The fluid-dynamic disturbances induced on the ISS, based on the first acceleration measurements on board the space station

The different acceleration components on the ISS that are responsible for the generation of convective motions in a fluid cell either in the presence of density gradients or in quasi-isodense processes, are analyzed. The NASA measurements of the quasi-steady and periodic acceleration on the ISS are considered and their effects on fluid-dynamic experiments are computed and discussed under different assumptions. In particular, numerical simulations are carried out to identify the relative importance of linear and pendular accelerations, due to possible rotations of the P/L around its center of mass. The effects caused by variable accelerations created by an isolation mount that exhibits an attenuation factor not constant within the payload volume, caused by the reaction forces of the umbilicals, are computed and analyzed.     

空间站有效载荷真空支持系统方案评述

有效载荷真空支持系统是空间有效载荷支持系统的重要组成部分,为空间有效载荷实验的顺利进行提供真空环境支持和保证。文章详细分析了国际空间站包括美国“命运号”实验舱（USL）、欧空局哥伦布轨道舱（APM）及日本实验舱（JEM）内的有效载荷真空支持系统方案及使用情况;对美国实验舱内的一号微重力材料科学机柜及微重力燃烧科学机柜内部专用的真空支持系统作了主要介绍;最后提出了我国空间站有效载荷真空支持系统的初步方案设想,即合理安排有效载荷实验进行次序,将废气排放子系统及真空资源子系统合二为一,以节约资源,提高可靠性。     

Ariane transfer vehicle in service of man in orbit

The Ariane transfer vehicle (ATV), an Ariane 5 borne, unmanned propulsion vehicle, is designed to transport the logistics needed to resupply the International Space Station (ISS) and the man tended free flyer (MTFF) step 2 with pressurized and unpressurized cargo and to dispose the waste. The ATV is an expendable vehicle and is disposed of by a safe atmospheric burn up. In accordance with the AR5 schedule it should be operational in 1996 for missions toward ISS and beyond the year 2000 for MTFF 2 missions. The main constituents of the proposed ATV are the modified AR5 third stage L5, an upgraded VEB steering the launcher as well as the ATV and the P/L-adaptor providing mechanical and umbilical links to the payload. The mechanical part of the RVD-kit will be placed on the payload-module, the main RVD sensors are located on the adaptor and the needed computer intelligence will be integrated on the VEB. To minimize the development, and recurring costs, the ATV concept fully complies to the idea of maximum use of existing hardware and software, mainly from the AR5, Hermes and Columbus programs thus minimizing development and recurring costs. The ATV is compatible to ISS, MTFF and OMV and is able to transport logistic modules compatible with NSTS and U.S.-expendable launchers.     

Recent NASA research accomplishments aboard the ISS

The activation of the US Laboratory Module "Destiny" on the International Space Station (ISS) in February 2001 launched a new era in microgravity research. Destiny provides the environment to conduct long-term microgravity research utilizing human intervention to assess, report, and modify experiments real time. As the only available pressurized space platform, ISS maximizes today's scientific resources and substantially increases the opportunity to obtain much longed-for answers on the effects of microgravity and long-term exposure to space. In addition, it evokes unexpected questions and results while experiments are still being conducted, affording time for changes and further investigation. While building and outfitting the ISS is the main priority during the current ISS assembly phase, seven different space station crews have already spent more than 2000 crew hours on approximately 80 scientific investigations, technology development activities, and educational demonstrations.     

Cost effectiveness of Spacelab experiments

Spacelab permits investigation in new seicntific disciplines like material processing, life sciences, chemistry, etc. The large mass and volume capabilities of Spacelab offer better possibilities for some areas of traditional space sciences like infrared astronomy, multi-spectral solar observations and large instruments for astronomical observations.Since free-flyers will require normally a new spacecraft development for each mission, the reusability of space qualified components and experiments will be a significant cost reduction factor over a long period. In the early phase of Spacelab utilisation, however, the scaling factor introduced by Spacelab utilisation, however, the scaling factor introduced by Spacelab results in higher payload development costs than originally appreciated.The costs of Spacelab utilisation are computed and compared with those of conventional free-flying satellites. The mission implementation costs and experiment development costs are shown for both cases. The Spacelab mission implementation costs are subdivided into NASA charges for the Standard Shuttle Mission, NASA charges to fly and operate Spacelab, the European costs of Spacelab payload integration and experiment development costs. In order to evaluate and compare mission implementation costs, the simple parameters are adopted of the cost per kg of experiments and the data collection-transmission capability of Shuttle/Spacelab and ESRO/ESA satellites. The mission implementation costs turn out to be very favourable for Spacelab. The experiment development costs, which are not included in the mission implementation costs, are compared for several free flyers with the corresponding development costs for several experiments of the first Spacelab payload. The comparison shows that the cost per kg of Spacelab experiment development is about five times less than of satellite experiments.     

Safety implications of unscheduled situations in the operation of tethered satellite systems from the international space station

Space based experiments involving the use of tethers were examined with a view to identifying the implications of unscheduled events such as tether severance and interference between the tether and other hardware. It is the authors opinion that these type of events, which have important consequences for the operation of tethers in space, have received insufficient consideration in the extensive literature on the subject. In particular, the investigation of the interference event appears to be completely new. The examination focussed on tether experiments planned for the forthcoming International Space Station (ISS). Results were obtained through the use of a highspeed, non-linear, computer simulation model specifically designed for use with tethered satellite systems. Simulations showed that both severance and interference were possible during retrieval of the tether, particularly if ‘skip-rope’ motion is initiated. The motion following each of these incidents is predicted and shows that these unscheduled events are potentially very hazardous for the ISS. While the results of these simulations are not directly applicable to specific operations on the ISS, they fulfill the primary purpose of this paper which is the demonstration of this new technology.     

双体卫星对日定向姿态机动控制

研究了双体卫星(DFP)对日定向姿态机动控制问题。首先分析双体卫星工作机理，建立载荷舱与平台舱姿态模型，推导磁浮机构线圈和磁钢相对距离的数学表达式。提出基于PD控制的载荷舱对日姿态机动、平台舱姿态跟踪以及两舱避碰等控制策略。在此基础上，为提高平台舱姿态跟踪速度，设计反步控制器对平台舱飞轮的动态特性进行补偿。进一步，为提高两舱协同控制性能，对传统PD控制进行改进，提出基于变增益PD控制的载荷舱姿态机动控制律，将两舱相对姿态信息包含在载荷舱对日姿态机动控制律中，有效降低了两舱碰撞风险，提高了两舱姿态机动速度。仿真结果表明，本文控制算法能有效实现双体卫星对日定向，且能避免两舱碰撞。     

Testing and evaluation of a method for locating potentially hazardous sites of eventual microdestruction and detecting marks of ISS RS hull leakage

In 2008, two experiments – BAR and EXPERT – were performed on the Russian segment (ISS RS) during ISS missions 16 and 17 using diagnostic equipment BAR. The experiments were aimed to enhance ISS safety by proposing means and methods of detecting leaks due to many factors including microdestruction of pressurized modules of the vehicle. The BAR experiment was designed to assess the ultraviolet background in 56 potentially dangerous locations identified by RS ISS designers and engineers. The method for locating sites carrying the risk of microdestruction of pressurized structure was verified. The study showed that the rate of microdestruction is highly affected by level of ultrasound vibrations caused by onboard equipment. The ultrasound measurements in 200 RS ISS sites were performed within the BAR experiment. The method consists of looking for surfaces with atmospheric condensate in the areas of increased levels of ultrasound vibrations. Twenty six sites were added to the nomenclature of potentially risky sites to be monitored on the regular basis. Some of these sites were contaminated by fungi and bacteria.     

EXPERT: An atmospheric re-entry test-bed

In recognition of the importance of an independent European access to the International Space Station (ISS) and in preparation for the future needs of exploration missions, ESA is conducting parallel activities to generate flight data using atmospheric re-entry test-beds and to identify vehicle design solutions for human and cargo transportation vehicles serving the ISS and beyond. The EXPERT (European eXPErimental Re-entry Test-bed) vehicle represents the major on-going development in the first class of activities. Its results may also benefit in due time scientific missions to planets with an atmosphere and future reusable launcher programmes.

The objective of EXPERT is to provide a test-bed for the validation of aerothermodynamics models, codes and ground test facilities in a representative flight environment, to improve the understanding of issues related to analysis, testing and extrapolation to flight. The vehicle will be launched on a sub-orbital trajectory using a Volna missile. The EXPERT concept is based on a symmetrical re-entry capsule whose shape is composed of simple geometrical elements. The suborbital trajectory will reach 120 km altitude and a re-entry velocity of . The dimensions of the capsule are 1.6 m high and 1.3 m diameter; the overall mass is in the range of , depending upon the mission parameters and the payload/instrumentation complement. A consistent number of scientific experiments are foreseen on-board, from innovative air data system to shock wave/boundary layer interaction, from sharp hot structures characterisation to natural and induced regime transition.

Currently the project is approaching completion of the phase B, with Alenia Spazio leading the industrial team and CIRA coordinating the scientific payload development under ESA contract.     

Ground based ISS payload microgravity disturbance assessments

In order to verify that the International Space Station (ISS) payload facility racks do not disturb the microgravity environment of neighboring facility racks and that the facility science operations are not compromised, a testing and analytical verification process must be followed. Currently no facility racks have taken this process from start to finish. The authors are participants in implementing this process for the NASA Glenn Research Center (GRC) Fluids and Combustion Facility (FCF). To address the testing part of the verification process, the Microgravity Emissions Laboratory (MEL) was developed at GRC. The MEL is a 6 degree of freedom inertial measurement system capable of characterizing inertial response forces (emissions) of components, sub-rack payloads, or rack-level payloads down to 10(-7) g's. The inertial force output data, generated from the steady state or transient operations of the test articles, are utilized in analytical simulations to predict the on-orbit vibratory environment at specific science or rack interface locations. Once the facility payload rack and disturbers are properly modeled an assessment can be made as to whether required microgravity levels are achieved. The modeling is utilized to develop microgravity predictions which lead to the development of microgravity sensitive ISS experiment operations once on-orbit. The on-orbit measurements will be verified by use of the NASA GRC Space Acceleration Measurement System (SAMS). The major topics to be addressed in this paper are: (1) Microgravity Requirements, (2) Microgravity Disturbers, (3) MEL Testing, (4) Disturbance Control, (5) Microgravity Control Process, and (6) On-Orbit Predictions and Verification.     

一种卫星在轨自由边界条件模拟方法

随着观测精度的提高,卫星观测设备对微振动愈加敏感,需要在地面开展卫星在轨微振动环境模拟试验及测试验证,而卫星在轨自由边界条件的模拟对于提高地面试验的有效性至关重要。文章提出了一种低频弹性支撑方法,用于模拟卫星在轨飞行时的自由边界条件;并基于该方法,设计和研制了一套模拟试验装置,通过模态和频率响应分析以及型号的整星微振动模拟试验,评估了模拟自由边界条件对卫星动力学特性的影响,也证明了低频弹性支撑模拟方法的有效性。     

Contributions of the International Space Station towards future exploration missions

When the idea of a large space station in Low Earth Orbit (LEO) was conceived in the 1980s, it was primarily planned as an orbiting laboratory for microgravity research. Some even thought of it as an industrial plant in space. Whereas the latter did not materialize because of various reasons, the former is absolutely true when you talk about the International Space Station (ISS). Since the transition to a six astronaut crew in 2009 and the completion of its assembly in 2011, it has been intensively used as laboratory in a wide field of scientific topics. Experiments conducted on ISS have yielded first class results in biology, physiology, material science, basic physics, and many more. While its role as a laboratory in space is widely recognized, the awareness for its potential for preparing future exploration missions beyond LEO is just increasing. This paper provides information on how the ISS programme contributes to future exploration efforts, both manned and unmanned. It highlights the work that has been done or is currently underway in the fields of technology, operations, and science. Further potentials and future projects for exploration preparation are also shown. A special focus lies on experiments and projects primarily funded by the German Aerospace Center (DLR) or with strong German participation in the science team.     

Astronaut training for the European ISS contributions Columbus module and ATV

An essential part of increment preparation for the ISS is the training of the flight crews. Each international partner is responsible for the basic training of its own astronauts, where a basic knowledge is taught on space science and engineering, ISS systems and operations and general astronaut skills like flying, diving, survival, language, etc. The main parts of the ISS crew training are the Advanced Training, e.g., generic ISS operations; nominal and malfunction systems operations and emergencies, and the Increment-Specific Training, i.e., operations and tasks specific to a particular increment. The Advanced and Increment-Specific Training is multilateral training, i.e., each partner is training all ISS astronauts on its contributions to the ISS program. Consequently, ESA is responsible for the Basic Training of its own astronauts and the Advanced and Increment-Specific Training of all ISS crews after Columbus activation on Columbus Systems Operations, Automated Transfer Vehicle (ATV), and ESA payloads.

This paper gives an overview of the ESA ISS Training Program for Columbus Systems Operations and ATV, for which EADS Space Transportation GmbH is the prime contractor. The key training tasks, the training flow and the training facilities are presented.     

星载激光雷达高精高稳探测卫星系统保证技术

激光雷达探测精度高,具备全天时工作和垂直探测能力,在大气环境天基遥感领域应用广泛。基于CO_2柱线浓度激光遥感探测原理,分析了积分路径差分吸收星载激光雷达测量系统的激光波长、能量精度和稳定性及光轴指向精度等关键指标要求和功能模块配置,重点开展了星载激光雷达光机头部稳定安装、良好机热环境保障及星敏载荷一体化布局等整星层面系统设计保证,仿真结果初步表明设计方案可行。同时,提出了激光雷达波长、能量精度及稳定性实时监测、卫星对地光轴指向高精度测定和星地载荷光轴指向测量误差标定的地面试验验证要求,以确保系统设计的有效性,为激光雷达遥感卫星的研制提供了技术参考。     

New microgravity fundamental physics research areas in the ISS era

NASA's microgravity fundamental physics program has used the Space Shuttle to perform high resolutions experiments in space. As we come to the end of the Shuttle era, we will begin to perform research aboard the ISS. A large stable of ground based experiments have been selected from NASA Research Announcements in a variety of disciplines. These investigations will form the backbone from which to select future flight candidates. Research in Laser Cooling and Atomic Physics will enable us to operate highly precise clocks in space. Low temperature physics experiments will use a liquid helium facility with a six-month lifetime. This facility can also support experiments in gravitational physics. Researchers in biological physics will be offered an opportunity to develop future experiments that can benefit from space experimentation. An overview of the future research directions and the benefits to the community of performing research aboard the ISS will be presented.     

Adaptive environmental control for optimal results during plant microgravity experiments

The SVET Space Greenhouse (SG)--the first and the only automated plant growth facility onboard the MIR Space Station in the period 1990-2000 was developed on a Russian-Bulgarian Project in the 80s. The aim was to study plant growth under microgravity in order to include plants as a link of future Biological Life Support Systems for the long-term manned space missions. An American developed Gas Exchange Measurement System (GEMS) was added to the existing SVET SG equipment in 1995 to monitor more environmental and physiological parameters. A lot of long-duration plant flight experiments were carried out in the SVET+GEMS. They led to significant results in the Fundamental Gravitational Biology field--second-generation wheat seeds were produced in the conditions of microgravity. The new International Space Station (ISS) will provide a perfect opportunity for conducting full life cycle plant experiments in microgravity, including measurement of more vital plant parameters, during the next 15-20 years. Nowadays plant growth facilities for scientific research based on the SVET SG functional principles are developed for the ISS by different countries (Russia, USA, Italy, Japan, etc.). A new Concept for an advanced SVET-3 Space Greenhouse for the ISS, based on the Bulgarian experience and "know-how" is described. The absolute and differential plant chamber air parameters and some plant physiological parameters are measured and processed in real time. Using the transpiration and photosynthesis measurement data the Control Unit evaluates the plant status and performs adaptive environmental control in order to provide the most favorable conditions for plant growth at every stage of plant development in experiments. A conceptual block-diagram of the SVET-3 SG is presented.     

The International Space Station human life sciences experiment implementation process.

The selection, definition, and development phases of a Life Sciences flight research experiment has been consistent throughout the past decade. The implementation process, however, has changed significantly within the past two years. This change is driven primarily by the shift from highly integrated, dedicated research missions on platforms with well defined processes to self contained experiments with stand alone operations on platforms which are being concurrently designed. For experiments manifested on the International Space Station (ISS) and/or on short duration missions, the more modular, streamlined, and independent the individual experiment is, the more likely it is to be successfully implemented before the ISS assembly is completed. During the assembly phase of the ISS, science operations are lower in priority than the construction of the station. After the station has been completed, it is expected that more resources will be available to perform research. The complexity of implementing investigations increases with the logistics needed to perform the experiment. Examples of logistics issues include- hardware unique to the experiment; large up and down mass and volume needs; access to crew and hardware during the ascent or descent phases; maintenance of hardware and supplies with a limited shelf life,- baseline data collection schedules with lengthy sessions or sessions close to the launch or landing; onboard stowage availability, particularly cold stowage; and extensive training where highly proficient skills must be maintained. As the ISS processes become better defined, experiment implementation will meet new challenges due to distributed management, on-orbit resource sharing, and adjustments to crew availability pre- and post-increment.     

Dextre: Improving maintenance operations on the International Space Station

The Special Purpose Dexterous Manipulator (SPDM), known as “Dextre”, is currently slated to launch in February 2008 for deployment on the International Space Station (ISS) as the final component of Canada's Mobile Servicing System (MSS). Dextre's primary role on the Space Station is to perform repair and replacement (R&R) maintenance tasks on robotically compatible hardware such as Orbital Replaceable Units (ORUs), thereby eventually easing the burden on the ISS crew.This burden on the on-orbit crew translates practically into crew time being a limited resource on the ISS, and as such, finding ways to assist the crew in performing their tasks or offloading the crew completely when appropriate is a bonus to the ISS program. This is already accomplished very effectively by commanding as many non-critical robotics tasks as possible, such as powering up and free-space maneuvering of the Space Station Remote Manipulator System (SSRMS), known as “Canadarm2”, from the Ground.Thus, beyond its primary role, and based on an increasing clarity regarding the challenges of external maintenance on the ISS, Dextre is being considered for use in a number of ways with the objective of improving ISS operations while reducing and optimizing the use of crew time through the use of ground control for various tasks, pre-positioning hardware, acting as a temporary storage platform to break an Extra Vehicular Activity (EVA) day into manageable timelines, and extending the physical reach and range of the Canadarm2.This paper discusses the planned activities and operations for Dextre an rationale for how these will help optimize the use of crew resources on the ISS.     

The dynamics of the space shuttle orbiter with a flexible payload

The Space Shuttle Orbiter will be used as an orbital base for near-term space operations. Its payloads will range from compact satellites to large, flexible antennas. This paper addresses the problem of the dynamics and control of the Orbiter with a flexible payload. Two different cases are presented as examples. The first is a long, slender beam which might be used as an element in a large orbiting structure. The second is a compact satellite mounted on a spin table in the Orbiter payload bay. The closed loop limit cycles are determined for the first payload and the open loop eigenvalues are calculated for the second. Models of both payloads are mechanized in a simulation with the Shuttle on-orbit autopilot. The vehicle is put through a series of representative maneuvers and its behavior analyzed. The degree of interaction for each payload is determined and strategies are discussed for its reduction.