RF communications subsystem for the Radiation Belt Storm Probes mission

The NASA Radiation Belt Storm Probes (RBSP) mission, currently in Phase B, is a two-spacecraft, Earth-orbiting mission, which will launch in 2012. The spacecraft's S-band radio frequency (RF) telecommunications subsystem has three primary functions: provide spacecraft command capability, provide spacecraft telemetry and science data return, and provide accurate Doppler data for navigation. The primary communications link to the ground is via the Johns Hopkins University Applied Physics Laboratory's (JHU/APL) 18 m dish, with secondary links to the NASA 13 m Ground Network and the Tracking and Data Relay Spacecraft System (TDRSS) in single-access mode. The on-board RF subsystem features the APL-built coherent transceiver and in-house builds of a solid-state power amplifier and conical bifilar helix broad-beam antennas. The coherent transceiver provides coherency digitally, and controls the downlink data rate and encoding within its field-programmable gate array (FPGA). The transceiver also provides a critical command decoder (CCD) function, which is used to protect against box-level upsets in the C&DH subsystem. Because RBSP is a spin-stabilized mission, the antennas must be symmetric about the spin axis. Two broad-beam antennas point along both ends of the spin axis, providing communication coverage from boresight to 70°. An RF splitter excites both antennas; therefore, the mission is designed such that no communications are required close to 90° from the spin axis due to the interferometer effect from the two antennas. To maximize the total downlink volume from the spacecraft, the CCSDS File Delivery Protocol (CFDP) has been baselined for the RBSP mission. During real-time ground contacts with the APL ground station, downlinked files are checked for errors. Handshaking between flight and ground CFDP software results in requests to retransmit only the file fragments lost due to dropouts. This allows minimization of RF link margins, thereby maximizing data rate and thus data volume.     

Learning ‘smaller, faster, cheaper’ from the Applied Physics laboratory

By demonstrating the ability to build ‘smaller, faster, and cheaper’ space devices, the Johns Hopkins University Applied Physics Laboratory (APL) has played a key role in influencing NASA's current Discovery program. The APL Space Department was founded by Richard B. Kershner. This article examines the key elements of Kershner's leadership and management philosophy through the Transit satellite program and the Delta series spacecraft.     

NASA'S Robotic Lunar Lander Development Project

Over the last 5 years, NASA has invested in development and risk-reduction activities for a new generation of planetary landers capable of carrying instruments and technology demonstrations to the lunar surface and other airless bodies. The Robotic Lunar Lander Development Project (RLLDP) is jointly implemented by NASA Marshall Space Flight Center (MSFC) and the Johns Hopkins University Applied Physics Laboratory (APL). The RLLDP team has produced mission architecture designs for multiple airless body missions to meet both science and human precursor mission needs. The mission architecture concept studies encompass small, medium, and large landers, with payloads from a few tens of kilograms to over 1000 kg, to the Moon and other airless bodies. To mature these concepts, the project has made significant investments in technology risk reduction in focused subsystems. In addition, many lander technologies and algorithms have been tested and demonstrated in an integrated systems environment using free-flying test articles. These design and testing investments have significantly reduced development risk for airless body landers, thereby reducing overall risk and associated costs for future missions.     

Principal investigators and project managers: Insights from Discovery

NASA’s Discovery, Explorer, and Mars Scout mission lines have demonstrated over the past 15 years that, with careful planning, flexible management techniques, and a commitment to cost control, small space science missions can be built and launched at a fraction of the price of strategic missions. Many credit management techniques such as co-location, early contracting for long-lead items, and a resistance to scope creep for this, but it is also important to examine what may be the most significant variable in small mission implementation: the roles and the relationship of the principal investigator, responsible to NASA for the success of the mission, and the project manager, responsible for delivering the mission to NASA. This paper reports on a series of 55 oral histories with principal investigators, project managers, co-investigators, system engineers, and senior management from nearly every competitively selected Discovery mission launched to date that discuss the definition and evolution of these roles and share revealing insights from the key players themselves. The paper will show that there are as many ways to define the principal investigator/project manager relationship as there are missions, and that the subtleties in the relationship often provide new management tools not practical in larger missions.     

基于FMS和J2EE的视频会议系统的研究

探讨了基于FMS（Flash Media Server）和J2EE技术的B/S结构视频会议系统的设计及实现,整体采用J2EE技术,使用FMS作为视频流媒体服务器。设计分析了系统的整体架构及各功能模块,采用Web Services技术解决了流媒体服务器的访问控制,利用远程共享对象实现视频流的切换。相比传统的C/S结构以及硬件视频会议系统,具有容易部署、成本低以及容易与现有企业应用系统、OA系统集成的优点。     

Project Catch: A space based solution to combat illegal,unreported and unregulated fishing: Part I: Vessel monitoring system

Space assets have a unique opportunity to play a more active role in global resource management. There is a clear need to develop resource management tools in a global framework. Illegal, Unregulated and Unreported (IUU) fishing is placing pressure on the health and size of fishing stocks around the world. Earth observation systems can provide fishery management organizations with cost effective monitoring of large swaths of ocean. Project Catch is a fisheries management project based upon the complimentary, but independent Catch-VMS and Catch-GIS systems. Catch-VMS is a Vessel Monitoring System with increased fidelity over existing offerings. Catch-GIS is a Geographical Information System that combines VMS information with existing Earth Observation data and other data sources to identify Illegal, Unregulated and Unreported (IUU) fishing. Project Catch was undertaken by 19 Masters students from the 2010 class of the International Space University. In this paper, the space-based system architecture of Project Catch is presented and analyzed. The rationale for the creation of the system, as well as the engineering trade-off studies in its creation, are discussed. The Catch-VMS proposal was envisaged in order to address two specific problems: (1) the expansion of illegal fishing to high-latitude regions where existing satellite systems coverage is an issue and (2) the lack of coverage in remote oceanic regions due to reliance on coastal-based monitoring. Catch-VMS utilizes ship-borne transponders and hosted-payload receivers on a Global Navigation Satellite System in order to monitor the position and activity of compliant fishing vessels. Coverage is global and continuous with multiple satellites in view providing positional verification through multilateration techniques. The second part of the paper briefly describes the Catch-GIS system and investigates its cost of implementation.     

Lunar settlements--a socio-economic outlook.

The primary ingredient in a Lunar Settlement Program is the people. At the very high cost that will be required to transport, maintain and supply the people who will staff the Lunar operation, it is important to do everything possible to ensure their continued effectiveness in such an isolated, confined, and barren environment. This paper will attempt to identify the issues involved in providing for effective human performance in Lunar Settlements. The approach to be used will be contextual, and thus will not only examine the facets of the Lunar Settlement itself, but will also look at the organizational elements and the design and development processes used in project management from the point of view of long term success and cost effectiveness. The approach will also attempt to look at the Lunar Settlement "in time" as it is connected to events and experiences as they will evolve from the Space Station to Lunar Settlements. Finally, the approach will be contextual in the range of disciplines considered and their impact on planning, evolution, and activities in the entire process of Lunar Settlement. We will hope that Lunar settlers will be able to work and live as effective team members, and to make that possible, the designers, developers, builders, and managers must also function as a coherent team working together to bring about a common goal.     

Products from NASA's in-space propulsion technology program applicable to low-cost planetary missions

Since September 2001, NASA's In-Space Propulsion Technology (ISPT) program has been developing technologies for lowering the cost of planetary science missions. Recently completed is the high-temperature Advanced Material Bipropellant Rocket (AMBR) engine providing higher performance for lower cost. Two other cost saving technologies nearing completion are the NEXT ion thruster and the Aerocapture technology project. Under development are several technologies for low-cost sample return missions. These include a low-cost Hall-effect thruster (HIVHAC) which will be completed in 2011, light-weight propellant tanks, and a Multi-Mission Earth Entry Vehicle (MMEEV). This paper will discuss the status of the technology development, the cost savings or performance benefits, and applicability of these in-space propulsion technologies to NASA's future Discovery, and New Frontiers missions, as well as their relevance for sample return missions.     

项目组织管理能力不足造成的项目成本损失分析

文章旨在描述一种对项目组织管理能力不足造成的成本损失进行分析的思路和方法。在项目管理中,通过对“项目组织管理成本损失因子”的分析和有效管理,实现对项目组织管理能力的综合量化评价提供参考依据。     

Dream project: Applications of earth observations to disaster risk management

The field of disaster risk management is relatively new and takes a structured approach to managing uncertainty related to the threat of natural and man-made disasters. Disaster risk management consists primarily of risk assessment and the development of strategies to mitigate disaster risk. This paper will discuss how increasing both Earth observation data and information technology capabilities can contribute to disaster risk management, particularly in Belize. The paper presents the results and recommendations of a project conducted by an international and interdisciplinary team of experts at the 2009 session of the International Space University in NASA Ames Research Center (California, USA). The aim is to explore the combination of current, planned and potential space-aided, airborne, and ground-based Earth observation tools, the emergence of powerful new web-based and mobile data management tools, and how this combination can support and improve the emerging field of disaster risk management. The starting point of the project was the World Bank’s Comprehensive Approach to Probabilistic Risk Assessment (CAPRA) program, focused in Central America. This program was used as a test bed to analyze current space technologies used in risk management and develop new strategies and tools to be applied in other regions around the world.     

Hyperspectral imaging—An advanced instrument concept for the EnMAP mission (Environmental Mapping and Analysis Programme)

In the upcoming generation of satellite sensors, hyperspectral instruments will play a significant role. This payload type is considered world-wide within different future planning.Our team has now successfully finalized the Phase B study for the advanced hyperspectral mission EnMAP (Environmental Mapping and Analysis Programme), Germans next optical satellite being scheduled for launch in 2012. GFZ in Potsdam has the scientific lead on EnMAP, Kayser-Threde in Munich is the industrial prime.The EnMAP instrument provides over 240 continuous spectral bands in the wavelength range between 420 and 2450 nm with a ground resolution of 30 m×30 m. Thus, the broad science and application community can draw from an extensive and highly resolved pool of information supporting the modeling and optimization process on their results. The performance of the hyperspectral instrument allows for a detailed monitoring, characterization and parameter extraction of rock/soil targets, vegetation, and inland and coastal waters on a global scale supporting a wide variety of applications in agriculture, forestry, water management and geology. The operation of an airborne system (ARES) as an element in the HGF hyperspectral network and the ongoing evolution concerning data handling and extraction procedures, will support the later inclusion process of EnMAP into the growing scientist and user communities.     

Lessons learned from the York University Rover Team (YURT) at the University Rover Challenge 2008–2009

In this paper, we explore the lessons learned from the work of the York University Rover Team (YURT), which designed, built, and operated two prototype rovers for the University Rover Challenge (URC) in 2008 and 2009, placing third in the first year, and winning first place in the second year. We outline the competition, the team, and briefly describe the York University space engineering program. Both of the rovers are described with evaluations of each major component and the resulting design changes. A general trend toward design modularity, purpose-driven customizations, and better critical thinking in the design process is evident as the team gains experience. Also, the value of this project as an educational medium is evaluated with respect to traditional classroom learning. Participating students from a wide range of disciplines gained real-world experience in both “hard” engineering skills such as mechanical and electronic design, fabrication, and testing, and “soft” skills such as project management, system-level thinking, creative problem solving, and interpersonal skills. Lessons learned from this include the necessity of good financial management, the importance of marketing and outreach, the use of short and simple development steps, and the need for comprehensive contingency planning. We conclude that the URC provided an inter-disciplinary, cooperative educational environment, and that student engineering projects such as this can provide “soft” skills through experiential education that are normally difficult to teach in the classroom.     

水电工程项目施工成本管理与控制

随着市场经济体制的逐步完善和国企改革的深入,强化企业管理,提高科学管理水平是水利水电施工企业转换经营机制、实现扭亏增盈的重要途径之一。水电工程施工项目作为水利水电施工企业经营管理的基点、效益的主体、信誉的窗口,加强项目成本管理是水利水电施工企业提高管理水平、经济效益和持续稳定发展的关键因素之一。     

一种低轨卫星高灵敏度辅助定位服务系统

本文针对全球导航卫星系统(GNSS)接收机低信噪比环境下的快速定位需求，在充分分析扩频信号相干积分关键影响要素的基础上，设计了一种低轨卫星高灵敏度辅助定位服务系统。针对空间段信号发射机低相噪信号生成技术所需的参考源、时钟树给出了详细设计及指标分析，通过发射信号误差向量幅度EVM对比测试，所设计的发射信号(EVM)指标可控制在优于1.19%。针对系统服务能力进行了星地一体化性能测试，实验结果表明，该系统可有效实现终端在灵敏度提升12 dB前提下有效定位且辅助定位时间优于3.5分钟。     

Mars Express spacecraft: design and development solutions for affordable planetary missions

The spacecraft designed to support the ESA Mars Express mission and its science payloads is customized around an existing avionics well suited to environmental and operational constraints of deep-space interplanetary missions. The reuse of the avionics initially developed for the Rosetta cometary program thanks to an adequate ESA cornerstone program budget paves the way for affordable planetary missions.The costs and schedule benefits inherited from reuse of up-to-date avionics solutions validated in the frame of other programs allows to focus design and development efforts of a new mission over the specific areas which requires customization, such as spacecraft configuration and payload resources. This design approach, combined with the implementation of innovative development and management solutions have enabled to provide the Mars Express mission with an highly capable spacecraft for a remarkably low cost. The different spacecraft subsystems are all based on adequate design solutions. The development plan ensures an exhaustive spacecraft verification in order to perform the mission at minimum risk. New management schemes contribute to maintain the mission within its limited funding.Experience and heritage gained on this program will allow industry to propose to Scientists and Agencies high performance, low-cost solutions for the ambitious Mars Exploration Program of the forthcoming decade.     

航天国际合作项目的特点和管理模式

随着经济全球化趋势的不断加强,航天方面的国际承包项目、国际合作必然会越来越多,提高我国航天国际合作项目的管理水平迫在眉睫。文章整合了国际上常见的一些工程项目管理模式,从融资和建设角度出发,对这些模式的特点、实施方式作出了详细分析,尤其对各种模式在应用中存在的优势及特点以及适用范围进行了研究,对于发展适合中国航天领域的国际合作项目管理模式提供了参考。     

Lunette: A network of lunar landers for in-situ geophysical science

Over the last 3 years, a team at JPL has worked to design a new concept for a small, low cost lander applicable to a variety of in-situ lunar exploration activities. This concept, named Lunette, originated as a design which would exploit potential excess capacity of EELV launches by being compatible with the EELV Secondary Payload Adapter (ESPA). The original Lunette mission concept would have allowed up to six low cost landers to be delivered to a targeted region of the moon, with landings separated by a few km, allowing establishment of a regional network with a single, shared launch. The original concept faced limits in the extent of regional distribution of landing sites since all six landers were dependent on a single solid rocket braking motor. In the last year the Lunette team has focused on a modification of the original ESPA-based concept to a design that would allow launch of multiple individual landers (each with its own braking stage) on a single launch vehicle, where each lander would be capable of independent targeting and landing. With such an implementation, the entire lunar surface could be accessed for establishment of network nodes that could enable high priority geophysical measurements on a scale not seen since Apollo. The present paper discusses the current state of the design of the Lunette geophysical network lander, as well as describing mission design, science operations, and an innovative design solution allowing the lander to take critical data continuously, even over the lunar night, without the need for radioisotope power systems.     

Excel2000在工程造价管理中的应用

Excel2000主要是用来管理、组织和处理各种各样的数据.本文主要介绍了Excel2000在工程造价管理方面发挥的功能,从而方便地减轻了繁杂的计算工作问题.     

航天器系统方案设计模式研究

航天器系统方案设计是航天器系统工程研制的关键阶段工作,直接决定了航天器的综合性能及研制成本。分析了当前系统方案设计模式存在的问题;根据航天器系统工程的特点及要求,提出了系统方案设计模式改进的原则与思路;重点从组建专职系统方案设计项目组、改进系统方案设计工作管理、完善系统方案设计过程方面,研究探讨了系统设计模式改进方案。