Mars Observer (MO) was envisioned to be the first of a series of spacecraft, known as the observer series, which were the early 1980’s version of the “faster, better, cheaper” mantra that was to be adopted by NASA during the following decade. Contact with the MO spacecraft was lost in August 1993, three days before it was to have entered orbit around the planet Mars. Due to the lack of telemetry, it was never possible to determine with certainty what caused the loss of the spacecraft, and review boards were only able to narrow the probable cause of the failure to a handful of credible failure modes. The Mars Global Surveyor (MGS) spacecraft was designed as a replacement for the failed Mars Observer (MO) mission. The propulsion system was designed and developed in 16 months to meet the aggressive schedule and cost targets. The MGS spacecraft was launched on November 6, 1996. Major propulsion system events were all performed as expected. China will initiate a series of deep space exploration, the reliability and safety of propulsion system is extreme important to the spacecraft. This paper presents an overview of the potential failure modes identified by the JPL review board. The design and flight performance along with some enlightenments is presented herein.

Abstract：The fault diagnosability analysis method of the liquidfloated gyro based on the dependency model is proposed to enhance its fault diagnosis performance. Considering the relationship of the functional modules in the liquidfloated gyro, we obtain the information flow model firstly. And then the relative matrix between the faults and sensors is given according to the FMEA results. Based on the relative matrix, the fault detectability and isolability analysis process and sensor selection and optimization are addressed. Because the relative model belongs to the qualitative model, the presented fault diagnosability analysis method is easy to establish and compute. Our method not only evaluates the diagnosability design of the liquidfloated gyro but also offers some important information for optimization of sensor allocation. Keywords：dependency model; fault diagnosability design; sensor placement optimization; liquidfloated gyro

Abstract：According to the strong coupling and nonlinear characteristics of the hypersonic vehicle model, we propose a gainscheduled statefeedbackbased robust control design method, which is based on polytopic LPV systems. Firstly, Jacobian linearization is used on several selected equilibrium points in the trajectory of the scheduling parameters to get the LPV models. Then the system matrix is discretized and stored into a tensor, and the reducedrank tensor is reconstructed to obtain a finite number of LTI polytopic vertex systems by HOSVD approach. To reduce the conversation of controller design, slack variable matrix is introduced and different Lyapunov function matrix is used on each vertex. The designed polytopicLPVsystembased control in the form of LMI can place all the system closedloop poles in the required region and satisfy the H∞ performance. The numerical simulation results illustrate the validity of the proposed method.

Abstract：The state of the boundary lubrication and the fatigue life of the bearing assembly of reaction wheels are analyzed in this paper. And the friction models with the condition of boundary lubrication are partially simplified. The relation between the wear rate and the fatigue life is established by Archard theory of wear. According to the comparison between the states of the boundary lubrication and the elastohydrodynamic lubrication, the calculation equations of the reaction wheels life with zerocrossing conditions are developed, which can be used to quantitatively estimate the corresponding life.

Abstract：This paper is mainly concerned with the closedloop drive control of flexible solar arrays. Based on a modal identity of the flexible structure, the generalized statespace formalism of the flexible solar array drive system is derived. By the Lyapunov’s method, an outputfeedbackbased PD control is developed, and the regularity and impulsefreeness of the closedloop system are investigated in the framework of generalized system theory, followed which the admissibility of the control system is guaranteed. The effectiveness of the closedloop control algorithm is verified by the numerical simulations and comparison with the openloop algorithm. Finally, conclusions are drawn and a possible research topic is proposed.

Abstract：With the sudden temperature change of the solar panels considered, Lagrange’s energy equation of the system is established. The quasistatic bending is factorized into two types of functions: one is the shape function and the other is time function. Using the extended assumed modal method, the system dynamics model is derived. Analytical results demonstrate that temperature difference results in the attitude error.  And the effects of thermal time constant and temperature difference on the attitude dynamics of the vehicle are studied. In the frequency domain, the effect of thermally induced disturbance torque on the spacecraft attitude control system is analyzed. Finally numerical simulations are provided to verify the correctness of the analysis.

Abstract：Focused on the ambiguity of the statistical information about GIS measurement error and the random, timedelay characteristics of the measurement output, this paper gives a filter algorithm for solving the problem derived from incoordinate interval and measurement delay. This paper designes the corresponding Kalman filter and the LS algorithm. Based on the INS/GIS integrated navigation mathematical model, the accuracy of the improved Kalman filter and the improved LS algorithm are analyzed. The simulation results verify the validity of the improved Kalman filter.

Abstract：The structure of the 260type evacuation tube used in some kind of flywheel is compact, but the compact structure may lead to possible vacuum leakage if the strain force on the solder is too large, when the tube is squeezed shut. This paper mainly analyzes the squeezing mechanical conditions of the existing tube and the improved tubes by finite element analysis approach. The analysis shows that the existing tube is safe. Then an optimal tube scheme is present and the optimal one provides a reference for perfecting the structure design and increasing the reliability of the flywheel sealing in the future work.

Abstract：Based on the vacuum plume effect test system of some SinoRussian cooperation project built in Beihang University, and the mission requirements of the space station plume effects experimental research, this paper successfully conducts the aerodynamic force experiments of 10N bellshaped thruster plume by impacting on the tablet. The vacuum chamber, the vacuum pumping system, working fluid supply system, data acquisition system, 10N bellshaped thrusters and aerodynamic measurement devices are introduced. To be closer to the engineering practice, the aerodynamic experiments are equipped with real bell thruster, and the associated aerodynamic experimental scheme is given. The pressure distributions of plate surface with three different flatpanel installation locations are presented. This work provides insight into the future study of the plume aerodynamic force.

Abstract：Software testing is an important means of ensuring embeddedsoftware quality, in which the completeness of test cases is a key factor. In this paper, a method of generating test cases based on the unified modal language (UML) state diagram is studied. According to the state, migration invariance principles and action mapping, the UML state diagram can be transformed to an extended finite state machine (EFSM). With breadthfirst search, the state and migration covering principles are satisfied. Then test cases are generated by test sequences and the lookup table. Finally, an example is given to demonstrate the feasibility and efficiency of the method.