Space Solar Power Satellite Research Articles

Solar microwave fabric paper on the key technology for making our future satellite and skin surfaces for aircraft, eliminating APU’s

Solar-Microwave Fabric (SMF) is a mass-produced, thin, flexible membrane upon which is imprinted various combinations of solar cells, microwave patch antennas, and analog control devices. This is for applications such as solar power collection, power transmission, communication, and defense. It can be folded into a compact volume for transport and then unfurled for its operation. In its most sophisticated form, the SMF features the full complement of printed devices: solar cells, patch antennas, transceivers, and retro-directive phased array capability. This most mature capability can be applied to the Power-Star in section 1.6 (Figure 46) space solar power satellite, and to ground installations for combined solar power and air defense. The SMF has various modes of operation of, Solar Power Collection, Communications, Distribution & Defensive systems. Ultimately the Power/ Comm/Defense has one side printed as an “active” mode of power transmission whereby radiation is broadcast to a non-cooperative target and the return from the target is used as the beacon for the direction of a high-power density beam with focusing (vaporization). This could be applied for both ground-based power collection and air/space defense. World’s 1st exposure to: US Patent 11,251,658, Japan Patent 6,987,935.

Microwave wireless power transfer efficiency analysis framework for a thin film space solar power satellite

Space-based solar power systems (SSPS) envision the usage of focused microwave beams to transfer power from space to ground. To supply a large amount of power and to be able to focus a microwave beam efficiently, a large infrastructure must be assembled in orbit, thus, making the implementation of SSPS an arduous task. In the history of SSPS designs, aside from economical obstacles, technical obstacles such as large ohmic losses due to long DC lines in the structure, large rotary joints to decouple beam pointing and solar power collection, heating problems from power lines converging into a single point, and complex control mechanisms, manufacture, and assembly are present. A simpler implementation using multiple foldable thin film membrane satellite modules is proposed as a feasible design, born from the advancement of thin film electronics. Its economical feasibility is achieved through the reduced weight, large surface area, and membrane’s ability to be stowed. The thin film SSPS combines advantageous properties of past designs such as a simple structure, simple control mechanism, and a distributed power collection and transfer architecture avoiding the ohmic loss and heating problems. However, due to the thin film membrane hosting both the antenna and the solar cells, competition occurs between maximum solar power collection and high efficiency power transfer capabilities. In this paper, we propose a framework to analyze the performance of the thin film SSPS solar cell-antenna integration design in terms of the wireless power transfer efficiency and fuel consumption, from which we identified the trade-offs on designing and operating the station. We used this framework to analyze three different antenna element designs in combination with three different attitude control goals, and found out that the key aspects of the antenna design are beam width, radiation efficiency, and efficient solar cell integration.

Scaling laws of Space Solar Power Satellite concentrator unit distortion model obtained by performance-driven separate similitude analysis method

The distortion model may arise due to the inability to isometrically scale the thickness dimensions when utilizing similitude theory to develop scaling laws for large-scale concentrator units in the Space Solar Power Satellite. Previous works to address the distortion model neglect its negative impacts and persistent limits, resulting in insufficient prediction accuracy for prototype. To obtain scaling laws of the distortion model, this paper introduces a novel strategy called the performance-dominated separate similitude analysis, which significantly reduces the distortion model's negative impacts and persistent limits on similitude prediction. Firstly, performance parameters sensitive to the distortion model are generated by dimensional analysis and the governing equation method. Secondly, the distortion model is separated into two scaled models: complete and partial similitude, based on the sensitive performance parameters. Subsequently, the scaling laws of complete and partial similitude models are derived, respectively. Finally, the scaling laws of the distortion model are derived by combining the complete and partial similitude laws. The proposed method is validated through finite element model simulation for both the concentrator unit prototype and the distortion model. Results indicate that in the best case, the prediction error doesn't exceed 0.2 %, and the prediction accuracy can be improved by up to 87.34 % compared to the existing methods.

On the Innovation, Design, Construction, and Experiments of OMEGA-Based SSPS Prototype: The Sun-Chasing Project

This study systematically introduces the development of the world’s first full-link and full-system ground demonstration and verification system for the OMEGA space solar power satellite (SSPS). First, the OMEGA 2.0 innovation design was proposed. Second, field-coupling theoretical models of sunlight concentration, photoelectric conversion, and transmitting antennas were established, and a systematic optimization design method was proposed. Third, a beam waveform optimization methodology considering both a high beam collection efficiency and a circular stepped beam shape was proposed. Fourth, a control strategy was developed to control the condenser pointing toward the sun while maintaining the transmitting antenna toward the rectenna. Fifth, a high-efficiency heat radiator design method based on bionics and topology optimization was proposed. Sixth, a method for improving the rectenna array’s reception, rectification, and direct current (DC) power synthesis efficiencies is presented. Seventh, high-precision measurement technology for high-accuracy beam-pointing control was developed. Eighth, a smart mechanical structure was designed and developed. Finally, the developed SSPS ground demonstration and verification system has the capacity for sun tracking, a high concentration ratio, photoelectric conversion, microwave conversion and emission, microwave reception, and rectification, and thus satisfactory results were obtained.

Identification of time-varying inertia tensor parameters of a space solar power satellite based on a robust weighted recursive algorithm under impulsive disturbance

Considering changes in the structural size and mass caused by the on-orbit assembly process in a planar space solar power satellite, this study proposes an improved robust recursive algorithm to identify the time-varying inertia tensor parameters of the system. In this algorithm, to decrease the effect of impulsive disturbance on inertial parameter identification during the on-orbit assembly and improve computational accuracy, robust weighted factor and multi-innovation theory are involved. Then, the time-varying inertia tensor parameters of this large flexible structure are identified based on the distributed measurement results of multiple attitude sensors. The simulation results indicate that the proposed algorithm improves the identification accuracy and has better robustness than the original method under the impulsive disturbance. The relative values of the average relative error caused by the impulsive disturbance under the proposed algorithm are approximately 27.8–73.0% less than those under the original method. Additionally, the results also demonstrate that the proposed algorithm has higher noise immunity than the classical recursive least-squares method in a time-varying system. When the impulsive disturbance and zero-mean Gaussian white noise are applied to the system, compared with the conventional recursive least-squares method, the proposed algorithm yields lower absolute and relative values of the average relative error by approximately 4.2% and 44.9%, respectively.

Bi-level multi-objective optimization of the structure and attitude for space solar power station

To utilize space solar energy efficiently, this study focuses on the optimization of multi-rotary joints space solar power satellite (MR-SSPS), which is designed to efficiently collect and transmit solar energy to Earth. A constraint multi-objective optimization model is proposed for the MR-SSPS, which encompasses three objectives: truss mass, structural stiffness, and attitude control energy. A bi-level optimization method is proposed, considering the characteristics of the structure and attitude control models. The first-level optimizes the structure of the solar array system and truss, while the second-level optimizes the attitude controller. The mass and certain structural parameters serve as correlation variables linking the two levels. To enhance efficiency, a database and parallel computing are employed. Compared to the traditional multi-objective optimization approach, the proposed bi-level method achieves better solutions in both accuracy and efficiency. The optimized MR-SSPS structure meets attitude control accuracy constraints while reducing mass and energy consumption. This research provides insights into the design of MR-SSPS and demonstrates the effectiveness of the bi-level optimization approach for complex engineering problems.

Recursive identification of the time-varying frequency parameters of a space solar power satellite using a robust subspace tracking method based on the variable forgetting factor

Considering changes in the structural configuration caused by the rotation of solar panel arrays in space solar power satellites, this study proposes an improved robust recursive subspace tracking algorithm to identify the time-varying modal frequency parameters of the system. In this algorithm, variable forgetting factor and robust weight coefficient are involved to improve the tracking adaptability of time-varying system and decrease the influence of impulsive disturbance. Then, the time-varying pseudo modal frequency parameters are identified using the recursive projection subspace tracking. In the numerical simulations, the influence of the different rotation speeds of the solar panel arrays on the frequency identification results is studied. The computational results for the different rotation speeds reveal that the tracking performance of the proposed algorithm is better than that of the original method for time-varying system. Under the influence of impulsive disturbances, the relative values of the average relative error under the proposed algorithm are approximately 65.9–75.2% less than those under the original algorithm. Additionally, the results reveal that when the rotation speed of the solar panel arrays is time-varying, the proposed algorithm achieves a better tracking performance than the conventional recursive methods by the adjustment of the variable forgetting factor. When the signal-to-noise ratio is 15 dB, the absolute and relative values of the average relative error under the proposed algorithm are less by approximately 6.4% and 64.8%, respectively, under the two reference methods with a fixed forgetting factor.

Placement and size-oriented heat dissipation optimization for antenna module in space solar power satellite based on interval dimension-wise method

Space solar power satellite is one of the large space systems for supplying solar energy in the future, and its effective thermal management and heat dissipation can affect safety and efficiency. To balance the mass and temperature distribution in the antenna module, a novel placement and size-oriented heat dissipation optimization is proposed in space solar power satellite based on an interval dimension-wise method considering both design and uncertain variables. To improve the accuracy of the interval propagation, a novel interval dimension-wise method is investigated based on the Legendre polynomial approximation model and the union operator of the boundary points combinations. A novel mapping matrix with sensitivity analysis is developed to determine the final design variables from the candidate ones, which constitutes a relationship between the uncertain parameters and design variables. The placement and size-oriented heat dissipation optimization is solved using the coevolutionary constrained multi-objective optimization framework (CCMO), and thermophysical response intervals of optimal heat dissipation layout can be obtained using the interval dimension-wise method again. The effectiveness of the proposed method is verified by two numerical examples, which can reflect the applicability of the proposed heat dissipation.

Quasi-Geostationary Earth Orbits for Space Solar Power Infrastructure and Other Low Area Density Satellites

This paper explains non-Keplerian orbital behavior for thin, large earth-based satellites with very low area density. We demonstrate a unique new solution that produces a new, quasi-geostationary earth orbit (QGEO) that can help with economical deployment of space solar power satellites as well as the mitigation of space debris for all satellites.

A 5.8-GHz Rectifier Using Diode-Connected MESFET for Space Solar Power Satellite System

To improve the power handling capability at ground stations of a 5.8-GHz solar space power satellite using microwave power transmission, a power charge-pump meta-semiconductor field-effect transistor (MESFET)-based rectifier is presented in this article. Unlike conventional microwave Schottky diodes, diode-connected MESFETs, whose nonlinear characteristics help them to have a unique current–voltage (I-V) curve that overcomes the limitations of a Schottky diode. Thus, the maximum input power of the proposed rectifier is extended up to 251.2 mW by replacing a Schottky diode with a diode-connected MESFET. Additionally, a class F harmonic processing network is introduced to control the voltage and current waveform at the load of the rectifier. Consequently, the RF-dc conversion efficiency is increased since the power dissipation is limited at the junction resistance of both the drain and the source of the MESFET. Owing to the abnormal characteristics of the diode-connected MESFET, the measured conversion efficiency of our rectifier is approximately 73.2% at 126 mW, and the input power range for rectifier efficiency higher than 50% is between 16 and 224 mW. The proposed rectifier for the space solar power satellite application is demonstrated and verified using a microwave wireless power transmission system.

Recursive identification of inertia tensor parameters of space solar power satellite based on distributed placement of attitude sensors

This study addresses the issue of recursive identification of the inertia tensor parameters for a space solar power satellite with planar configuration based on a distributed placement of its attitude sensors. Different from the centralized configuration of the attitude sensors in a traditional rigid spacecraft, multiple attitude sensors are used to reduce the impact of the vibration signals of the large flexible structure on the measured attitude signals and improve the identification accuracy. By establishing an attitude–vibration dynamic model of the system, achieving optimal placement of multiple attitude sensors is investigated and a corresponding optimization criterion is developed. Subsequently, based on the least squares theory, the variable forgetting factor is derived by minimizing the system mean square deviation. Moreover, an improved recursive least squares method is developed to estimate the system inertia tensor parameters using the coupled least squares estimation. Numerical simulations are conducted, and based on the attitude output signals obtained from the optimal sensor placement results, the inertia tensor parameters are identified using the developed algorithm. The results demonstrate that the structural flexibility significantly affects the identification accuracy of the inertia tensor parameters, and the distributed placement of the multiple attitude sensors reduces this influence to a certain extent. Compared to a single group of attitude sensors, the ten groups of sensors for identifying the inertia tensor parameters reduce the absolute and relative values of the average relative error by approximately 3.3%–5.4% and 36.5%–55.6%, respectively. In addition, the identification results reveal that the absolute value of the average relative error is decreased by approximately 2.8%–3.5% on using the proposed recursive algorithm compared to that obtained using the conventional recursive least squares method when the signal-to-noise-ratio is 10 dB.

Time-varying frequency parameter identification of space solar power satellites based on an improved recursive subspace algorithm and optimal sensor placement

This study focuses on the time-varying modal frequency identification of space solar power satellites. Accordingly, an improved recursive subspace identification algorithm based on the variable forgetting factor is proposed to enhance the tracking adaptability of the original method in time-varying systems. Considering the changes in the structural configuration induced by the rotation of the solar concentrator mirror, a time-varying attitude-vibration coupling dynamic model of a space solar power satellite with an integrated symmetrical concentrator configuration is developed based on the modal synthesis technology and the substructure method. Moreover, based on the projection subspace theory, the time-varying forgetting factor is determined by minimizing the mean square deviation of the system estimator. Subsequently, the variable forgetting factor subspace algorithm is adopted to recursively identify the time-varying pseudo modal frequency parameters. A finite element model of the space solar power satellite is established via numerical simulations, and several optimal sensor placement methods are applied to determine the positions of the vibration sensors. Based on the output signals obtained from the optimal sensor placement results, the time-varying frequency parameters of the system are obtained using the proposed algorithm. The computational results reveal that a decrease in the average relative error by 4.2% compared with that obtained via the conventional recursive subspace method is observed when the signal-to-noise-ratio of the measured output is selected as 15 dB. In addition, the results also reveal that an average relative error reduction of approximately 0.4%–1.4%, over two other methods with a fixed forgetting factor, can be achieved using the proposed algorithm when the rotation speed of the solar concentrator mirror is increased. The findings of this study confirm that the proposed algorithm demonstrates a high noise-immune ability and tracking performance for fast time-varying systems.

A comprehensive review on space solar power satellite: an idiosyncratic approach.

Space solar power satellite (SSPS) is a prodigious energy system that collects and converts solar power to electric power in space, and then transmits the electric power to Earth wirelessly. The main principle of this system is to supply constant solar energy by placing collectors in geo-synchronous orbit and collecting it on an Earth-based receiver, known as a rectenna. This system can overcome serious drawbacks, especially the pseudo-random intermittent capacity factor of ground-based solar power or photovoltaic systems and modules. This paper discusses some old and new concepts of solar power satellite designs and the effects of various parameters on the efficiency of collecting medium, transmission media, and receivers' area. We evaluated and reviewed the three major components of the space-based satellite that have a hand in affecting the overall efficiency of the system, which are (1) collection unit, (2) power transmission unit, and (3) the receiving unit. This paper reviews the system as a whole, as proposed in the last three decades. Many of the microwave-based SSPS models that were proposed so far are based on solar concentrators. The required launch mass and system cost could be significantly reduced by using solar concentration and hence higher efficiency can be achieved. SSPS requires new microwave technology to achieve a high power conversion efficiency of over 80% and extremely accurate beam control from the 2km phased array transmitting antenna. Such specifications are extremely demanding and therefore significant effort is required for proper research and development. Under this technology roadmap, current research and development lead to the beginning of the new SSPS era in the coming decades.

Space solar power satellite for the Moon and Mars mission

This paper presents an overview of space solar power satellites for the Moon and Mars mission and simultaneously demonstrates the compression of traditional power generation methods for the orbiter, lander, and habitat on Mars and the Moon. Interplanetary missions are where the space engineers work on the satellites, conceptual design of space habitat, and exploration system. The state of the art in those missions relies on radioisotope thermoelectric generators or solar panels attached with batteries to store power, both of which are plagued by limitations. For instance, when a spacecraft moves away from the Sun, the energy collection efficiency on the solar panel is reduced, and at temperatures below -100°Celsius, individual solar cells degrade unpredictably, deteriorating the performance of solar arrays. Furthermore, these power generation unit satellites carry a pack of batteries to store energy whose total system accounts for more than 10-25 % of the mass of the satellites. In an interplanetary mission, power generation and management are essential for research and investigation on the surface. For Mars, sandstorms affect the collection of energy at the attached solar panel to the rover. Moreover, the rovers must investigate at the far side of the Moon, where sunlight is unavailable for few consecutive days. This challenge can be suitably overcome by employing space solar power satellites, which can be used for wireless power transmission, independent of its location. Such techniques have possible applications towards power transmission for unmanned aerial vehicles for faster mapping purposes. As such, the dependence of those aerial vehicles towards fixed energy storage becomes alleviated. In hindsight, space solar power satellite serves as a potential for an improved energy transmission source than the traditional method for interplanetary rovers and habitat.

Wireless power transfer self‐adaptive to incident power density

Inspired by the envision of space solar power satellite, microwave-based wireless power transfer has been intensively studied. To date, while significant progresses have been achieved, bottlenecks still exist. Among them, the deterioration of the radiofrequency (RF)-to-direct current (DC) efficiency due to the variation of incident microwave power is a major problem. It prevents this technology from many practical applications. In this work, based on the dependence between the incident power density and the resistive DC load, we propose a self-adaptive approach to mitigate this deterioration by introducing a continuous DC load modulation. Experiments based on a complex-conjugate rectifying surface showed effective improvements of the RF-to-DC efficiency for the incident power density varied in a wide range.

Iterative two-layer thermal design strategy for step sandwich antenna of space solar power satellite using modified constrained multi-objective optimization

To utilize space solar energy efficiently, a concentrating-type space solar power satellite (SSPS) that can collect solar energy in space and transmit it to Earth through energy conversion and transmission is proposed. Given that the thermal subsystem is affected by high temperatures, which directly restricts its development, an iterative two-layer thermal design is proposed herein to optimize the step sandwich antenna (SSA) in the SSPS using a novel modified multi-objective optimization algorithm. To improve the feasibility of the SSPS, the thermal control coating requirements and structural configurations of the SSA are examined. The optimization of the SSA entails thermal analyses involving the conduction and radiation modes using thermophysical and structural parameters. The iterative two-layer thermal design of the SSA includes top-layer conceptual and bottom-layer precise designs. The coating requirement and structural configuration of the top-layer and the precise configuration and temperature uniformity of the bottom layer are improved iteratively to ensure global optimal solutions. Thus, the theoretical critical values of the optical properties of coatings are revealed using the proposed thermal design strategy. Furthermore, the solution set at the Pareto front is appraised, and the constrained multi-objective optimization algorithm is modified to obtain a more dispersed solution set. Finally, an actual SSA with the optimal design variables of the coatings and configurations is constructed using the two-layer strategy to achieve better heat dissipation with a mean temperature gradient of 7.22 °C/m and mass of approximately 2729 t; the effectiveness and feasibility of the design were also verified.

A synchronous placement and size-based multi-objective optimization method for heat dissipation design on antenna module of space solar power satellite

As a potential space building for supplying solar energy, space solar power satellite (SSPS) has become an important aspect of its feasibility study. For such a high-power system, the heat dissipation problem caused by the large external heat flux and internal heat source must be resolved. This study investigates an optimum layout for heat dissipation of an antenna module in SSPS exposed to an extreme thermal environment using optimization with an iterative two-layer design. A synchronous placement and size-based multi-objective optimization problem is constructed with temperature constraints to balance the module’s mass and temperature distribution with the optimum location, placement, and size. To improve the solution efficiency, an iterative two-layer heat dissipation design is developed to avoid the limitations of directly solving the high-dimensional optimization. The first-layer design optimizes the placement and basic size of the thermal control equipment using the constrained NSGA-II, and the size factors are continually optimized in the second-layer design. This innovative design can not only overcome the large-scale calculation, but also meet the actual engineering needs, which optimize the key indicators and balance accuracy and efficiency. The proposed method with statistical analysis is applied to realize 2.6% weight reduction and acceptable temperature distribution with effectiveness.

Modular Line-Focused Space Solar Power Satellite

The Space Solar Power Satellite is an ultra-large space structure, which collects sunlight directly in space and then transmits it into the ground. Since the idea was invented in 1968, scientists around the world have proposed several typical conceptual design models. Nevertheless, the conceptual models have not been implemented for technological, manufacturing, and cost reasons. This paper presents a novel Space Solar Power Satellite scheme with modular line-focused concentrators and low concentration photovoltaic modules. First, the line-focused mode is analyzed and the optical performance of the circular trough concentrator is evaluated via ray-trace technique. Then, shape optimization for the cell array based on the Bézier curve is carried out to improve the optical property. Numerical examples indicate that the optimized cell array could obtain high power collection efficiency and suitable energy distribution. Moreover, the area of the photovoltaic cell array is reduced, which is conducive to cost reduction. Furthermore, modular design is conducted on the circular trough concentrator. Finally, the primary scheme of the novel Space Solar Power Satellite is designed with the previous modular concentrator and optimized cell array.

Towards the realization of the Space Solar Power Satellite Systems

Towards the realization of the Space Solar Power Satellite Systems

Shape reconstruction of planar flexible spacecraft structures using distributed sun sensors

Flexible planar spacecraft, such as solar sails, phased antenna arrays and space solar power satellites vary their shape in flight and also may not have a known shape after deployment. To allow applications where spacecraft shapes are measured to allow the closed-loop correction of flight or payload parameters, this paper presents a method for measuring shapes with miniature sun sensors embedded within the structure. Two algorithms to reconstruct the shape of the structure from the two local angles to the sun are presented; the first one is geometry-based, whereas the second one uses a finite element model of the structure. Both algorithms are validated on a 1.3 m × 0.25 m structure with 14 novel miniature sun sensors with an accuracy of 0.5∘, developed for the present research. The structure was reconstructed to an accuracy better than one millimeter by both algorithms, after undergoing bending and torsional deformations. While the geometrically based algorithm is fast and accurate for small deformations, the finite element based algorithm performs better overall, especially for larger deformations.