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We design and complete an experiment of debris detection under the Milky Way background. The data analysis shows that the strong Milky Way background reduces the detector's ability to detect the weak debris, but has little effect on the accuracy of the astronomical positioning of debris. This paper verifies the rationality of using the limit detection magnitude method based on the detection probability to characterize the limit detection ability of detectors. It also verifies the feasibility of using the simulation method to increase the data completeness. The work in this paper will provide a basis for the design of the spacebased detectors and the development of the detection experiments. [ABSTRACT FROM AUTHOR]

In order to improve the payload ratio of spacecraft and reduce the weight of the platform .this paper presents a new way to reduce the harness weight by using matrix control and telemeter harness. To optimize the harness design method to the greatest extent, a mathematical model of matrix harness based on undirected graph was established.Two factors affecting harness weight lose were extracted by the model： topology and matrix resource distribution. The concept of visiting order was introduced in the paper， and the organic combination of the two factors was realized. Basic principles for optimization design were presented,and simulation verification was carried out.The results show that the optimized matrix harness weight is about 50% less than the discrete harness weight， improving the system reliability effectively. [ABSTRACT FROM AUTHOR]

This paper studies the impact fluxes calculation for the orbiting space objects via the Chan's model which does not invoke either the kinetic theory of gases model or the Poisson distribution function. Four cases are discussed for the space objects on elliptical orbits passing through a thin spherical shell surrounding the spacecraft. The paper also compares the circular orbit assumption with the elliptical assumption. The satellite Iridium 86 is used to estimate the impact fluxes under both assumptions. It shows that the ratio of the impact flux between the elliptical orbits case and the circular case decreases from about 4 times to 1. 4 times as the thickness increases. The statistical number of the objects gets a big fluctuation as the increased thickness in circular case. The elliptical case is 60 times more than the circular case when the shell' s thickness equals to 5 km. [ABSTRACT FROM AUTHOR]

In order to optimize the layout of the spacecraft thermal control fluid loop with multiple radiators, improve the heat dissipation efficiency of the fluid loop, and reduce the fluid loop temperature, based on entranspy dissipation theory, this paper analyzes the heat-dissipation process of the fluid loop layout in series and in parallel with multiple radiators. The results show that when the same amount of heat is dissipated, the uniformity of the temperature difference between the fluid and the wall of the pipeline is better, and the smaller the entranspy dissipation of the heat dissipation process of the fluid loop is, the better the cooling process of the system is. Further, for the case of two radiators, the radiators are respectively provided with different space heat fluxes, and the radiators are compared with different fluid loop layout patterns. The results show that when the radiators are connected in series with the fluid loop, the heat dissipation performance of the system is better than the parallel connection of the radiators and the fluid loop. At the same time the fluid temperature level of the system is the lowest. The result is completely consistent with the prediction of the entranspy theory. The conclusion of the study has guiding significance for the design of the spacecraft thermal control fluid loop with multiple radiators. [ABSTRACT FROM AUTHOR]

Each module of China Space Station has its own power system. Due to the sunshade effect, some modules can be in the state of power shortage. To solve this problem, the scheme of using electrically isolated high power supplement controller ( PSC) is proposed. The PSC is modularly designed with basic converter unit (CU),the output capacity of PSC can be increased by CU parallel. This paper mainly describes the power bus electrically isolated conversion topology, double-loop of constant voltage and constant current control, maximum current sharing control, output digital regulation, and the design of Fault detection, Isolation and Recovery (FDIR). On this basis, PSC realizes high reliability power supply between different modules of China Space Station with the 4kW power level, and the scheme is proved by the experimental results. [ABSTRACT FROM AUTHOR]

A method for calculating ihe translucent shadow is proposed in this paper for the needs of the design and simulation of the solar array of spacecraft with a large deployable antenna, which can cause translucent shadow. The proposed method builds 3D-model of the metal mesh with the minimum repeating unit to obtain the light transmission rate of the metal mesh under different illumination and builds up a table. When calculating the shadow caused by the metal mesh components, the position relation of the triangular face and the incident light is calculated firstly. The light transmittance of the triangular face is calculated by the table lookup and the light intensity of the projection area is reduced correspondingly. An example of the radial rib antenna shows that the method is fast and accurate. It can generate the light transmission mask pattern correctly, which lays the foundation for the simulation analysis oi the solar array. [ABSTRACT FROM AUTHOR]

The problem of the relative position and attitude coupled control for rendezvous and docking is investigated in this paper, which takes the external disturbances into consideration and assumes that the target spacecraft is freely tumbling. An adaptive 6-DOF control scheme is proposed based on the concept of the fixed-time stabilization. Besides, the singularity problem is solved through a switch function which not only makes the settling time estimable, but also the estimated value is independent of the initial values of states. Then the stability proof is accomplished by the development of a Lyapunov function. The numerical results show that this method achieves good performance and robustness. [ABSTRACT FROM AUTHOR]

In order to solve the problems of temperature prediction concerned with the spacecraft thermal balance test, a particle swarm optimization algorithm of temperature prediction is proposed in this paper. According to the thermal balance temperature model, the objective function to be optimized and the temperature calculation process of thermal balance based on particle swarm optimization is established. Based on the prophase temperature data of a spacecraft thermal balance test, the thermal balance stable temperature and tranient temperature are predicted. By comparison . the error between the predicted data and the measured data are very little and acceptable. The results show that the proposed method can be effectively applied to temperature prediction of spacecraft thermal balance test. [ABSTRACT FROM AUTHOR]

Prediction method and test validation techniques of vibro-acoustic mechanical environment of large complex spacecraft are presented in this paper. The vibro-acoustic modeling method for spacecraft is discussed based on hybrid finite element-statistical energy analysis (FE-SEA) method, then the satellite-level and systematic-level (fairing-spacecraft- instrument bay-adaptor assemblies) hybrid models are established respectively. In the end, the comparisons between prediction results and acoustic test results have demonstrated the effectiveness of the predication method and hybrid model, and the key issues related to the prediction precision are also discussed. [ABSTRACT FROM AUTHOR]

Single event protection is more and more important in the development of spacecraft. This paper firstly analyzes the characteristics of the impact of single event soft errors on the spacecraft, and then establishes a criticality model for evaluating the impact of a single event soft error on spacecraft. Finally, a weakness identification method and the steps of single event protection are presented, which results provide an objective basis for improving the single event protection design. [ABSTRACT FROM AUTHOR]

Under the influence of the space environment, the organic pollutants applied in the spacecraft have the potential to degrade performance of the sensitive components or devices. In order to control the molecular contamination on-orbit, a method for the zoelite molecular sieve due to its adsorption of organic molecular contamination is proposed in this paper. The absorption capacity of Naβ, NaY and 13X in vacuum is studied with contaminant source from outgassing of cables. It is found that 13X is the best adsorbents compared to Naβ and NaY, and its absorption capacity is 14. 03%. Zeolite-coated cordierite molecular absorbers can be used to collect and retain outgassed molecular effluent emanating from spacecraft materials, thus effectively controlling the contamination of the critical sensitive surfaces to enhance reliability. [ABSTRACT FROM AUTHOR]

A novel nonsingular saturated terminal sliding mode (NSTSM) based control law is investigated for a rigid spacecraft, in which the actuator control input saturation and even external disturbances are explicitly considered simultaneously. Specifically, in this proposed control scheme, the fast convergence of spacecraft attitude maneuvering is achieved, and also singularity can be avoided in comparison with traditional terminal sliding mode, the spacecraft is allowed to perform the given operations within the saturation magnitude. It is important to note that the results of this paper are derived with respect to magnitude saturation and under the condition of no additional restrictions on upper bound of disturbances, and need not to make any small-angle assumption. The stability analysis further shows that the controller ensures the closed-loop system to converge to the small neighborhood of the sliding surface fast and then to the small neighborhood of the equilibrium point, and has better robustness to external disturbances. The attitude maneuvering performance of the controller is evaluated by using a numerical example. [ABSTRACT FROM AUTHOR]

As the shaded effect must be fully taken into account in the electrical and thermal design of spacecraft's solar array, a method for accurately calculating the shadow of solar array is proposed. Firstly, the triangular grid method is used to construct the 3D model of spacecraft, secondly, the relative motion among the spacecraft components is considered, then a "bounded box" is used to intercept the triangular grid points of the model, and these points are projected to solar array plane, finally point by point comparing method and minimal rectangle method are used to generate the shadow graph. The example of lunar rover's shadow calculation is given to validate the proposed algorithm. Simulation analysis shows that the minimal rectangle method costs less time in generating the shadow graph. The algorithm proposed in this paper can calculate the shadow of solar array which is shaded by complex spacecraft whose components have relative motion. And meanwhile accurate shadow graph which is be generated, thus laying foundation for the calculation of the output characteristics of the shaded solar array. [ABSTRACT FROM AUTHOR]

An in-plane maneuver detection method based on orbit perturbation is proposed in this paper to solve the maneuver detection problem of incomplete orbit information of LEO spacecraft that can't propagate directly. Semi-major axis and eccentricity are chosen as characteristic parameters in this method. The orbit parameter boundary of target spacecraft is established by analyzing the effect of atmosphere perturbation and J2 perturbation on LEO spacecraft orbit. By comparing with the actual orbit parameter., whether the data point detected is in the normal boundary can be judged. At last, the orbit parameter of X-37B is detected by this method, and 10 maneuver points exist. The detection result has demonstrated the effectiveness of the approach proposed. [ABSTRACT FROM AUTHOR]

A detection method based on prediction dispersion was presented to deal with LEO spacecraft orbit anomaly caused by maneuvers, collisions, and atmospheric environment. The semi-major axis and inclination were selected as orbit characteristic parameters. Prediction values of orbit characteristic parameters can be achieved by orbit extrapolation based on SGP4 model secular term. After data smoothing process, prediction dispersion sequence can be obtained by calculating the difference between prediction and catalog values of the characteristic parameters. The orbit anomaly was detected through the prediction dispersion data based on Mahalanobis distance. The detection results of Terra in 2010 is consistent with the maneuver history published by NASA, which indicate that the method presented in this paper can detect the times, epoch and type of orbit anomaly and can be widely applied to the space surveillance and space situational awareness. [ABSTRACT FROM AUTHOR]

The multi-layer optical windows are usually installed in spacecraft for scientific observation, in which the homogeneity of temperature distribution has effects on image quality. In this paper, considering semitransparent and specularly reflecting interfaces, based on the ray tracing-node analysis method, a multi-layer transient coupled radiative and conductive heat transfer model is used to examine the effects of thickness and the number of heat insulation glass layers on temperature distributions of the multi-layer optical windows. The changes of absorption coefficient and refractive index of the optical window changing with wave length are approximately expressed by using a set of rectangular spectral bands. The study shows that in outer space, thermal radiation plays a very important role in the cooling process of the multi-layer optical window, and in the very thin layer of glass medium very close to the surface of glass layer, the radiative heat flux and the conductive heat flux are coupled with each other intensively. The thinner the insulation glass layer is, the more homogeneous the temperature distribution therein is, thus helpfully improving the image quality. The more the number of insulation glass layers are, the more homogeneous temperature distribution of the multi-layer optical window is, thus also helpfully improving the image quality. Also determination of the optimized number of heat insulation glass layers needs to consider the other factors. [ABSTRACT FROM AUTHOR]

Specification of spacecraft mechanical environment is the essential input for design and testing of spacecraft and its payloads, which could directly affect the level of the spacecraft design. Along with the rapid development of space industry, higher payload capability is demanded for modern spacecraft due to the new missions, whereas the mechanical environment analysis and specification determination have been the bottlenecks for payload ratio increase of spacecraft in China. In this paper, a research review of the mechanical environment prediction methods, finite element modeling & model updating and specification determination methods, which are the key techniques related to the mechanical environment analysis, is presented. In the end, according to the requirement of the domestic space engineering, the main research directions in the spacecraft mechanical environment analysis and specification determination are emphasized. [ABSTRACT FROM AUTHOR]