An alternative strategy process for planning government space programs

This paper presents some thoughts and a methodical approach to the strategic planning of large government projects that takes into account the dynamic development of global problems. Given that an overarching strategic intent is in place and budgetary resources are limited, the methods described herein allow its user to generate and evaluate a set of project proposals according to their individual problem solving potential. In a final step, one is able to select those proposals that are preferable for further planning. Rather than generating detailed programs that are hard to implement in a dynamic environment, the method described herein is only modeling the priorities of different project alternatives. This is less detailed as the plans that result from a classic strategic planning approach, yet is highly usable as a roadmap for implementation. The most important advantage of this approach is its suitability for a dynamic planning with inherent learning cycles that can easily be adapted to dynamic changes in the planning environment. Since change is a well-known phenomenon in space program planning, a paradigm shift towards more flexible and adaptable ways of planning seems to be required.     

启发式深空探测器任务规划方法

针对深空探测器的任务规划过程特点,考虑约束的数值特性,提出一种基于规划活动相关度的领域无关启发式规划方法。定义了活动的相关度,结合规划过程,给出自学习式的相关度动态更新过程。设计基于相关度的活动选择机制,形成启发式规划算法。数值计算结果表明,文中提出的方法有效地减少了规划过程中规划步数和回溯步数,提高了深空探测器规划的效率。     

International Academy of Astronautics 5th cosmic study--preparing for a 21st century program of integrated,Lunar and Martian exploration and development (executive summary)

This report is an initial review of plans for a extensive program to survey and develop the Moon and to explore the planet Mars during the 21st century. It presents current typical plans for separate, associated and fully integrated programs of Lunar and Martian research, exploration and development, and concludes that detailed integrated plans must be prepared and be subject to formal criticism. Before responsible politicians approve a new thrust into space they will demand attractive, defensible, and detailed proposals that explain the WHEN, HOW and WHY of each stage of an expanded program of 21st century space research, development and exploration. In particular, the claims of daring, innovative, but untried systems must be compared with the known performance of existing technologies. The time has come to supersede the present haphazard approach to strategic space studies with a formal international structure to plan for future advanced space missions under the aegis of the world's national space agencies, and supported by governments and the corporate sector.     

21世纪国外深空探测发展计划及进展

21世纪初期,国外深空探测计划层出不穷,各类深空探测器不断升空。文章主要概述新世纪各航天国家或地区的深空探测计划,并分别论述对月球、火星和其他行星以及小天体的探测计划及其进展,最后进行综合分析研究。     

Space commercialization: Lessons from history

Private enterprise seeks to undertake virtually any activity that is institutionally and technologically feasible and that promises a high return on investment. Commercial activities in space would seem to be no exception. Indeed, it is reasonable to expect that, at some future date, commercial activities in space will overshadow government-sponsored research and military activities combined. But this date remains well into the future, it is highly uncertain, and it depends on government policies. Two major factors inhibiting further space commercialization are the current lack of necessary infrastructure and the lack of viable commercial activities. The necessary infrastructure is developing with the increasing operational status of the Space Shuttle and plans for a space station. It remains, however, to place increasing emphasis on the conduct of research in space to identify valid commercial uses of space.     

基于遗传算法的空间自由漂浮机械臂系统运动规划

为了研究空间自由漂浮机械臂系统的运动规划问题,本文将其动力学模型转化为以关节角速度为控制输入变量的非线性控制系统状态方程,确定了以能耗最小为主要目标,同时满足一定约束条件的多种目标函数,提出了运用遗传算法求解最优控制变量的运动规划方法。同时,以机械臂从初始位形运动至指定终端位形的过程为仿真算例,对上述规划算法及其应用进行了分析和验证。仿真结果表明该算法有效可行,能够为机械臂系统的空间操作提供理论参考。     

A new era? Military space policy enters the mainstream

A military dimension to the use of space has existed since the earliest days of space activity. Historically, military space policy has been somewhat peripheral, but the ever increasing use of space in support of military objectives has now driven it into the mainstream of military planning. This has resulted in new consideration being given, particularly in the USA, to the organisation of space for national security and also raised the question as to whether national security interests demand space superiority and dominance.     

Damage assessment of large space structures through the variational approach

The present investigation is focused on the solution of a dynamic inverse problem which is concerned with the assessment of damage in large space structures by means of measured vibration data. This inverse problem has been presented as an optimization problem and has been solved through the use of the conjugate gradient method with the adjoint equation, also called the variational approach. When a high number of damaged elements has to be found and these elements are also severely damaged, it is shown that the use of an additional method is necessary in order to provide a better initial guess for the conjugate gradient method. A stochastic method, represented by the genetic algorithm method, has been chosen because it provides robust search in complex spaces and also reduces the chance of converging to local optima. The application of this hybrid approach showed that better results can be achieved, although the computational time for the application analyzed here could increase. The damage estimation has been evaluated using noiseless and noisy synthetic experimental data, and the reported results are concerned with a space truss structure.     

The risks and impacts of space weather: Policy recommendations and initiatives

Space weather affects global technological systems and societies. Space weather, or the dynamic conditions on the Sun and in the space environment and their impacts on technological systems, can produce coronal mass ejections, solar energetic particles, and geomagnetic disturbances. These space weather events can cause extreme currents in the electric grid, widespread blackouts, and phone and internet communication failures both in space and within the Earth's atmosphere. Severe space weather can damage satellites used for global positioning, communications, and weather forecasting. It also creates a risk of radiation exposure to astronauts and commercial airline crews and passengers. Accurate forecast knowledge of the space weather threat and timing of events is critical to planning and preparation to minimize socioeconomic impacts. This paper reviews the scope of the space weather threat on the global community today. It describes current international and US public policy initiatives to mitigate risk to infrastructure, public safety, and human life. It examines recent international reports and US federal disaster reduction plans to meet these challenges and provides recommendations to increase public awareness and implement public policies to prepare, prevent, and recover from possible catastrophic failures of commercial and government infrastructures caused by a major space weather event.     

Space station orbit design using dynamic programming

A space station orbit design mission is characterized by a long-duration and multi-step decision process. First, the long-duration design process is divided into multiple planning periods, each of which consists of five basic flight segments. Second, each planning period is modeled as a multi-step decision process, and the orbital altitude strategies of different flight segments have interaction effects on each other. Third, a dynamic programming method is used to optimize the total propellant consumption of a planning period while considering interaction effects. The step cost of each decision segment is the propellant for orbital-decay maintenance or lifting altitude, and is calculated by approximate analytical equations and combining a shooting iteration method. The proposed approach is demonstrated for a typical orbit design problem of a space station. The results show that the proposed approach can effectively optimize the design of altitude strategies, and can save considerable propellant consumption for the space station than previous public studies.     

Stepping stones toward global space exploration

Several nations are currently engaging in or planning for robotic and human space exploration programs that target the Moon, Mars and near-Earth asteroids. These ambitious plans to build new space infrastructures, transport systems and space probes will require international cooperation if they are to be sustainable and affordable. Partnerships must involve not only established space powers, but also emerging space nations and developing countries; the participation of these new space actors will provide a bottom-up support structure that will aid program continuity, generate more active members in the space community, and increase public awareness of space activities in both developed and developing countries. The integration of many stakeholders into a global space exploration program represents a crucial element securing political and programmatic stability. How can the evolving space community learn to cooperate on a truly international level while engaging emerging space nations and developing countries in a meaningful way? We propose a stepping stone approach toward a global space exploration program, featuring three major elements: (1) an international Earth-based field research program preparing for planetary exploration, (2) enhanced exploitation of the International Space Station (ISS) enabling exploration and (3) a worldwide CubeSat program supporting exploration. An international Earth-based field research program can serve as a truly global exploration testbed that allows both established and new space actors to gain valuable experience by working together to prepare for future planetary exploration missions. Securing greater exploitation of the ISS is a logical step during its prolonged lifetime; ISS experiments, partnerships and legal frameworks are valuable foundations for exploration beyond low Earth orbit. Cooperation involving small, low-cost missions could be a major stride toward exciting and meaningful participation from emerging space nations and developing countries. For each of these three proposed stepping stones, recommendations for coordination mechanisms are presented.     

美国空间监视系统最新发展及趋势分析

近几年,美军为增强空间态势感知能力,大力发展空间监视系统,发展重点包括两个方面：一是对原有空间监视网进行改进,二是研制和部署新的天基和地基空间监视系统。文章介绍了美国空间监视系统最新发展计划,总结了各计划的进展情况,研究了未来新系统的能力,并分析了美国空间监视系统总体发展趋势。     

国外空间环境试验与探测技术现状与发展趋势

文章分析了与航天器飞行有关的4类空间环境的特点;介绍了国外空间环境试验技术的现状与发展概况。文章还重点分析了未来空间环境探测的发展趋势:加强了对空间环境动态变化的探测;将星座探测摆在重要地位;以地球轨道卫星为发展的主流;利用卫星加大对空间环境探测的力度;加强国际合作。国外空间环境探测的经验表明,我国应重视发展地球轨道探测卫星,尽快提高卫星有效载荷的水平。     

空间目标轨道信息软件平台的建设

空间目标轨道信息是空间态势感知的重要要素,是空间碰撞预警、空间碎片环境模型和许多空间应用的基础。因而,空间目标轨道确定成为空间态势感知的主要任务之一。文章介绍武汉大学测绘学院正在开发建设的空间目标轨道信息服务软件平台,该平台拥有的主要功能有:利用多源数据的卫星/空间碎片轨道确定(包括初轨确定)与预报、大气质量密度模型精化、空间碰撞预警和半解析法快速精密轨道传播等。文章还针对软件平台功能的研究进展进行了综述,介绍了软件平台发展规划。     

一种改进阻尼倒数的空间机器人避奇异算法

针对自由漂浮空间机器人运动规划过程中存在的动力学奇异问题,提出一种动力学奇异转化加改进阻尼倒数的奇异回避算法。首先,通过运动学分解,间接求解机器人逆运动学方程,避免直接求解逆广义雅可比矩阵,以实现奇异参数的分离;然后,采用改进的高斯分布阻尼因子的阻尼倒数代替奇异参数的普通倒数,回避运动学奇异的影响。与现有阻尼倒数方法相比,提高了算法在奇异点附近的连续性,进一步减小了算法带来的跟踪误差。在PUMA类型空间机器人模型上进行仿真试验,校验算法的有效性。     

Modelling Dynamic Spatial Systems in the Situation Calculus

Abstract

We propose and systematically formalise a dynamical spatial systems approach for the modelling of changing spatial environments. The formalisation adheres to the semantics of the situation calculus and includes a systematic account of key aspects that are necessary to realize a domain-independent qualitative spatial theory that may be utilised across diverse application domains. The spatial theory is primarily derivable from the all-pervasive generic notion of “qualitative spatial calculi” that are representative of differing aspects of space. In addition, the theory also includes aspects, both ontological and phenomenal in nature, that are considered inherent in dynamic spatial systems. Foundational to the formalisation is a causal theory that adheres to the representational and computational semantics of the situation calculus. This foundational theory provides the necessary (general) mechanism required to represent and reason about changing spatial environments and also includes an account of the key fundamental epistemological issues concerning the frame and the ramification problems that arise whilst modelling change within such domains. The main advantage of the proposed approach is that based on the structure and semantics of the proposed framework, fundamental reasoning tasks such as projection and explanation directly follow. Within the specialised spatial reasoning domain, these translate to spatial planning/re-configuration, causal explanation and spatial simulation. Our approach is based on the hypothesis that alternate formalisations of existing qualitative spatial calculi using high-level tools such as the situation calculus are essential for their utilisation in diverse application domains such as intelligent systems, cognitive robotics and event-based GIS.     

An innovative approach for distributed and integrated resources planning for the Space Station Freedom

The widely distributed nature of the Space Station Freedom program, plus continuous multi-year operations will force program planners to develop innovative planning concepts. The traditional centralized planning operation will not be adequate. It will be replaced by multiple small planning centers working within guidelines issued by a central planning authority. Plans will not be optimized; rather, operating efficiency and user flexibility will be blended to satisfy program goals. The key to this new approach is the application of new planning methodologies and system development technologies to accommodate distributed resources that must be integrated. Resources will be distributed to the multiple planning entities in such a way that, when the several plans are built and then integrated, they will fit together with minimal modification. The plan itself will be an envelope schedule containing resource limits and constraint boundaries within which users will be free to make choices of the specific activities they will execute, up to the time of execution. Some level of margin within program guidelines will be built in to allow for variation and unforeseen change. This paper presents the authors' recommended planning approach and cites two NASA systems being developed that will utilize these resource distribution/integration planning concepts, methodologies and development technologies.     

基于角动量守恒的空间机器人动力学参数辩识

空间机器人由于加工、装配误差以及在轨燃料消耗等因素使其名义公称参数与实际 动力学参数相比存在一定的误差。空间机器人路径规划和地面机器人不同,其广义雅克比 矩阵包含动力学参数,使计算的轨迹偏离实际要求的路径,引起末端位姿误差。本文根 据自由飘浮空间机器人的角动量守恒方程式,对一种两自由度空间机器人的基座以及机械臂 的各个关节分别单独做三次多项式轨迹激励,利用基于偏差模型的最小二乘法和遗传算 法对动力学参数进行辨识。仿真结果表明,遗传算法的计算稳定性和对动力学参数辩识精 度优于最小二乘法。〖JP〗     

临近空间高超声速目标跟踪动力学模型

针对临近空间滑跃式高超声速目标(NSHV)跟踪问题,提出一种新型的动力学跟踪模型。首先从动力学方程与横纵向机动样式两个方面分析了NSHV运动特性,将其抽象为滑跃式NSHV气动加速度相关性的一般规律;在此基础上将气动加速度中的阻力与爬升加速度建模为二阶时间相关模型,使其加速度自相关函数同时具备周期性与衰减性,并据此建立了动力学跟踪模型状态方程;此外,为应对有无动力段转换的误差突变问题(有动力的情况),引入强跟踪滤波进行突变点的滤波补偿。最后通过与不同现有算法比较验证了模型的优 越性 。     

Near space as a sui generis zone: A tri-layer approach of delimitation

The lack of a legal boundary between air space and outer space has not given rise to significant difficulties in the determination of applicable law with respect to traditional flight craft – aircraft and space objects, due to their separated sphere of activities. But the advent of new flight craft that are capable of operating in the intermediate “near space”, i.e. Near Space Vehicles, would render a clarification of their applicable law and the legal status of the zone requisite. For the purpose of balancing the right of exploration and use of near space and the security interest of subjacent States, this short note proposes a tri-layer approach of delimitation by which near space is established as a sui generis zone reserved exclusively for peaceful purposes, while the space below the upper operative limit of aircraft and that above the lower operative limit of space craft are air space and outer space respectively.