Analysis of an algae-based CELSS. Part 1: model development

A steady state chemical model and computer program have been developed for a life support system and applied to trade-off studies. The model is based on human demand for food and oxygen determined from crew metabolic needs. The model includes modules for water recycle, waste treatment, CO2 removal and treatment, and food production. The computer program calculates rates of use and material balance for food. O2, the recycle of human waste and trash, H2O, N2, and food production supply. A simple non-iterative solution for the model has been developed using the steady state rate equations for the chemical reactions. The model and program have been used in system sizing and subsystem trade-off studies of a partially closed life support system.     

Effects of photoperiod on wheat growth,development and yield in CELSS

A Controlled Ecological Life Support System (CELSS) is a sealed system used in spaceflight in order to provide astronauts with food and O₂ by plants. It is of great significance to increase the energy-using efficiency because energy is extremely deficient in the space. Therefore, the objective of this research was to increase the energy-using efficiency of wheat by regulating the photoperiod. Sixteen treatments were set in total: four photoperiods before flowering (PBF) combined with four photoperiods after flowering (PAF) of 12 h, 16 h, 20 h and 24 h. The light source was red–blue LED (90% red+10% blue). As a result, the growth period of wheat was largely extended by shorter PBF, particularly the number of days from tillering to jointing and from jointing to heading. The period from flowering to maturity was extended by shorter PAF. Shorter PBF and longer PAF could increase not only the yield but also the energy-using efficiency of wheat. As for the nutritional quality, longer photoperiod (both PBF and PAF) increased starch concentration as well as decreased protein concentration of seeds. The effects of PBF and PAF were interactional. The lighting strategy with PBF of 12 h and PAF of 24 h was proved to be the optimum photoperiod for wheat cultivation in CELSS. The mechanisms of photoperiod effect contain two aspects. Firstly, photoperiod is a signal for many processes in plant growth, particularly the process of ear differentiation. Shorter PBF promoted the ear differentiation of wheat, increasing the spikelet number, floret number and seed number and thus enhancing the yield. Secondly, longer photoperiod leads to more light energy input and longer time of photosynthesis, so that longer PAF provided more photosynthate and increased seed yield.     

国外空间基础设施项目投融资方式分析(下)

三、国外空间基础设施项目投融资方式的利弊空间基础设施项目工程浩繁,耗资巨大,政府投入是空间基础设施建设的决定性力量和主要资金来源,而其他各种投资方式都是作为空间基础设施建设的有益补充。各种投资方式各有千秋,有利有弊。下面对各种投融资方式的利弊进行分析。1、纯政     

欧美通信卫星的发展简史和市场竞争现状（二）

２．洛克希德·马丁商业空间系统公司 洛克希德·马丁商业空间系统公司是洛克希德·马丁公司的子公司。从１９７５年１２月１２日发射世界上第一颗三轴稳定的通信卫星“萨特康”１至今，该公司４０多年来共制造卫星约７５０余颗，其中１５０颗为通信卫星。根据市场需求，该公司逐步推出了３０００、４０００、５０００、７０００系列以及最新的Ａ２１００系列卫星平台。 从表３可以看出，该公司在不断推出大型卫星，而且产品的更新换代周期越来越短。１９９２年，公司在原３０００、４０００、５０００和７０００系列的基础上开始研制Ａ２１…     

Brazilian-Chinese space cooperation: an analysis

This paper aims to examine some of the most important juridical issues raised during the short, but rich, history of Brazilian-Chinese space cooperation. It tries to assess the effectiveness of the agreements signed by these countries on space matters.At the same time, it seeks to present the political and legal concepts which founded the main phases of this history.     

从风云2C卫星项目看商业航天保险的发展(下)

上世纪80年代，全球卫星故障频频，主要原因是未经飞行验证的新卫星产品不断涌现。直到90年代这种情况才得到改善。从1994年至1997年，尽管仍有一些卫星产品出现故障，导致航天保险市场出现下滑，但市场承保能力不断增加和保险费率持续下降的趋势抵消了某些航天产品出现故障所造成的损失。90年代末，卫星市场不断繁荣，航天市场纷纷推出新一代运载火箭和卫星。由于某些技术没得到真正考验，又导致卫星和火箭发生了多次故障。     

全球探测战略:协调框架(二)

第二章让空间探测服务于社会全球规模的空间探测代表的是各国和国际上开展的众多项目的总和。但它也表明了寻找深奥的科学问题的答案、造就新的经济机遇和把人类的生活空间拓展到地球以外的一种集体意愿。这些让空间探测服务于社会的目标包含在反复出现的"全球探测战略"各个主题中。     

2008年国际空间站好戏连台（下）

灵活能干看巧手 3月11日与实验后勤舱一增压段一起升空的还有加拿大研发的巧手双臂机器人,是由加拿大专门为空间站制造的,耗资2.74亿美元.它臂长约3.4米,肩宽约2.4米,高约3.7米,装5台摄像机、2只抓手和全套工具,可算是太空中最复杂的机器人,需通过三次太空行走来安装.     

卫星结构件可制造性分析系统

提出了卫星结构件可制造性分析系统的系统结构,建立了卫星结构件的信息模型和特征加工的知识库,针对卫星结构件的典型特征,深入分析了可制造性分析的方法、策略和步骤,并基于Pro/Engneer2001软件,利用Pro/Toolkit二次开发工具建立了卫星结构件可制造性分析系统。     

2008～2012年及以后英国民用航天战略(二)

愿景:管理不断变化的地球 要应对全球环境挑战,实现社会效益. 经济和人口的快速增长正在日益加大对自然资源的压力,而且人类活动正在引起前所未有的环境变化.气候变化如今已有了无可辩驳的科学依据:它带来了严重的全球威胁,急需做出全球性的反应.     

论系统工程与项目管理(下)

<正>二系统工程与项目管理的现状和发展趋势1.系统工程发展启示纵观美、俄、欧洲等大国,可将各类系统工程技术的发展现状总结为以下三点:     

美俄太空行走谁执牛耳(下)--从空间站第10长期考察组首次出舱说起

美国航天飞机航天服是目前最先进的出舱活动航天服之一，由14层组成，现也用于国际空间站。     

基于熵权的灰色关联概率数据关联算法

在多目标信息融合中,通过数据关联判断来自不同传感器的数据是否代表同一个目标,传统数据关联一般采用联合概率数据关联算法,单纯依靠状态量测且计算复杂。而基于灰色关联的概率数据关联算法,能够利用目标的多个特征信息进行数据关联,且计算简单准确。特征信息一般由专家主观判断给出。提出了基于熵权的灰色关联概率数据关联算法,由量测数据自适应的给出各特征的权重系数,不依赖于专家。仿真表明,该关联算法具有很好的工程实用性。     

美国的空间对抗装备技术(下)

3.机载动能反卫星系统1976年美国空军开始发展由F-15战斗机携带的空射型直接上升式动能反卫星武器。在由F-15发射后,寻的拦截器与发动机分离,通过长波红外探测器     

Planetary Defense From Space: Part 2 (Simple) Asteroid Deflection Law

A system of two space bases housing missiles for an efficient Planetary Defense of the Earth from asteroids and comets was firstly proposed by this author in 2002. It was then shown that the five Lagrangian points of the Earth–Moon system lead naturally to only two unmistakable locations of these two space bases within the sphere of influence of the Earth. These locations are the two Lagrangian points L1 (in between the Earth and the Moon) and L3 (in the direction opposite to the Moon from the Earth). In fact, placing missiles based at L1 and L3 would enable the missiles to deflect the trajectory of incoming asteroids by hitting them orthogonally to their impact trajectory toward the Earth, thus maximizing the deflection at best. It was also shown that confocal conics are the only class of missile trajectories fulfilling this “best orthogonal deflection” requirement.The mathematical theory developed by the author in the years 2002–2004 was just the beginning of a more expanded research program about the Planetary Defense. In fact, while those papers developed the formal Keplerian theory of the Optimal Planetary Defense achievable from the Earth–Moon Lagrangian points L1 and L3, this paper is devoted to the proof of a simple “(small) asteroid deflection law” relating directly the following variables to each other:

(1) the speed of the arriving asteroid with respect to the Earth (known from the astrometric observations);

(2) the asteroid's size and density (also supposed to be known from astronomical observations of various types);

(3) the “security radius” of the Earth, that is, the minimal sphere around the Earth outside which we must force the asteroid to fly if we want to be safe on Earth. Typically, we assume the security radius to equal about 10,000 km from the Earth center, but this number might be changed by more refined analyses, especially in the case of “rubble pile” asteroids;

(4) the distance from the Earth of the two Lagrangian points L1 and L3 where the defense missiles are to be housed;

(5) the deflecting missile's data, namely its mass and especially its “extra-boost”, that is, the extra-energy by which the missile must hit the asteroid to achieve the requested minimal deflection outside the security radius around the Earth.

This discovery of the simple “asteroid deflection law” presented in this paper was possible because:

(1) In the vicinity of the Earth, the hyperbola of the arriving asteroid is nearly the same as its own asymptote, namely, the asteroid's hyperbola is very much like a straight line. We call this approximation the line/circle approximation. Although “rough” compared to the ordinary Keplerian theory, this approximation simplifies the mathematical problem to such an extent that two simple, final equations can be derived.

(2) The confocal missile trajectory, orthogonal to this straight line, ceases then to be an ellipse to become just a circle centered at the Earth. This fact also simplifies things greatly. Our results are thus to be regarded as a good engineering approximation, valid for a preliminary astronautical design of the missiles and bases at L1 and L3.

Still, many more sophisticated refinements would be needed for a complete Planetary Defense System:

(1) taking into account many perturbation forces of all kinds acting on both the asteroids and missiles shot from L1 and L3;

(2) adding more (non-optimal) trajectories of missiles shot from either the Lagrangian points L4 and L5 of the Earth–Moon system or from the surface of the Moon itself;

(3) encompassing the full range of missiles currently available to the USA (and possibly other countries) so as to really see “which missiles could divert which asteroids”, even just within the very simplified scheme proposed in this paper.

In summary: outlined for the first time in February 2002, our Confocal Planetary Defense concept is a simplified Keplerian Theory that already proved simple enough to catch the attention of scholars, popular writers, and representatives of the US Military. These developments would hopefully mark the beginning of a general mathematical vision for building an efficient Planetary Defense System in space and in the vicinity of the Earth, although not on the surface of the Earth itself!We must make a real progress beyond academic papers, Hollywood movies and secret military plans, before asteroids like 99942 Apophis get close enough to destroy us in 2029 or a little later.     

深空探测活动年表(二)

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国外航天企业并购重组及其启示(下)

四、航天企业并购重组的影响分析 (1)形成了少数更具有垄断性的“巨人”公司,使世界航天市场的竞争主要集中在几大“巨人”公司之间。 合并后的新公司年销售额大多可达到200亿美元以上,最多的将直逼600亿美     

中国返回式卫星的发展历程（下）

三、取得众多成果 中国返回式卫星带回了大量遥感数据和照片,广泛应用于国土普查、地质调查、水利建设、石油勘探、地图测绘、环境监测、地震预报、铁路选线、考古研究等领域,产生了很好的社会和经济效益.在完成空间遥感这一主要任务的同时,利用其剩余的空间和载荷能力,多次以搭载的形式进行了一系列空间技术试验和微重力实验,在材料加工和太空育种等方面也取得了可喜成果.