Test results after refurbish of cryogenic system for smiles

Superconducting Sub-millimeter-wave Limb-Emission Sounder (SMILES) is to be operated aboard the Japanese Experiment Module (JEM) of the International Space Station (ISS) in 2009. SMILES uses two superconductor-insulator-superconductor (SIS) mixers for sub-millimeter-wave atmospheric observation and they are cooled to 4 K levels by a cryogenic system with a two-stage Stirling cooler, a Joule-Thomson (JT) cycle cooler and a cryostat composed of three stages. Two-stage Stirling cooler precools the JT circuit and also cools radiation shields in the cryostat. JT circuit has three tube-in-tube type heat exchangers and an orifice for JT expansion in the cryostat. The cryogenic system is built, tested and delivered.     

Shielding against space debris. A comparison between different shields: The effect of materials on their performances

The space environment requires the Space Station to be shielded against orbital debris. A technological programme undertaken by the European Space Agency has led to a preliminary definition of the shield configuration for the European Attached Pressurized Module. The envisaged shield is a modified Whipple shield. A second bumper is located midway between the first bumper and the backwall.

The work described has been initiated to quantify experimentally the merits of different shields compatible with the APM system requirements. For this technological investigation, two requirements had to be satisfied. The spacing between the front bumper and the backwall had to be limited to 120 mm. The backwall thickness could not be reduced to technological limits as it has structural functions as well. In addition, the long life requirements of the Space Station precludes the use of unproved materials for the external parts of the shield.

Different materials have been tried as second bumper. The effect of the first bumper thickness on the projectile fragmentation has been explored as well. Shields based on Aluminium, Kevlar and Glare have been investigated. Kevlar 29 fabrics impregnated with epoxy resin were used for this work. Glare is a material developed to improve the fatigue strength of metal structures. It is primarily intended for aircraft skin applications. Glare consists of a 60 percent fibre volume adhesive prepreg with high-strength unidirectional or cross-ply R-glass fibres. A variety of lay-up sequences is available ranging from 2/1 (two layers of aluminium alloy sheet bonded by one layer of prepeg) to any number of layers. The 2/1 layers version of the Glare material has been used for this work.

The tests results indicate the performances of materials can change significantly with the impact conditions. Glare shows the best performances in the low velocity regime while Kevlar is very promising in the high velocity regime. It is concluded the use of Kevlar can improve substantially the performances of the APM shield.     

Whipple shield ballistic limit at impact velocities higher than 7 km/s

The Whipple bumper shield was the first system developed to protect space structures against Meteoroids and Orbital Debris (M/OD), and it is still extensively adopted. In particular, Whipple shields are used to protect several elements of the International Space Station, although the most exposed areas to the M/OD environment are shielded by innovative low weigh and high resistance systems.

Hydrocode simulations were used to predict the ballistic limit of a typical aluminium Whipple shield configuration for space applications in the impact velocity range not accessible by the available experimental techniques. The simulations were carried out using the AUTODYN-2D and the PAMSHOCK-3D codes, allowing to couple the gridless Smoothed Particles Hydrodynamics with the Lagrange grid-based techniques. The global damage of the structure after the impact was determined with particular attention to the back wall penetration, and the results obtained with the two hydrocodes were compared with those given by semi-empirical damage equations.

A few hypervelocity Light Gas Gun impact experiments, performed on the same shield configuration at velocities up to 7.2 km/s, were previously simulated in order to assess the capability and limitations of the two hydrocodes in reproducing the experimental results available in the lower velocity regime. The influence of material models on the numerical predictions is discussed.     

Research Opportunities on the Low Temperature Microgravity Physics Facility on the International Space Station

The Low Temperature Microgravity Physics Facility (LTMPF) is a state-of-the-art facility for long duration science investigations whose objectives can only be achieved in microgravity and at low temperature. LTMPF consists of two reusable, cryogenic facilities with self-contained electronics, software and communication capabilities. The Facility will be first launched by Japanese HIIA Rocket in 2004 with at least five months cryogen lifetime on the Japanese Experiment Module Exposed Facility (JEM EF) of the International Space Station (ISS). Future missions will be launched and retrieved by the Space Shuttle. A number of high precision sensors of temperature, pressure and capacitance will be available, which can be further tailored to accommodate a wide variety of low temperature experiments. This paper will describe the LTMPF and its goals and design requirements. Currently there are six candidate experiments in the flight definition phase to fly on LTMPF. Future candidate experiments will be selected through the NASA Research Announcement(NRA) process. Opportunities for utilization and collaboration with international partners will also be discussed.     

Optimised inner boundary shapes in circular rings under diametral compression

Using a method developed by the authors, the configuration of the inside boundary of circular rings, subjected to diametral compression, has been optimised, keeping cleared the space enclosed by the original circular inside boundary. The range of diameters studied was 0.33ID/OD0.7. In comparison with circular rings of the same ID/OD, the stress concentrations have been reduced by about 30%, the weight has been reduced by about 10% and coefficients of efficiency of about 0–96 have been attained. The maximum values of compressive and tensile stresses on the edge of the hole, are approximately equal, there are practically no gradients of stress along the edge of the hole, and sharp corners exhibit zero stress. The geometries for each ID/OD design are given in detail.     

Lifetime test and heritage on orbit of coolers for space use

This report describes the results and operating status of ground lifetime testing and achievements on orbit of coolers for space use. Ground lifetime tests of coolers of three types were conducted to demonstrate their long life and reliability. Three single-stage Stirling coolers were tested for 89,016, 71,871 and 68,273 h from 1998, a two-stage Stirling cooler was tested for 72,906 h, and a 4-K class cooler with a two-stage Stirling cooler and a Joule–Thomson cooler was tested for over 2.5 years. After lifetime tests were completed, a few coolers were investigated to determine the cause of the cooling performance degradation. Additionally, the filled gas of the coolers was analyzed. These coolers have shown good results on orbit. Three single-stage Stirling coolers were carried on the X-ray astronomical satellite “SUZAKU” (launched in July 2005), Japanese lunar polar orbiter “KAGUYA” (launched in September 2007), and the Japanese Venus Climate Orbiter “AKATSUKI” (launched in June 2010). Two units of a two-stage Stirling cooler were carried on the infrared astronomical satellite “AKARI” launched in February 2006. A 4-K class cooler was carried on the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) aboard the Japanese Experiment Module (JEM) of the International Space Station (ISS). SMILES was launched in September 2009.     

A multi-shock concept for spacecraft shielding

The results of an advanced spacecraft shielding program conducted at the NASA Johnson Space Center Hypervelocity Impact Research Laboratory (HIRL) are presented. The results include two new aspects of shielding design: the geometrical configuration and the type of material used for the shield. The geometrical configuration of the shield will be the prime focus of this paper due to its application over a large range of materials. The uniqueness of this concept is in the utilization of a multi-shock (MS) shielding technique where ultra-thin (t_s) spaced (ΔS), shield elements are used to repeatedly shock the impacting projectile (diameter d_p) to a high enough energy state to cause melting and vaporization at velocities which normally would not produce these results. Although the concept of multi-sheet shields has been proposed and tested many times (Christiansen, 1987; Gehring, 1970; Rajendra and Elfer, 1989; Richardson, 1970), the t_s/d_p ratio has always been large enough that the shield material has provided a large percentage of the debris plume mass which the back sheet must withstand. This concept does not produce the same results. The low t_s/d_p adds very little shield material to the debris plume allowing a substantial decrease in the thickness (strength) of the backsheet and the proper spacing between sheets prevents the debris plume from destroying successive sheets prior to the particulates reaching the sheet. The present concept, using aluminum as an analog for comparison to a dual sheet (aluminum) “Whipple shield” results in a 30% reduction in weight.

The use of other materials with this concept can result in even greater weight savings. The concept was tested at normal impact, oblique impact, and low velocity impact (2.7 km/s) and performed as well as an equivalent dual sheet shield. The scaling characteristics of the new cincept were tested and verified for impacting projectiles of mass 45 milligrams and 1.27 grams at velocities of 6.7 km/s. The new concept provides a shield which can be tailored to meet many design requirements, produce minimal secondary debris particles, provide a means for designing an augmentable shielding system, and most important reduce the weight of debris shielding.     

Optimized configurations for passively shielded magnetic resonanceimaging magnets

A design approach is presented for the development of passive shields for coil configurations, with particular emphasis on those used for magnetic resonance imaging (MRI). The approach is based on minimizing the weight of the shield by ensuring that the shield material is everywhere near saturation. A mathematical model is developed to describe the shielding efficiency of a cylindrical shield as a function of shield geometry and type of shield material. The model is used to develop a possible multiple-shield configuration for a 1.5-T MRI magnet     

The design of space vehicles

In this paper, an attempt has been made to summarise the essential elements of a space vehicle design. After giving an overview of the methodology of spacecraft sizing and configuration, a brief outline of the technical considerations related to the design of different subsystems of the vehicle has been presented. The essential aspects related to manned systems are also discussed. The article concludes with the identification of some of the important payload interfaces, that are relevant to the design of material processing experiments in space.     

Secondary debris impact damage and environment study

All long-duration spacecraft, such as Space Station Freedom (SSF), are subject to impacts by micrometeoroid and orbital debris (MM/OD) particles in low Earth orbit. The secondary effects of such impacts on SSF was the subject of the Secondary Debris Impact Damage and Environment Study. The primary objective was the assessment of possible damage to SSF hardware in the vicinity of large surface areas impacted by typical MM/OD particles. Several SSF components were evaluated that showed varying degrees of damage due to secondary ejecta. A comparison of the results from 45° and 60° MM/OD impacts revealed that penetration ejecta had greater damage potential at 45° and ricochet ejecta had greater damage potential at 60°. The significant ricochet damage was concentrated within an angle of 15° with respect to the primary target. The impact distribution data was evaluated further using a previous math model. The comparison was inconclusive due to insufficient data within the bounds of the model. Preliminary results of the study showed that secondary debris has the potential to penetrate and induce some damage to SSF hardware. The failure of hardware due to the damage is unknown. Further testing with larger MM/OD particle sizes and varying impact angles is recommended.     

Key Technologies and Applications of the Design and Manufacturing of Non-Circular TBMs

With the rapid development of the exploitation of underground space, more and more large- or super-large-diameter tunnel-boring machines (TBMs) are being employed to construct underground space projects. At present, because conventional circular TBMs cannot completely meet the requirements of underground space exploitation regarding the cross-section and space-utilization ratio, non-circular TBMs, which are the tunneling equipment for an ideal cross-section, have become the new market growth point. This paper first presents the technical features and development status of non-circular TBMs. Next, in reference to typical projects and technological innovation, this paper investigates key techniques including shield design optimization, multi-cutterhead excavation, special-shaped segment erection, and soil conditioning in loess strata for a rectangular pipe-jacking machine and a horseshoe-shaped TBM, in order to provide a set of feasible solutions for the design, manufacture, and construction of non-circular TBMs. Relevant engineering practice shows that non-circular TBMs with customized design and manufacture have great advantages in terms of construction schedule, settlement control, and space utilization.     

An autonomous module for supporting mice during spaceflight

The Animal Module for Autonomous space Support (A-MASS) was developed to enable 30-day spaceflight for mice on the first Commercial Experiment Transporter mission. Because space hardware did not previously exist to support mice without astronaut intervention, the A-MASS presented considerable technical and animal care challenges. The technical challenges included maintaining a 42.5l payload volume and 20-g structural conformance while providing 30 days of autonomous mouse support. Sensors, video, a pressurized oxygen supply system and an internal data logging system were incorporated. The A-MASS met NIH guidelines for temperature, humidity, food and water access, oxygen supply, air quality and odor control. These technical and animal care challenges, along with power and mass constraints, were addressed using a novel design which ensures a fresh food and water supply, a clean view path into the cage for the camera system, and removal of the wastes from the air supply. The payload was successfully tested in an enclosed chamber and passed animal health, vibrational, mechanical, and electrical tests. The physiological, tactical and animal support information gathered will be applicable to the development of mouse support modules for the Shuttle Middeck and Space Station Freedom Express Rack environments.     

空间站卫生间人机仿真评估与实践

目的 对空间站卫生间的人机关系进行分析,评价其人机工效,为空间站卫生间人机工程评价、设计优化提供理论方法和技术支持。方法 以DELMIA软件为分析工具,在对空间站卫生间环境建模后,导入航天飞行乘员人体尺寸模型,构建人机仿真虚拟场景。将空间站卫生间如厕过程分解,调整人体模型的如厕姿态及舒适角度范围,对空间站卫生间可达可视域进行判别,开展空间站卫生间如厕姿态舒适性仿真分析与评价。结果 仿真结果显示虚拟航天成员如厕各阶段姿态可达性、可视性、舒适性均满足人机工程学需求。结论 该空间站卫生间能为航天乘员提供一个舒适的如厕环境,其总体结构与布局符合人机工程学设计原则。     

Status of CIEMAT work on PETS

The goal of the present CLIC Test Facility (CTF3) is to demonstrate the technical feasibility of the CLIC scheme, where the RF power extracted from the drive beam is used to accelerate the main beam. Several prototypes of the RF power extractor so-called PETS (Power Extraction and Transfer Structure) have been developed at CIEMAT for this facility. The first device was embedded in a steel vacuum tank and installed at the Test Beam Line (TBL), whose aim is to prove the beam stability during deceleration and power extraction. Presently, CERN and CIEMAT share the responsibility to build eight additional PETS for TBL. Finally, in the framework of EuCARD (European Coordination for Accelerator Research and Development) collaboration, a new PETS configuration is presently under engineering design at CIEMAT. It is based on a compact concept developed at CERN. This device will be installed in the Test Module at CTF3, in a similar configuration to that of the final two-beam scheme acceleration of CLIC. This paper describes the PETS prototype fabrication techniques used at CIEMAT, with particular attention to the production of the long copper rods which induce the RF generation and the welding and assembly procedures. The characterization of the devices with low RF power and the first tests with beam are also described.     

5A06铝合金单层板超高速撞击弹道极限分析

日益增长的空间碎片对在轨航天器的安全运行构成了严重威胁,毫米级空间碎片的防护已成为航天器结构设计必须考虑的问题之一.航天器的蒙皮是抵御空间碎片超高速撞击的最基本防护结构.采用数值仿真并结合试验验证的方法,对5 mm厚5A06铝合金单层板承受2A12铝合金球形弹丸正撞击下的弹道极限进行了研究.研究表明,在验证实验速度范围内,数值仿真结果与实验结果吻合良好;使用数值仿真对实验速度以上的区间进行拓展研究,获得了其弹道极限曲线和弹道极限方程;数值仿真和实验结果与已有经验方程对比表明,经验方程与具体材料的弹道极限有较大偏差,因此,应具体问题具体分析.     

浅谈地铁车站空调箱的配置

我国早期地铁标准车站的公共区（站厅／站台）均按每端配备二台大型空调箱进行设计,为了节省地铁空调设备初投资和土建造价,本文在分析对比了我国近年来东南部主要城市已建成地铁工程实例的基础上,提出地铁标准车站的公共区（站厅／站台）可按每端配备一台大型空调箱进行设计,经过多年运行实践检验,完全满足地铁运营的需要,并显著节省了设备初投资和土建造价,成为我国地铁标准车站公共区空调设计的主要形式。     

Development of a 30–50 K dual-stage pulse tube space cooler

There has been a trend towards increasing heat loads for cryogenically cooled Earth Observation instruments in recent years.This is the case at both the current operational temperature levels (∼50K), as well as at lower operational temperature levels (30–50 K). One solution to meet this trend is to use existing pulse tube technology in a double stage configuration. With such technology increased cooling power at a lower temperature can be achieved at the payload detector. Another advantage of such a system is the possibility to increase overall system efficiency by cooling an intermediate shield to avoid parasitic heat losses towards the detector.Therefore a consortium consisting of Thales Cryogenics B.V. (TCBV), Alternative Energies and Atomic Energy Commission (CEA) and Absolut System (AS) is working on the development of a space cryostat actively cooled by a 2-stage high reliability pulse tube cryocooler. This work is being performed in the frame of an European Space Agency (ESA) Technical Research Program (TRP) (refer 4000109933/14/NL/RA) with a target TRL of 6.This paper presents the design of the overall equipped cryostat and cryostat itself but is mainly focused on the 2-stage cryocooler. Design, manufacturing and test aspects of cryocooler and its the lower level components such as the compressor and cold finger are discussed in detail in this paper. The cryocooler test campaign is meanwhile in final stages of completion and the obtained test results are in line with program objectives.     

External maintenance rate prediction and design concepts for high reliability and availability on space station Freedom

As envisioned in 1990^*, international space station Freedom (SSF) was to be a large, complex, multi-purpose manned facility with a 30-year design life. The presence of a crew and the size of the investment would require high reliability and availability for safety- and mission-critical systems, but even with these requirements satisfied, long life and complexity would make equipment failure and repair inevitable. Recognizing this fact, in 1990 NASA and its contractors performed a study of the maintainability of the then-current space station configuration. Based on well-founded predictions of equipment failure rates, life limits, maintenance rate factors, and repair times, maintenance on equipment outside the pressurized modules of the station alone would have absorbed more than 3000 crew hours per year, which was clearly prohibitive. The chief reason for this maintenance overload was not the unreliability of equipment; it was the sheer number of components present. This paper summarizes this study, and presents a number of design and operational concepts which promise to alleviate the maintenance overload, many of which have been adopted in the current design.The central recommendation was to think of Freedom as a long-term ‘facility’ analogous to a ground-based research laboratory or manufacturing plant, rather than as a ‘space mission’. This philosophy leads to placing as much emphasis on maintainability as reliability in design; rethinking conventional manned-spacecraft design rules such as ‘fail-op-fail-op-fail-safe,’ which contributed heavily to the complexity of the baseline configuration; prioritizing maintenance by time-to-effect as well as ‘criticality,’ and zero-basing systems to wring out excessive complexity while retaining acceptable performance and safety.     

CATIA V5人机工程学功能及应用

介绍了CATIA V5的发展和技术特点,介绍了其人机工程功能,以一个香烟条盒包装机防护罩的设计为例,说明了 CATIA V5在产品设计中的具体应用方法.