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.     

Towards a lunar base programme

When the requisite technology exists, the US political process will inevitably include lunar surface activities as a major space objective. This article examines a manned lunar base in terms of three distinct functions: the scientific investigation of the Moon and its environment; development of the capability to use lunar resources for beneficial purposes throughout the Earth-Moon systems; and conduct of R&D leading to a self-sufficient and self-supporting manned lunar base. Three scenarios are outlined with respect to each possible function.     

On a lunar space elevator

We consider a space elevator system for lunar surface access that consists of a space station in circumlunar orbit, a cable reaching down to some meters above the surface and a magnetically levitated vehicle driven by a linear motor. It accelerates the load to be lifted to the speed of the cable end. Loads to be delivered are either put on the vehicle and slowed down by it or they are slowed down by a sand braking technique in a mare terrain. It is technically possible to operate this transport system nearly without fuel supply from Earth. We calculate various steel cable dimensions for a static stress maximum of $\text{1}\text{5}\text{th}$ of the tensile strength. The process of takeover is considered in detail. Five ways of eliminating the adverse large cable elongation due to the load are described. The touchdown process and behaviour of the cable after disconnection are analysed. The positive difference between the speed of the load at takeover and cable end can excite a large inplane swing motion. We propose to damp it by a dissipative pulley that hangs in a loop of wire leading to the ends of two beams mounted on the space station tangentially to the orbit, the pulley's core being connected with the load. Roll librations are damped by energy losses in the elastic beams; damping can be reinforced by viscous beam elements and/or controlled out-of-plane motions of the beams. We argue in favour of the possibility of fast deployment. The problems of vehicle vibrations and agglutination at sand braking blades are underlined and their combined experimental investigation is suggested.     

Promoting the coalition for a lunar power system

Powering human civilization in the 21st century with clean energy from the Moon became the focus of a unique conference conducted at the Sea Lodge in LaJolla, California, 9–11 July 1990. Organized by Netrologic Inc of San Diego, the lunar-based Solar Power Planning Workshop attracted an elite group of 25 distinguished scientists, engineers and other professionals to formulate an international Coalition for a Lunar Power System. The participants ranged from Buzz Aldrin of Starcraft Enterprises and Bryan Erb of the Canadian Space Agency, to Osamu Inoue of Shimizu Corporation and Gary McAllister of Bechtel Corporation.     

Stepping stones to the future: Achieving a sustainable lunar outpost

The current emphasis in the US and internationally on lunar robotic missions is generally viewed as a precursor to possible future human missions to the Moon. As initially framed, the implementation of high level policies such as the US Vision for Space Exploration (VSE) might have been limited to either human lunar sortie missions, or to the testing at the Moon of concepts-of-operations and systems for eventual human missions to Mars [White House, Vision for Space Exploration, Washington, DC, 14 January, 2004. [1]]. However, recently announced (December 2006) US goals go much further: these plans now place at the center of future US—and perhaps international—human spaceflight activities a long-term commitment to an outpost on the Moon.Based on available documents, a human lunar outpost could be emplaced as early as the 2020–2025 timeframe, and would involve numerous novel systems, new technologies and unique operations requirements. As such, substantial investments in research and development (R&D) will be necessary prior to, during, and following the deployment of such an outpost. It seems possible that such an outpost will be an international endeavor, not just the undertaking of a single country—and the US has actively courted partners in the VSE. However, critical questions remain concerning an international lunar outpost. What might such an outpost accomplish? To what extent will “sustainability” be built into the outpost? And, most importantly, what will be the outpost's life cycle cost (LCC)?This paper will explore these issues with a view toward informing key policy and program decisions that must be made during the next several years. The paper will (1) describe a high-level analytical model of a modest lunar outpost, (2) examine (using this model) the parametric characteristics of the outpost in terms of the three critical questions indicated above, and (3) present rough estimates of the relationships of outpost goals and “sustainability” to LCC. The paper will also consider possible outpost requirements for near-term investments in enabling research in light of experiences in past advanced technology programs.     

Design of a high performance suspension for lunar rover based on evolution

In this paper, we propose a new suspension for lunar rover called obverse and reverse four-linkage suspension (ORF-L suspension for short). Its two components are designed based on the evolutions of bogie and rocker. Firstly, we analyze the character of bogie and research the approach to improve its performance. Based on that research, an evolved mechanism of bogie is proposed, named obverse four-linkage. It has better capacity than bogie. In addition an evolved mechanism of rocker is also proposed, named reverse four-linkage. The bogie, rocker and their evolved mechanisms can compose four available suspensions including the interested ORF-L suspension. Because ORF-L suspension is composed of two evolved mechanisms, it has the highest performance. In order to check that, the performance comparison between ORF-L suspension and rocker-bogie suspension are carried out based on simulation. Finally, a prototype rover with ORF-L suspension is designed and manufactured. It shows excellent performance as expected.     

Analytical definition and proposed concept for the manned infrastructure of a lunar outpost

A recent study made by ESA has reviewed the scientific investigations to be only, or best, performed on the Moon (Return to the Moon, ESA SP-1150, June 1992), and has identified the need for a manned lunar outpost to provide support to field geologists in sampling and in-situ observations of the lunar surface, and to allow the refurbishments of surface stations and rovers. Planning and development for a manned outpost on the Moon requires an in-depth understanding and analysis of the functions this outpost is expected to perform. We therefore analyzed the impact of the proposed scientific investigations on the design of a manned lunar outpost. The specific questions raised in our study were: What are the medical, physiological and psychological risks for a crew to stay and to work on the Moon? What transit and lunar surface infrastructures (habitats and vehicles) are needed to minimize those risks?     

Does the lunar surface still offer value as a site for astronomical observatories?

Current thinking about the Moon as a destination has revitalized interest in lunar astronomical observatories. Once seen by a large scientific community as a highly enabling site, the dramatic improvement in capabilities for free-space observatories prompts reevaluation of this interest. Whereas the lunar surface offers huge performance advantages for astronomy over terrestrial sites, free-space locales such as Earth orbit or Lagrange points offer performance that is superior to what could be achieved on the Moon. While astronomy from the Moon may be cost-effective once infrastructure is there, it is in many respects no longer clearly enabling compared with free space.     

Heat storage and electricity generation in the Moon during the lunar night

One of the biggest challenges of the exploration of the Moon is the survival of the crew and the lunar assets during the lunar night. The environmental conditions on the lunar surface and its cycle, with long periods of darkness, make any long mission in need of specific amounts of heat and electricity to be successful. We have analyzed two different systems to produce heat and electricity on the Moon's surface. The first system consists of Thermal Wadis, sources of thermal power that can be used to supply heat to protect the exploration systems from the extreme cold during periods of darkness. Previous results showed that Wadis can supply enough heat to keep lunar devices such as rovers above their minimum operating temperature (approximately 243 K). The second system studied here is the Thermal Energy Storage (TES), which is able to run a heat engine during the lunar night to produce electricity. When the Sun is shining on the Moon's surface, the system can run the engine directly using the solar power and simultaneously heat a thermal mass. This thermal mass is used as a high temperature source to run the heat engine during the night. We present analytical and numerical calculations for the determination of an appropriate thermal mass for the TES system.     

An exploration of the effectiveness of artificial mini-magnetospheres as a potential solar storm shelter for long term human space missions

If mankind is to explore the solar system beyond the confines of our Earth and Moon the problem of radiation protection must be addressed. Galactic cosmic rays and highly variable energetic solar particles are an ever-present hazard in interplanetary space.     

一种新的红外烟幕遮蔽效果时域特性评估方法

提出了基于分形特征和Aitkin插值技术的烟幕遮蔽效果时域特性评价的方法,计算了目标热像区域的分数维和分形拟合误差,采用了Aitkin插值技术来获得烟幕场遮蔽效果的时域特性。     

Analysis of volatile lunar compounds: The study of gas retention time on Carbosieve SIII adsorbent with respect to temperature

This work presents the study of the characteristic retention times on Carbosieve SIII adsorbent for several permanent gases CO₂, CO, CH₄, N₂ with respect to the temperature of cooling of adsorption accumulators. To perform this work, a laboratory model of a gas chromatograph that included all key components of a standard instrument has been designed.     

Ground-based simulations of cosmic ray heavy ion interactions in spacecraft and planetary habitat shielding materials

This paper surveys some recent accelerator-based measurements of the nuclear fragmentation of high energy nuclei in shielding and tissue-equivalent materials. These data are needed to make accurate predictions of the radiation field produced at depth in spacecraft and planetary habitat shielding materials and in the human body by heavy charged particles in the galactic cosmic radiation. Projectile-target combinations include 1 GeV/nucleon 56Fe incident on aluminum and graphite and 600 MeV/nucleon 56Fe and 290 MeV/nucleon 12C on polyethylene. We present examples of the dependence of fragmentation on material type and thickness, of a comparison between data and a fragmentation model, and of multiple fragments produced along the beam axis.     

航天员空间活动接受辐射剂量限值的研究

空间生物学辐射效应是由空间辐射环境引起的,空间辐射环境的变化受太阳活动性影响。空间辐射水平比地表面水平高,航天员在空间所接受剂量比地面人员接受的吸收剂量高出100倍甚至更高,并且高能重离子的生物效应显著。文章简要阐述了空间辐射环境、空间辐射生物学效应与航天员的辐射剂量限值等问题。     

Determination of the density and percentage of metal oxides in the lunar soil based on radar data

Results of laboratory measurements of the dielectric characteristics of lunar soil samples returned to the Earth by the Luna and Apollo missions have been analyzed. The feasibility of determining the density of the upper cover of the Moon from the permittivity, which is restored as a result of solving the inverse problem of radiolocation, has been discussed. A formula has been proposed for approximating the frequency dependence of the loss tangent for the regolith and bedrock. Relationships have been deduced for estimating the percentage of metal oxides in the lunar soil.     

Policy making in China’s space program: A history and analysis of the Chang’e lunar orbiter project

China’s space program is one of the most advanced, rapidly improving and opaque in the world. Insight into the program’s policy-making process could help eliminate misunderstandings, make intentions more clear and promote stability in US–China relations. This case study of China’s first lunar orbiting probe traces the project from initial policy proposal through agenda-setting, policy approval and final policy implementation. It reveals a highly rational decision-making process that is ruled by incrementalism, consensus building, scientific judgment and the use of leading small groups to coordinate among ministries. This research was guided by several relevant theories, including the “fragmented authoritarian” framework of power, the theory of the “policy entrepreneur” and the recently developed “inside access model”. The paper is one of the first published accounts in the English language to detail, from policy proposal to policy implementation, China’s first mission to the Moon.     

Application of a magnetohydrodynamic element in the control loop of a rotating spacecraft with cavities partially filled with liquid

This paper is a continuation of [1–3] and a generalization of the results for a rotating spacecraft with cavities partially filled with liquid and equipped with an operational magnetohydrodynamic (MHD) element in the loop of its attitude control. This element makes possible the creation of hingeless systems of stabilization and orientation that do not require rocket propellant consumption. The application of an MHD element is considered for stabilization in the mode of spin-up of a spacecraft not having gyroscopic stability.     

Zero-gravity simulation of liquids in contact with a solid surface

This experimental study concerns the behaviour of liquid spheres in contact with finite solid surfaces, in simulated microgravity conditions by immersion in a liquid of equal density. The liquid spheres are submitted to axial forced oscillations provoked at the contact solid-liquid. The shapes, frequency and amplitude of the liquid sphere oscillations are determined as functions of the sphere and solid-liquid surface dimensions, of the forced oscillations characteristics and of the liquid viscosity. Some conclusions can be drawn from these results about crystal growth in space.     

航天器中一种典型O形密封圈的有限元分析

对于有密封要求的航天器而言,O形密封圈在其中起到了至关重要的作用。文章首先对一种典型的法兰-O形密封圈结构进行合理的简化建模,然后利用有限元分析软件ABAQUS计算了特定压缩率下O形圈的力学性能参数,并讨论了摩擦系数、安装方式、法兰间隙、内压、温差等因素对密封性能的影响,对航天器密封接口的设计具有现实的指导意义。