecular hydrogen bubbles on metallic surfaces. Additionally, it calculates the decrease of reflectivity of the by blistering degraded foils. First theoretical results show that the reflectivity of an Aluminum foil decreases by about 27 % for a bubble surface density of 1,500 cm

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and an average bubble radius of 100 μm. Therefore, if blistering occurs, the propulsion performance of any sail-craft will be decreased by a significant factor.

Theoretical aspects of a solar sail material degradation are presented when the solar electromagnetic and corpuscular forms of radiation were considered as sources of degradation. The analysis of the interaction of two components of solar radiation, the electromagnetic radiation and radiation of low- and high-energy electrons, protons, and helium ions emitted by the Sun with the solar-sail materials is discussed. The physical processes of the interactions of photons, electrons, protons and α-particles with sail material atoms and nuclei, leading to the degradation and ionization of solar sail materials are analyzed. The dependence of reflectivity and absorption for solar sail materials on temperature and on wavelength of the electromagnetic spectrum of solar radiation is investigated.

Since 2011 DLR is preparing 3 orbit demonstrations of deployment and operation of a solar sail. For this mission bundle a new deployment control mechanism for DLR’s tubular CFRP shell booms has been developed that is applicable to all 3 evolution steps of the GOSSAMER—Road Map. According to the mission goal of GOSSAMER-1 and its addressed deployed sail size of 5 × 5 m

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, a down scaled configuration of the booms and an adapted deployment mechanism are currently under development. The paper introduces the boom and its deployment mechanism concepts and describes and concludes tests and simulations that have been performed to proof the mechanical performance of the deployed booms.

This paper presents novel ultra-light booms for solar sails and other large deployable space structures. These CFRP booms have a unique property: bistability over the whole length (BOWL), which enables simple and compact deployment mechanism designs that can reduce overall system mass. They were produced to solve some of the previously encountered problems with bistable composite tubular booms that reduced their optimal length and scalability due to local buckling phenomena when the diameter of the coil increased. A new low-cost manufacturing technique, which consists of using braids with a variable angle change over the boom length, was found to have a positive effect in reducing that tendency. An analytical model is used to explain this behavior and predict the secondary stable state properties and natural diameter of the coiled/packed boom. A 3.6 m tape spring version of these bistable CFRP booms has been designed for a 25 m

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Gossamer Sail Deorbiter of future space assets and is being considered for an upcoming solar sail demonstration mission called CubeSail. Larger booms are being designed for a new scalable roll-up solar array concept.

The recent successful flight of the JAXA IKAROS solar sail has renewed interest within NASA in spinning solar sail concepts for high-performance solar sailing. The heliogyro solar sail, in particular, is being re-examined as a potential game-changing architecture for future solar sailing missions. In this paper, we present an overview of ongoing heliogyro technology development and feasibility assessment activities within NASA. In particular, a small-scale heliogyro solar sail technology demonstration concept will be described. We will also discuss ongoing analytical and experimental heliogyro structural dynamics and controls investigations and provide an outline of future heliogyro development work directed toward enabling a low-cost heliogyro technology demonstration mission ca. 2020.

This article presents a methodology for analyzing the solarelastic stability of a solar sail spacecraft blade. This paper couples linear and non-linear rotating structural models with an optical solar radiation pressure model for a completely reflective surface. The resulting time varying ordinary differential equations are solved in a quasi-static sense, where an instantaneous stability boundary is determined. The quasi-static analysis with the linear model predicts a divergence type instability and slow and non-uniform modal convergence using parameters for a representative heliogyro spacecraft blade. The non-linear model predicts a flutter instability at a lower radiation pressure and has improved modal convergence characteristics. The paper uses the non-linear model to evaluate the stability of a NASA heliogyro concept design and explore the dependence of the stability boundary on the spacecraft rotation rate for the case of the sun directly overhead. Increasing the spin rate of the spacecraft improves the solarelastic stability, but must be traded off with decreased spacecraft maneuverability.

Heliogyros generate attitude control moments by pitching their sail membrane blades collectively or cyclically, similar to a helicopter. Past work has focused on simple blade pitch profiles with the heliogyro normal to the sun; however, most solar sail missions will require sun angles of at least 35°. Furthermore, combination pitch profiles (e.g. cyclic plus collective) are needed for attitude control during all mission segments. The control moments for such situations vary in an unintuitive, nonlinear fashion. This paper explores heliogyro control moment authority with varying sun angle and combinations of pitch profiles, providing critical insight for future development of heliogyro attitude control schemes. Three strategies for generating control moments using various profile combinations are investigated for three-axis attitude control. These strategies indicate that the heliogyro can generate control moments while edge-on to the sun, allowing for recovery from any orientation. A control algorithm is presented that determines the required blade pitch profile combination to generate the desired attitude control torques. This algorithm could be employed for closed-loop control in attitude dynamics simulations.

As a necessary precursor to a heliogyro solar sail flight demonstration, meaningful ground test experiments are necessary for predicting the linear and nonlinear structural dynamics of the heliogyro membrane blades in flight. This paper describes analytical comparisons of linear and nonlinear behavior of a multi-link discrete model of a heliogyro blade under 1-g gravitational and centrifugal loads, and one setup for experimental validation of 1-g out-of-plane motion. Linear system-identification is performed on the multi-link experimental data to validate the 1-g multi-link model of a heliogyro membrane blade.

Initial studies of a Heliogyro membrane blade have shown significant nonlinearities in the equations of motion. The objective of this paper is to demonstrate a system identification method applicable for describing the dynamic behavior of a Heliogyro membrane blade and to use it for control design.

This paper is about research of dynamics of spatial motion of two-blade heliogyro solar sail considering different types of perturbing effects with their responsiveness and range. The main purpose of this work is determination of list of design objectives and their range to provide sustainable movement of picosatellite with two-blade solar sail in experiment BMSTU-Sail.

Sail attitude equilibria exist under the influence of aerodynamic, gravity gradient and solar torques. Precession of the sail normal from these equilibria causes sail normal coning about that equilibrium attitude. If the coning happens at orbit rate, wide variety of orbital effects can be induced. Past work developed a coning controller that enables orbit rate circular coning of the sail normal about the attitude equilibrium. This controller enables the sail normal vector to trace a desired coning trajectory at orbit rate. In this analysis, the performance of spinning vs. non-spinning solar sails in inducing orbital effects is studied using the coning controller. Results show that control torques required are on the order of 10

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Nm, and it is advised to operate a non-spinning sail to avoid complex mechanisms and to maintain system robustness.

The aim is to develop a conceptual satellite that combines the scalability and stability of a spinning sail with the agility of a 3-axis stabilized sail. A tri-spin satellite is proposed making use of a spinning sail and a momentum countering system (MCS) rotating relative to the satellite body. The MCS reduces the angular momentum bias increasing the maneuverability of the satellite. Induced oscillations in the non-rigid elements due to attitude changes are investigated. A complete attitude determination and control system (ADCS) for such a satellite in an earth-centered orbit is proposed and simulated. The simulation reveals that the tri-spin concept is viable.

The solar sail is large and highly flexible, and its motion involves a coupling of the orbit, the attitude and structural vibration. This paper establishes the reduced dynamic model for a flexible solar sail with foreshortening deformation and coupling of its attitude and vibration. In the process of attitude control with the large-angle maneuvers, large orbital deviations and structural vibrations are generated. When initial deviations and solar pressure disturbance torques are considered, the process of attitude control leads to greater accumulated error in the transfer trajectory, which demonstrates that the process of attitude control is important to the solar sail mission.

Electrochromic device has been proposed for the attitude control of spacecraft for that the optical characteristics of the device can be altered by applying electrical excitation to generate a torque on the spacecraft. The technology was recently employed and verified successfully on IKAROS, the world’s first interplanetary solar sail. It is found that the reflection control device can not only be used to generate desired torque to control the attitude of a sail, but also it can be used to change the total force on the sail instantaneously. The property is proved to be very helpful for the active control of a sailcraft. In this study, the force and torque models of a reflectivity modulated spinning disk sail experienced by solar radiation pressure are discussed. A reflectivity modulation scheme, which was used in IKAROS mission, is investigated for the active control in a GeoSail formation flying application. The main objective of the study is to construct a method for the active control of solar sail in some situation where an additional control input is required in addition to two sail attitude angles. The coupled attitude and orbit dynamics of the sail on a GeoSail orbit is discussed and the equation of relative orbit and attitude motion is given. Finally, the performance of the reflectivity modulation control for GeoSail formation flying is numerically demonstrated.

The deployment stability of the spinning solar sail spacecraft has been discussed in this paper. First, two-step deployment method is discussed. To get the solar sail model in every deployment stage, we study a three-dimensional reduced model including a rigid body and four cables with corner masses, consider the cables noncoplanar and the mass of the cables and derive the analytical model. After that, the characteristics of every stage are analysed. Finally, with the given controller, we study the deployment stability of the system and discuss how to keep the successful deployment with small pitch angle and none re-wrapping.

A simplified solar sail steering law is discussed in which the sail clock angle is used as the only control variable, while the sail cone angle is maintained constant along the whole spacecraft heliocentric trajectory. Within this control strategy, the steering law that minimizes the flight time is obtained with a closed form solution using a classical variational approach. Sub-optimal performances, that is, optimal constrained solutions, have been analyzed for different mission scenarios assuming three-dimensional (ephemeris free) problems. Numerical simulations show that for suitable combinations of cone angle and spacecraft characteristic acceleration, the percentage increase of flight time of the simplified steering law is moderate when compared to a minimum time solution, in which the sail cone and clock angles are both allowed to vary during the whole transfer phase.

This chapter presents new families of Sun-centered non-Keplerian orbits (NKOs), where the motion of a high-performance solar sail is confined to either a cylindrical or spherical surface. These orbits are found by investigating the geometrically constrained sail dynamics and imposing further constraints on the angular velocity and lightness number to generate pure solar sail trajectories. By considering the sail motion in the phase space of the problem, families of new NKOs are identified, and by investigating the oscillating behavior of the orbits, true periodic orbits are found. As extension to the well-known families of displaced NKOs, these three-dimensional NKOs generate a wealth of new solar sail orbits and novel sail applications.

We use the numerical continuation package AUTO to investigate families of periodic orbits in the solar sail circular restricted three-body problem. For a sail orientated perpendicular to the Sun-line we find significant differences to the classical case for some families near the Earth, including the

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Halo family and retrograde satellite family. Specifically, we expand on existing results and find that the change in the Halo family H1 is associated with a bifurcation of a branch point in the retrograde satellite family, which splits H1 in half. We also track regions of stability within the family, and find some large amplitude stable orbits. For a sail tilted relative to the Earth-Sun line only we find large amplitude families with some stable orbits. Interestingly there is also a small range of parameters for which

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bifurcates into three separate points in this system.

In this paper we consider the Hill 3-body problem with the extra effect of the solar radiation pressure as a model for the motion of a solar sail close to an asteroid. To model the sail’s acceleration, we include both reflectivity and absorption of the sail’s material. We describe the most relevant dynamical properties of the system for different reflectivity and absorption coefficients as well as different fixed sail orientations. We show families of periodic orbits, describe how they relate to the parameters of the sail and discuss their stability.

Variable geometry solar sailing potentially offers enhanced delta-V capabilities and new orbital solutions. We propose a device with such capabilities, based upon an adjustable quasi-rhombic pyramid sail geometry, and examine the benefits that can be derived from this additional flexibility. The enabling technology for this concept is the bevel crux drive, which can maintain tension in the solar sail across a wide range of apex angles. This paper explores the concept of such a device, discussing both the capabilities of the architecture and the possibilities opened up in terms of orbital and attitude dynamics.

Ideal solar sails are perfectly flat, rigid, and reflective, can hold arbitrary sun angles perfectly, etc. Real sails are very different. Yet much preliminary mission analysis is done with ideal sails, on the assumption that the only important effect of non-ideal behavior is slightly reduced performance. This assumption is often false. Real sails simply cannot fly some mission plans that look plausible for ideal sails, and in other cases, realistic mission design and realistic sailcraft design much consider some aspects of non-ideal sail behavior from the start.

The use of a solar sail allows a spacecraft to generate thrust at no expense of propellant. However, there is little data to quantify the effect of sail structure on thrust performance. The InspectorSat mission will use a microsatellite to autonomously perform close proximity manoeuvres to inspect a co-orbital solar sail. Using a novel microelectromechanical thruster for precision orbital and attitude control and a simple monocular imaging sensor for inspection, the InspectorSat will observe sail deployment, surface features and record measurements of solar radiation pressure. This work, therefore, reflects the mission analysis inputs to the PRECISE micro-chemical propulsion system development, demonstrating the utility of a microscopic, low impulse thruster for the actuation micro- and nanosatellite platforms. Simulation results are used to determine thruster performance and Δv requirements for deployment, rendezvous and inspection. The proposed inspection schemes are designed to allow the inspector to take advantage of multiple observation opportunities. The results of this study provide a comprehensive analysis of the manoeuvring requirements of a small inspector satellite in close proximity to a passive observation target. As such, the analysis demonstrates the practicality of the micro-chemical propulsion system for inspection manoeuvres.

The Space Tow is a modular solar sail design, uniting versatility of size with ease of manufacturing in an easily stowable package. All stowed structures must be deployed to their mission configuration, which is challenging for such a light and flexible design. The present study explores the “leave behind” and “drag along” deployment strategies in simulation and mathematical analysis. The conclusions are that the “drag along scheme” is sensitive to perturbations and that the “leave behind” scheme needs careful consideration of its parameters or risk that the undeployed stack is overrun by the deployed structure. The present study also discusses the energy dissipation needed for a robust deployment and proposes both a frictional and acceleration-rate proportional damping such as occurs in deformations in an accelerating frame.

The deployment, dynamics, and control of the electric solar wind sail is addressed in terms of the single tether motion. Based on a simple model of a rotating rigid tether as a spherical pendulum, estimates for the goodness of the control system are shown for strictly planar tether tip orbits. It is concluded that the control system is rather inefficient for a slowly rotating sail with a large tether coning angle. The results are conservative as they do not take into account the actual shape of the tether. The long and short-term effects on the sail rotation rate arising from the single tether dynamics are addressed. We also present preliminary results on a new control scheme assuming non-planar tether tip orbits. It is argued that the scheme will improve the electric sail control system efficiency.