Erdbeobachtende missionen—Anforderungen und konzepte

(Earth Observation Missions—Requirements and Concepts)—Ten years ago, on 23 July 1972. NASA launched the first satellite specifically designed for Earth observation. With Landsat 1 the importance and attractiveness of remote sensing from space increased worldwide.The paper presents in an overview former remote sensing missions with their applications and the system elements required for gathering Earth observation information. Main elements are the sensors (optical, microwave, and other instruments), the platforms (satellites, space stations, aircraft and Earth based stations) and their orbits.It is shown how these elements are interrelated and which constraints must be considered for planning an Earth observation mission. The feasibility, the amount of hard- and software, the costs, and the performance of a system are decisive for the realization of a satellite concept.Examples for different concepts investigated to date at Dornier System are given; included is the first ESA Remote Sensing Satellite ERS-1, which is now under definition at Dornier System, the main contractor of ESA.     

European R&D in the satellite communication user Earth segment

This paper refers to a study (specificaly to its chapter 7)¹ carried out by Euroconsult for ESA on the key characteristics of European R&D in the satellite communications user Earth segment. The study was initiated by the Working Group on Satellite Communications Policy² of the Joint Board on Communications Satellite Programmes (JCB), which was established by the Director General of ESA in July 1990 to contribute to the European agency's response to the EC Green Paper. The working group specifically expresses the European space communications industry's point of view.     

Norway's future in space

Norway has recently published its national long-term plan for space activities (1993–1996) and the main points of this are reproduced here. While telecommunications, positioning and navigation and Earth observation are understandably given a high priority, there is also an emphasis on space transportation and space science, and a belief that Norwegian industry and research institutes are capable of gaining contracts beyond the agreed scope of the country's participation in ESA.     

Remote sensing in the information age

A large percentage of the public today perceives the majority of applications of Earth observation data from satellite and aircraft altitudes to be focused on the understanding and management of the renewable and non-renewable resources of the Earth and its environment. Originally conceived as a tool for gathering intelligence information, remote sensing has just fully emerged from its military womb to the public domain. Advances in the technology, a variety of indirect benefits that could be derived from space exploration, commercialization of remote sensing and the drive of the value-added companies - all of these hold promise for new opportunities for many other novel applications of Earth observation data and related information. In the advent of the more advanced, user-friendly, cost effective, and problem solving operations being championed by the private sector, particularly in the industrialized countries, it appears that the commercial future for remote sensing programmes and related information generated in the process is promising. This paper examines how the information age is influencing the metamorphosis of remote sensing technology particularly through international legal instruments and converging technologies. In spite of the progress attained to-date, of international concern is possible radio frequency interference between remote sensing satellite and communication satellite services. There is also a major knowledge gap between the providers of raw remote sensing data and the user community, particularly those interested in the new high-level information. A resolution of these issues will enhance the contributions of remote sensing to the information economy.     

The work of the US National Satellite Land Remote Sensing Data Archive Advisory Committee: 1998–2000

Earth observation data have been acquired and stored since the early 1970 s. One of the world's largest, and most important, repositories for land satellite data is the Earth Resources Observation Systems (EROS) Data Center (EDC). It is a data management, systems development and research field center for the US Geological Survey's (USGS) National Mapping Division in Sioux Falls, SD, USA. It was established in the early 1970 s and, in 1992, the US Congress established the National Satellite Land Remote Sensing Data Archive at EDC. Although data have been acquired and stored for decades, the world's remote sensing community has only recently begun to address long-term data preservation and access. One such effort was made recently by remote sensing leaders from academia, industry and government as members of a federal advisory committee from 1998 to 2000.² This paper provides a brief account of the Committee's work product.     

The enigma of small satellites for earth observation

Small satellites have captured a continuously increasing share of the market in the fields of science, technology and recently also in the telecommunications and Earth observation areas. User requirements and market opportunities for space based satellite systems for Earth observation products have grown substantially in the past decade. Criteria for the utilization of different classes of satellite systems (small and large) and analogies to developments in other areas, e.g. the telecommunications field are discussed. The end to end character of service and product oriented systems as key criteria for market success in the scientific, applications and commercial areas is underlined. Recent developments in the global change, the Earth observation applications and commercial sectors are reviewed and compared. Opportunities for small satellites in the field are related to technology advancements, cost reduction options, and progress in the state of the art in system design.     

Progress in multilateral Earth observation cooperation: CEOS, IGOS and the ad hoc Group on Earth Observations

The Committee on Earth Observation Satellites (CEOS) coordinates international civil space-borne missions designed to observe and study planet Earth. With over 100 Earth observation satellites expected to be launched during the next 10 years, it is clear that collaborative opportunities have not been fully maximized. In 2003 CEOS has been focusing on articulating a more comprehensive satellite data utilization approach and in following up on its significant involvement in the World Summit on Sustainable Development. The CEOS Chair also serves as Co-Chair of the Integrated Global Observing Strategy (IGOS) Partnership, which seeks to reduce observation gaps and unnecessary overlaps and to harmonize and integrate common interests of space-based and in situ systems. IGOS focused in 2003 on development of a number of themes, including Carbon Cycle, Water Cycle and GeoHazards. The IGOS Ocean Theme is now in its implementation phase. NOAA, while chairing CEOS and co-chairing IGOS, has also been actively involved in organizing and hosting a ministerial-level Earth Observation Summit with a follow-on Group on Earth Observations (GEO) charged with developing the framework for a comprehensive global Earth observation system(s). All these activities demonstrate the commitment to developing more coherent and sustained Earth observation strategies for the good of the planet.     

A failure of international space cooperation: the International Earth Observing System

This paper examines the failure of the Earth Observation International Coordination Working Group to implement an International Earth Observation System. Tracing the history of both the Group and the mission concept, it explains the political and organizational failures that took place. It shows that these failures were linked to different approaches to international cooperation in Earth observation data policy. The main points of contention existed between Working Group members, NASA and ESA. NASA favored formal and binding legal arrangements, while ESA preferred to avoid institutionalized legal commitments. Success in coordinating and harmonizing data policy on a multilateral basis for Earth observation missions is more likely to be achieved by pursuing agreement on general principles and terms of reference than by seeking specific legal agreements.     

基于三轴磁强计与雷达高度计的融合导航算法

为了减小近地轨道(小于1000km)地磁导航的估计误差协方差，提高导航的可靠性和准确性，在地磁导航系统中引入雷达高度计作为一个新的测量设备，提出了一种基于三轴磁强计与雷达高度计的融合导航算法。该算法取卫星的位置和速度向量作为状态向量，建立状态方程；取卫星周围的磁场强度和卫星到星下点实际海平面距离求出的地心距，作为观测量建立观测方程；利用扩展卡尔曼滤波构成一种融合导航算法。仿真结果表明，提出的融合导航算法对轨道位置的估计误差小于20米，速度的估计误差小于1米／秒，导航算法的精度和收敛性都优于使用单一地磁导航的系统。     

导航卫星有效载荷新型扩频码研究及实现*

针对导航卫星中Gold扩频码存在的不足,卫星导航系统的多个频点在下一代系统建设中选用Weil码作为扩频码。首先对Gold码和Weil码的特性进行仿真分析,仿真结果表明,Weil码的自相关特性和互相关特性有明显的优势。针对导航卫星有效载荷需要提供长期稳定可靠的导航服务且资源有限,对Weil码的实现方式也有很高的要求,设计一种基于FPGA平台的Weil码实现方案,解决了导航卫星有效载荷中Weil扩频码生成的资源和可靠性问题,已实际在轨连续运行超过一年没有出现故障。     

基于地月信息的奔月探测器自主光学导航

基于地月信息提出了一种奔月转移轨道的自主光学导航算法。该算法首先利用导航相机得到的地球和月球边缘图像与地、月几何形状模型，运用扩展源的空间获取算法导出地心和月心对应的像素，然后利用地心和月心像素、探测器的惯性姿态和该观测历元的地、月星历信息，通过基于UD分解的递推加权最小二乘算法确定了探测器轨道。还引入导航系统的可观度定义来分析了导航系统的可观性，数学仿真结果表明导航的位置误差小于30km，速度误差小于0．3m／s，证明该自主光学导航算法是有效的。     

The use of remote sensing to support the application of multilateral environmental agreements

There is a growing realisation of the increasingly varied and interesting possibilities for the use of Earth observation data to ensure compliance with international obligations generally, and treaty obligations in particular. Most examinations of the application of Earth observation data to monitoring states’ compliance with international obligations focus on the environmental sector. This paper proposes the use of remote sensing satellites for the support of multilateral environmental agreements (MEAs), especially land monitoring MEAs such as the Convention on Biological Diversity (1992) and the Kyoto Protocol (1997). It discusses the uses of remote sensing for treaty implementation or enforcement in general, and the admissability of satellite imagery as legal proof, before examining how Earth observation-derived data could be of benefit to specific MEAs. As sensors become increasingly sophisticated the use of remote sensing in this area should grow but it needs to be supported by its more widespread legal recognition as proof.     

第二类无奇点根数的北斗历书参数设计

为统一北斗三类卫星的历书拟合算法,提出基于第二类无奇点根数进行历书参数设计的方法,设计了以倾角向量变率作为摄动参数的历书参数模型,并给出新的历书模型的用户使用算法。利用覆盖2013年全年的实际在轨卫星的数值轨道进行了历书拟合试验。结果表明,地球静止轨道（GEO）和倾斜地球同步轨道（IGSO)卫星的拟合位置误差为2~4km,拟合用户距离误差（URE）约为1km,中圆地球轨道（MEO）卫星的拟合位置误差为1~2km,拟合URE约为500m。通过分析6个轨道根数和2个摄动参数全年的变化范围,对新历书模型进行量化单位和占用比特位的通信接口设计,定量分析量化单位对历书表达精度的影响。结果表明,参数截断后对位置误差的影响小于50m,对URE误差的影响小于5m。因此,历书量化误差对信号捕获以及首次定位时间带来的影响可以忽略不计。     

Satellite services for disaster management and security applications

Advantages of communications satellites are the inherent broadcast capability, high bandwidth, reliability and flexibility in network expansion. Small transportable terminals can be made operational very quickly. Recent developments in communications and computer technology allow to provide low-cost equipment, which is affordable even in developing countries. Communications satellites can also play an important role in case of emergencies or natural disasters. The combination of satellite communications and navigation can support new services for emergency teams.

At the Institute of Applied Systems Technology and the Institute of Communication Networks and Satellite Communications highly transportable terminals have been developed, both for star and mesh network topologies. A fully meshed VSAT system is used for symmetrical links. For other applications, which do not require high return link capacity an asymmetrical system is an efficient solution. It uses low-cost DVB technology for the forward link and satellite phones with data capability on the return link. Novel multicast protocols allow to use these asymmetrical links in an efficient way. The paper describes the different systems and their applications in disaster management and security applications. Emphasis is put on transfer of remote sensing images and voice over IP (VoIP) as well as videoconference services.     

From initial ideas to a European plan: GMES as an exemplar of European space strategy

Global Monitoring for Environment and Security (GMES) is an idea which originated during a meeting in Baveno, Italy, in May 1998, which generated a call for Europe to get its act together in the field of environmental monitoring from space, to define a well articulated strategy in this area and to build upon its excellent scientific research community, its proven technical prowess in Earth observation from space and its nascent political will to express its objectives in international fora related to climate change and other global environment topics. While Europe was already active in the most advanced areas of global monitoring, its rather uncoordinated efforts (even within the European Commission) lacked visibility and did not appear to fit into a clearly established strategy. The ‘Baveno initiative’ was an attempt to remedy this situation and find a place within a developing ‘European Strategy for Space’, which requires ESA and the European Union to work more closely together. GMES was extended to include the ‘security’ (in its wider sense) aspects of global monitoring, a move that produced a number of questions and misunderstandings, but which allowed many in Europe to realize that monitoring the activities of the Earth’ land masses, oceans and atmosphere do include a security dimension. GMES will eventually incorporate an implementation plan which will call upon various monitoring techniques, ambitious modelling projects and connections with society's more urgent requirements with respect to environmental protection and prevention or reduction of risks related to natural hazards. This will entail significant efforts to inform the user communities and to convince them of the relevance and usefulness of this initiative. It will also provide a sound basis for the European contribution to the new initiative for improved coordination of strategies and systems for Earth observations called for by the July 2003 Earth Observation Summit.     

Measuring performance: Moving NASA Earth science products into the mainstream user community

Demonstrating performance of the applications of Earth observation satellite-based science data products and services is increasingly a requirement of government research agencies. We present efforts from the NASA-funded Earth Observing System Data and Information System's Synergy Project to measure performance in the development of applications from NASA research and development projects. We summarize challenges in monitoring performance and share our experience in evolving metrics over a 5-year project life. We demonstrate how to adapt project management processes and metrics from the information technology (IT) industry to Earth observation applications research and development. A roadmap for adapting IT processes and developing metrics and examples of quantitative and qualitative metrics are provided. Our findings suggest that designing and implementing these IT metrics will enhance project success, as defined by the degree of penetration of NASA products into the user community and level of non-NASA funding secured.     

Rosetta: The ESA comet rendezvous mission

Rosetta was selected in November 1993 for the ESA Cornerstone 3 mission, to be launched in 2003, dedicated to the exploration of the small bodies of the solar system (asteroids and comets). Following this selection, the Rosetta mission and its spacecraft have been completely reviewed: this paper presents the studies performed the proposed mission and the resulting spacecraft design.

Three mission opportunities have been identified in 2003–2004, allowing rendezvous with a comet. From a single Ariane 5 launch, the transfer to the comet orbit will be supported by planetary gravity assists (two from Earth, one from Venus or Mars); during the transfer sequence, two asteroid fly-bys will occur, allowing first mission science phases. The comet rendezvous will occur 8–9 years after launch; Rosetta will orbit around the comet and the main science mission phase will take place up to the comet perihelion (1–2 years duration).

The spacecraft design is driven (i) by the communication scenario with the Earth and its equipment, (ii) by the autonomy requirements for the long cruise phases which are not supported by the ground stations, (iii) by the solar cells solar array for the electrical power supply and (iv) by the navigation scenario and sensors for cruise, target approach and rendezvous phases. These requirements will be developed and the satellite design will be presented.     

海洋资料浮标观测系统通讯和导航的一种新方法

提出了利用中国区域定位系统(Chinese Area Positioning System,
CAPS)和CAPS终端开展海洋资料浮标通讯和导航的一种新方法。根据海洋资料浮标发送数据 量大而接收数据量小的特点,创新性地提出利用复合导航电文的方法,将通信地面站出站发 送给通信卫星转发改为导航系统下行转发,将CAPS终端通信部分接收改为导航定位部分接收 ,成功地把CAPS终端发展到CAPS\|OC(Chinese Area Positioning System\|Ocean Communi cation, CAPS\|OC)终端。海上实验表明CAPS\|OC终端及CAPS系统可以满足各种海洋资料浮 标的通讯和导航定位的功能要求,目前有两台CAPS\|OC终端已经成功地应用在浅海大型锚 系浮标观测系统的数据传输中。
     

一种航天器星光折射连续导航方法

针对星光折射航天器自主导航应用中观测缺失导航折射星造成误差上升甚至导航发散的情况，提出一种适用于航天器星光折射导航空白段的新方法。阐述了星光折射导航机理，给出了导航星观测窗口，进而设计基于神经网络的导航算法，该方法充分利用已有信息，有效预测并修正航天器状态信息，使星光空白段前后导航误差变化平稳，发挥星光折射间接敏感地平精度高的特点，保证了航天器高精度定位，且不需要添加硬件设备，算法简洁、实用。最后，通过计算机仿真校验了该导航方法的有效性。     

一种基于磁强计的卫星自主导航方法研究

以地磁场强度矢量的模为观测量,将Unscented卡尔曼滤波(UKF)用于近地卫星的磁测自主导航。给出了包括采样点生成、时间更新和量测更新的滤波模型,以及卫星瞬时轨道根数的计算公式。仿真结果表明,UKF滤波方法优于扩展卡尔曼滤波(EKF),精度更高。