Dose estimates in a lunar shelter with regolith shielding

Beyond the Earth's atmosphere, galactic cosmic radiation (GCR) and solar energetic particles (SEPs) are a significant hazard to both manned and robotic missions. For long human missions on the lunar surface (months to a year) a radiation shelter is needed for dose mitigation and emergency protection in case of solar events. This paper investigates the interaction of source protons of solar events like those of February 1956 that emitted many fewer particles with energies up to 1000 MeV and of the October 1989 event of lower protons energy but higher fluence, with the lunar regolith and aluminum shielding of a lunar shelter. The shelter is 5 m in diameter and has a footprint of 5×8 m and a 10 cm thick aluminum support structure, however, actual thickness could be much smaller (～1–2 cm) depending on the weight of the regolith shielding piled on top. The regolith is shown to be slightly more effective than aluminum. Thus, the current results are still applicable for a thinner aluminum structure and increased equivalent (or same mass) thickness of the regolith. The shielding thicknesses to reduce the dose solely due to solar protons in the lunar shelter below those recommended by NASA to astronauts for 30 day-operation in space (250 mSv) and for radiation workers (50 mSv) are determined and compared. The relative attenuation of incident solar protons with regolith shielding and the dose estimates inside the shelter are calculated for center seeking, planar, and isotropic incidence of the source protons. With the center seeking incidence, the dose estimates are the highest, followed by those with isotropic incidence, and the lowest are those with the planar incidence.     

An inversion approach for lunar regolith layer thickness using optical albedo data and microwave emission simulation

An approach to inversion of the lunar regolith layer thickness by using multi-channel brightness temperature observation in passive microwave remote sensing is developed. To first make simulation of brightness temperature from the lunar layered media, the lunar regolith layer thickness (d) is proposed being constructed by available lunar DEM (digital elevation mapping) and on site measurements. The physical temperature distribution (T) over the lunar surface is also empirically assumed as a monotonic function of the latitude. Optical albedo of the lunar nearside from the telescopic observation is employed to construct the spatial distribution of the FeO+TiO₂ content (S) in the lunar regolith layer. A statistic relationship between the DEM and S of the lunar nearside is further extended to construction of S of the lunar farside. Thus, the dielectric permittivity (ε) of global lunar regolith layer can then be determined. Based on all these conditions (d,T,ε), brightness temperature of the lunar regolith layer in passive microwave remote sensing, which is planned for China's Chang-E lunar project, is numerically simulated by a parallel layering model using the strong fluctuation theory of random media.Then, taking these simulations with random noise as observations, an inversion method of the lunar regolith layer thickness is developed by using three- or two-channels brightness temperatures. When the S is low, and the four channels brightness temperatures in China's Chang-E project are well distinguishable, the regolith layer thickness and physical temperature of the underlying lunar rock media can be inverted by the three-channels approach. When the S becomes high that the brightness temperature at high frequency channels such as 19.35, 37 GHz are saturated, the regolith layer thickness is alternatively inverted only by the two-channels approach.Numerical simulation and inversion approach in this paper make an evaluation of the performance for lunar passive microwave remote sensing, and for future data calibration and validation.     

浅表层月壤铲挖采样的振动减阻技术仿真研究

文章对振动铲挖技术在浅表层月壤采样过程中的适用性进行了研究。根据月壤宏观、细观参数,采用离散元法建立了月壤模型,对月球表面低重力低气压环境下的月壤应力—应变特性进行仿真,并结合采用Balovnev机—土交互模型描述的月壤铲挖阻力公式,对月壤的振动减阻机理进行了分析。在此基础上,通过向采样器施加不同振幅和频率的振动,开展了浅表层月壤铲挖仿真,给出了铲挖过程中不同振动参数与月壤采样阻力的关系。同时,通过对比不同工况下的月壤孔隙率,验证了月壤的振动铲挖减阻机理及适用性。     

月球表面热环境数值分析

月球表面热环境的研究对探月活动有重要意义,本文用数值方法分析了月球表面的热环境.首先计算了不同纬度地区地表辐射平衡温度的周期波动,然后建立了月球地表土壤的一维非稳态热传导模型,用此模型计算了不同纬度地区地表温度的波动、月壤温度的波动及恒温层温度和深度,并讨论了月壤热物性对温度波动的影响.结果表明白天的地表温度主要取决于地表的辐射平衡温度,而夜晚的地表温度受到月壤热物性的影响.     

Building components for an outpost on the Lunar soil by means of a novel 3D printing technology

3D-printing technologies are receiving an always increasing attention in architecture, due to their potential use for direct construction of buildings and other complex structures, also of considerable dimensions, with virtually any shape. Some of these technologies rely on an agglomeration process of inert materials, e.g. sand, through a special binding liquid and this capability is of interest for the space community for its potential application to space exploration. In fact, it opens the possibility for exploiting in-situ resources for the construction of buildings in harsh spatial environments. The paper presents the results of a study aimed at assessing the concept of 3D printing technology for building habitats on the Moon using lunar soil, also called regolith. A particular patented 3D-printing technology – D-shape – has been applied, which is, among the existing rapid prototyping systems, the closest to achieving full scale construction of buildings and the physical and chemical characteristics of lunar regolith and terrestrial regolith simulants have been assessed with respect to the working principles of such technology. A novel lunar regolith simulant has also been developed, which almost exactly reproduces the characteristics of the JSC-1A simulant produced in the US. Moreover, tests in air and in vacuum have been performed to demonstrate the occurrence of the reticulation reaction with the regolith simulant. The vacuum tests also showed that evaporation or freezing of the binding liquid can be prevented through a proper injection method. The general requirements of a Moon outpost have been specified, and a preliminary design of the habitat has been developed. Based on such design, a section of the outpost wall has been selected and manufactured at full scale using the D-shape printer and regolith simulant. Test pieces have also been manufactured and their mechanical properties have been assessed.     

一种综合式载人月球基地总体方案及建造规划设想

构建载人月球基地是实现对月球资源深度开发和利用的重要手段之一,文章提出了刚性舱、刚性＋柔性结构以及建造式等三种典型结构的载人月球基地方案,并对三种典型方案的优缺点进行对比分析,在此基础上提出了一种综合式载人月球基地方案设想,基地内部主体创新性地采用充气式柔性连接的方式,外部主体包括月壤防护层、植物密封舱和应急救生飞船,活动系统包括月球车和月球机器人。围绕该方案并结合文章提出的载人月球基地主要技术指标,并对载人月球基地选址、结构设计和构建、空间辐射防护、热管理、能源、通信与导航、生命保障和应急救生技术等关键技术方案进行了分析,为中国未来建设载人月球基地提供了参考。     

Designing from minimum to optimum functionality

This paper discusses a multifaceted strategy to link NASA Minimal Functionality Habitable Element (MFHE) requirements to a compatible growth plan; leading forward to evolutionary, deployable habitats including outpost development stages. The discussion begins by reviewing fundamental geometric features inherent in small scale, vertical and horizontal, pressurized module configuration options to characterize applicability to meet stringent MFHE constraints.A proposed scenario to incorporate a vertical core MFHE concept into an expanded architecture to provide continuity of structural form and a logical path from “minimum” to “optimum” design of a habitable module.The paper describes how habitation and logistics accommodations could be pre-integrated into a common Hab/Log Module that serves both habitation and logistics functions. This is offered as a means to reduce unnecessary redundant development costs and to avoid EVA-intensive on-site adaptation and retrofitting requirements for augmented crew capacity. An evolutionary version of the hard shell Hab/Log design would have an expandable middle section to afford larger living and working accommodations.In conclusion, the paper illustrates that a number of cargo missions referenced for NASA’s 4.0.0 Lunar Campaign Scenario could be eliminated altogether to expedite progress and reduce budgets. The plan concludes with a vertical growth geometry that provides versatile and efficient site development opportunities using a combination of hard Hab/Log modules and a hybrid expandable “CLAM” (Crew Lunar Accommodations Module) element.     

Lunar Base 2015 Stage 1

This paper is a design study for a modular Lunar Base built of at least six cylindrical modules. For launching an ARIANE-Rocket with a payload of 12 ton can be used.To land the modules on the moon the author has designed a Teleoperated Rocket Crane, which is assembled in the Lunar Orbit. The modules are made of aluminium sheets, using a double-shell structure to protect a crew of eight astronauts from radiation, micrometeorites, heat and low temperatures during the lunar night.Lunar material (regolith) is used for shielding.     

月球表面次级中子辐射环境仿真研究

由于缺少磁场和大气,宇宙线高能粒子轰击月壤可以形成月球特有的强中子辐射环境,并对航天员和电子设备造成潜在威胁。文章采用蒙特卡罗方法仿真研究宇宙线高能粒子辐射与月壤成分核反应产生的次级中子能谱特征,给出不同太阳活动、不同月壤深度下月球中子能谱特征和空间分布特征。仿真结果表明,宇宙线高能粒子导致的次级中子随着月壤深度的增加先增大后减小,大约在1 m深度达到最大值,深度越深银河宇宙线诱发的中子贡献越大。相关结果可为我国后续载人月球探测任务的辐射防护设计提供参考。     

月壤剖面锥型螺旋刃成孔钻头设计

针对月壤剖面钻进成孔探测需求,提出一种锥型螺旋刃成孔钻头,建立其钻进排屑性能的理论模型,并以此开展钻头结构参数的优化设计。在此基础上,分析螺旋刃切削姿态及其切削参数,基于直线刃平面切削理论建立锥型螺旋刃成孔钻头钻进切削负载预估模型,开展锥型螺旋刃成孔钻头模拟月壤剖面钻进负载特性试验验证。研究结果表明,相比于直线刃钻头,锥型螺旋刃成孔钻头的钻进排屑性能更优,而且钻进切削负载模型与试验结果具有较好的吻合度。研究成果对我国拟实施的月面钻取采样工程具有重要的借鉴价值。     

Apollo: Learning from the past,for the future

This paper shares an interesting and unique case study of knowledge capture by the National Aeronautics and Space Administration (NASA), an ongoing project to recapture and make available the lessons learned from the Apollo lunar landing project so that those working on future projects do not have to “reinvent the wheel”. NASA’s new Constellation program, the successor to the Space Shuttle program, proposes a return to the Moon using a new generation of vehicles. The Orion Crew Vehicle and the Altair Lunar Lander will use hardware, practices, and techniques descended and derived from Apollo, Shuttle, and the International Space Station. However, the new generation of engineers and managers who will be working with Orion and Altair are largely from the decades following Apollo, and are likely not well aware of what was developed in the 1960s. In 2006, a project at NASA’s Johnson Space Center was started to find pertinent Apollo-era documentation and gather it, format it, and present it using modern tools for today’s engineers and managers. This “Apollo Mission Familiarization for Constellation Personnel” project is accessible via the web from any NASA center for those interested in learning answers to the question “how did we do this during Apollo?”     

A novel autonomous low-cost on-board data handling architecture for a pin-point planetary lander

There has been increased interest in the exploration of the Moon in recent years. Pin-point precision landing is highly desirable for future lunar missions. This paper is concerned with the design of the on-board data handling (OBDH) subsystem for the pin-point lunar lander of the Magnolia-1 project, funded by NASA. Four proposed on-board data handling architectures are outlined and compared in terms of power consumption, performance and reliability. Implementation results are presented, which are obtained from prototyping of the flight computer for the optimal OBDH architecture option on a Xilinx Virtex-5 Field Programmable Gate Array.     

载人登月舱概念设计阶段多方案比较方法初探

载人登月舱是完成载人登月任务的关键环节,也是登月飞行器系统的核心部分。由于登月舱推进剂占总质量的70％以上,因此在概念设计阶段,多方案比较应重点针对推进剂类型及其对应的构型开展对比分析,从而明确总体方案的深入方向。文章给出了该多方案比较的基本思路,并利用美国Altair登月舱作为实例具体说明该方法的基本流程,首先开展月面着陆器的分级方案选择分析、多种推进剂选择分析,并根据推进剂选择分析的结果,完成上升级、二级方案下降级、三级方案制动级的构型方案分析以及气闸舱的布局分析,最后给出组合多种可行方案,并对多种方案进行综合评价,开展比较分析,筘得帚倦对比音塞曲詹缝铖人签目舱柏袷证工椎打下了基础。     

双探针法测量月壤热物性参数的影响因素分析

针对双探针法测量月壤热物性过程,建立了探针与月壤组成的多层介质在太阳辐照加 热与月表辐射散热作用下的二维非稳态传热模型。通过数值模拟,分析了探针长度、直径、 中心间距和加热功率等因素对测量结果的影响。结果表明,若月壤导热系数在0.01W／
(m·K)左右,则月壤的弱导热性是双探针探测设计中需考虑的主要因素。在上述分析的基 础上,设计了双探针结构,对一导热性能较差的松散介质进行了地面测量实验,通过试错法 反演测量数据得到该介质的热扩散率与导热系数,为进一步应用研究提供了参考。     

Canada's role on space station

The paper addresses the evolution of the Canadian Space Station Program between 1981 and 2003. Discussions with potential international partners, aimed at jointly developing the current International Space Station program, were initiated by NASA in 1982. Canada chose, through the further development of the technologies of Canadarm on the space shuttle, to provide and operate an advanced and comprehensive external robotics system for space station, and to use the space station for scientific and commercial purposes. The program was to become a corner-stone of the new Canadian Space Agency. The development phase of the Canadian Space Station Program has been completed and two of the three major elements are currently operational in space.     

月球着陆器着陆稳定性仿真分析

随着中国深空探测的发展,在月球表面进行着陆探测成为新的关注热点,因此月球着陆器的着陆稳定性研究成为一项重要课题。文章利用ADAMS软件及其用户子程序,对一种可展开四腿式月球着陆器的着陆稳定性进行了研究,研究结论为着陆器的着陆缓冲机构及总体设计提供参考。     

模拟月壤激光熔融成型工艺参数试验初探

月壤3D打印可以实现月球的原位资源利用,有望成为月球基地建设和持久运营维护的关键技术手段。文章综述了模拟月壤激光3D打印方法的研究现状,搭建了以CUG-1A模拟月壤为原料的激光熔融成型原理试验系统,并开展了常规环境工艺参数的初步试验。结果显示:激光功率和扫描速度影响激光熔融深度和直径,是模拟月壤激光熔融成型的关键工艺参数;模拟月壤熔融成型过程易出现孔洞、球化等典型缺陷,需要进一步对月壤激光相变机理和上述成型工艺参数进行解析优化。     

A Lunar Laser Ranging Retroreflector Array for the 21st Century

Over the past 40 years, the Lunar Laser Ranging Program (LLRP) to the Apollo Cube Corner (CCR) Retroreflector Arrays (ALLRRA) [1] has supplied almost all of the significant tests of General Relativity. The LLRP has evaluated the PPN parameters, addressed the possible changes in the gravitational constant and the properties of the self-energy of the gravitational field. In addition, the LLRP has provided significant information on the composition and origin of the moon. This is the only Apollo experiment that is still in operation. Initially the ALLRRAs contributed a negligible fraction of the ranging error budget. Over the decades, the ranging capabilities of the ground stations have improved by more than two orders of magnitude. Now, because of the lunar librations, the existing Apollo retroreflector arrays contribute a significant fraction of the limiting errors in the range measurements.The University of Maryland, as the Principal Investigator for the original Apollo arrays, is now proposing a new approach to the Lunar Laser Array technology [2]. The investigation of this new technology, with Professor Currie as Principal Investigator, is currently being supported by two NASA programs and by the INFN-LNF in Frascati, Italy. Thus after the proposed installation during the next lunar landing, the new arrays will support ranging observations that are a factor 100 more accurate than the current ALLRRAs.The new fundamental cosmological physics and the lunar physics [3] that this new Lunar Laser Ranging Retroreflector Array for the 21st Century (LLRRA-21) can provide will be described. In the design of the new array, there are three major challenges: (1) validate the ability to fabricate a CCR of the required specifications, which is significantly beyond the properties of current CCRs, (2) address the thermal and optical effects of the absorption of solar radiation within the CCR, reduce the transfer of heat from the CCR housing and (3) validate an accurate emplacement technique to install the CCR package on the lunar surface. The latter requires a long-term stable relation between the optical center of the array and the deep regolith, that is, below the thermally driven expansion and contraction of the regolith during the lunar day/night cycle.     

Thick galactic cosmic radiation shielding using atmospheric data

NASA is concerned with protecting astronauts from the effects of galactic cosmic radiation and has expended substantial effort in the development of computer models to predict the shielding obtained from various materials. However, these models were only developed for shields up to about 120 g/cm² in mass thickness and have predicted that shields of this mass thickness are insufficient to provide adequate protection for extended deep space flights. Consequently, effort is underway to extend the range of these models to thicker shields and experimental data is required to help confirm the resulting code. In this paper empirically obtained effective dose measurements from aircraft flights in the atmosphere are used to obtain the radiation shielding function of the Earth's atmosphere, a very thick, i.e. high mass, shield. Obtaining this result required solving an inverse problem and the method for solving it is presented. The results are shown to be in agreement with current code in the ranges where they overlap. These results are then checked and used to predict the radiation dosage under thick shields such as planetary regolith and the atmosphere of Venus.