ESA research and development activity on SSA-NEO preliminary definition

The paper gives an account of goals, prospects, and planning of the first ESA research associated with definition of the SSA-NEO segment and puts it in the context of ESA system engineering practices of ESA (as defined in ESA’s ECSS standards).     

Guidance of the Scientific Equipment of the International Space Station to Objects under Study

Cosmic Research - The technology of guiding scientific equipment to objects under study using a steerable platform onboard the Russian segment of the International Space Station (ISS) is presented....     

基于借力飞行技术的星际多目标交会转移轨道设计

针对深空探测中的转移轨道问题,提出一种星际多目标交会转移轨道设计方法。该方法基于Tisserand原理,采用能量曲线确定交会目标的序列,由Pork-Chop图确定设计参数的可行域和时序,避免了传统方法在交会目标序列和初始轨道段设计中的缺陷。将多目标交会转移轨道设计问题归结为一种非线性多约束多变量搜索寻优问题,通过梯度下降法,选取目标函数的负梯度方向作为每步迭代的搜索方向,逐步逼近目标函数的极小值点,从而使转移轨道优化问题得到简化。最后,将本文的设计方法用于解决欧空局的ROSETTA任务深空转移轨道的设计,设计结果与欧空局公布的结果一致,从而验证了该设计方法的可行性和正确性。     

Individual Differences in Object Localization in Virtual Environments

The present research examined the effects of disorientation on human ability to locate objects in space in a virtual environment (VE). Participants were asked to memorize the location of virtual objects, and then they were asked to indicate where the objects were located while they were inside a virtual chamber. This procedure was repeated in both eyesclosed and disoriented conditions. Subject pointing responses were used to measure memory for the relative location of objects in virtual space. This method was extended from previous research in a real-world setting. The results showed systematic individual differences in the effects of disorientation on the ability to locate objects in space. Further, the use of strategies played a role in object localization ability, but strategy use was affected by the individual differences in spatial representations used by subjects.     

Strategy for detection of eccentric objects near the geosynchronous region

Detection of eccentric objects near the geosynchronous region is a very important issue. However, the extremely narrow fields-of-view of optical telescopes hinders us from identifying eccentric objects. An observation strategy to systematically detect these objects and determine their orbits precisely with one telescope is outlined in this presentation. Basically, one specific geosynchronous location (not one specific celestial position) is observed on two nights. Objects which pass through that location in the first night must pass through that location again in the second night. By identifying the same objects from two nights of data, rough orbits for those objects are determined. A third night is needed for precise orbital determination. An application of this strategy to the observation for Titan fragments is also discussed.     

Detection technique for artificially illuminated objects in the outer solar system and beyond

Existing and planned optical telescopes and surveys can detect artificially illuminated objects, comparable in total brightness to a major terrestrial city, at the outskirts of the Solar System. Orbital parameters of Kuiper belt objects (KBOs) are routinely measured to exquisite precisions of<10(-3). Here, we propose to measure the variation of the observed flux F from such objects as a function of their changing orbital distances D. Sunlight-illuminated objects will show a logarithmic slope α ≡ (d log F/d log D)=-4, whereas artificially illuminated objects should exhibit α=-2. The proposed Large Synoptic Survey Telescope (LSST) and other planned surveys will provide superb data and allow measurement of α for thousands of KBOs. If objects with α=-2 are found, follow-up observations could measure their spectra to determine whether they are illuminated by artificial lighting. The search can be extended beyond the Solar System with future generations of telescopes on the ground and in space that would have the capacity to detect phase modulation due to very strong artificial illumination on the nightside of planets as they orbit their parent stars.     

动能撞击偏转近地小天体研究进展

以近地小天体防御为背景,介绍了近地小天体的基本概念和物理特性,分析了超高速动能撞击偏转近地小天体的研究进展。讨论了超高速动能撞击近地小天体表面成坑形貌、相似律以及成坑过程中抛射物产生机制、演化过程和抛射物质量速度分布相似律。总结了基于结合点源假设、实验和数值模拟结果建立的超高速动能撞击小天体动量传递理论模型和相似律。分析了近地小天体的物理特性和撞击条件对动量传递系数的影响规律。归纳了超高速动能撞击偏转近地小天体研究中存在的问题,对超高速动能撞击防御小天体的发展趋势提出了若干建议。     

航天器碰撞分析方法研究

作为航天器碰撞与规避控制方法研究课题的一部分,为此分别建立了航天器及其它空间目标的轨道确定方法;并在此基础上,提出了可能与航天器碰撞的其它空间编目目标的初选准则和碰撞预报算法。实测数据计算表明,该方法对于航天器轨道设计以及飞行安全性分析等均是实用可行的。     

The role of motor processes in mental rotation: selective shaping of cognitive processing via specific sensorimotor experience

The involvement of motor processes in mental rotation is experience-dependent: different levels of expertise in sensorimotor interactions lead to different strategies in mental rotation. In the present study, wrestlers, gymnasts, and nonathletes physically rotated objects that were either light (wooden) or heavy (lead) but otherwise having the same sizes and shapes. They then performed a mental rotation task using photographs of these objects in which the material and therefore the weight was visible. I hypothesized that wrestlers would rely more heavily on experience-based sensorimotor strategies in performing mental rotation because during their athletic practice they not only manipulate external “objects” (i.e., their opponent) but also have to plan future actions taking into account past experience of these “objects” (for example their weight). All participants reported that lead objects were harder to physically rotate than wooden ones. However, only wrestlers mentally rotated lead objects more slowly than wooden ones—as they would if they were physically rotating them—suggesting the involvement of motor processes. These findings show that the involvement of motor processes in mental rotation depends on specific rather than mere sensorimotor experience.     

双模态超音速燃烧室的实验研究

本文设计了由等截面段、扩张段和等截面段构成的超音速燃烧室，并进行了燃烧实验。用一维计算分析实验结果，表明由等截面段、扩张段和等截面段构成的超音速燃烧室，通过一定的喷油方式，能按飞行状态可分别实现超音速燃烧和亚音速燃烧，从而达到把超燃冲压发动机的工作范围下限扩大到飞行马赫数为３。     

Ground assisted rendezvous with geosynchronous satellites for the disposal of space debris by means of Earth-oriented tethers

Previous studies have shown that extended length Earth-oriented tethers in the geosynchronous (GEO) region can be used to re-orbit satellites to disposal orbits. One such approach involves the extension of a GEO based tether, collection of a debris object, and retraction of the tether, which transfers the retracted configuration to a higher energy orbit for debris disposal. The re-extension of the tether after debris disposal returns the configuration to the near-GEO altitude. The practical feasibility of such a system depends on the ability to collect GEO debris objects, attach them to a deployed tether system, and retract the tethers for transfer to the disposal orbits.This study addresses the collection and delivery of debris objects to the deployed tether system in GEO. The investigation considers the number, type and the characteristics of the debris objects as well as the collection tug that can be ground controlled to detect, rendezvous and dock with the debris objects for their delivery to the tethers system.A total of more than 400 objects are in drift orbits crossing all longitudes either below or above the geostationary radius. More than 130 objects are also known to librate around the stable points in GEO with periods of libration up to five or more years. A characterization of the position and velocity of the debris objects relative to the collection tug is investigated. Typical rendezvous performance requirements for uncooperative GEO satellites are examined, and the similarities with other approaches such as the ESA's CX-OLEV commercial mission proposal to extend the life of geostationary telecommunication satellites are noted.     

月球探测中通信跟踪(C&T)技术遇到的新问题

以技术成熟的GEO以下近地轨道的C&T技术为参照点,提出月球探测遇到的新问题———长时间、远距离地月转移轨道测量、环月轨道段测量和月面登陆段测量中的新问题,给出解决这些问题的合理方法。     

空间目标态势行为与事件本体设计与构建

针对空间目标态势威胁响应和预警研究不完善的问题，为实现空间目标行为和事件的智能推理、实时响应和主动预警，保障航天活动和空间利益，提出面向行为与事件的空间目标态势本体模型(BEO-SO2)。基于基本形式本体(BFO)，构建空间目标态势行为与事件本体模型。在统一时空框架下建立空间目标关系模型，实现空间目标行为执行和事件发生过程的动态推演。以空间目标碰撞威胁为背景，设计对象实体等级体系和碰撞威胁行为与事件要素，建立碰撞威胁推理规则，基于空间目标态势行为与事件本体进行实现、验证与展示。结果表明,空间目标态势行为与事件本体能够实现空间目标碰撞威胁的等级推理与预警，并指导进一步的空间活动，为航天任务与空间活动提供有效保障。     

Exploring the Kuiper Belt: An extended Pluto mission

A robotic flyby mission to the planet Pluto is being planned for launch early in the next decade. The spacecraft will continue on out of the solar system in an almost radial direction traveling at about four AU per year and begin transiting the Kuiper Belt shortly after Pluto encounter. Recent discoveries and observations of Kuiper Belt objects have generated increased interest in the characteristics of these bodies. This paper examines the opportunities and requirements for extending the Pluto mission to include the search for, and encounters with, objects in the Kuiper Disk at 40+ AU. The trajectory and ΔV requirements will be presented. An automated, on-board sky survey will be proposed to inventory the Kuiper objects in the vicinity of the flight path and to identify which objects are candidates for altering the trajectory for a close flyby. A possible Kuiper object encounter science scenario will be described.     

Prioritized Spatial Updating in the Intrinsic Frame of Reference

In order to maintain valid situation awareness, people need to update the spatial representations of their surroundings as objects, including themselves, move. The present study investigates the properties of spatial updating in the intrinsic frame of reference, where spatial relations are represented with respect to an external object (other than the viewer self) with an intrinsic reference direction. Three experiments were conducted using a task of direction pointing. It was found that given a relatively stable intrinsic reference direction, responses to a small number of salient objects were faster than responses to non-salient objects (Experiment 1 and Experiment 3). The salience effect disappeared when the intrinsic reference direction was no longer stable (Experiment 2). Furthermore, all three experiments revealed a type of orientation dependence similar to that found in egocentric spatial updating. Our results indicate that spatial updating in the intrinsic reference system can be easy only if a fixed reference direction is maintained and the number of objects that need to be tracked is limited.     

Signs of hypothetical flora on the planet venus: Revision of the TV experiment data (1975–1982)

Unique archive data from investigations of the surface of Venus performed with television cameras on the VENERA missions in 1975 and 1982 were reprocessed with up-to-date techniques, which substantially improved their level of detail. Numerous objects exhibiting a complex regular structure and presumably very slow motions (in the case of hypothetical fauna) have been found. The objects are noticeable in size and may testify to the existence of life. This paper reviews the results of searching for and identifying hypothetical objects of Venusian flora. The detected and identified hypothetical objects considerably exhaust the corresponding potential of the television images. It is concluded that, to investigate the surface of Venus, a new special mission, much more sophisticated than the VENERA missions (1975–1982), should be urgently carried out.     

基于稀疏重构的杂波环境下红外图像空间邻近目标超分辨方法

基于稀疏重构的超分辨方法是应对空间邻近目标的有效方法之一,但是当目标处于杂波环境下时,杂波会布满在整个视场范围内,导致场景原有的稀疏性被破坏。针对这一现象提出了一种在杂波环境下的超分辨方法。该方法充分利用了传感器的结构特性以及重构算法中的参数,通过建立观测信号的红外成像模型并利用像元网格划分的方式,建立空间邻近目标群的位置和幅度信号的稀疏表示,并利用其光学系统的点扩散函数来构造超完备字典,最后通过控制重构场景中非零元素的个数比例来使重构参数处于一个合理的区间范围,以此来达到去除杂波干扰并准确重建稀疏目标的目的。     

Spatial Memory Organized by Environmental Geometry

We investigated the simultaneous effects of different reference systems on spatial memory. Participants studied a configuration of objects surrounding them. During retrieval, they imagined themselves in the center of the object configuration facing a particular object, and then indicated the directions of other objects relative to this imagined heading. Besides strong effects of egocentric retrieval direction, retrieval was enhanced for objects and headings aligned with an object-centered reference system (triangular object configuration within a neutrally-shaped room), or with a sufficiently salient environmental reference system (triangular room surrounding a neutrally-shaped object configuration). Moreover, remembered object positions were spatially distorted by the object-centered reference system. Results suggest that object positions are accessed by imagining oneself within a topographical representation of objects which is preorganized in terms of both environmental and object-centered reference systems.     

空间目标碰撞预警技术研究综述

随着在轨空间目标数量的不断增加,空间目标碰撞预警工作变得越来越重要。通过对国内外相关文献的调研分析,对空间目标碰撞预警的相关技术及其研究进展进行了全面地介绍。给出了空间目标碰撞预警的总体框架、关键技术和涉及的理论问题,对主要技术问题的研究进展进行了综述,提出了一些需要解决的问题,可供从事空间目标监视和碰撞预警等任务和研究的技术人员参考。     

A preliminary assessment of an orbiter in the Haumean system: How quickly can a planetary orbiter reach such a distant target?

With the recent discoveries of planetary objects beyond Neptune and Pluto, the vast majority of all sizeable Solar System planetary objects lie now beyond Uranus, where insertion into orbit after a reasonably short travel is still not within the current capabilities of our spacecraft. Being able to go and stop at a transneptunian dwarf planet would represent a step stone for ambitious long-term goals. The pressure to send spacecraft to these bodies will grow, as, among the tens or hundreds of large objects, some will emerge as high priorities for science and exploration missions. It is subsequently necessary to prepare the technologies required for such spacecraft. In addition, being able to achieve a fast journey to a distant object will benefit also missions to closer targets.Thales Alenia Space has carried out a preliminary parameter exploration of such a mission with a challenging target: an orbiter in the Haumean system. The main parameters are the characteristics of the propulsion and power system, as well as the masses of the spacecraft. The exploration has inferred the technological improvement needed for reaching these objects within a reasonable time.