航天功能复合材料发展现状及趋势

文章综述了航天功能复合材料的发展现状及趋势,内容包括各种类型的功能复合材料及主要应用领域。对当前用于航天领域的热防护功能复合材料分别作了重点介绍,包括航天器热防护系统及材料、抗烧蚀热防护复合材料、梯度功能复合材料以及它们的组成、作用机理和主要应用。最后探讨得出功能复合材料的发展趋势是高性能化、多功能化和低成本化。     

Toward a global space exploration program: A stepping stone approach

In response to the growing importance of space exploration in future planning, the Committee on Space Research (COSPAR) Panel on Exploration (PEX) was chartered to provide independent scientific advice to support the development of exploration programs and to safeguard the potential scientific assets of solar system objects. In this report, PEX elaborates a stepwise approach to achieve a new level of space cooperation that can help develop world-wide capabilities in space science and exploration and support a transition that will lead to a global space exploration program. The proposed stepping stones are intended to transcend cross-cultural barriers, leading to the development of technical interfaces and shared legal frameworks and fostering coordination and cooperation on a broad front. Input for this report was drawn from expertise provided by COSPAR Associates within the international community and via the contacts they maintain in various scientific entities. The report provides a summary and synthesis of science roadmaps and recommendations for planetary exploration produced by many national and international working groups, aiming to encourage and exploit synergies among similar programs. While science and technology represent the core and, often, the drivers for space exploration, several other disciplines and their stakeholders (Earth science, space law, and others) should be more robustly interlinked and involved than they have been to date. The report argues that a shared vision is crucial to this linkage, and to providing a direction that enables new countries and stakeholders to join and engage in the overall space exploration effort. Building a basic space technology capacity within a wider range of countries, ensuring new actors in space act responsibly, and increasing public awareness and engagement are concrete steps that can provide a broader interest in space exploration, worldwide, and build a solid basis for program sustainability. By engaging developing countries and emerging space nations in an international space exploration program, it will be possible to create a critical bottom-up support structure to support program continuity in the development and execution of future global space exploration frameworks. With a focus on stepping stones, COSPAR can support a global space exploration program that stimulates scientists in current and emerging spacefaring nations, and that will invite those in developing countries to participate—pursuing research aimed at answering outstanding questions about the origins and evolution of our solar system and life on Earth (and possibly elsewhere). COSPAR, in cooperation with national and international science foundations and space-related organizations, will advocate this stepping stone approach to enhance future cooperative space exploration efforts.     

典型空间聚合物介质的抗内带电改性技术

消除航天器介质内带电所产生脉冲放电威胁的最佳方式,除有效屏蔽外,就是研制不会产生脉冲放电的介质材料和绝缘结构件.通过对航天器用聚酰亚胺、环氧树脂和聚四氟乙烯等几种典型聚合物的改性研究发现,采用微米级无机粉料对聚合物介质材料进行改性,只要添加剂的电导率显著低于聚合物的电导率,该复合介质材料即可产生显著的非线性电阻率特性,可以实现在介质内带电程度达到放电阈值时迅速以非脉冲电导电流方式释放掉所储存的危险电荷,有可能达到消除脉冲放电的目标;当该添加剂含有微量"施主"杂质时甚至还可以提高介质材料在正常情况下的电阻率.对复合介质非线性电阻特性的产生机理进行了分析.      

Planetary protection implementation on Mars Reconnaissance Orbiter mission

In August 2005 NASA launched a large orbiting science observatory, the Mars Reconnaissance Orbiter (MRO), for what is scheduled to be a 5.4-year mission. High resolution imaging of the surface is a principal goal of the mission. One consequence of this goal however is the need for a low science orbit. Unfortunately this orbit fails the required 20-year orbit life set in NASA Planetary Protection (PP) requirements [NASA. Planetary protection provisions for robotic extraterrestrial missions, NASA procedural requirements NPR 8020.12C, NASA HQ, Washington, DC, April 2005.]. So rather than sacrifice the science goals of the mission by raising the science orbit, the MRO Project chose to be the first orbiter to pursue the bio-burden reduction approach.     

月球粉尘的研究现状

随着我国探月工程的开展,面临着月球粉尘危害性的问题,急需开展月球粉尘的研究。文章在调研的基础上,阐述了目前国外在月球粉尘方面的研究现状,主要是美国"阿波罗"计划中对月尘的特性、危害性、探测和防护方面的研究。     

卫星总装过程静电防护研究

静电防护是卫星总装过程中质量控制和安全保障的一个重要方面.为了提高航天器总装过程的静电控制水平,文章以某型号卫星为例,针对卫星总装实施特点,对卫星的总装过程进行了静电防护的相关试验和分析研究.首先使用FMEA分析表格,提出静电防护的关键项目,再利用静电检测手段,对这些关键项目进行静电测试.根据测试结果数据分析,查找出卫星总装过程中静电防护的薄弱环节,并针对性地提出相应的静电控制措施.这些研究成果为航天器总装静电控制的具体实施提供了技术支持,是对航天器总装过程静电防护深入研究的有益探索.     

国际行星保护发展综述

首先介绍了行星保护的定义,然后回顾了国际行星保护政策的提出和演化过程,给出了当前国际行星保护政策针对不同目标和任务形式的最新要求,简要介绍了美、欧、日、俄和印度等世界各主要航天国家/机构在行星保护方面的管理制度和实施情况等发展现状,对行星保护实施过程中的主要技术途径进行了分析,最后介绍了行星保护领域的最新进展,并提出了思考和建议。     

Thermal protection system development,testing, and qualification for atmospheric probes and sample return missions: Examples for Saturn,Titan and Stardust-type sample return

The science community has continued to be interested in planetary entry probes, aerocapture, and sample return missions to improve our understanding of the Solar System. As in the case of the Galileo entry probe, such missions are critical to the understanding not only of the individual planets, but also to further knowledge regarding the formation of the Solar System. It is believed that Saturn probes to depths corresponding to 10 bars will be sufficient to provide the desired data on its atmospheric composition. An aerocapture mission would enable delivery of a satellite to provide insight into how gravitational forces cause dynamic changes in Saturn’s ring structure that are akin to the evolution of protoplanetary accretion disks. Heating rates for the “shallow” Saturn probes, Saturn aerocapture, and sample Earth return missions with higher re-entry speeds (13–15 km/s) from Mars, Venus, comets, and asteroids are in the range of 1–6 KW/cm². New, mid-density thermal protection system (TPS) materials for such probes can be mission enabling for mass efficiency and also for use on smaller vehicles enabled by advancements in scientific instrumentation. Past consideration of new Jovian multiprobe missions has been considered problematic without the Giant Planet arcjet facility that was used to qualify carbon phenolic for the Galileo probe. This paper describes emerging TPS technologies and the proposed use of an affordable, small 5 MW arcjet that can be used for TPS development, in test gases appropriate for future planetary probe and aerocapture applications. Emerging TPS technologies of interest include new versions of the Apollo Avcoat material and a densified variant of Phenolic Impregnated Carbon Ablator (PICA). Application of these and other TPS materials and the use of other facilities for development and qualification of TPS for Saturn, Titan, and Sample Return missions of the Stardust class with entry speeds from 6.0 to 28.6 km/s are discussed.     

舰船含腐蚀缺陷通海管路失效压力数值分析

为研究舰船通海管路腐蚀后失效压力预测问题,在DNV RP-F101准则的基础上设置模型系数,建立了管路预测模型,并通过数值分析修正模型系数.使用Abaqus软件分析管道爆破失效力学行为,研究缺陷形貌和腐蚀深度、腐蚀轴向长度对失效压力的影响.对比预测模型与数值分析可知,模型系数为YFEA=1.034时,预测模型可以较好地...     

氩气保护镍基复合镀层中增强相热稳定性研究

研究了Ｎｉ－Ｂ４Ｃ复合镀层中，增强相Ｂ４Ｃ颗粒的热稳定性及镀层组成和性能的相应变化。金相显微结果表明，Ｂ４Ｃ颗粒在５００℃时开始分解，至８００℃分解完毕。Ｘ－ｒａｙ衍射、ＸＰＳ试验证实Ｂ４Ｃ颗粒分解后与Ｎｉ生成新相Ｎｉ３Ｂ，而且，由于Ｂ元素有着向镀层表面聚集的趋势，导致Ｎｉ３Ｂ首先在邻近表面的镀层中出现。Ｂ４Ｃ颗粒的分解，极大地降低镀层的硬度，但能有效地提高镀层的抗氧化能力。因此，Ｎｉ－Ｂ４Ｃ若作为耐磨材料，使用温度不宜大于５００℃，倘若利用它的抗氧化能力，即使在８００℃高温下，仍能耐受相当长的时间。