单粒子效应对航天器的威胁及空间飞行试验评论（二）

列举了若干航天器因单粒子效应而出现的异常或故障。阐述了单粒子效应空间飞行试验方法和预估方法。总结了多颗航天器单粒子效应空间飞行试验结果。依据空间飞行试验结果，对静止卫星、低太阳同步轨道卫星和椭圆轨道卫星在太阳宁静和太阳耀斑期间单粒子效应作了比较。     

航天器柔性热控薄膜研究现状

柔性热控薄膜材料广泛应用于各种航天器平台,其性能对维持航天器正常工作环境至关重要.本文针对空间热控技术发展要求,综述了国内外柔性热控薄膜材料的技术指标以及应用现状.介绍了国内外各种航天器上普遍应用的一次表面镜、二次表面镜、腐蚀防护膜和热控带等柔性热控材料的工作原理及应用范围,并对国内外典型柔性热控产品性能进行了对比.并介绍了相变热控材料、CCAG热控薄膜等新型智能柔性热控材料的研究情况.     

An interactive computer program for elliptical beam optimization

Elliptical antenna beams are used for planning of direct broadcast satellite systems. In this paper concepts of the beam optimization process are described briefly. A method of plotting the optimized beam on a suitable map projection is discussed. An interactive computer program, which can be used for the optimization and plotting of beams on a given territory, is described with the help of examples.     

Accelerator test of an angle detecting inclined sensor (ADIS) prototype with beams of Ca and fragments

The measurement of cosmic rays and Solar energetic particles in space is basic to our understanding of the Galaxy, the Sun, phenomena in the Heliosphere and what has come to be known broadly as “space weather”. For these reasons, cosmic ray instruments are common on both scientific spacecraft and operational spacecraft such as weather satellites.

The resource constraints on spacecraft generally mean that instruments that measure cosmic rays and Solar energetic particles must have low mass (a few kg) and low power (a few W), be robust and reliable yet still highly capable. Such instruments must identify ionic species (at least by element, preferably by isotope) from protons through the iron group. The charge and mass resolution of heavy ion instruments in space depends upon determining ions’ angles of incidence. The Angle Detecting Inclined Sensor (ADIS) system is a highly innovative and uniquely simple detector configuration used to determine the angle of incidence of heavy ions in space instruments. ADIS replaces complex position sensing detectors (PSDs) with a system of simple, reliable and robust Si detectors inclined at an angle to the instrument axis.

In August 2004, we tested ADIS prototypes with a ⁴⁸Ca beam at the National Superconducting Cyclotron Laboratory's (NSCL) Coupled Cyclotron Facility (CCF). Among the analyses performed on the data taken at the NSCL, we demonstrate that our prototype design with an ADIS system has a charge resolution of less than 0.25e. We also present a more generalized analytic derivation of instrument response and report on the corresponding analysis of Monte-Carlo modeling data.     

MALEO: Modular Assembly in Low Earth Orbit: Alternate Strategy for Lunar Base Development

Modular assembly in low Earth orbit (MALEO) is a new strategy for building an initial operational‐capability lunar habitation base, the main purpose of which is to safely initiate and sustain early lunar base buildup operations. In this strategy the lunar base components are brought up to low Earth orbit (LEO) by the Space Transportation System (STS), and assembled there to form the complete lunar base. Specially designed propulsion systems are then used to transport the MALEO lunar base, complete and intact, all the way to the moon. Upon touchdown on the lunar surface, the MALEO lunar habitation base is operational. The strategy is unlike conventional concepts, which have suggested that the components of the lunar base be launched separately from the Earth and landed one at a time on the moon, where they are assembled by robots and astronauts in extravehicular activity (EVA). The architectural drivers for the MALEO concept are, first, the need to provide an assured safe haven and comfortable working environment for the astronaut crew as safely and as quickly as possible, with the minimum initially risky EVA, and secondly, the maximum exploitation of the evolutionary benefits derived from the assembly and operation of space station Freedom (SSF‐1). Commonality and inheritability from the space station assembly experience is expected to have an advantageous impact on both the space station program as well as the MALEO lunar base.     

Space solar cells—tradeoff analysis

This paper summarizes the study that had the objective to tradeoff space solar cells and solar array designs to determine the best choice of solar cell and array technology that would be more beneficial in terms of mass, area and cost for different types of space missions. Space solar cells, which are commercially now available in the market and to be available in the near future, were considered for this trade study. Four solar array designs: rigid, flexible, thin film flexible and concentrator solar arrays were considered for assessment. Performance of the solar cells along with solar array designs were studied for two types of space missions: geo synchronous orbit (GEO) and low earth orbit (LEO) spacecraft. The Solar array designs assumed were to provide 15 kW power for 15 years mission life in GEO and 5 kW power for 5 years mission life in LEO altitudes. To perform tradeoff analysis a spread sheet model was developed that calculates the size, mass and estimates the cost of solar arrays based on different solar cell and array technologies for given set of mission requirements. Comparative performance metrics (W/kg, W/m², kg/m², and $/W) were calculated for all solar arrays studied and compared, at the solar array subsystem level and also at the spacecraft system level. The trade analysis results show that high-efficiency multijunction solar cells bring lot of cost advantages for both types of missions. The trade study also show that thin film solar cells with moderate efficiency with ultra lightweight flexible array design may become competitive with well-established single crystalline solar cell technologies in the future.     

Buckling analysis and design of anisogrid composite lattice conical shells

Composite lattice anisogrid shells have now become a popular choice in many aerospace applications. Their use in various structural components, such as rocket interstages, payload adapters for spacecraft launchers, fuselage components for aerial vehicles, and parts of the deployable space antennas requires the development of more advanced finite-element models and analysis techniques capable of predicting buckling behaviour of these structures under variety of loadings. A specialised finite-element model generation procedure (design modeller) is developed and applied to the buckling analysis of the composite anisogrid conical shells treated as three-dimensional frames composed of the curvilinear ribs made of unidirectional composite material. Featuring a dedicated control procedure for positioning the beam elements, the design modeller enables a close approximation of the original twisted geometry of the curvilinear ribs. The parametric finite-element buckling analyses of the anisogrid conical shells subjected to axial compression, transverse bending, pure bending, and torsion showed the robustness and potential of the modelling approach. It was demonstrated that the buckling resistance can be significantly enhanced by either increasing the stiffness of a few hoop ribs located in the close proximity to the section with the larger diameter, or by introducing the additional hoop ribs in the same part of the conical shell. The effectiveness of the design analyses is demonstrated using particular examples. It has been shown that the resultant optimised designs can produce up to 22% mass savings in comparison with the non-optimised lattice shells.     

Preparation and Properties of Smart Thermal Control and Radiation Protection Materials for Multi-functional Structure of Small Spacecraft

Considering the unique properties of small spacecraft,such as light weight,low power-consumption and high heat flux density,a new kind of lightweight boron carbide(B 4 C) radiation-protection coating material was proposed.New techniques for preparing LSMO thermal control coating and B 4 C radiation-protection coating were developed.The sample piece of multi-functional structure was manufactured by using the proposed materials,and a series of performance tests,such as thermal control and radiation-protection behaviors were evaluated.Test results show that:the emissivity of the multi-functional structure varies from 0.42 to 0.86 at 240 K to 353 K and the phase transition temperature is about 260 K.The electron radiation-protection ability of the multi-functional structure is 3.3 times better than that of Al material.The performance index of this multi-functional structure can meet the requirements for space application in on-board electronic equipment.     

航天发射系统运行安全性评估研究进展与挑战

航天发射作为人类太空活动最为基础和最为重要的环节之一,是评判一个国家综合国力的重要指标,而航天发射系统运行安全性评估作为现代航天发射控制指挥与决策系统的核心,是保证航天发射安全运行的基础.首先,本文概述了现代航天发射系统,简要回顾了系统安全性研究发展历程,阐述了航天发射系统运行安全性评估的内涵.其次,通过综述航天发射系统运行故障检测与诊断、异常运行工况识别、运行过程安全分析与预测、安全性动态评估技术等方面的研究现状的基础上,总结出了航天发射系统运行安全性评估面临着系统极度复杂、决策风险性极大、先验信息少以及评估结果要求高准确性与实时性等方面的挑战.最后,本文对航天发射系统运行安全性评估有待研究的基础前沿问题进行了思考.     

基于质谱分析的航天器工质原位检漏技术研究

航天器推进系统、热控系统、环控系统及流体回路系统有严格的泄漏指标要求,基于质谱分析的检漏方法存在本底信号干扰及重复性较差等难点,建立了工质原位检漏方法的理论模型,分析了质谱室直接进样与分流进样的特点,确定了分流进样的技术方案;通过试验,获得了大气环境取样条件下质谱室工作压力与本底信号的关系;同时,通过氦气、氪气、氙气等标准漏孔重复性试验获得了工质气体校准系数与本底信号的关系,并验证了系统检漏灵敏度满足航天器检漏要求。