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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]

In the process of space object cataloging, because the observation data of new object is sparse, the orbit determination error is large and the orbit correlation success rate of fixed threshold method is low. This paper aims at associate tracks that cannot be associated with the object database through the orbit covariance propagation and the Mahalanobis distance dynamic association method. The simulation process of UCTs correlation includes the calculation of orbital ephemeris, the simulation of observation data, orbit determination and covariance propagation, and the dynamic correlation based on Mahalanobis distance. Covariance propagation is the main process of UCTs association. In this paper, a covariance generation and propagation algorithm based on linear and unscented Kalman filter (UKF) is established. Jacobian transform and UKF method were applied to space object orbital covariance propagation. The model of covariance propagation is applied to the project of uncorrelated track dynamic association. Through the model of covariance propagation and the uncorrelated track dynamic association method, a statistical measure called k is computed to measure how closely the two state correlate. 20 of 104 satellites which launched by India are simulated as UCTs to correlate, when the threshold of k is set as 200, all of the 200 satellites can be correlated. But as the interval between two tracks increases, the value of k decrease. With the same interval,the value of k of different satellite is different. [ABSTRACT FROM AUTHOR]

To obtain the most appropriate magnetic topological structure to improve the discharge efficiency and reduce the discharge loss of the annular-engine, this paper studied the effect of different types of magnetic structure on the discharge process of the annular discharge channel. By applying the PIC/MCC method to simulate the generation and transport process of the plasma, this paper analyzed the influence of magnetic field distribution on the distribution of plasma, the loss rate and the discharge stability. According to the statistical results, the discharge performance curve of the annular-engine was obtained and validated by the experimental results. The results show that the ring-cusp magnetic refines the motion of the primary electrons better than the muli-pole field, it can reduce the loss rate significantly, increase the probability of the collision between electrons and neutral atoms, improve the discharge efficiency and decrease the discharge loss. [ABSTRACT FROM AUTHOR]

This paper provides an optimal entry trajectory of the winged Mars probe, right after it changed the orbit into the Martian atmosphere braked by reverse thrust engine. This paper establishes Martian atmosphere model and gravitational field model corresponding on the density of the Martian atmosphere and gravitational field parameters, and determined the dynamic equations of the Mars probe. Within all the constraint conditions in the entering process, this paper designs an optimal entry trajectory based on the genetic algorithm. In addition, this paper provides different thrust engine scheme through comparing them. The results show that the second scheme can achieve the optimal performance index and the landing speed is 13.6 m/s, ultimately realizing the minimum consumption of energy and aerodynamic heat emission structure quality in the process of entering and soft landing. [ABSTRACT FROM AUTHOR]

Understanding the species and characteristics of airborne moulds in spacecraft AIT center is of great importance for developing techniques to prevent mould contamination during the assembly and testing process of spacecraft. In this paper, the air samples were collected in three AIT centers located in different areas, and 53 purified strains of mould were acquired using traditional culture-based method. ITS sequencing result shows that these strains belong to eight mould genera. Then the characteristics of these mould strains were studied further. The growth rates measurement shows that different strains of Penicillium and Aspergillus differ greatly in their growth rates. In addition, it is found that the sensitivity of different mould strains to disinfectant PHMB is quite different. It implies that the diversity of both growth rate and disinfectant sensitivity will bring difficulties to the prevention and control of microbial contamination. [ABSTRACT FROM AUTHOR]

The Hall thruster plume exerts an attenuation influence on S-band electromagnetic wave and plays an important role in the layout strategy of the thruster and antenna on the satellite. In order to study the law of the signal attenuation, an algorithm of geometric light-path was established to numerically describe the transportation of electromagnetic wave in Hall plume. A rectification test of the algorithm accuracy was conducted, and the signal-noise ratios (SNR) were measured by the method of wave transmission in space. According to the test and calculation results at same operation cases, the maximum relative error was 26.1%, and the average relative error was 7.3%. The calculation results kept qualitatively consistent with the test results. Based on those, the 84 typical operation cases of the SNR attenuation of the S-band electromagnetic wave were computed. The calculation results show that the absorption by plume exerted a more remarkable effect than the reflection on signal attenuation, and that the max attenuation region covered the antenna position of 0.3 - 0.6 m, the direction angle of 15° - 30°, and the attenuation value of SNR between -7 dB and - 4dB. This paper provides a reference base for the layout strategy of the thruster and the antenna on satellites. [ABSTRACT FROM AUTHOR]

With the development of space optical technology, diffraction imaging system has become a research hotspot in the field of space optics. In this paper, a structural design scheme of an inflatable membrane diffraction imaging structures is presented. Thermodynamic coupling effects of inflatable structures under the space thermal environment were studied. A coupled thermal-structural sequence analysis framework for inflatable structures was developed. The thermal-structural coupling analysis of the inflatable structure was realized by l-DEAS and ANSYS secondary development technology. The transient heat transfer, thermal stress and thermal deformation of the structures in orbit were investigated. The results show that there is large thermal deformation in the inflatable support structures, but the maximum thermal stress is much less than the tensile strength of the polyimide membrane, and there is no large thermal deformation response at the center of the structures. The technology support for thermal protection design of inflatable membrane diffraction imaging structures is provided. [ABSTRACT FROM AUTHOR]

In order to meet the requirements of the rapid recovery of sounding rocket and reduce the development cost， a new type of sounding rocket skirt reel deceleration program was proposed. It has light weight， changeable expansion angle， expanded resistance area and some other advantages. The aerodynamic characteristics of the supersonic sounding rocket reducer were analyzed, the external flow field was simulated and analyzed. The influence of different taper angles on the aerodynamic characteristics and overload was given. The stress and strain of the external flow field, the pressure field and the gear unit were presented. The results show that the pneumatic resistance of the gear unit is obviously related to its cone angle and has the nonlinear characteristics, and the maximum stress of the reducer is less than the allowable stress. This paper can provide reference for the design of sounding rocket and new reducer. [ABSTRACT FROM AUTHOR]

Inflatable and deployable space module is the most desired for future space stations and space structures. The outer shell of such inflatable module is made up of several layers for debris protection, seal and thermal control. In order to protect the module from the debris and make it easy to be packaged and deployed, the outer protection shields of such modules were designed to be made of polyurethane foam and some kinds of fabrics. This paper proposes a design of such flexible and inflatable protection shield based on the multi-shock structure. The parameters of such shields are determined by home-made Basalt fiber and aromatic polyamide fiber. Before test verification, the design parameters of such debris shield are determined by simulation based on multi-shock structure and such ballistic limit equation. And then High Velocity Impact (HVI) test program was conducted to verify that the design parameters can meet the design requirement of the inflatable and deployable structure. [ABSTRACT FROM AUTHOR]

In order to study the cavitation of certain type of aerospace centrifugal pump, the multiphase model on the basis of Mixture was used together with cavitation model. The steady constant value of vapor-liquid phases was simulated under the condition of different negative pressures at inlet of water glycol inside the centrifugal pump with long and short composite impellers, and the cavitation test was conducted with different inlet pressures. The results indicate that the vaporization area expands along with the increase of negative pressure. In case the negative pressure at inlet is - 50kPa and the pressure difference at pump inlet and outlet is 155kPa.already approaching the 3% allowance of rated pressure difference, the pressure at outlet of centrifugal pump is 105kPa which is the critical cavitation pressure at outlet. In case the negative pressure at inlet is -60kPa, the flow rate at outlet suddenly changes to 300L/h, the critical cavitation state occurs to the pump, and the inlet pressure is less than 10kPa that is the minimum pressure required in technical specification. Therefore, cavitation will not occur when the pump operates at its working range, and reliability of the value simulation in this paper is also verified. [ABSTRACT FROM AUTHOR]

The use of Radar Cross Section (RCS) sequences for spatial target structure recognition is an important part of space situational awareness. RCS sequence is easily affected by the target physical characteristics and attitude characteristics, and the nonstationary characteristics of the sequence signal are obvious. In this paper, deep neural network (DNN) algorithm was used to solve the problem of spatial target structural feature recognition. For the problem of feature extraction without distinguishing degree, fractal features were used to extract the fractal features of RCS sequences, and the Fisher′s decision rate was used for selecting traditional features. What′s more, the DNN algorithm and data processing process were introduced. Finally, a set of simulation test data were used to verify the algorithm. The analysis results show that the DNN algorithm is robust and accurate in solving the problem of using RCS sequence to identify the target structure. [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]

Considering the application requirement of distributed satellite system, the autonomous navigation algorithm based on relative position measurements between satellites was studied. In order to solve the problem that extended Kalman filter (EKF) is sensitive to observable degree, improve precision and reduce computation load, the navigation algorithm founded on state-dependent Riccati equation filter (SDREF) was deduced. Furthermore, a new characteristic variable reflecting the system observable degree on line was defined. According to the new characteristic variable, this paper presented a modified state-dependent Riccati filter (MSDREF) which was formed with the on-line method of filtering gain matrices adjustment. Finally, numerical simulation results illustrate that the computation load of MSDREF is about 87% less than that of EKF and the steady state error is about 79% less than that of EKF. [ABSTRACT FROM AUTHOR]

Pulsed plasma thrusters ( PPTs) have been criticized for their low efficiency over long time periods. However, few studies were about the PPT energy distribution mechanism which is very important for providing references for the designs of high-performance PPTs. In this paper, a parallel-plate ablative pulsed plasma thruster was studied. The voltage, current and ablated mass of the PPT were measured under four different discharge energies. The propulsion performance of the PPT was estimated by the experimental data. In addition, a numerical model was established and used to calculate propellant utilization of a PPT. The results show that the low efficiency of PPTs comes form their low energy utilization and low propellant utilization. As the discharge energy increases, the PPT efficiency and energy utilization increase from 5.07% to 16.5% and from 2.88% to 5.23%, respectively. However, the propellant utilization decreases from 56. 8% to 31.8% as the discharge energy increases. [ABSTRACT FROM AUTHOR]

The traditional liquid-cooled copper coils which provide applied magnetic field have significant disadvantages such as large volume, big mass and high power dissipation. Therefore, high-temperature superconducting (HTS) magnets have received widespread attention in the application of applied-field magnetoplasmadynamic thruster (AF-MPDT) because of their tiny volume, low power dissipation and high current density. Due to the critical characteristics of superconductor material, HTS magnets are susceptible to quenching due to the influence of external magnetic field. In this paper, by simplifying the discharge circuit of MPDT, simulation and experimental methods were used to analyze the magnetic field of discharge simulator, and to study the influence on the HTS magnet. The simulation results show that the magnetic field inside the MPDT discharge chamber is mainly composed of the circumferential direction, and due to the shielding effect of the anode current, there is almost no magnetic field distribution outside the discharge chamber. The experimental results also achieved good agreement with the simulation. Therefore, when designing a HTS magnetic nozzle, it is not necessary to consider the influence of the magnetic field from the discharge chamber. This research provides a reference for the application of the HTS magnet on the AF-MPDT. [ABSTRACT FROM AUTHOR]

The sputtering effect of the Hall thruster plume has a large influence on operating performance and power support stability of the solar panel. In order to study the sputtering mechanism of plume bombarding on the solar panel under different installation conditions of Hall thruster. a hybrid model based on Particle in Cell/Directional Simulation of Montecarlo Collisions was employed .and the ion diffusion model was corrected to solve the plume field. Meanwhile, the Yamamura sputtering model was used to calculate the sputtering yield on the solar panel caused by the plume bombardment. A diagnose test of plume in the vacuum chamber was conducted to verify and correct the feasibility and accuracy of the calculation model, and the diffusion coefficient was corrected to make calculation agree with the test. According to the comparison between the test and calculation results, the error of the calculation model is about 8.7% with kd = 1.26 x 10-36N ⋅ m4. Based on those, the corrected model was used to calculate the sputtering yield on the solar panel with different on-orbit conditions of thruster installation angle and thruster-panel distance. The calculation results provide the changing rules of the surface sputtering mass distribution on the panel under different conditions, and the light transmittance influenced by sputtering was also predicted. This paper can provide a reference of Hall thruster installation strategy on the satellite. [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]