Exploration and protection of Europa's biosphere: implications of permeable ice

Europa has become a high-priority objective for exploration because it may harbor life. Strategic planning for its exploration has been predicated on an extreme model in which the expected oceanic biosphere lies under a thick ice crust, buried too deep to be reached in the foreseeable future, which would beg the question of whether other active satellites might be more realistic objectives. However, Europa's ice may in fact be permeable, with very different implications for the possibilities for life and for mission planning. A biosphere may extend up to near the surface, making life far more readily accessible to exploration while at the same time making it vulnerable to contamination. The chances of finding life on Europa are substantially improved while the need for planetary protection becomes essential. The new National Research Council planetary protection study will need to go beyond its current mandate if meaningful standards are to be put in place.     

Is there really any duplication in Europe''s space activities?

At a time of declining space budgets in Europe, and of a consequent need to make savings, accusations of wasteful duplication—resulting from the large number of national agencies pursuing programmes alongside ESA—are rife, as are calls for the space industry further to consolidate. This viewpoint argues that duplication is not really the issue, however, since most national agencies have become specialists in particular fields. Nor would industry restructuring be straightforward, given the fact that Europe cannot be satisfied with a single source of supply. What is needed is better coordination between space agencies upstream to avoid later duplication, as is now being pursued through ESA's ‘harmonisation process’. The move to create a Network of Centres could also promote worthwhile collective action. These initiatives are more realistic than the technocratic aim of completely restructuring European space.     

International coordination of space solar power related activities

Because the need for energy is global, and many energy networks are already interdependent, because no one country has sufficient technological capability or sufficient funds to provide a space solar powered solution on its own, and because any such solution will require international regulation, international coordination will be vital to any attempt to produce energy for Earth from space. This will be made easier by the fact that work on the subject has already been widely publicized and distributed and cooperative efforts have already been made. Various coordinating approaches are described and the need to forge partnerships between government, industry and academia — with greater involvement of all non-space groups concerned with energy — is emphasized. A “terracing approach” to the actual implementation of SPS is suggested and outlined.     

人文精神当代构建的几点思考

传统儒学的回潮是一个热点,但其能否解决当前中国的“精神危机”还存在疑问。科学的态度是我们既要重视历史遗产,也要推陈出新。人文精神的当代构建需要对于其自身的出发点、实现路径和理想实现加以批判。     

The benefits and dilemmas of an international space station

Serious recommendations have been made about the development and mutual manning of an international space station. The achievements of ESA show that such international organizations can work successfully in high technology projects, although with problems. However, other work on isolated and confined environments suggests that sustained cooperation in the unique quarters of a space station for long durations may have special inter-cultural difficulties that need to be examined before any long term commitment is made. Also, a careful look at international activities in general suggests that in spite of the fact that there are many potential benefits for cooperative activities, there are also many international obstacles. If such an effort is to be embarked upon, it is important to look candidly at the problems that can be generated from the multi-national social, economic, and cultural systems in order to do serious and direct analyses. Such a project might be strangled by unanticipated and complex problems of a socio-cultural nature.     

Editorial: Cognitive Semantics and Spatio-Temporal Ontologies

How do people describe the location of a target object to another? This task requires a reference object or frame and terms of reference. Traditional linguistic analyses have loosely organized perspectives around people, objects, or environments as reference objects, using reference terms based on a viewpoint or the intrinsic sides of an object, such as left, right, front, and back or based on the environment, such as north, south, east, and west. In actual communication, social, spatial, and cognitive factors may also affect perspective choice. We examine those factors by varying the spatial information (landmarks and cardinal directions), the communication task (relative cognitive burden to speakers and addressees), and the culture of participants (American and Japanese). Speakers used addressees' perspectives more when addressees had the greater cognitive burden. They also used landmarks and cardinal directions when they were available, especially to avoid difficult discriminations like left/right. Some cases appearing to be perspective taking can be interpreted as using a person as a landmark. Finally, terms like near indicating close proximity were preferred to far and to terms requiring projection of directions. Globally, perspective choices of American and Japanese samples were strikingly similar; that is, Japanese did not select addressees' perspectives more than Americans. The traditional linguistic analyses need to be enhanced to account for effects of cognitive, situational, and social factors.     

Astromedicine and astrolaw: Emerging issues for advanced missions beyond Earth orbit

It is generally agreed within the scientific community that provision of appropriate medical facilities and administration of quality health care to astronauts are of great importance. However, for the more complex and remote missions envisaged for the future, issues of liability, responsibility and damage relating to medical practice may take on a greater significance and will need to be addressed. The author briefly reviews potential issues which may arise in the context of medical emergencies, crew autonomy and environmentally altered physiological status which characterize some projected advanced space missions and argues that the law of outer space will need to be expanded to take account of them.     

Making space law relevant to basic space science in the commercial space age

Space science has been at the heart of humanity's activity in space, a fact reflected in the body of space law set up to regulate such activity. The increase in commercial utilisation of space may threaten the conduct of space science; reform of space law, however, could alleviate this situation. Using the examples of radio and light interference, and space debris, this articles examines ways in which the law could be reformed to improve conditions for scientists. It also discusses the need for, and equitable ways of, prioritising space activities. The forthcoming IHY 2007 should provide an opportunity for scientists to showcase their achievements.     

Summary of medical investigations in the U.S.S.R. manned space missions.

The results of biomedical investigations carried out in the U.S.S.R. manned space missions are discussed. Their basic result is well-documented evidence that man can perform space flights of long duration. The investigations have demonstrated no direct correlation between inflight or postflight physiological reactions of crewmembers and flight duration. In all likelihood, this can be attributed to the fact that special exercises done inflight efficiently prevented adverse effects of weightlessness. However, human reactions to weightlessness need further study. They include negative calcium balance and anemia as well as vestibulo-autonomic disorders shown by crewmembers at early stages of weightlessness. Attention should be given to psychological, social-psychological and ethical problems that may also limit further increase in flight duration.     

基于视觉的飞行器运动参数串行式递归估计

针对利用视觉方法进行飞行器运动参数估计中旋转与平移参数耦合及计算量大的问题 ,设计了一种适用于递归方法的串行式运动参数估计模型。证明了旋转运动参数的估计不依 赖于平移参数,据此建立了基于特征线的旋转运动参数估计模型,进而设计了串行式运动参 数估计模型。给出并证明了利用该模型进行运动参数估计时解的唯一性结论。仿真实验和实 测试验表明：相对于集中式模型,使用串行式递归模型进行飞行器运动参数估计时计算耗时 减小、姿态精度更高、鲁棒性更强。
     

A System of Stabilizing the Angular Motion of a Spacecraft Based on a Neuron-like System of Autonomous Adaptive Control

The aim of this paper is to apply the Autonomous Adaptive Control method to the problem of stabilization of a spacecraft's angular motion. The method is being developed at the Department of Simulation Systems of the Institute for System Programming, Russian Academy of Sciences. As applied to the problem under study, the main advantages of this method lie in the fact that there is no need to construct and incorporate into the control system a mathematical model of the controlled object, while it provides high-quality control, which cannot be ensured by a traditional control system. By optimizing the system with the use of genetic algorithms, one can save computational and hardware resources without losses in the quality of control and in the adaptive properties of the control system.     

A case for permanent lunar development and investment

This Viewpoint argues that the promise of the Apollo Moon landings was not fully realized and that we should now think seriously about developing a lunar base. This could be effective in a number of economic and environmental sectors and would provide a focus for conversion of the defence industry to more peaceful activities. However, the existing UN space treaties would need to be amended and a new authority created to govern activities on the Moon.     

Finding a second sample of life on earth

If life emerges readily under Earth-like conditions, the possibility arises of multiple terrestrial genesis events. We seek to quantify the probability of this scenario using estimates of the Archean bombardment rate and the fact that life established itself fairly rapidly on Earth once conditions became favorable. We find a significant likelihood that at least one more sample of life, referred to here as alien life, may have emerged on Earth, and could have coexisted with known life. Indeed, it is difficult to rule out the possibility of extant alien life. We offer some suggestions for how an alternative sample of life might be detected.     

一种基于COTS器件的SiP微系统的抗总剂量效应加固设计与试验评估

总剂量效应是制约COTS器件空间应用的主要因素之一。为满足空间应用对电子系统高性能、小型化及抗辐射的需求,对一种基于COTS器件的SiP微系统的抗总剂量效应加固方案进行设计,采用模型分析与地面试验结合的方法对微系统的抗总剂量辐射能力进行评估。该评估方法将微系统作为设备与器件的一种结合体,先按照设备进行整体模型评估,后按照器件进行试验评估,提高了评估的效率,具有较强的工程实用价值。⁶0Co γ射线辐照试验结果表明：加固后SiP微系统的抗总剂量能力不低于150 krad(Si),可以满足相关任务应用需要。该微系统的抗总剂量效应加固设计和总剂量效应评估方法可为相关微系统研制提供参考。     

空间高速总线SpaceWire节点的设计与实现

根据SpaceWire总线的组成结构以及采用的数据-滤波编解码技术,针对SpaceWire节点需要与主机设备、SpaceWire接口设备进行异步交互的特点,文章给出了一种SpaceWire节点的高效实现方案。首先,该方案在硬件设计中采用了SpaceWire节点的多时钟域设计,使得节点整体性能得以显著提升;第二,采用双倍数据速率寄存器设计来降低SpaceWire节点发送端设计难度,解决了高速数据发送问题;第三,采用手动布局接收端的底层器件来满足时序要求,解决了高速数据接收问题;第四,计算出接收端RX FIFO的理论读出时钟频率指导硬件程序设计。在此基础上,采用SpaceWire节点的点对点数据传输实验对文章设计验证,结果表明文章给出的方案可以工作在240MHz时钟频率下,满足空间高速数据传输中高可靠性、低误码率和低复杂度的要求。     

基于信源信道联合编码的遥感图像传输

针对遥感应用对图像质量日益提高的需要,提出了一种基于层次树的集合分割算法（SPIHT）和低密度校验（LDPC）码联合编码的遥感图像高质量传输方案。此方案充分利用SPIHT编码后数据流按重要性排序,以及LDPC码的误码率性能与码率和迭代次数密切相关的特性,克服了SPIHT压缩数据流对噪声敏感的缺陷。高斯信道仿真结果表明,在码元噪谱密度比（Eb/N0）较低的情况下,利用此传输方案获得的图像恢复峰值信噪比（PSNR）,比传统的分离编码高7dB以上。     

Media reaction to a SETI success

Consideration of the reaction to a SETI detection by the media, and the effect this will have on the public, is more than mere sociological speculation. An accurate forecast of the media's interest can lead to actions that will help ensure that correct and comprehensible information reaches the public. This is most critical in the first few weeks following a discovery. While a widely accepted protocol for dealing with a detection exists in the "Declaration of Principles Following the Detection of Extraterrestrial Intelligence," it gives scant consideration to the fact that the actual situation will be chaotic and not subject to easy control. The 1996 story about the possible discovery of martian microfossils has provided a useful precedent for what will happen if astronomers uncover the existence of alien intelligence.     

An inexpensive apparatus for growing photosynthetic microorganisms in exotic atmospheres

Given the need for a light source, cyanobacteria and other photosynthetic microorganisms can be difficult and expensive to grow in large quantities. Lighted growth chambers and incubators typically cost 50-100% more than standard microbiological incubators. Self-shading of cells in liquid cultures prevents the growth of dense suspensions. Growing liquid cultures on a shaker table or lighted shaker incubator achieves greater cell densities, but adds considerably to the cost. For experiments in which gases other than air are required, the cost for conventional incubators increases even more. We describe an apparatus for growing photosynthetic organisms in exotic atmospheres that can be built relatively inexpensively (approximately 100 dollars U.S.) using parts available from typical hardware or department stores (e.g., Wal-mart or K-mart). The apparatus uses microfiltered air (or other gases) to aerate, agitate, and mix liquid cultures, thus achieving very high cell densities (A750 > 3). Because gases are delivered to individual culture tubes, a variety of gas mixes can be used without the need for enclosed chambers. The apparatus works with liquid cultures of unicellular and filamentous species, and also works with agar slants.     

Taking space to the public

The UK space industry is an important part of the British economy and likely to become more so, but it needs well-educated graduates, government support and investment. Such an effort would be aided by an educated public. Education is an important part of a successful space industry policy. The Space Education Council, supported by the BNSC, is doing important work talking to the public about space. This article argues that there is a need for more space education work and reports on the Space Education Council's recent symposium.     

基于IM/DD体制的星间激光通信测距技术

随着当前低轨卫星组网星座计划的日益增加，对卫星间高精度校时、测距需求也越来越迫切。提出基于直调直检IM/DD（Intensity Modulation with Direct Detection）的测距技术的实现方法，使其能同时兼顾测距精度及系统成本。基于IM/DD的测距是利用高精度的秒脉冲到达时间来测量距离。使用IM/DD光通信的数据传输方式，在正常的数据帧传输中插入少量的测距信息，无需中断正常的通信模式，也无需网络时钟频率同步，数据帧的发送周期也无需与秒脉冲保持同步关系，即可使用双向单程测距方法进行测距。使用秒脉冲对本地时钟进行频率测量，对测距过程参数进行修正，只需要采用普通晶体振荡器作为本地时钟源，不需要使用高精度测距通常所需的全网络同步时钟信号或者高稳定度时钟源，便可以达到IM/DD通信码元时间量级的测距准确度和精确度，同时降低了时频同步系统的复杂度、对元器件的要求以及整个通信测距系统的成本，解决了现有技术中测距精度及系统成本不易同时兼顾的问题。