基于地面任务-空间姿态映射的敏捷卫星任务规划

面向观测时间窗口相互重叠的多点目标观测任务需求,对敏捷卫星单星单轨任务规划问题进行研究。针对传统方法在卫星机动能力受限和成像任务冗余两种情况下求解效率低的缺陷,引入任务-姿态协同规划思想。首先,建立地面任务和空间姿态映射关系,并考虑相邻任务间姿态机动时间的最优性使得卫星在观测相邻任务时无多余等待时间,以此来设计任务-姿态协同规划数学模型。其次,根据任务-姿态协同规划数学模型,设计自适应伪谱遗传算法（APGA）,用以求解满足调整时间最优性的敏捷卫星任务规划问题。最后,通过仿真实验,验证了模型和算法能够有效地解决传统算法求解敏捷卫星任务规划问题时存在的求解效率低的缺陷。     

基于Transformer层次预测的多星应急观测任务规划方法

应急观测任务规划是一个强时效性的复杂组合优化问题,必须在规定的时限内完成相应的计算。采用机器学习的方法对规划问题进行初始规划方案预测,可以有效地简化计算复杂度。为此,提出一种基于Transformer层次预测的多星应急观测任务规划方法,将多星任务规划的求解过程分解为3个步骤：首先,利用基于Transformer的任务可调度性预测模型预测待规划任务是否执行,得到预执行任务集合;然后,基于Transformer的任务分配模型对预执行任务集合分配卫星,得到初始规划方案;最后,利用基于随机爬山的约束修正算法对初始规划方案进行优化调整,得到可行规划方案。为验证所提方法的有效性,通过大量仿真实验与CPLEX优化器、标准遗传算法、长短期记忆网络等方法模型进行比较,实验结果表明所提方法计算耗时短,规划收益高,适用于多星观测任务快速规划。     

The Swedish Small Satellite Program for Space Plasma Investigations

The success of the Swedish small satellite program, in combination with an active participation by Swedish research groups in major international missions, has placed Sweden in the frontline of experimental space research. The program started with the development of the research satellite Viking which was launched in 1986, for detailed investigations of the aurora. To date, Sweden has developed and launched a total of six research satellites; five for space plasma investigations; and the most recent satellite Odin, for research in astronomy and aeronomy. These fall into three main categories according to their physical dimension, financial cost and level of ambition: nano-satellites, micro-satellites, and mid-size satellites with ambitious scientific goals. In this brief review we focus on five space plasma missions, for which operations have ended and a comprehensive scientific data analysis has been conducted, which allows for a judgement of their role and impact on the progress in auroral research. Viking and Freja, the two most well-known missions of this program, were pioneers in the exploration of the aurora. The more recent satellites, Munin, Astrid, and Astrid-2 (category 1 and 2), proved to be powerful tools, both for testing new technologies and for carrying out advanced science missions. The Swedish small satellite program has been internationally recognized as cost efficient and scientifically very successful.     

Low cost satellite ground control facility design

A design approach common to the areas of satellite operations command and control, tracking, subsystem analysis, system planning and scheduling, orbit determination and maintenance, and data routing and control is discussed. Specific satellite mission applications and operations are isolated from the remainder of the design to allow application to a broad variety of satellite systems. Discussions of specific satellite missions are limited to the context of understanding the general magnitude and scope of what a ground control facility is required to support. By isolating the common satellite operational functions, a low cost generic approach that allows for phased implementation of system changes with minimal impact to on-orbit assets and mission performance is developed. The goals of this approach are to provide the capability for growth, maintainability, and operability of the satellite system. A brief discussion of satellite systems followed by the introduction of the general function of any satellite control facility sets the stage for the overall design approach. The factors that define the design along with the key design features are presented, with a discussion of each product available in each functional area     

人工智能在卫星任务规划中的应用

智能规划与调度是实现卫星自主规划其飞行任务的关键。将人工智能方法应用于卫星的任务规划,以执行对地观测任务为例,将任务规划问题归于组合优化问题,建立了相应的数学模型,并应用Hopfield神经网络算法进行求解,结果表明,该方法可用于单个仪器的任务规划。     

NAVSAT: A Global Satellite Based Navigation System

The NAVSAT concept, developed by the European Space Agency, in close cooperation with the industries and user organizations has been conceived to fulfill the civilian user requirements for a better navigation capability and mobile communication needs in the future. In selecting the NAVSAT architecture, special care has been devoted to different satellite constellation alternatives in order to identify the most promising solution in terms of navigation performance and system cost. The paper describes the present NAVSAT baseline and status. This baseline while offering precise navigation performance comparable or better than GPS, cuts significantly the overall cost of a satellite navigation system. The particular constellation selected is also easing the set up of the integrated navigation-communications-search and rescue service.     

The ESRO I Attitude Measurement System

A system for measuring the attitude of a small scientific satellite is described. It consists of a magnetic aspect system and a solar aspect system, and has been flown successfully on two missions. The development was aimed at achieving maximum precision while observing the severe restrictions natural in a small satellite. The result is a set of instruments differing in several respects from previously existing hardware. The flight results have proved very interesting and are expected to yield useful technological experience.     

基于云平台的飞行试验数据中心架构设计

近年高密度航天发射任务和不断提升的数据采集处理能力使得试验数据规模呈几何级数增长,但目前采用的传统试验数据存储管理和应用服务手段已难以适应任务发展的形势要求.针对航天任务参试系统多、地域跨度广、试验数据采集源多、规模增长迅速、业务应用复杂及用户多样等特征需求,采用云存储和云计算技术,提出了一种基于云平台的分布式数据中心架构,论述了基于两级数据中心的应用服务模式,实现了两级数据中心的整体设计,支持全系统计算资源、存储资源、网络资源和业务资源的统一调度管理,支持计算节点、存储节点和网络节点的动态扩展,能够较好地满足海量飞行试验数据的长期存储管理和高效应用服务需求.     

一种基于偏好MOEA的卫星地面站资源多目标优化算法

随着中国航天事业的发展,卫星地面站资源匮乏问题日益突出,需要对其进行统筹优化使用。因此,卫星地面站资源规划问题得到了广泛关注。在分析问题特点的基础上,对用户规划结果的偏好信息进行建模表达,建立了涵盖用户偏好的多目标数学规划模型,提出了基于偏好多目标进化算法的卫星地面站资源规划算法。为了进一步提升算法性能,设计了基于领域知识的启发式策略,包括：任务扩充策略、冲突消解策略以及任务缩减策略等。实验结果表明,与现有算法相比,用户偏好信息的引入能有效提升问题求解针对性,在IGD-CF （Inverted Generational Distance based on Composite Front）指标上取得了更好的效果。     

Tethered dual spacecraft configuration: a solution to attitude control problems

A new dual spacecraft configuration comprising of two spacecraft halves judiciously connected through extremely short tethers is proposed. The simple tethered configuration induces stabilizing torques when subjected to attitude disturbances, thus ensuring 3-d pointing stability of both the satellite platforms. The enhanced system performance obtained using tethers enables a much greater flexibility in the choice of satellite mass distribution. Three particular TSS models involving parallel tethers, a `parachute-like' conical tether layout as well as a single tether connection have been considered. A detailed numerical response simulation shows that these modes of tether attachments bring about a radical change in the satellite attitude behavior from the nominal one involving relatively large librational amplitudes or instability to a virtually fixed desired orientation. Of these, the parachute configuration appears to be superior. The passive nature of the proposed mechanisms using tether lengths on the order of merely a couple of meters needed for small and medium size systems makes the concept particularly attractive for future space missions. Finally, it is felt that the proposed tethered dual satellite systems may offer a simple answer to three-axis attitude control problems.     

对地观测卫星调度的混合整数规划模型及求解

首先简要介绍对地观测卫星的成像过程，详细分析多星调度过程中涉及的各种约束。在此基础上，将对地观测卫星调度问题看作一类具有时间窗口的并行机器调度问题，对其进行了数学描述，并建立对地观测卫星调度的混合整数规划模型。采用列生成法，将多卫星调度问题分解为集合分割主问题和单卫星调度子问题，通过循环迭代来求解调度模型。最后，针对本文提出的算法设计一个问题实例，并给出算法计算结果。结果分析表明，列生成法的效率与问题规模大小相关。     

基于分层控制免疫遗传算法的多卫星联合任务规划方法

 研究面向复杂任务需求的多卫星联合下的任务规划技术,对于提高对地观测系统的保障能力具有重要意义。各种类型的复杂任务需求由于需求特点的差异,使得相对于针对点观测任务的规划更加复杂。在提炼问题特点的基础上,建立了整数规划问题模型,并提出了分层控制免疫遗传算法。该算法采用双层操作,在父层采用遗传操作算子,在子层采用免疫操作算子,并引入基因重组、自适应免疫更新、小生境等机制改进搜索过程。仿真实验表明,分层控制免疫算法在解决复杂任务的任务规划中是可行有效的。     

An overview of a Global Positioning System Mission Plannerimplemented on a personal computer

The Global Positioning System (GPS) Mission Planner (GMP) program, which has been implemented on an IBM PC, is described in terms of its features and architecture, and sample outputs are presented. The GMP was written to permit operational units to plan missions and to accomplish survivability and navigation assessments based on realistic trajectories, GPS almanac data, broadband jammer specifications, and digital terrain elevation data (DTED). GMP supports trajectory generation for generic air, land, or naval vehicles and has `sanity' checks for altitude acceleration, terrain slope, and velocity limits. A survivability measure is computed based on exposure time to various threat types. Yuma-type almanac data are used to support the GMP to define GPS satellite orbits. Jammers, threats, and trajectory wavepoints may be defined by either keyboard entry (e.g. longitude, latitude, and altitude) or via mouse and cursor on a displayed pseudo-color DTED map on the PC monitor. Satellite visibility and best dilution-of-precision (DOP) are computed using DTED. jammer visibility and power levels at the vehicle are similarly computed. A realistic body masking and antenna gain model is used to compute carrier-to-noise densities for each visible satellite. A navigation assessment program emulates a multichannel receiver to generate position and velocity measurement uncertainties. An integrated Kalman filter generates position and velocity navigation estimates. Results are graphically displayed to the operator     

Strategies for in-orbit calibration of drag-free control systems

Drag-Free Satellites (DFS) are a class of scientific satellite missions designed for research on fundamental physics as well as geodesy. They consist, basically, of a small inner satellite (test mass) located in a cavity inside a larger satellite, the normal one. The Drag-Free Attitude Control System (DFACS) is the most complex technology on-board these satellites. This key technology allows the residual accelerations on experiments on board the satellites to be significantly reduced. In order to achieve this very low disturbance environment (for some missions <10⁻¹⁴ g) the drag-free control system has to be optimized. This optimization process is required because of uncertainties in system parameters that demand a robustness of the control system. This paper will present approaches for in-orbit calibration of drag-free control systems. The discussion includes modeling, with scale factors and cross couplings, possible excitation signals, comparison of different parameter identification/estimation methods as well as simulation results.     

Performance improvement for constellation SAR using signal processing techniques

A new concept of spaceborne synthetic aperture radar (SAR) implementation has recently been proposed - the constellation of small spaceborne SAR systems. In this implementation, several formation-flying small satellites cooperate to perform multiple space missions. We investigate the possibility to produce high-resolution wide-area SAR images and fine ground moving-target indicator (GMTI) performance with constellation of small spaceborne SAR systems. In particular, we focus on the problems introduced by this particular SAR system, such as Doppler ambiguities, high sparseness of the satellite array, and array element errors. A space-time adaptive processing (STAP) approach combined with conventional SAR imaging algorithms is proposed which can solve these problems to some extent. The main idea of the approach is to use a STAP-based method to properly overcome the aliasing effect caused by the lower pulse-repetition frequency (PRF) and thereby retrieve the unambiguous azimuth wide (full) spectrum signals from the received echoes. Following this operation, conventional SAR data processing tools can be applied to focus the SAR images fully. The proposed approach can simultaneously achieve both high-resolution SAR mapping of wide ground scenes and GMTI with high efficiency. To obtain array element errors, an array auto-calibration technique is proposed to estimate them based on the angular and Doppler ambiguity analysis of the clutter echo. The optimizing of satellite formations is also analyzed, and a platform velocity/PRF criterion for array configurations is presented. An approach is given to make it possible that almost any given sparse array configuration can satisfy the criterion by slightly adjusting the PRF. Simulated results are presented to verify the effectiveness of the proposed approaches.     

成像观测卫星多星联合调度模型及其列生成求解算法研究

首先介绍成像观测卫星调度问题的特点和主要约束,将成像观测卫星调度分为调度预处理、调度模型及求解、调度结果评估3个阶段。在此基础上,论述成像观测卫星调度模型,并采用列生成法,将多卫星调度问题分解为集合分割主问题和单卫星调度子问题,通过循环迭代来求解调度模型。最后,针对本文提出的算法设计一个问题实例,并给出算法计算结果。结果分析表明,本文提出的模型和算法能较好解决实际应用问题。     

飞秒光学频率梳测距技术的研究进展

飞秒光学频率梳测距技术以其快速、高准确度等优点已经成为国际研究热点。该技术有望广泛应用于大规模制造、卫星编队飞行等测距任务。文中介绍了飞秒光学频率梳测距技术的国内外进展,阐述了飞秒光学频率梳目前的主要测距方法,分析了各种飞秒光学频率梳测距技术的原理、技术方法的优缺点、测距结果的影响因素及技术应用范围,并对飞秒光学频率梳测距未来的发展趋势作了阐述。     

基于执行时段滑动调整策略的中继卫星任务规划算法设计

针对中继卫星任务规划问题开展研究,提出一种基于执行时段滑动调整策略的任务规划算法。首先分析了中继卫星资源调度过程,并对任务申请的时间特征进行形式化描述,然后归纳出任务分配的主要约束,从而完成问题建模。在此基础上,对优化算法进行设计,给出了执行时段滑动调整步骤。通过调整已规划任务执行时段的方法,使部分原本无法执行任务具备执行可能,提升了任务执行率和资源利用率。在仿真实验中,通过大规模测试分析对比不同算法的优化效果,验证了文中所提方法的有效性。     

MINISAT-01: a successful spanish satellite

The MINISAT-01 mission, launched in 1997, has been an important success in the technological area due to the platform qualification in the technological area due to the platform qualification, and also from the scientific point of view. Thinking of MINISAT 01 as the first step in the whole INTA MINISAT programme, the behaviour of this satellite allows us to tackle with confidence more ambitious satellites, such as Earth Observation missions where the requirements and constraints are more strict.     

Past,Present and Future of Active Radio Frequency Experiments in Space

Active ionospheric experiments using high-power, high-frequency transmitters, “heaters”, to study plasma processes in the ionosphere and magnetosphere continue to provide new insights into understanding plasma and geophysical proceses. This review describes the heating facilities, past and present, and discusses scientific results from these facilities and associated space missions. Phenomena that have been observed with these facilities are reviewed along with theoretical explanations that have been proposed or are commonly accepted. Gaps or uncertainties in understanding of heating-initiated phenomena are discussed together with proposed science questions to be addressed in the future. Suggestions for improvements and additions to existing facilities are presented including important satellite missions which are necessary to answer the outstanding questions in this field.