Earth & Space 2006: Engineering, Construction, and Operations in Challenging Environment

The Jupiter Icy Moons Orbiter (JIMO) Space System is part of the NASA's Prometheus Program. As part of the JIMO engineering team at NASA Glenn Research Center, the structural integrity of the JIMO Heat Rejection Subsystem (HRS) is evaluated. An initial goal of this study was to investigate the use of sensitivity analysis results to determine the relative importance of the input variables on the structural responses of the radiator panel. The desire was to let the sensitivity analysis information identify the important parameters. The probabilistic structural performance evaluation of a HRS radiator sandwich panel was performed. The radiator panel structural performance was assessed in the presence of uncertainties in the loading, fabrication process variables, and material properties. The stress and displacement contours of the deterministic structural analysis at mean probability was performed and results presented. It is followed by a probabilistic evaluation to determine the effect of the primitive variables on the radiator panel structural performance. Based on uncertainties in material properties, structural geometry and loading, the results of the displacement and stress analysis are used as an input file for the probabilistic analysis of the panel. Consequently, design critical material and geometric parameters of the considered sandwich panel are identified.

Structural Health Monitoring (SHM) systems that report in real-time a flight vehicle's condition are central to meeting the demanding goals of increasing flight vehicle safety and reliability while reducing costs. To detect damage with maximum probability, sensors must be placed optimally. This study develops a methodology for sensor placement optimization (SPO) for SHM systems under uncertainty. To achieve this, the structural component under consideration is analyzed via a finite element method (FEM) and model input uncertainties are included via random processes and fields. Probabilistic FEM analyses are performed to determine the model output variability and using their results, damage detection procedures such as feature extraction and state classification are applied to assess the current structural state of the component. Repeating these two steps using both healthy and damaged structural models allows for reliability estimates of a given sensor layout. Finally, SPO is achieved to maximize the reliability of damage detection. The sensor layout design of a thermal protection system component is presented to illustrate the proposed methodology.

Failure of sensitive electronics and fragile substructures resulting from acoustic loading has been identified as a principal cause of payload degradation during launch. Depending on the mission launch vehicle, the fragilities of the payload and other factors, payload protection can range from an un-insulated payload fairing, to the addition of 3 to 6 inches of various acoustic blankets, to various resonant systems (i.e. Helmholtz resonators) to trap energy of critical frequency. Alliant Tech Systems (ATK) has suggested an innovative method for significantly reducing acoustic propagation through the fairing. They have suggested and hold a patent (Ref. Hopkins, Oyler, Raun, Jessen) on a concept of providing a temporary water jacket during the first tens of seconds of launch, while acoustic noise reflected from the surface of the earth generates maximum acoustic loads. For this concept a hollow sandwich panel construction is filled with water and carried a few thousand feet vertically (out of ground reflections). The jacket is then ported, pressurized and evacuated to lighten the mass of the fairing. Although the water mass is a significant factor in total payload/accommodations mass pre-launch, the actual rocket fuel expended in changing the potential and kinetic energy of the water prior to ejection can be very similar to that required to carry conventional acoustic measures to fairing separation. The benefit of the system is a dramatic improvement in acoustic attenuation at low altitude. The Air Force Research Laboratory (AFRL) has developed a patented structural system (ChamberCore), which consists of axial hollow tubes of composite cores bonded between balanced ply configurations of inner and outer composite skin plies. This configuration lends itself easily to supporting the ATK concept for water filled sandwich panels. In 2001, AFRL tested a payload ground transportation module with 5 cm thick voids in both filled and unfilled ChamberCore configuration. Results indicated potential for up to 12 Db of acoustic mitigation over a wide range of frequencies (100 to 5000 Hz). For the present study the AFRL has built and tested a 60 inch tall x 60 inch diameter ChamberCore cylinder filled with various impedance media to test the influence of baseline hollow response to water-filled, denser saturated CaCl₂ solution-filled and to air-entrained water-filled configurations. Results of these tests clearly demonstrate improved acoustic mitigation for all of the fluid variants. Contrary to anticipated results, the type of fluid media had only a small impact on overall acoustic mitigation. These cylinder test results have led to speculation that the internal structure (ribs) between tubes provides a dominant acoustic path below about 6 dB of acoustic attenuation in the fluid media. To test this hypothesis a series of smaller one-dimensional acoustic transmission tests were conducted with varying amounts internal web structure and varying material stiffness, as well as a matrix of various fill media.

Risk taking is the driving force of innovation and success. Aerospace is one such field where calculated risks are essential for progress. Deciding which are necessary and which are not is often difficult. During the first few decades of the space age, the successes in space travel were seen as the measure of a country's vision, leadership in technology, and national defense. From the Challenger to the Hubble, and most recently the Columbia, the space program has experienced technically avoidable disasters. The issues causing these disasters were known prior to launch and were not given the proper priority or did not reach the appropriate decision-makers in time. Organizational culture drove these decision-making breakdowns. In this redaction, we discuss the role of the organizational culture problems that permitted the Challenger tragedy, and how these problems affect decision-making. The goal of this paper is not to further investigate the technical causes of the disasters, but to understand and address the organizational culture that has permitted them. The focus will be on NASA's culture during the 1980s to understand organizational behavior as it relates to the flow of decision-making through the management structure. We propose solutions, to assess high-risk decision-making and a preliminary design for decision-aiding software that could prove beneficial to organizations exposed to high risk. The design for this computer-aided application is supported by current theories in the value of anonymity within group decision-making. Probability theories were incorporated to understand and design the program. To validate the potential and foresee its limitations, this program is applied as a case study to the Challenger Tragedy.

The present work deals with the investigation of aerodynamic forces on grid finned missile configuration over the conventional planar fins. The work is done in this area to provide some further insight reasons why the use of grid fins would be advantageous over more conventional control surfaces. Grid fins usually produce much higher lifting forces and pitching moments to overcome the drag they create. The work involves experimental analysis using wind tunnel testing and comparing the results for both the fin configuration. The dimensions of the missile body configurations are same with only the fin configurations being different. This allows for one—to—one comparison of the data to isolate the effects of fin geometry. The experimental work has been performed using the low speed wind tunnel of Department of Aerospace Engineering, MIT-AU. The tunnel is having a rectangular test section of 3ft height, 4ft width and 6 ft length. The models have been tested in the Reynolds number range of Re = 4.79 x 10⁵ to 1.3 x 10⁶ for different angle of attack ranging from –15 to +15. Free stream pressure of the test section is 1 bar and the blockage area was kept less than 5%. The force measurements were taken using a six-component internal strain gauge balance associated with a 20-channel data acquisition system (VISHAY 5100 B Scanner). The force and aerodynamic coefficients obtained were plotted and the results were reported.

Though theoretical, design and experimental studies connected with the creation of large deployable antenna reflectors have already been carried out for quite a long time, this area still remains of lively interest and has good application prospects. An example is the program of the European Space Agency (ESA) on the creation of a qualified variant of a 15 m deployable space offset reflector. It should be said that by the time the ESA adopted a decision on the implementation of this program, a deployable space reflector 7 m in diameter had already been created in Georgia and, in 1999, this space reflector was successfully tested aboard the orbital station "Mir" according to the joint Georgian-Russian program. The Georgian Institute for Space Constructions continues developing new design principles for large space deployable systems. In the paper we describe the invention of an absolutely new design of a space antenna for symmetric and nonsymmetric radio telescopes, which has been developed by the team of Georgian designers headed by Professor E. Medzmariashvili. The novelty consists in that new engineering and technological effects we obtained by synthesis of ring-shaped and rib-umbrella type systems. In particular, the central hinge that connects the main levers of the pantograph is arranged asymmetrically. As a result of this asymmetric arrangement, during deployment the consoles (folded along the package longitudinal axis and connecting the adjacent sections) move in radial directions from the center to the periphery and, simultaneously, deploy in an umbrella-like manner.

When the diameter of a space antenna reflector exceeds the launcher shroud dimensions, a large deployable reflector technology must be applied. For deployable reflector concepts different approaches are available ranging between shells, rod-cables and rod-membrane systems. For the latest ones having dimensionally stable thin membranes with high in plane stiffness and/or finite bending stiffness facilitating for the stowablity is significant. Using such membranes, highly accurate double curved large reflector surfaces, so called flexible thin shell-membranes can be built. New types of flexible shell-membranes based on fibre reinforced silicone technology being developed at the Institute of Lightweight Structures (LLB) are discussed and an evaluation of thermo-mechanical properties is given in the paper. Evaluation is performed via mechanical tests and FEM nonlinear analyses. Large deployable reflector SMART is presented next, which uses the mentioned shell-membrane. The design principles and building blocks of SMART as well as results of thermo-elastic and dynamic analysis using a fully parametric FE model are addressed. The feasibility of creation of the flexible shell-membrane reflecting surface for LDRs using triax carbon fibre reinforced silicone (CFRS) technology is proved. SMART reflector with CFRS surface has demonstrated the credibility of RF and mechanical concepts up to 10–12 GHz. Reflector demonstrator is being built.

This paper presents an investigation into the dynamic properties of a deployable membrane structure for space altimeter applications. In particular, equations of motion are formulated which account for the viscous forces as well as the tensile ones which are normally addressed in a deployed membrane. Two commercially- available finite element codes, NASTRAN and ANSYS, are examined for their suitability in implementing the governing equations for three-dimensional membrane structures. In particular, the challenges of nonlinear governing equations and their implementation for a three-dimensional membrane structures are explored. The finite element formulation is used to evaluate the influence of membrane boundary shape and boundary tensile forces on the normal modes of the structure when atmospheric pressure is eliminated. The membrane under examination here is a prototype for the development of a possible on-orbit flight experiment in thin structure deployment, where such an experiment addresses necessary questions related to the use of this technology for membrane altimetry and synthetic aperture radar. The prototype includes multiple layers for signal radiation, grounding, and thermal protection, which must be kept parallel in the deployed configuration.

Synthetic aperture radar (SAR) membranes have very stringent flatness requirements. SAR antennas are designed to be perfectly flat with electrical elements at a stable position one with respect to another. Although membranes open the possibility of greater packaging possibilities and a much lower mass, these flatness and dimensional stability requirements must still be respected. Several phenomena will affect the flatness of the membrane: the quality of the tensioning system, the modes of vibration of the membrane, and the material behaviour. Past research has shown that using a pocket adopting the shape of parabola is an excellent way of uniformly tensioning a membrane. The uniform tension along one side of a membrane is needed to avoid the creation of ripples in areas where the tension would differ. This paper shows the need to take into account the slope the cable takes as it exits the tensioning pocket. If this slope differs from the slope imposed by the geometric constraints, the position of the membrane with respect to the pulley, there will be a decrease in tension in the membrane near the extremities of the pocket, and this will lead to ripples in that area of the membrane. The equation system allowing the design of a tensioning system using parabolas and taking into account the geometry of the membrane antenna and its supporting structure is described. An analysis of the first mode of the membrane shows that the deflection brought be this mode could be much larger than any creases created by a faulty tensioning system. Solutions to this problem using our current tensioning system have not been found yet, but other others have started exploring options which could be applicable to our tensioning system.

This paper presents the numerical modeling of the folding of a deployable structure with elastic hinges. Elastic hinges are tape springs, doubly slit cylindrical shells, and coilable longeron truss. We examine the folding process of a deployable structure with nine elastic hinges. The elastic hinge of the deployable structure is a doubly slit cylindrical segment made of composite materials. It allows bending about a lateral axis for stowage. The elastic hinge behaves like a standard beam-like truss member when deployed. The numerical model will be validated using the experimental data to be generated at the Air Force Research Laboratory where the deployment of the same physical deployable structure will be studied using photometry technique. Successful validation will allow designer to use the numerical model for future space structures with the elastic hinges.

Stay-cables are susceptible to external disturbances because of intrinsic low damping. Due to their position restriction, the vibration reduction effectiveness of mechanical dampers can not be fully utilized. A Magnetorheological (MR) fluid based Tuned Mass Damper (TMD) is therefore proposed, which combines the position flexibility of TMDs and the adjustability of MR dampers, to overcome the frequency sensitivity of TMD effectiveness. The developed MR-TMD can be clipped in any place along the cable. Its good vibration reduction effect on the cable vibration is demonstrated experimentally for periodic excitation. The vibration reduction efficiency affected by the relationship among the excitation frequency, the cable frequency, and the damper frequency is discussed. The frequency-tuning strategy of the damper is provided accordingly. The developed strategies may also be applied to other similar vibration reduction problems, such as transmission lines.

Two distinct structural dynamics models for a spacecraft with a symmetric pair of flexible appendages are developed. The first model is a lumped parameter idealization in which the appendages are depicted by rigid bodies attached to the spacecraft central body by torsional springs. In the second model, the appendages are represented by Euler-Bernoulli beams rigidly attached to the spacecraft central body at their roots and free at their terminal end points. Appendages such as long slender antennas and solar arrays can be approximated by both idealizations where for the later case, the primary bending modes of the spacecraft are characterized by deflections of the solar arrays out of their nominal planes. The system natural frequencies and mode shapes are determined analytically, and the effects of geometric offsets are explicitly shown. For the continuum model, the orthogonality conditions for the symmetric and antisymmetric modes are established in the form of an inner product which diagonalizes the system kinetic and potential energies.

This paper emphasizes on the study of mixing behavior of low speed multiple rectangular jets in the presence of the wall. The experimental studies are carried out at the near field of the jet, as most of the mixing processes of technical interest take place in this region. The practical relevance of this work is generally associated with thrust augmenting ejectors for VTOL / STOL aircraft, gas turbine combustors, furnaces, rocket combustors and noise level reduction in jet flows. The exit velocity of the jet is 40 m/s. The Reynolds number based on the width and exit velocity of the jet is 42900. The number of jets used in the present work is varied from one to four with the help of thin splitter plates of 1 mm thickness. A flat plate is placed at the exit of the orifice, to study the effect of the wall on single and multiple jets. Total pressure measurements are taken along the horizontal plane containing the jet axis and also along the plane perpendicular to the jet axis using a pitot probe arrangement. The local velocity of the flow field is calculated by using atmospheric pressure as reference static pressure. The experimental results show that the presence of the wall (α = 0°) at the exit plane of the orifice results in increased jet centerline velocity. The near field flow velocity at Z/D_e value of 8 is increased by 16.3% due to wall effect, in case of rectangular jet without spacer. Similar arguments hold well in case of rectangular jets with one, two and three spacers respectively Velocities along the transverse direction of the jet are greater due to wall effect. Besides, it has detrimental effects on jet mixing.

The flow over delta wing provides a real challenge for experiments and simulations. The leading edge vortex system that forms at high incidence can have significant impact on air vehicles. Couple of features which have caused much controversy over the years have been vortex break down and the formation of substructures in the shear layer rolling up to form the leading edge vortex. A further difficulty is that the vortex breakdown location is highly unsteady, exhibiting oscillations in the streamwise direction. These factors significantly affect the usefulness of the experimental data for aerodynamic analysis and design. Computational simulations are also useful in understanding the role of these factors. The present study deals with experimental and computational investigation of Delta wing with three different leading edge profiles. The experimentations were conducted in a low speed wind tunnel to measure the forces and pressure fields acting on the wing for different angles of attack from –15° to 15° in steps of 5°. The lift and drag coefficients are plotted from the force measurements. The sharp leading edge wing shows an increment in lift at 15° angle of attack. Pressure values obtained are plotted across various spans located at different root chord locations. The change in angle of attack has shown a drastic change in the wing upper surface pressure loading. Computational simulations are made exactly as the experimental conditions using a standard software package and the results are plotted. The experimental values obtained for 21m/s and 38m/s are compared with the computational values, the comparison has show variation in the values. The large radius leading edge wing has shown a better performance than sharp wing at lower angles of attack but at higher angles of attack the sharp wing shows better performance. The results obtained serve as a database for the future delta wing studies.

This paper describes planning required for construction and installation of an infrared aircraft deicing facility at John F. Kennedy International Airport.

Different technological options are presented for an evolutionary architecture towards space-based solar power. The space power grid approach integrates the issues of global warming and energy demand with the technologies for space-based solar power. In the first stage, a constellation of satellites in low earth orbit will transact power exchanges between earth-based power plants. In a second stage, solar energy will be collected and directly converted in low earth orbit to microwave or laser beams. In the final stage, low-mass collectors will focus sunlight on the converters in low earth orbit, opening up large-scale power generation from space with an established ground infrastructure. The system has the potential to enhance the commercial viability of solar and wind-based power plants on earth, by opening markets around the world to smoothen fluctuations in supply and demand.

Cannon launch has been proposed on several occasions as a comparatively inexpensive means of earth-to-space propulsion. In most of these proposals, an initial boost is given to a spacecraft by an electric or light gas gun, followed by a rocket burn that places the spacecraft into a stable orbit. In this study, we examined the accuracy needed to successfully achieve missions based on primarily ballistic trajectories, avoiding midcourse corrections to the extent possible. The results for four different missions are presented. First, launch of a payload from the moon's surface to a "catcher" at Lagrange points 1 and 2, previously studied by Heppenheimer. Next, launch from the earth to a catcher at L1, and, finally, launch from the earth directly to the moon. It was found that the accuracy required in launch speed is within the realm of possibility for electromagnetic launch methods that include feedback control of speed; for example, the accuracy requirement for earth to moon launch is + or –45 m/s at 12 km/s, or + or –0.4%. The acceptable error in launch time for this mission is quite large as well. Assuming an exact speed at the time that the projectile leaves the atmosphere, the launch can occur within a window of approximately one hour. The prospects for achieving these missions with developing electromagnetic launch technology are also presented.

In the mid 70's, researchers proposed using a mass driver for lunar and asteroid mining. The mass driver concept has since been extended to missions where the drivers can be used to alter the orbital trajectory of an asteroid on a collision course with Earth. The potential of using the material of the asteroid itself as reaction mass to provide the impulsive force is undeniably attractive. The mass driver must be able to deliver enough impulse upon an asteroid to prevent it from Earth impact. The results of the preliminary study presented in this paper discuss some of the parameters involved in sizing a mass driver. A finite element program was used to calculate the performance of the mass drivers, and the results were compared with Δv needed to mitigate the Earth-bound asteroid threat. There are many difficulties involved with designing this mission and some of these are discussed. It was found that significant developments in all technology areas involved in this mission are needed for this concept to be considered as a possible solution to save Earth from an asteroid impact.

We report on new experiments undertaken in a study of cratering caused by a turbulent jet associated with, for example, rotorcraft and rocket-propelled vehicles during landing and take-off operations. The experiments were performed using a subsonic air jet exiting a nozzle vertically and impinging upon a horizontal bed of loose particles. To study the high velocity jets associated with rotorcraft and rockets we observed cratering caused by flows about four times stronger than previously studied jet flows. Three bed materials were used: spherical glass beads (80-μm mean diameter, 2.44 g cm^–3), sand (130 μm mean diameter, 2.65 g cm^–3) and crushed polypropylene particles (6 mm mean diameter, 0.9 g cm^–3). These last two materials, sand and polypropylene, were angular, non-spherical particles and are thus geometrically representative of natural soils. This study is distinguished from earlier efforts by our focus on, among other things, high-velocity jets. Our experiments reveal two end-member geometries of craters associated with an impinging jet that can be described as either relatively "weak" or "strong". Under a weak jet a single crater is formed in which sidewall slopes are at or below the angle of repose of the material. The shape of the crater persists after the jet is shut off. Under a strong flow, however, a temporary crater-within-a-crater forms. The inner crater has sidewalls that are steeper than the material angle of repose; in contrast, the shape of the outer crater is conical with sidewall slopes approximately equal to the material angle of repose. This complex geometry persists only during jet impingement and collapses after shutdown to a single, conical crater with side slopes at the material angle of repose. A method for scaling dynamic crater geometry across fluid and particle types, as a function of the flow strength, is presented. We propose that evolving crater geometry may be self-similar in time, thus enabling graphical collapse of existing and new experimental data.

When launching or landing a spacecraft on the regolith of a planetary surface, special attention needs to be paid to the rocket exhaust cratering effects. If the effects are not controlled, the rocket cratering could damage the spacecraft or other surrounding hardware. The cratering effects of a rocket landing on a planet's surface are not understood well, especially for the lunar case with the plume expanding in vacuum. As a result, the blast effects cannot be estimated sufficiently using analytical theories. It is necessary to develop physics-based simulation tools in order to calculate mission-essential parameters. In this work we test out the scaling laws of the physics in regard to growth rate of the crater depth. This will provide the physical insight necessary to begin the physics-based modeling.

The constitutive behavior and deformation characteristics of uncemented granular materials and aggregates are to a large extent derived from the fabric or geometry of the grain structure and interparticle friction resulting from normal forces acting on particles or particle groups. The shear strength of such materials is mainly attributed to the true friction, particle rearrangement/interlocking (dilatancy effects), and crushing. During shearing, particles will slide and/or roll as they interact with each other. In this paper, Computed tomography (CT) was used to acquire high-resolution 3D images of a cylindrical specimen composed of spherical plastic particles. The specimen was tested under axisymmetric triaxial loading condition. Post CT analysis included conducting a comprehensive digitization of particle coordinates at 3 sequential loading stages. Particle-to-particle interaction and visualization in 3D space is presented and discussed. Compared to particle sliding, rotation plays a major role in the shearing resistance of granular materials. The cumulative vertical rotation angles can be as high as 38° and the horizontal rotation angles have values as high as 60°.

In this paper we study the angle of repose and the incline flow behaviors under the Earth and Moon gravity fields, where particles of a range of contact friction are subject to different electrostatic forces. A two-dimensional discrete element method is used in this analysis with two particle shapes. The results show little sensitivity of the angle of repose to gravity. The sensitivity to friction and electrostatic charges can be significant or negligible, depending on the range of these values. The mass flow rate over an incline may be non-dimensionalized so that it collapses to a single curve independent of gravity.

This paper describes an entire procedure to realize an image-based DEM (Discrete Element Method) simulation with lunar soil. Since the detailed grain shape information of the returned sample of the lunar soil is not available, one of its simulant, FJS-1, is used in this study. High resolution micro X-ray CT system at SPring-8, a synchrotron radiation facility in Japan, makes it possible to visualize 3-D image of FJS-1 granular assembly in details. Then a newly developed image analysis procedure is adopted to identify each individual grain from the others. Using the obtained grain shape data, a sufficient number of FJS-1 grains are directly modeled for DEM simulation. A preliminary simulation is performed using these FJS-1 DEM grains and its performance is discussed.

The Moon, which is exposed to the solar wind and solar UV radiation, develops a surface charge which in turn produces an electric field near the surface. The complex plasma environment immediately above the Moon's dusty surface varies over the course of the lunar day and with the passage of the Moon through the Earth's magnetotail. Dust particles injected into this plasma from the regolith, either from human and mechanical activity or from meteoroid impacts or electrostatic forces, are affected by the electrostatic force as well as gravity while above the lunar surface. Sub-micron dust particles may be stably levitated above the lunar surface by the electric force, while larger particles follow nearly ballistic trajectories once they are above the near-surface plasma sheath. These processes pose dust contamination hazards for equipment operating on and near the lunar surface.

Multiple methods, technologies and protocols have been proposed to address the many disparate aspects of dust mitigation. Effective integration of this emerging patchwork of solutions will require consistent metrics across disciplines. We posit a multi-layered mitigation architecture with attainable criteria for each layer. With astronaut(s) at the `center' of the protection layers, environmental standards would set the criteria for the innermost level. Construction of the architecture will establish specific definitions, specifications, standards, implementation contexts and exceptions. Key to the success of the methodology proposed are successive layers of application, providing a robust redundancy. The baseline environmental definitions deliberately set the design points to reasonable and adequate standards. Provisional working standards are set as placeholders. The architecture will serve to align the many mitigation opportunities into a manageable set of engineering guidelines.

The scarcity of lunar soil available for engineering investigations on Earth, in preparation for human return to the Moon, means lunar soil simulants must be used. It is imperative that we know the composition and mineralogy of these so as to better understand the processes under study. We have defined the bulk-chemical composition and mineralogy of three lunar soil simulants, and determined their validity for use in ISRU investigations.

The size distribution of the lunar particles has been determined on Apollo 11 soil sample 10084, 1998. Scanning electron microscopy (SEM) was utilized to photograph areas of particle dispersion, and to measure the areas and diameters of the particles. The specific process for the SEM sample preparation is described. The measured sizes feature a Gaussian distribution having a single mode at around 700nm. These particle-size distribution data are paramount for the effective design of the filtration system for the human habitats, as well as studies of toxicological effects of dust upon respiratory and pulmonary functions.

Wheeled mobile robots are required to negotiate various types of terrain during planetary exploration missions. The associated mobility is a direct function of the wheel—terrain interactions especially in rough landscapes. This paper presents preliminary results of an ongoing study of the interaction of a rigid wheel of a robot with deformable terrains based on a micro-mechanical modeling of the underlying soil. Analyses were conducted under 1 g as well as 0.375 g to compare Earth and Martian gravitational conditions. The performed simulations provided an insight into the patterns of soil-wheel interaction. The stress distribution as well as particle movement beneath the driven rigid wheel showed a response heavily dependent on the gravity level. These simulations also furnished valuable formation on wheel sinkage in terrain.

The behavior of soils at shallow depth is studied for different particle characteristics, packing density and gravity, using both numerical and experimental methods. Higher frictional resistance is observed in angular and well-graded soils. Packing density and inter-particle coordination prevails over individual particle characteristics, and gravity has a secondary effect on the normalized foundation response.

This paper describes ongoing development of a methodology to model large-displacement behavior of non-cohesive soils, such as sands and gravels. A set of artificial neural networks are trained to learn the underlying knowledge behind the large displacement behavior of granular media. Data from a large number of discrete element simulations is used to train the neural networks. Particularly, the NN's are used to relate the stresses at any point inside the soil to the history of stress at some surrounding points as well as soil property and configuration in vicinity of that point. A numerical framework is developed to utilize the trained NN's in simulation environments of granular material flow. The results of 2D and 3D simulations are presented.

Models of granular materials that incorporate grain scale behaviour can be developed using a "bottom-up" approach known as micromechanics. Typically these models are derived from laws introduced to represent inter-particle contact behaviour. Here models based on two separate contact laws are compared. The first law is based on a binary contact interaction governed by spring-slider systems similar to those used in discrete element methods. In the second model, an effective contact law is introduced that is based on the observed behaviour of particle clusters. While the model based on the binary contact law can reproduce some aspects of granular behaviour, it is not capable of predicting both strain softening and dilatant behaviour under biaxial compression. In contrast, the effective contact law is able to reproduce not only the correct stress-strain response, but also the observed microstructural evolution in the two cases examined: uniform deformation and strain localisation. It has the additional advantage that it is able to simulate granular assemblies where the numbers of particles involved would make discrete element methods impractical. To demonstrate this ability results from a finite element simulation of an assembly consisting of over half a million particles are presented. These results suggest that the contact laws used in micromechanical models must account for physical mechanisms occurring in at least two length scales: at the contacts and within particle clusters.

The extremely remote location of Mars suggests that it is not possible to carry enough flight resources to make a roundtrip. Therefore, in-situ mining, conveyance, and transporting of Martian soil must be conducted with the aid of wheel-based vehicles. However, there is limited understanding of the behavior of granular materials in rough rolling contacts with prescribed wheel roughness (or traction). On earth, rolling contacts in the presence of liquid surfaces oftentimes exhibit boundary-traction and hydrodynamic slip, where accurate prediction of the traction behavior between the wheel and the surface is governed by dry friction and hydrodynamic theory. Since granular materials have been known to behave as solids and liquids, a predictive modeling framework is needed to study the behavior of these complex materials under load and as a function of wheel roughness in interfaces. This work describes the usefulness of employing a tribology-based continuum modeling approach, known as granular kinetic lubrication (GKL), to model granular flows in a rough and fixed-load parallel shear cell. Additionally, a lattice, rule-based mathematics modeling approach, known as cellular automata, is explored as a more simplified tool for modeling complex granular systems in shear cells. Results from the two modeling approaches are compared and comments about their usefulness in advancing an understanding of vehicle transport on Martian regolith are made. Lastly, preliminary experimental results are presented on granular flows with varying wheel roughness.

The effects of changing gravity on force transmission within a particulate material that is subject to indentation on its surface by a frictionless rigid flat punch is examined. Particular attention is given to the development of the force chain network as indentation proceeds. As gravity decreased, or, as packing fraction increased, the spatial distribution of the force chain network changed from a dense, tangled network to one consisting of less tangled, longer chains. The distribution of chain lengths was found to be exponential. The magnitude of the resistance force experienced by the punch as it indents scaled with gravity, as did the magnitude of the fluctuations in the load-deflection relation. Using the force chain network, the origin of these fluctuations was examined. Consistent with experiments, the fluctuations in the load-deflection graphs were found to be due to the formation and collapse of force chains. The collapse of force chains was found to be correlated with the transition from solid-like behaviour to liquid-like behaviour of the material, that is, the transition regime at which dilatation and large particle rotations occur in the material surrounding the punch corners.

A 2-dimensional model of a granular assembly, subjected to quasistatic loading conditions (i.e., biaxial compression and pure shear), is examined using the Discrete Element Method (DEM). A series of simulations is performed for dense assemblies of circular particles with varying polydispersity and mode of deformation. The evolution of the contact force distributions (magnitude and orientation) is analyzed and correlated with the development of strain-induced structural anisotropy. A statistical analysis of force chains and their evolution is also performed. The assemblies are found to undergo dilatation and strain-softening. This behavior is correlated with the underlying loss of contacts and increasing structural anisotropy. In the strain-hardening regime, an increase in the average length of the force chains is observed, although there is little change in the overall percentage of particles that constitute these chains. The onset of strain-localization signals a transition to fluid-like behavior and is correlated with the critical coordination number and the maximum degree of contact anisotropy. Evolution of the distribution of the normal contact forces also captures the increasing fragility of the system and the emergence of subsystems of strong and weak particle networks (i.e. particles with above average contact forces and below average contact forces, respectively). The mechanical properties of the granular assemblies are analyzed at the microscale (particle scale), mesoscale (longer range correlations spanning several particles like force chains) and macroscale (e.g. dilatation, strain-softening).

Micrometeorites that continuously impact on the lunar surface are responsible for creating agglutinates which are uniquely irregular, jagged and high porosity. Due to process of agglutinates formation, the amount of agglutinates in lunar soil can be used to estimate the exposure history of the soil by using a lunar soil evolution model. Using commercially available simulation software called the PFC2D^TM, we can simulate the mechanical behavior of a system of particles in general. In the companion paper, the lunar agglutinates are simulated using the parallel-bond model which allows us to incorporate the resistance to moment, and the same approach is taken here. In this paper, we study the formation of agglutinates by simulating the initial lunar surface soils with no agglutinates, and then generating small particles (<20 μm for example) with very high velocities (>5 km/sec for example) impacting the surface lunar soil particles. The kinetic energy associated with an impacting micrometeorite is high enough to fragment/pulverize the coarse particles and the agglutinates and also produce the crater ejecta. In this analysis the equation developed by O'Keefe and Ahrens is used to estimate the volume of melt.

Granular material beds have significant space application, especially in the Advanced Life Support Systems (ALSS). Long-term space missions are possible by using ALSS that facilitate in successively recycling vital life sustaining elements, like water, thereby preventing high re-supply costs. This paper presents results from analytical, computational, and experimental studies of a dry granular bed media of activated alumina enclosed in a cylinder to determine the variation of axial stress and displacement along the bed medium due to applied loads at one end of the bed. A set of closed form analytical expressions has been developed to predict the axial stress and displacement variations based on equilibrium equations, appropriate boundary conditions, and other relevant relations among normal and shearing stresses in the medium. This model takes into account the friction between the media and the walls of the housing cylinder, and considers the fact that the bed is of finite length. The computational model utilizes the finite element method. The bed media and the cylinder walls are modeled using axi-symmetric continuum elements. Frictional contact between the cylinder walls and the bed media is considered. In the experimental study, under the action of an axial applied load at on end, the axial stress in the granular bed was measured at various depth using a load/pressure sensor. The axial stress and deformation results from the experiments, analytical method and computational model are found to match relatively well among each other.

The shearing behavior of a Lunar soil can be described by a Cam yield envelope with best-fitting parameters of friction angle (for critical state, constant-volume shearing) of 40° and critical pressure (compactional strength) of 0.22 MPa. At lower confining pressure, shearing at angles of friction > 40° is dilational, whereas shearing at confining pressures greater than about 0.1 MPa produces compactional flow with negative dilation angles. Lunar soils have large shear strength, due to irregularly shaped particles, and small compactional strength, due to small particle strengths. More accurate determination of the yield envelopes requires laboratory testing of Lunar soils and measurement of the volumetric strains.

From the experiences during the Apollo missions, it is clear that the lunar dust (<20 μm portion of regolith) was deleterious: causing seal failures, particularly to the rock boxes sealed at 10^–12 torr; abrasively cutting through fabric layers; scratching of astronauts' sun visors; contaminating the breathing air in the lunar modules, etc. Because of these unusual and extreme properties of lunar dust, particularly as they apply to the toxicological effects on astronauts, methods for abatement of lunar dust must be addressed before any human presence on the Moon can be fully evaluated. As part of this endeavor, we have conducted a morphological (shape, size, abundance) study of Apollo 17 dust sample 70051. It was determined that the dust particles consist mainly of impact-produced glass, with complicated morphologies, extensive surface areas per grain, and sharp, jagged edges. Importantly, many grains contain elaborate vesicular textures, representing minute agglutinates. These data have profound implications for dust mitigation and in-situ resource utilization on the Moon.

The lunar surface is virtually entirely covered by regolith. Exploration will require interaction with the material, and its potential use for infrastructure and fuel may be vital to support future exploration activities. Engineering challenges and issues that must be addressed in order to utilize and work with the lunar regolith are identified through examination of its geotechnical properties.

We proposed a concept of virtual soil bin for lunar locomotion studies, where 2D DEM analysis was employed with a part of achievements from former Apollo Project. The purpose of this approach is to obtain more reliable and rational solution in the lunar locomotion studies by DEM. The demonstrated concept application suggests that the larger diameter of wheel would be effective for traction-slip performance. The validation of mechanical parameters for contact model of DEM under low-gravity condition should be added for further development of DEM simulation.

A novel method for self-propulsion in granular beds is proposed, which is similar in many respects to self-propulsion at low Reynolds number. Experiments are performed using a robot where the robot's swimming strategy and and dimensions are varied. A simple scaling relation is found that collapses the swimming displacement and qualitatively is similar to Purcell's swimmer, which is a low Reynolds number swimmer.

Abiotic ammonia mass transfer phenomena within a novel biotrickling filter was investigated. The wastestream consists of graywater (hygiene, shower, laundry and food prep water) and waste gas from an upstream solids treatment unit. The bioprocessor is designed to promote absorption of waste gas and biodegradation of contaminants. Following the assumption that advection, diffusion and subsequent bioreaction(s) are independent, transport processes may be analyzed separately and thus only the abiotic mass transfer of ammonia and the effect of surfactants are considered herein. Operating conditions included various gas-phase and liquid-phase flowrates. The experiments were conducted in the presence and absence of the three surfactants of concern, one amphoteric, one anionic, and one nonionic to determine the effect of the surfactants on waste gas absorption. Results indicated that surfactants did not play a significant role in the abiotic mass transfer of ammonia within the system (p-value = 0.998). The data were analyzed using various mass transfer correlations to ensure the validity of this conclusion. Multicomponent gas mixtures and the presence of biofilm(s) during future studies may potentially alter ammonia mass transfer and future research will take this into account.

Resource recovery, including that of urine water extraction, is one of the most crucial aspects of long-term life support in interplanetary space travel. This effort consequently examined an innovative approach to processing raw, undiluted urine based on low-temperature freezing. A strategy uniquely different from NASA's current emphasis on either `integrated' (co-treatment of mixed urine, grey, and condensate waters) or `high-temperature' distillation processing strategies, whereby this liquid freeze-thaw (LiFT) procedure avoids both chemical and microbial cross-contamination concerns while at the same time securing highly desirable reductions in likely energy requirement levels. In essence, this research effort investigated an innovative, first-generation eutectic freeze concentration strategy for extraction of potable water from urine. The existing project's experimental unit, which couples the sequential steps normally associated with conventional eutectic freeze crystallization (e.g., seed crystal growth followed by ice ripening, concentration, washing, extraction, and final ice-water recovery), has proven capable of generating high-quality product water, (i.e., greater than 99% reduction of contaminant concentrations; inorganics, organics, biological and antibiotics), along with a theoretical percent water recovery of 85–95%.

Biodegradation of wastes generated during a long-term crewed space mission is very promising to reduce waste volume, facilitate recycling of water, carbon, and nutrients and to reduce the resupply needs of such missions. Thermophilic aerobic digestion of biodegradable wastes is under investigation as part of the NASA Center of Research and Training (NSCORT) at Purdue University. The Solids Thermophilic Aerobic Reactor (STAR) is under investigation for the initial treatment of all biodegradable solid wastes that would be generated in a crewed mission, including inedible plant wastes, paper, fecal matter, and food wastes. The projected advantages of the STAR system include a reduced retention time, increased rapid pathogen inactivation, lower reactor volume requirements, and ease of automation as compared to other biological waste treatment systems. Preliminary optimization of the system relative to influent solids loading and start-up pH control are reported. The optimal influent solids loading was determined to be 8% total solids, with an HRT of 10 days. It was determined that initial pH control for the first 8 hours of system start-up was required for successful start-up and optimum performance.

The Advance Life Support (ALS) community has intensively researched bioreactors utilizing membrane dissolution technology for bioregenerative water recovery applications. The inherent benefits of bubble less oxygen transfer make them attractive for microgravity environments. A novel membrane reactor currently operating at Kennedy Space Center is being used to evaluate the nitrification efficiency of an early planetary base (ESB) wastestream. The Aerobic Rotational Membrane System (ARMS) utilizes membrane rotation to facilitate increased mass transfer and turbulent flow to optimize nitrification. Investigations have shown that operation under this flow regime plays an important role in both treatment efficiency and also bacterial spatial gradients. A wide range of rotational frequencies has been used during operation of the ARMS. The initial results indicate that increasing rotational frequency corresponds in increasing nitrification. In addition (RTD) tracer analyses verified that turbulent flow exists in the ARMS. It was also found that membrane module packing porosity becomes independent of rotational frequency in the ARMS at frequencies greater then 15 RPM. This paper summarizes the preliminary results of treatment efficiency and hydrodynamic characterization.

The Redox Control Reactor is a new bioreactor design that delivers both oxygen and hydrogen simultaneously through hollow fiber membranes. A prototype is currently being evaluated that is treating an analog urine-based spacecraft wastewater. During initial operation on oxygen only, nitrification rates of 4.5 g/m²-day NH₃-N have been reached, indicating the high transformation rates of the prototype design. Hydrogen supply will be initiated to evaluate the potential for complete nitrogen removal in the Redox Control Reactor through simultaneous nitrification and denitrification.

The Moon is due for re-visitation, not because there is need to re-examine the lunar rocks, but because our technological base has grown continuously to a point that it is possible to establish a permanent global human presence on the Moon. The Moon has a wealth of resources that can be used to support a broad range of human activities from science and engineering to commerce and tourism. President Bush's Vision for Space Exploration sets NASA on a course to have sustained and affordable human and robotic exploration of the Moon, Mars and more destinations in the Solar System. NASA will send human and robotic explorers as partners, leveraging the capabilities of each where most useful. Starting no later than 2008 a series of robotic missions to Moon will explore, prepare and support future human exploration activities. The first extended human expedition to the lunar surface is slated as early as 2015, but no later than 2020. We discuss a step-by-step and a cost-effective approach for colonization of the Moon starting with robotic exploration, identification of key regions of exploration, human return to the Moon using the Crew Exploration Vehicle and other spacecrafts, the lunar surface exploration, setting up of electric grid, manufacturing and mining operations using the lunar regolith and colonization of the Moon. The resources, for returning, exploring and colonizing the Moon, some of them are already present while others are in conceptual design mode. The interdependence of these resources and their utility in the lunar exploration has been explained.

NASA has begun charting a new future, which includes a journey that will take humans back to the Moon, and eventually to Mars and beyond. This new vision for space exploration calls for a "building block" strategy of human and robotic missions to achieve new exploration goals. Robotic missions to the Moon are to begin no later than 2008, followed by human expeditions as early as 2015. This type of accelerated space exploration will require a Space Traffic Control (STC) system to supply guidance to spacecraft, to prevent collisions and efficiently manage space orbital traffic flow. The STC system will need to interface with existing terrestrial Air Traffic Control (ATC) systems and at the same time incorporate Network Centric principles to support operations for a solar wide System of System (SOS) concept. STC Mission Assurance (MA) quantifies the systems ability to reduce operational risk to an acceptable level by the disciplined application of SOS engineering analysis of the STC mission, architecture, design, performance, environment and operations. The acceptable level of operational risk focuses on those mission and safety critical functions whose failure (or degradation) would directly affect system/personnel safety, mission success, and the efficiency of STC operations. The operational risk incorporates the sequence of all value-added activities performed to complete the STC mission, establishing criteria for measuring operational risk and defining the tolerance for operational risk. The Raytheon SOS concept will integrate STC operational goals, existing system capabilities and existing NASA (industry) standards. This will result in a strategic implementation roadmap, which establishes a functional baseline for achieving optimized mission effectiveness through the four mission phases of launch, orbit, en-route and landing. The SOS elements for the STC system are tightly coupled with the incorporation of space travel technological innovations. This paper addresses how the principles of MA support the SOS development of the technologies required for the implementation of a STC system. To incorporate these technological innovations, the STC system MA principles and standards address: 1) Availability Availability is the degree to which the STC system will result in a successful mission. The availability of the STC system influences the impact of emerging technological innovations which control and monitor space traffic. 2) Accuracy Accuracy is the degree of conformity of a detected or predicted position in space to its actual position. Enhancing STC system efficiency and productivity will increase the accuracy of collision avoidance performance bounding for both spacecraft/spacecraft and spacecraft/debris collisions. 3) Integrity Integrity is the correctness and reliability of the STC system. STC integrity issues are associated with the evolutionary transition processes for operations and procedures of tracking and prediction of space debris and space weather. 4) Continuity Continuity combines STC availability, accuracy and integrity to define the level of risk for STC mission assurance. It defines the STC route authority environment that directly influences global planning methodology, systems and facilities.

This paper provides an overview of a lunar miner design to extract solar wind volatiles from the lunar surface at a rate of 69 kg/hr. An in-depth study to determine the optimal combination of compression, intercooling, and storage of the volatiles is described in detail. This optimization makes it possible to minimize the mass and get realistic values for the power and size required for this subsystem. Compared to previous miner designs, this design is less than half the size and nearly half the mass, but retains all the capabilities. The final miner mass is 9.5 tonnes, and is capable of fitting into a rocket payload compartment with an inner diameter of 5.4 meters and length of 13.5 meters.

New information about the internal structures of asteroids and comets continues to be obtained. Meanwhile, renewed emphasis on exploration of the Solar System is sharpening the focus on extra-terrestrial raw materials to facilitate the process. The overall energy cost will be reduced significantly by maximizing usage of locally available resources. This paper refines a previously proposed classification of asteroids and comets for mining purposes, based on updated information about their mechanical properties. Class 0, ice composites, appears less homogeneous than before. Class 1, friable rock, may be the largest group, at the expense of Class 0 and especially Class 2, hard rock. Class 3 remains metallic, divided according to the amount of rock present. Additional information is needed for complete classification, so asteroid/comet mining operations can be planned realistically.

Droplets or bubbles in liquid- or gas-filled tubing, respectively, should be expected in habitats and the construction of habitats in reduced gravity. Life support systems, thermal control loops, transfer of fuels or other liquids, and similar necessities will create situations in which two-phase fluid systems operate or sit quiescent. In all cases — static or flowing droplets in gas or bubbles in liquid — droplets or bubbles will often become wall-bound. Once in contact with the tubing wall, the contact angle of the liquid phase becomes of critical importance to the zero- and reduced-gravity environments. In an isothermal zero-gravity environment, for example, only tubing shape, contact angle, and volume determine the stable geometry of the droplet or bubble at static conditions.

Our understanding of gravity-driven granular flows is based almost exclusively on experiments under Earth's gravity. Here we show that the dynamic angle of repose, or slope, of the flowing shear layer in the canonical case of granular flow in a tumbler of radius r rotating at ω is properly characterized by the Froude number, Fr = ω² r/g, when the acceleration g is varied over a wide range in a large centrifuge. Creeping motion of the subsurface flow is also affected by the g-level.

For the last decade, most applications of microfluidics for "lab-on-a-chip" (LOC) technology have focused on the successful transfer of established technologies from conventional lab-bench methodologies to a chip-based format. Because of the unique environments offered within microfluidic networks, a variety of integration processes can be performed in a continuous format, on one platform. The Lab-on-a-Chip Application Development (LOCAD) team at NASA's Marshall Space Flight Center is utilizing LOC to support technology development specifically for Exploration. This paper will describe the design and operation of an integrated micro-channel/micro-array configuration. Specifically, the filling processes of a liquid inside a circular chamber hosting the micro-array, subjected to a specific inlet pumping velocity at various geometrical and/or operational parameters will be examined. Numerical simulations are performed for the movement of a liquid-gas two-phase flow inside the microchannel and the circular disk-shaped well. The numerical simulations were conducted using the free surface Volume of Fluid (VOF) method which allows for the interface between two immiscible fluids to be simulated while incorporating the effects of surface tension. The results are presented in terms of the movement of the gas-liquid interface. During the filling processes the two-phase flow patterns result from the competition among the inertia, adhesion and surface tension. The numerical results indicate that air bubble entrapment cannot be avoided by continuous pumping of the liquid. A pressure "pulse" in descending increments is necessary to eliminate air entrapment. Only by carefully "tuning" the appropriate balanced pressure drop across the microchannel at the last stage of pulsation, the liquid was able to contract into the small channel.

The concept of using force fields to collect particles into desired shapes has been applied to the problem of space construction. Various geometries of surfaces are obtainable by tailoring the force field. The force field is achieved by utilizing the radiation pressure present in electromagnetic waves. In this paper we show that the curing of the surface can also be achieved using a secondary field. The frequency of the force field is shown to be different from the frequency of the curing field and is strongly dependent on the material electrical properties. The time taken to heat and cure the surface is calculated and found to be within reason. Future experimental work is proposed to validate the theoretical studies shown here.

Long duration human expeditionary missions to the Moon and Mars, such as those currently proposed, will require extensive use of many systems to support exploration and maintain health and safety of the crew. Interaction with these systems for the purpose of control, monitoring and operation will be a full time job whether the crewmembers are in the field (EVA — Extravehicular Activity) or in the habitat (IVA — Intravehicular Activity). Understanding how to coordinate all of the functions and activities that must occur at an expeditionary outpost suggests recreating the same functions and activities at an earth analog site. The analog site includes the habitat/s, all habitat support systems, internal and external, rovers, balloons, science equipment, remote camps, etc., that would be required for an actual mission. This approach differs from analog studies that have been performed to date, as they tend to involve testing of one piece of equipment or one operational modality at a time. Facilities in extreme environments will also be used as precedents for the expeditionary analog. The facilities investigated may include polar outposts (South Pole Station), undersea habitats (Conshelf, Sealab, Tektite), space habitats (Skylab, Salyut, Mir, ISS) and planetary surface bases (the Apollo "J" mission landing sites — Apollo 15, 16 and 17). Study of these facilities may reveal systems and procedures that may be beneficial (or should not be duplicated) at the planetary Earth analog site. The author's experience in design of two (2) analog training facilities (The Antarctic High Station, 1993 and the Flashline Mars Arctic Research Station, 1998 to 2000) will be used to explain the nature of the test facility and the integration of all systems. An analysis of the various systems and the relationships between them and the human users will also serve to demonstrate the possible difficulties inherent in this undertaking and how mission success may be achieved with All-Up analog simulation.

Recent developments have caused an acceleration of business activity aimed at establishing commercial enterprise in space. While space activity for years was exclusively the province of national governments, and while even now national governments are usually involved as either a user or a provider in any space venture, space commerce through private initiative is catching up in a big way. Unfortunately the current legal regime with its idealistic principles restrains the commercialization and development of outer space, and consequently, the realization of its potentially immense economic and humanitarian rewards. The chief purpose of this paper would be to find a way to reconcile the international space law regime with commercial realities of the 21st century. This paper will explore the relevant existing law as it relates to space commerce in detail, highlight the lack of facilitating provisions and try to propose possible solutions to ensure harmonious co-existence between the two.

The current corpus juris spatialis is vague and riddled with inconsistencies as regards the issue of establishing a concrete regime of property rights on moon and other celestial bodies or parts thereof. Hence, the paper seeks to delve into a thorough analysis and interpretation of the governing regime in the contentious arena, whereby I shall elucidate upon the gaps left and the consequent imparting of a nebulous character. Concerning the Moon Treaty, it introduces the much lauded and maligned concept of the "common heritage of mankind" to the considerations of space property law. Therefore, I would contend that the common heritage principle must be defined in light of the Third LOS Convention. I shall further seek to put forth cogent economic arguments, favouring a regime of private property rights in outer space, evidently reflecting the essential basis of all human behaviour, which has been historically (though non-euphemistically) called the "Tragedy of the Commons." Besides, the international regulatory regime presently does contain some provisions which are invaluable to private exploitation of lunar minerals. Emphasis shall be laid on kinds of moratoria, if any, feared by the developed countries: a legal restriction against mineral exploitation and a de facto restriction which results from the ambiguity of the current treaties. Finally, I shall suggest alternative models of working out an efficient as well as equitable Property Rights Regime in outer space, which would take into account the interests of both the developed and the developing world at the same time. Moreover, a more concrete and consistent legal framework needs to be established so as to promote commercialization that has changed the very approach towards space activities, including prospects of extraterrestrial mining, space tourism and habitation.

Public support is critical if the Vision for Space Exploration (VSE) is to be sustained through multiple presidential administrations. This study found that only two national space goals, planetary defense and space energy generation were consistently supported by a significant percentage of the American public. Support for both goals remained constant over the three-year period that saw the Columbia shuttle accident, human spaceflight missions by the Chinese, the development of the VSE, and the success of SpaceShipOne. It is argued that only by linking the VSE to the twin goals of planetary defense and space energy generation will it be possible to create the bipartisan support VSE needs to succeed.

With the development of the TransHab hybrid inflatable habitat, a team at NASA's Johnson Space Center broke with historical paradigms by developing the first endoskeletal space module. The value of this design was cost-effectiveness, efficiency, and the possibility for new forms to support human-rated vehicles and modules for exploration missions. The "TransHab Paradigm" is a complex, semi-inflatable vehicle whose two basic configurations — launch and deployed — are each optimized for their respective environments while retaining fundamental system integration for autonomy and efficient deployment. In this study, the architecture team has undertaken to adapt the paradigm in two ways: first, by designing a module with similar operations concept, but operating in a different environment — that of a planetary surface; and second, by streamlining the relationship between the hard and membranous structures that make up this type of module's principal components.

With the eyes of NASA and other space organizations looking beyond Earth orbit towards Lunar and even Martian territories, more effective design techniques and philosophies must be explored and implemented to ensure a successful and safe mission while saving cost and complexity. This paper will explain the importance of applying a modular design approach in exploration-support and space transportation systems to improve significantly upon the "point solution" strategies traditionally used throughout most of the aerospace industry. A modular design shall imply a system consisting of parts that can be added or rearranged to allow the system to perform a number of different tasks. This would be analogous to a farm tractor in the respect that you can mow, haul, crop, etc. by simply changing the configuration of its attachments. Space exploration would greatly benefit from such a design approach if used throughout a program architecture. This paper will discuss how the implication of a modular design philosophy will reduce the complexity; improve the efficiency; and lower the cost of the entire program. Several examples will be introduced of advantages a modular design philosophy would have over a "point solution" strategy. This paper will then describe ways a modular design philosophy could be broadened to include operations planning for future space, lunar, and planetary travel and exploration. Component commonality is also extremely important to consider while using a modular design philosophy. This paper will focus on the necessity for commonality throughout a spacecraft or surface habitat architecture by discussing examples of how it can be utilized to reduce cost, improve performance and increase the safety of space exploration crews. This paper will also describe several ways that commonality between component interfaces throughout an architecture will not only simplify the architecture, but increase the safety for the crew and reduce the possibility of failure at the interface. Many challenges and struggles lie on the road ahead for the space program. With Lunar and inter-planetary exploration missions on the horizon, the aerospace industry must think smart to solve the ongoing problems of space travel. For this reason, a modular design philosophy must be implemented to simplify particular areas. With this approach the world will be able to effectively and safely explore where no man has ever gone before.

This paper presents the analysis of a proposed lunar base structure comprised of a 3-dimensional frame and an inflatable membrane combination, based on finite element technique, and obtains its stress and deformation response in the service environment. The geometry and dimension of the proposed lunar structure have been evaluated bearing in mind crucial factors such as ease of construction, utilization of local material, and curtailment of construction constituents, and thus, payload to be carried from the earth. The design has been evolved, considering internal pressurization load, regolith shielding load, and self-weight of the structure, satisfying yield strength and buckling strength criteria of the frame members. In the structure the membrane serves as the containment for the internal pressurization as well as supports the regolith covering the structure for radiation and temperature shielding while the 3-D frame gives the stiffness and strength to the structural system to carry the loads. The results predicting the stress and deformation behavior of the frame-membrane composite system for two cases of support conditions are presented.

An interdisciplinary team of designers and researchers are rethinking the design for initial deployment greenhouse modules for the first Martian exploration in order to test the viability of growing enough biomass to support life. Researchers wanted a new model from outside the established aerospace industry's mode of thought in order to question existing strategies for greenhouse design. The resulting schematic ideas awaiting further evaluation represent an architectural sketch for a small modular growth chamber for the surface of Mars.

For future lunar and planetary exploration activities such as in-situ resource utilizations and surface operations, an idea for estimating both c and φ of the lunar surface was proposed. The strength parameters were estimated from the soil-tool response involved in soil cutting processes with blades That is to say, the soil cutting is considered as an in-situ testing, and the boundary problem is inversely analyzed to determine c and φ through a soil-tool interaction model. The method of stress characteristics was used to establish the theoretical model. Moreover, laboratory model tests for the soil cutting were performed using a lunar soil simulant to investigate force-distance behavior and verify the validity of the proposed estimation method. As a result of the verifications, it became clear that the estimated strength parameters are in agreement with drained strength parameters obtained from direct shear box tests. Hence it can be said that there is a possibility that soil cutting process may enable the strength characterization of the lunar surface.

A major component of the Construction & Resource Utilization eXplorer (CRUX) project is a drill system capable of reaching to a depth of 2 m or more in lunar regolith that is hypothesized to contain frozen water. In an initial phase of the project, coring drills were tested in two lunar soil simulants, JSC-1 and FJS-1. Prior to drilling, the soil samples were mixed with 10 wt% water, compacted to 2 g/cc and refrigerated at –85 °C. These conditions aimed to simulate the realistic worst case for drilling conditions at the lunar cold traps. A rotary coring bit, with a 38mm outer diameter, and Polycrystalline Diamond Compact (PDC) cutters, was used to obtain 25 mm cores. Cuttings removal was done by an auger with flutes placed at a pitch angle of fifteen degrees. To prevent the ice in the simulants from thawing during the drilling process, and to reduce convective heat dissipation, all tests were conducted at an atmospheric pressure of 4 torr. The results of these tests showed that the simulated frozen lunar soil was as hard and strong as ice bound sandstone. The data showed a large improvement in the efficiency of drilling and cuttings removal when the rotational speed was increased. It was found that strategically placed channels in the drill bit, designed to convey cuttings from the bottom of the hole to the auger, drastically reduced chances of auger choking and made drilling more steady and predictable. Drilled cuttings were found to be composed of smaller particles than the original soil, indicating that the drill bit crushed the ice-soil mixture rather than detaching individual soil particles from the ice matrix. Drilling data was very similar when tests were conducted in JSC-1 and FJS-1 simulants. The results of these tests are being used to guide the development of the eventual CRUX drilling approach, in terms of both hardware and operational algorithms.

The Construction and Resource Utilization eXplorer (CRUX) project is developing a flexible integrated suite of instruments with data fusion software and an executive controller for in situ regolith resource assessment and characterization. CRUX includes two neutron detectors, the Surface Neutron Probe (SNeuP) and the Borehole Neutron Probe (BNeuP) to help locate and assess potential hydrogen-bearing deposits at the lunar poles and on Mars. Carried on a rover, SNeuP locates near-surface water (or other hydrogenous volatiles) in a lightweight (481 g) package. BNeuP determines the stratigraphy of hydrogenous subsurface layers to depths of 10 meters (or more if an integrated neutron source is used) while operating within a drill string segment. It weighs 517 g, and consumes 2.25 W. The instruments' heritage includes the Lunar Prospector neutron spectrometer and numerous programmatic space instrument applications at Los Alamos. We have tested the SNeuP and BNeuP prototypes and have demonstrated their ability to detect near-surface hydrogenous materials. In a lunar or Mars exploration application the instruments could be passive, sounding materials through the detection of neutrons produced by cosmic ray spallation in soils and ice. However, in terrestrial field tests we have used a neutron source to `illuminate' surrounding materials and gauge the instruments' efficacy.

The chemical and physical characteristics of lunar soil, the fine fraction (<1 cm) of the lunar regolith, are at the root of the unique properties of this abundant resource on the Moon. These characteristics of the lunar soil make the soil an effective feedstock for microwave processing. Approximately 50% of typical lunar soil is <50 μm and consists mainly of impact-produced glass. This glass contains a myriad of tiny metallic Fe grains (3–40 nm). Most soil grains in a mature soil are also coated with thin patinas of silica-rich glass, containing additional and abundant nanophase Fe⁰. These minute metallic Fe grains impart properties to the soil that make it an excellent feedstock for numerous ISRU products. The lunar dust (<20 μm) has a high magnetic susceptibility such that it is almost completely reactive to a simple magnet. The unique abundance of nanophase Fe in the lunar soil also makes for the extreme coupling of the soil to microwave radiation. Effectively, "If a pile of lunar soil is placed in your kitchen microwave oven next to your cup of tea, the soil will melt at 1200 °C before your tea water will boil at 100 °C." Truly a remarkable and startling discovery, but true. This process involves the microwave heating of the fine fraction of the lunar soil, containing the majority of the impact glass with its minute metallic Fe grains which readily couple with 2.45 GHz microwaves. The microwave-treated ISRU products that can be used at a human lunar outpost are only limited by ones imagination.

Microwaves have been used for a number of years as a convenient source of controlled, penetrating radiation providing rapid and selective heating through differential coupling. This paper describes using microwave radiation to drive the carbothermic reduction of iron oxide present in a lunar soil simulant (JSC-1). The goal is to repeat a previous experiment which used a Martian soil analog (JSC Mars-1) and compare results of both experiments. Microwave energy is used to directly convert iron oxide into metallic iron using a minimum amount of energy and equipment without beneficiation. A two-gram sample of JSC-1 was used along with an amount of powdered graphite equal in mass to the percent of elemental Fe contained in the soil. The samples were placed in small alumina crucibles and heated in a domestic microwave oven. The reaction occurs after only a few minutes of exposure to high power. Mössbauer spectroscopy analysis indicates that about nine percent of the iron oxide was converted into elemental iron which corresponds surprising well to the previous experiments with the Martial soil similant.

CRUX is a suite of modular geophysical and borehole instruments combined with a display and decision support system (Mapper/DSS) to characterize regolith resources, surface conditions, and geotechnical properties. CRUX is a NASA-funded Technology Maturation Program effort to provide enabling technology for Lunar and Planetary Surface Operations (LPSO). The Mapper/DSS uses data fusion methods with CRUX instruments, and other available data and models, to provide information about regolith properties needed for LPSO that cannot be determined otherwise. We demonstrate how the data fusion method might be applied to characterize the form of hydrogen and its 3D distribution using a Borehole Neutron Probe and Thermal Evolved Gas Analyzer data as a function of depth to help interpret Surface Neutron Probe data. Information from other CRUX instruments, along with physical models, improves the accuracy of hydrogen distribution characterization, enabling information products for operational decision-making.

This paper reports the results of an ongoing research effort aimed at developing "waterless" concretes based on JSC-1 lunar regolith simulant. "Waterless" concrete, composed of lunar regolith used as an aggregate, and either a provisioned binder or a binder extracted from lunar regolith, such as sulfur, which is used as a cementitious material. The paper also presents several concepts utilizing this concrete for lunar habitat integrated construction. Integrated construction technology trade study data are presented, along with conceptual designs of these concrete application methods. Results of initial technology prototype development efforts are reported.

For long duration missions on other planetary bodies, the use of in situ materials will become increasingly critical. As man's presence on these bodies expands, so must the structures to accommodate them including habitats, laboratories, berms, garages, solar storm shelters, greenhouses, etc. The use of in situ materials will significantly offset required launch upmass and volume issues. Under the auspices of the In Situ Fabrication & Repair (ISFR) Program at NASA/Marshall Space Flight Center (MSFC), the Habitat Structures project has been developing materials and construction technologies to support development of these in situ structures. This paper will report on the development of several of these technologies at MSFC's Prototype Development Laboratory (PDL). These technologies include, but are not limited to, development of extruded concrete and inflatable concrete dome technologies based on waterless and water-based concretes, development of regolith-based blocks with potential radiation shielding binders including polyurethane and polyethylene, pressure regulation systems for inflatable structures, production of glass fibers and rebar derived from molten lunar regolith simulant, development of regolithbag structures, and others, including automation design issues. Results to date and planned efforts for FY06 will also be presented.

Long-duration surface missions to the Moon and Mars will require bases to accommodate habitats for the astronauts, as well as indoor laboratory facilities, in-situ resource plants, power plants, and scientific/surface mobility equipment. Transporting the materials and equipment required to build the necessary habitats would be costly and difficult. However, the use of planetary resources to produce construction materials, or even as naturally found (such as lunar regolith utilized as an outer layer for radiation shielding, or regolith in bags as wall structure), could drastically reduce the upmass for habitats. The materials chosen for the habitat walls play a direct role in protection against each of the mentioned hazards. Choosing the best materials, their configuration, and the amount required is extremely difficult due to the immense size of the design region. For example a 3-layer habitat wall created from 20 possible materials all with varying thicknesses would have #number of layers^{(possible material types)}∧^{(possible thicknesses)} = 3^20&and;inf possible solutions. Clearly, an optimization method is warranted for habitat wall design. Standard optimization techniques are not suitable for problems with such large search spaces. To overcome the large search regions, a habitat wall design tool using genetic algorithms has been developed. GAs use a "survival of the fittest" philosophy, where the most fit individuals are more likely to survive and reproduce, therefore transmitting their genes to the next generation. This paper focuses on finding optimal GA parameters for the habitat optimization tool. This tool is a multiobjective formulation of structural analysis, heat loss, radiation, and meteoroid protection. Some of the constraint calculations (i.e. safety factor, deflection, and heat loss) require long computation times. Even though each material has a designated thickness range, the number of different values within that range is near infinite; therefore, the search space is infinite. Both of these concerns make a more efficient genetic algorithm optimization very appealing. The effect of varying the genetic algorithm parameters (population size, mutation rate, etc.) to find a suitable GA parameter set for this tool will be analyzed and presented here. This produces a higher fidelity of analysis and quicker run times.

Deployable structures for planetary habitats hold strong potential for mass reduction, volume savings, and reduced implementation effort when compared to traditional space structures. There are two major types of structures in this category: deployable metal/composite structures and thin film inflatable (TFI) structures. This paper addresses both of these classes of deployable structures. There has been much work performed in structural design of such concepts, but comparatively little in regard to combining such structures with the use of in-situ planetary resources. The research described in this paper will include (1) nearer-term inflatable and deployable components fabricated on earth and then combined with in-situ materials on a planetary surface, and (2) far-term concepts constructed primarily using in-situ resources. This effort addresses inflatable thin film liners, inflatable primary and secondary structures, and deployable metal/composite primary and secondary structures. The primary focus in the paper is upon nearer-term concepts that are a combination of terrestrial and in-situ materials.

Preliminary analyses have been performed of meteoroid impacts on lunar surface structures built with elements made from in situ materials. The SPHC hydrodynamic code was used to simulate impacts, and was validated against hypervelocity impact test results. Impact risk will affect necessary wall thicknesses, depth of burial, and placement of lunar base structures.

This paper presents a review of experimental data and theoretical models for distribution of near-surface water resources on Mars and the Moon. Theoretical models of the equilibrium between water vapor on Mars and the freezing subsurface temperatures predict the formation of an "ice table" near the surface at sufficiently high latitudes. Experimental data from orbit confirm this prediction. In addition, the orbital data indicate significant water deposits in some equatorial areas. It is not know if this is ground ice or hydrated minerals. Observations on the Moon are indicative of water deposits in some permanently shaded areas near the poles that act as cold traps. However, the data for the Moon are not as convincing as for Mars. It is highly probable that near-surface water resources will be accessible for in situ resource utilization (ISRU) on Mars, but the case for the Moon is less certain.

H₂O on Mars is an essential resource for future human exploration. H2O-based in-situ resource utilization (ISRU) on Mars will provide the necessary raw ingredients for propellant production and energy storage, oxygen and water for life support. The importance of H2O-based in-situ propellant production (ISPP) cannot be understated — there is no planned terrestrial launch vehicle in the near or longer term future that can deliver a fully fueled return launch vehicle to the surface of Mars. We provide a brief summary of trades considered when estimating mass requirements for H₂O for a surface mission to Mars. A companion session paper ("Accessible Water on Mars and The Moon" by Rapp and others) describes the current understanding for the existence of H₂O on Mars based on current orbital mapping missions and numerous existing corroborating models. Abundant, accessible Mars H₂O likely exists in the form of near-subsurface ice-filled porous regolith, particularly at latitudes ~50° and higher. The upcoming 2007 Phoenix mission will provide an additional datapoint to confirm or refute this expectation. In this paper, we describe a novel extraction mechanism for such an H₂O resource based on enhancing the optical properties of the surface to improve the coupling of solar energy into the soil and induce forced sublimation down to > 0.5m within 150 sols (martian days). Development and results of a theoretical model for describing the sublimation process are presented.

The technological and technical innovations needed to achieve the goal of a long-term presence on the lunar surface are seen as a necessary first step to landing a human mission on Mars. Given the lifting limitations of current rocket technology, this demands innovation to harvest in situ as many of the raw materials as possible for long-term existence in remote extraterrestrial environments. Many catalytic reactions currently engineered for industrial use have relied on gravity conditions on Earth, and make use of phase separation and the diffusion of materials in a liquid or gaseous state within an environment at 1g. Hence, such processes are poorly designed for efficiently producing raw materials in low gravity environments. Additionally, the regolith of the lunar surface is primarily a granular media containing both silica and iron oxides; Mars has a regolith dominated by iron oxide. Water and oxygen are two of the most vital resources that will need to be extracted constantly and efficiently in hostile and low gravity environments. In this paper, we report results of experiments in a 1g environment designed to study the effect of vertical vibration on the extraction of water from a silica oxide substrate. There is a significant effect observed of lowering the temperature at which water is released from the porous substrate in the presence of external agitation. The lower temperature corresponds to less heat energy required to remove water physically adsorbed and possibly release the interstitial water. A better understanding of this result could potentially benefit the efficiency of several catalytic reactions in low gravity environments through the release of interstitial and reactive elements at lower temperatures. The results of this pilot study could have significant repercussions on the remote processing that will be necessary in the lunar environment.

The simulation of lunar granular regolith requires the use of models that accurately represent the interaction of highly angular particles. Discrete element method (DEM) is an effective tool for the simulation of granular material behaviors such as particle flows and tool-medium interactions. This paper describes the development of a new three-dimensional discrete element code BLOKS3D for the simulation of polyhedral particles. New algorithms are presented for neighbor search and contact detection. These algorithms are more efficient than currently available in the literature and significantly improve the analysis speed. A series of simulation examples on direct shear tests are presented to demonstrate and evaluate the performance of the proposed algorithms and the overall DEM code. A comparison with a series of physical experiments of the interaction of earthmoving equipment with soil further demonstrates the performance of the developed DEM code.

A lunar base is an essential part of all the new space exploration programs because the Moon is the most logical first destination in space. Its hazardous environment will pose challenges for all engineering disciplines involved. A structural engineer's approach is outlined in this paper, discussing possible materials and structural concepts for second-generation construction on the Moon. Several different concepts are evaluated and the most reasonable is chosen for a detailed design. During the design process, different solutions, for example for the connections, were found. Although lunar construction is difficult, the proposed design offers a relatively simple structural frame for erection. A habitat on the Moon can be built with a reasonable factor of safety and existing technology. Even so, we recognize the very significant difficulties that await our return to the Moon. This paper and presentation is based on the works by Ruess, and Ruess, Schänzlin, and Benaroya.

This paper will present a methodology for assessing relative advantages, disadvantages and conditional implications of different habitat module choices and applications for lunar/ Mars settlements. The process is illustrated using a variety of module types, including conventional horizontal elements, and vertical and horizontal inflatable approaches. Considerations include surface transportation, site preparation, pressurization, outside viewing, and evolutionary settlement growth staging.

The purpose of this paper is to present the work done by the Habitation Strategy Team during Phase 1 of the RFT0019.05 JSC Lunar Surface Scenario Study conducted during the Spring 2005. The team started by reviewing the Lunar Roadmap Architecture Options, then identifying strategies related to habitation for each option. While doing this, the team developed an understanding of the functional attributes and interfacing systems of the Habitation System. The main intent of this was to identify any competing or similar components of strategies that would satisfy the goals of the four programmatic options. The Habitation Strategy Team coordinated with other strategy teams during this Phase 1 activity. This included Power, Radiation Protection, Lunar Surface Science, Life Science, ISRU and EVA.

The concept of the Technology Readiness Level is widely used in government agencies to compare the relative implementability of various design concepts and physical hardware. Recognizing the need for a similar metric for use with habitation systems, NASA has initiated an effort to develop a Habitation Readiness Level for use in comparing various proposed habitation systems for a lunar outpost, and eventually for Mars expeditions. With many concepts for planetary habitats proposed over the past 20 years, there are many strategic technical challenges facing designers of planetary habitats that will support NASA's exploration of the Moon and Mars. The systematic assessment of a variety of planetary habitat options will offer an important approach and will influence guideline requirements for human design, volumetrics, functionality, systems hardware and operations.

Ground-based space operations have historically focused on launch support facilities and ranges, reflecting the relative scarcity of spacecraft recovery as compared to launches. The future promises increasing application of recoverable spacecraft for returning crew and materials to Earth. Heritage recovery approaches may not effectively support future spacecraft operations. Future spacecraft recovery ports may be optimally realized to deal with this increasing recoverable traffic. Various space faring entities have established launch complexes reflecting the requirements and influencing factors of their particular space flight operations, (e.g. geographical location vis a vis launch performance, launch range versatility and safety, interfaces for terrestrial transportation, supportive services, material and equipment, and geopolitical considerations). Establishing spacecraft recovery complexes will demand that similar concerns be addressed in a versatile manner, especially if a common port is to accommodate an evolving set of vehicles and users. Entry vectors influence the selection of recovery sites, reflecting risk from over-flight of populated areas. Cooperation with air traffic regulators is required to coordinate entry airspace issues involving aviation traffic, monitoring and control. Coordination with maritime regulators, including oil platforms and vessels, addresses risk from spacecraft recovery operations occurring over water. If properly located, a shared recovery port complex may host land, maritime, or air-capture operations. Post-recovery transportation capabilities providing interactive multi-modal options for surface, sea, and air transportation would meet the needs of all users. Countries and commercial entities face common challenges in spacecraft recovery operational and facilities requirements. A common recovery port would promote affordability and reduce environmental impact otherwise associated with multiple recovery sites. Shared use must be reflected in the design philosophy and management paradigm under which the port is developed and operated. This paper explores concepts for a spacecraft recovery ports. Topics include range characteristics, recovery infrastructure, interfaces to industrial and user-supportive capabilities, social-economic and political issues, and concepts of operation. The paper closes with a description of a notional recovery port located in the continental United States.

The considerations and concepts presented in this paper are part of a comprehensive design project undertaken by Sasakawa International Center of Space Architecture (SICSA) in cooperation with SPACEHAB's Concept Exploration Evaluation & Refinement (CEE&R) contract with NASA. The paper discusses rationale and innovative ideas for the interior architecture of a lunar/ Mars surface habitat module using an "inflatable" construction approach. This technique utilizes soft pliable laminated wall sections that can be folded to minimize the launch volume, and later deployed on the surface to provide a substantially larger volume. This construction scheme incorporates proposed interior concepts and applications that can provide a variety of advantages. The major intent of this design is to create a habitable platform to: (1) Maximize crew safety, spatial efficiency, flexibility and versatility of function. (2) Minimize crew problems, conflicts and activity interferences. (3) Increase operational and performance advantages of partial-gravity environments. (4) Create solutions to optimize physical and psychological adaptation during long term planetary missions.

Pressurized rovers will be a critical component of successful lunar exploration to enable safe investigation of sites distant from the outpost location. A pressurized rover is a complex system with the same functions as any other crewed vehicle. Designs for a pressurized rover need to take into account significant constraints, a multitude of tasks to be performed inside and out, and the complexity of life support systems to support the crew. In future studies, pressurized rovers should be given the same level of consideration as any other vehicle occupied by the crew.

The first return of humans to the lunar surface will take the form of short-duration sorties. Current mission planning at the National Aeronautics and Space Administration (NASA) for lunar sorties includes four crew members living out of their landed lunar surface access module (LSAM) for 4 to 7 days. Potential landing sites of high scientific interest or with potential resources for development and utilization have been identified, including sites on the near side, far side, and polar regions. Extravehicular activities (EVAs) with suited astronauts out on the lunar surface will dominate surface operations. Critical capabilities that will be needed to support these activities include, surface mobility systems, long-lived power systems, global communication and navigation systems, teleoperated robotic systems, the ability to explore sub-surface, and dust mitigation and planetary protection techniques. Though extremely short in mission duration, human sorties to the Moon can also begin the testing of Mars-forward operational techniques and surface systems technologies.

Much has been made of NASA's new mission from the President on January 14, 2004 to "gain a new foothold on the moon and to prepare for new journeys to the worlds beyond our own." As public/private partnerships to begin the exploration of the moon's resources through commercial development on the lunar surface grow closer, now is the opportune time to ensure that community master planning is fully integrated into the thought processes. Planning for the sustainable human environment is vital to the success of the mission. Without livable cities, properly laid out with all amenities, few people will be enticed to stay for long periods of time, which is what will be required to realize the full economic benefits of lunar development. The community land use planning process will result in adequate allocation of land mass for all aspects of life on the moon including areas for housing, work, recreation, commercial space, industrial facilities, transportation, utilities and all life support and plenty of room for expansion as the colony grows. Unlike the haphazard, mostly uncontrolled development of communities on earth, lunar development must be tightly regulated. Because of the extreme complexity and life or death nature of life support on the lunar surface, the community master planning process must be a highly collaborative effort among those scientists and engineers in the business of space exploration and development and those professionals experienced in master planning, resulting in the best utilization of the moon's resources. What we don't know right now is much greater than what we do know, and we recognize that at this point not even all the questions that need to be asked are known for colonization of other planetary surfaces. What we do know, though, is that the collaborative master planning process will be more important than ever to meet these new challenges. This process will involve many scientists, future colonists, engineers, environmentalists, life safety and emergency services personnel, communications specialists, retailers, industry representatives, and planners meeting together to reach a common goal. Similar to the planning charrettes of today, having all participants together simultaneously creates synergy where each problem solved leads to more questions for the group to address. With a blank palette on which to create, colonization of other planetary surfaces is a unique opportunity to do the best job of community master planning possible. It will in fact be critical to the success of the venture. No one person that comes to the table will have all the answers but that is the beauty of the collaborative community master planning process. A successful community master plan can create cities that will be livable by the first generations of Lunarians and can be enjoyed by future generations as well. As citizens of Savannah, Georgia whose city plan was developed by its founder, General James Oglethorpe, two hundred and seventy five years ago we know how much more livable planned development can be. Every day the citizens of Savannah still benefit from the well thought out plan for the city with green squares and tree lined streets which provide space to work, live and play and relax. Our goal for lunar base community master planning is to create a lunar base and eventually cities that will be enjoyed by their inhabitants for 275 years and beyond.

Revitalization of NASA's lunar robotic and human exploration program is underway. Data from previous exploration missions is being reexamined, interpolated, and extrapolated to near term and far term needs for development of human outposts. Within the development process, site analysis will use this data and propose new data required to establish the infrastructure design for which environmental effects are accounted, facility functions and arrangement are optimized, safety and health risks are minimized, and science return is maximized. The content and application of site analysis to lunar outpost and base design and utilization will be discussed.

SelfSim, self-learning simulations, is a novel method that extracts the material constitutive behavior using boundary measurements of load and displacement. The method allows the numerical model to continuously learn from laboratory and field observations, and to characterize any material constitutive behavior. SelfSim has been extensively verified and applied to various problems using simulated and physical boundary measurements. The applications include: structural tests on metals, bridges, deep excavations and laboratory tests on granular material. This paper presents a brief overview of SelfSim method and its applications on the characterization of granular materials. For extra-terrestrial (lunar and Martian) environments it is possible to apply SelfSim in novel ways to extract relevant regolith constitutive properties using measurements of forces and displacements on instrumented rovers or other surface equipments. Specially designed probes can also be utilized to extract constitutive behavior at depth. The paper will describe conceptually how such probes and measurements can be made without the need to bring back samples for terrestrial laboratory testing.

Predictions of arching in sand mounds are discussed first. Admissible stress fields with a stress `dip' at the center of the base caused by arching are presented. It is argued that the nonlinearity of the yield condition may enhance the materials' tendency to arching. The problem of hopper flow is used to illustrate how the width of a hopper outlet can be estimated to prevent arching.

During preparations for the Apollo missions, regolith simulants were used for design, experiments and prototype development (e.g. the Lunar Roving Vehicle). The soils were not high-fidelity simulants, but were of great use during design and testing, leading to successful Apollo missions. When lunar exploration plans again were introduced in the late 1980s, new simulants were produced and widely distributed for research activities. Only small quantities of those simulants are still available. Future Lunar exploration will require re-examination of existing regolith simulants as well as the development and production of new simulants. This paper reviews properties of two existing lunar regolith simulants, MLS-1 and JSC-1, to provide the research community with a background for increased understanding of previous research and planned exploration methods. Both simulants discussed have variations from lunar regolith and were tested in the terrestrial environment, which can have significant effects on results. The variations between terrestrial simulants and lunar regolith and the related engineering implications are discussed.

This paper describes a newly designed crawler-type vehicle for the Moon exploration. It aims at achieving higher mobility for bigger and heavier transportations in the future as well as enhancing the mobility of current small or medium sized robotic vehicles, focusing on the slope-climbing capability on pure sand slopes. The designed vehicle has four mesh crawlers to reduce weight and the number of parts. A single crawler test was conducted using a slope traveling test apparatus to obtain the effects of slope inclination on the relationships between slip ratio and vertical load, or between ultimate current and vertical load. The results show that there is an optimal design point for the contact area and that the design point is fairly robust for the weight increase. The power consumption of the single crawler increased linearly along the traveling distance for all the test cases, which means that the slip ratio and current were stable during the test traveling. A single wheel test was conducted for comparison. The wheel's slip ratio and power consumption were bigger than that of the crawler at a slope of 20 degree and its power consumption increased non-linearly along the traveling distance. The test results obtained so far indicate that a crawler-type vehicle shows higher performance and lower power consumption than a wheel on steep slopes under the experimental condition.

Conventional concrete paving construction machinery has insufficient automation in design, standardized process, and controls for paving construction in hazardous environments on earth as well as other planets. Although the state-of-the-art paving process includes a high level of automation, the process is still labor intensive which hinders its use due to operation cost and safety in hazardous environments. Researchers at Ohio University are developing an autonomous robot to perform the rebar placement, vibration, screed, and curing tasks associated with a concrete paving process. These single tasks can be automated and integrated into a novel single paving robot called RoboPaver. This single robot is capable of operating in challenging environments on Earth and on other planetary bodies such as the Moon and Mars with minimal assistance. This paper presents the mechanical and controller design of a fully autonomous robot that will be used for concrete pavement construction. It is envisioned that with the aid of an autonomous paving robot, pavement construction can be safely conducted in hazardous environments, for which conventional paving equipment and operations are not suited.

Conventional teleoperation systems have been developed as an efficient solution to explore unstructured environments where hazardous materials have been accidently spilled or released. Due to inevitable restrictions in the field of view of the remote camera(s) and in the quality of the visual displays fed back from the remote worksite, the operator is often unable to maintain a level of situational awareness sufficient for safe and efficient task execution. To address some of the challenges of this nature, Mixed Reality (MR) technology that combines real environment with virtual information together on a single display is envisaged to enhance the current teleoperation visual interface for supporting decision making and judging while operating in unstructured environment. The paper presents an intuitive concept of applying techniques of MR to increase the operator's situational awareness and spatial cognitive skills critical to teleoperation, with a focus on remote navigation and excavation.

Mankind has continued challenging to the universe with curiosity since mid-1950s, and, as a result, the mankind could step on the moon and launch the satellites and exploration robots to several planets including Mars to collect desired information. The construction has contributed to the mankind's development and abundant life for a long time. The interests of mankind are focused on the universe, and the mankind set forth expanding their life to the space based on the accumulated information on the universe. To realize these wishes, the mankind has to construction technologies, and the construction engineers of ability shall play a core role for the universal development. This study is to determine the elements to be considered for the space construction through examining the materials of the construction robot and space development. This study is purposed to present the development direction of robots for the space construction.

Current NASA plans envision human beings returning to the Moon in 2018 and, once there, establishing a permanent outpost from which we may initiate a long-term effort to visit other planetary bodies in the Solar System. This will be a bold, risky, and costly journey, comparable to the Great Navigations of the fifteenth and sixteenth centuries. Therefore, it is important that all possible actions be taken to maximize the astronauts' safety and productivity. This can be achieved by deploying fleets of autonomous robots for mineral prospecting and mining, habitat construction, fuel production, inspection and maintenance, etc.; and by providing the humans with the capability to telesupervise the robots' operation and to teleoperate them whenever necessary or appropriate, all from a safe, "shirtsleeve" environment. This paper describes the authors' work in progress on the development of a Robot Supervision Architecture (RSA) for safe and efficient space exploration and operation. By combining the humans' advanced reasoning capabilities with the robots' suitability for harsh space environments, we will demonstrate significant productivity gains while reducing the amount of weight that must be lifted from Earth — and, therefore, cost. Our first instantiation of the RSA is a wide-area mineral prospecting task, where a fleet of robots survey a pre-determined area autonomously, sampling for minerals of interest. When the robots require assistance — e.g., when they encounter navigation problems, reach a prospecting site, or find a potentially interesting rock formation — they signal a human telesupervisor at base, who intervenes via a high-fidelity geometrically-correct stereoscopic telepresence system. In addition to prospecting, the RSA applies to a variety of other tasks, both on the surface: mining, transporting, and construction — and on-orbit: construction, inspection, and repair of large space structures and satellites.

Deep space drilling is necessary for appropriate chemical and biological sampling for subsurface exploration. The Smart Space Drilling System (SSDS), which is currently being developed at Northeastern University (NU), is a compact self-propelled, steerable electromechanical drilling system that can penetrate into large depths in planetary bodies. In this paper we present the detailed design and modeling of the SSDS. Its main components are: a) the drill bit/cuttings bucket, b) the rotary propulsion unit including three 3-degree of freedom (DOF) propulsion actuators, c) the power/control module, d) the non-rotating steering unit including three 1-DOF steering actuators and e) the communication module. Three 3-DOF propulsion actuators uniformly distributed around the rotary propulsion unit impart rotating, linear motion to the drilling bit, while another three 1-DOF steering actuators provide the steering force for automatic directional control. The SSDS is propelled in the manner of a turning screw, which offers simpler kinematics structure, higher efficiency and thus, potential for miniaturization and deep drilling. Mathematical modeling and analysis of the SSDS were conducted to predict, design and optimize its performance.

This paper reports on efforts to utilize real-time 3D graphics to produce visualizations of lunar architectures and vehicles for low to medium fidelity design simulations with a goal to support trade studies.

Humans have dreamed of exploring Mars for many years. However, the recent mandate by President Bush directing NASA to send humans to Mars (after first returning to the moon) has transformed the work in planetary exploration from the realm of paper studies and theory back into the realm of a near-term reality [4]. As humans prepare to venture out of low Earth orbit, robots will be integral teammates in this endeavor, if for no other reason than size of the area to be explored. The moon has a surface area approximately the size of the continents of North and South America combined, and Mars has a surface area approximately the size of the entire land mass of Earth. Because of the shear scale of this exploration area (and the limited number of humans who will be able to visit on any given mission), robots will be involved in any realistic exploration scenario. Many of these robots will operate on their own (or with other robots) and never work alongside humans. However, other robots (akin to the lunar rovers used during the later Apollo missions) will be specifically designed to assist humans and maximize their effectiveness during Extravehicular Activities (EVAs). These robots will afford the astronauts the mobility to explore much larger areas of the surface than they would be able to reach on their own, allow them to transport scientific equipment, and provide task assistance at several levels. Commands sent from Earth cannot travel faster than the speed of light, and data/images from the robots are also subject to this limit. This intergalactic speed limit leads to minimum round trip signal delays between Earth and the moon of about 2.5 sec, and for Mars the time varies from about 8 to 42 minutes, depending on the planetary alignment. Because of these delays, robots will be most effective if they primarily receive high level commands and goals from Earth. Deploying robots capable of accepting high level commands will require them to be more self-sufficient (and self-monitoring) so that they can work autonomously to achieve those high level goals. Designing these autonomous mobile robots will require careful planning and utilize a wide range of engineering and scientific disciplines/technologies which are currently in various stages of maturity. All robots intended to be used as human assistants will need to be designed to maximize the effectiveness of EVAs. Furthermore, these robots must be "safe" around the astronauts, so they do not increase the net risk involved in planetary exploration. The robots will help maximize EVA effectiveness by providing combinations of: increased EVA exploration range, increased EVA duration, increased payload capability, and increased situational awareness. These human-assistant robots must also be designed to minimize the overhead (repairs, maintenance, "boot time", etc) associated with their operation, so that they are truly providing assistance (and not a net hindrance) to the astronauts. This paper attempts to describe the robots most likely to be deployed as human assistant robots over the next 15 years to help support lunar surface exploration as a precursor to missions to Mars.

Large rockets can fail during launch and be very hazardous to the public. Risk analysis methods are necessary to determine the likelihood and magnitude of the risk. This is usually combined into a single measure, casualty expectation, which represents the average number of casualties per launch. Real-time safety controls are introduced and the steps to compute the risk are summarized. Also discussed are alternate risk presentations, level of risk acceptability and methods to mitigate the risk.

The Jet Propulsion Laboratory (JPL) formulates and conducts deep space missions for NASA (the National Aeronautics and Space Administration). The Chief Technologist of JPL has responsibility for strategic planning of the laboratory's advanced technology program to assure that the required technological capabilities to enable future missions are ready as needed. The responsibilities include development of a Strategic Plan. As part of the planning effort, a structured approach to technology prioritization, based upon the work of the START (Strategic Assessment of Risk and Technology) team, was developed. The purpose of this paper is to describe this approach and present its current status relative to the JPL technology investment strategy. The JPL Strategic Technology Plan divides the required technological capabilities into 13 themes. The results reported here represent the initial analysis of seven themes: In-situ Planetary Exploration Systems, Survivable Systems for Extreme Environments, Precision Flying Systems, Deep Space Communication, Planetary Protection Systems, Utilization of High Capability Computing, and Engineering Systems. The remaining six themes will be included in the study planned for FY '06. Each theme is hierarchically decomposed into component capabilities, to a level where quantitative estimates can be ascribed. For example, in the In-Situ Exploration theme, the sub-theme of Mobility is broken down into Surface Mobility, which allows an estimate of the meters traversed per command, a specific and measurable quantity. This structure is repeated and data filled in for each mission. All of this information is analyzed using an optimization technique formulated to maximize total missions technologically enabled subject to overall cost constraints. Note that capabilities are given credit only if all capabilities needed to enable a particular mission are selected for funding. The recommended investments at each area of the capability hierarchy are plotted as a function of the total budget available to the sponsor. The robustness of the investment strategy is quantitatively analyzed as a function of potential variation (the uncertainty) of the input data. In on-going work we are looking at measures for relative mission value, dependencies among missions and capability areas, and time profiles of the recommended investments.

This paper addresses how reliability analyses might be placed in a lunar structures framework. Key environmental aspects are summarized, as are strategic issues that impact how an engineering design might be pursued. This is then put in the context of a performance-based engineering framework.

Even though many disciplines familiar to the audience may have adopted a systems approach to the development of standards, the same is not currently widespread for natural hazards standards for infrastructure systems and components. Beginning with the formation of American Lifelines Alliance (ALA), this paper emphasizes the evolution of attempts to promote a systemic approach to performance standards for components in infrastructure systems. Covered are selected projects performed through ALA. In addition, projects for the Multidisciplinary Center for Earthquake Engineering/Federal Highway Administration (MCEER/FHWA), the California Department of Transportation (CALTRANS), the Port of Los Angeles, the Port of Oakland, San Francisco International Airport, and the United States Geological Survey (USGS) indicate the importance of a systemic approach to the development of standards for components in infrastructure systems. At the same time, reasons are provided as to why the notion of "system performance" standards have not yet been more widely extended to natural hazards generally.

This paper presents an overview of the development of the SEDRIS standards, their contents and applications, and examples of their implementation for the management and exchange of environmental data. This overview includes data applications involving Space Environment Effects; Space Science and Astronomy; Space-based Technologies for Water Resources, Hydrology & Environments; Remote Sensing, Geomatics, Global Positioning System usage and Geographic Information System applications; and Air Traffic and Air Transport.

This paper discusses the theoretical basis for the Spatial Reference Model (SRM) standard and presents coordinate transformation applications utilizing the SRM. Application areas include Near-earth Objects; Remote Sensing, Geomatics, GPS and GIS; Lunar and Martian Bases and Exploration; and Air traffic and Air Transport. Within the military environment, the SRM is embedded in the Department of Defense Test and Training Enabling Architecture (TENA) to facilitate precision coordinate transformations on-the-fly to support test events involving multiple ranges and sensor systems.

This paper describes detection of the sediment disaster due to the 2000 Tokai Heavy Rainfall in Japan, using IKONOS Pan-sharpen images. In most case of steep mountainside in Japan, slope failures are often covered by leaves in the forests. In this study, a detector based on region growing algorithm is proposed for high resolution satellite images to estimate the shadow area of the slope failure. The magnitude and the morphology of slope failures are calculated by the proposed method. On the other hand, the boundary of sub-compartment shown in forest planning maps was digitized, and the forest database was developed for the attributes such as forest management type shown in the forest register of Gifu Prefecture in Japan. The detected results of slope failures are stored in the database, and they are compared with the attribute data for the characteristic analysis. The GIS model was applied to detection of heavy rainfall induced slope failures in the upstream of the Yahagi River triggered by the 2000 Tokai Heavy Rainfall. The conclusion is shown as follows: (1) Most of sliding failures can be detected precisely using threshold value. The shaded relief processing was effective to detect the debris flow along a valley, and the accuracy was improved. (2) The quantitative theory analysis for slope failures and the database concerning the topography, geological features and forests is effective to create the hazard assessment map. This result is useful for planning of erosion control dams.

Consisting of rear-projected screen walls and a front-projected floor, the CAVE is a multiple person, high resolution, 3-D graphics video and audio environment. The CAVE's true stereoscopic capabilities, coupled with its uniquely immersive design, enable scientists and researchers to interact with geospatial data in ways never before possible. This paper presents an approach and results of using CAVE to fuse and visualize 3D image and elevation data containing critical infrastructure. Various formats of data are collected for 12 cities. The geospatial data includes image data, elevation data, and topographic map data in different files and in different formats. By using vGeo software and these data, we integrate the 2-dimensional image data and the elevation data into 3-dimensional images in the virtual world. The virtual world then can be presented in CAVE equipment, which helps to identify the geometric objects and their attributes.

Wind engineering has matured significantly since the 1960's. Many books and journals now cover its more common applications. One application that remains at the fringe of the discipline is urban planning and design. Individual technical papers and chapters in books on applications of wind engineering to urban design have been published since ancient times but there is no publication that focuses on the subject. The objective of the ASCE Task Committee on Urban Aerodynamics document will be to: (1) Identify the influences of wind in planning and designing urban environments. (2) Outline current opportunities for collaboration between wind engineers, urban planners, and urban designers. (3) Identify key references to published work on applications of wind engineering to urban planning and design.

Indoor and outdoor natural ventilation conditions of low-rise housing in small-lot residential subdivisions are strongly influenced by surrounding buildings. To account for the influence of surrounding buildings, the wind tunnel model must include sufficient surrounding buildings to yield reliable indoor and outdoor natural ventilation data. For small-scale building models the traditional test methods are not an economic method for estimating indoor and outdoor natural ventilation conditions in a wind tunnel. To accurately estimate indoor and outdoor natural ventilation conditions of low-rise housing in a wind tunnel correct modelling of the natural wind, appropriate building models and effective economic testing methods is required. This study discusses new testing methods in wind tunnels for estimating indoor and outdoor natural ventilation conditions of low-rise housing in small-lot residential subdivisions.

Large scale urban and suburban development or redevelopment offers an opportunity to use wind engineering in street orientation and building density to encourage summer breeze penetration or inhibit chilling effects of winter winds. This is not new. Egyptians used it while building the pyramids and the Romans orientated streets in garrison towns to exclude harsh winter winds. In more recent times concentration of airborne vehicular pollution in street canyons has been mitigated using wind engineering studies. The benefits of wind engineering during urban design are more difficult to achieve after street orientation and building density has been decided. Boundary layer wind tunnels studies and computational fluid dynamics modeling are the principal tools for this area of wind engineering. Urban planners and designers need to work closely with wind engineers during the early stages of design, before street patterns and building densities are decided in order to achieve the maximum benefits.

Town Planners are expecting that both city populations and the percentage of people living in cities will increase. Predictions are that between 1990 and 2025, the number of people living in urban areas will double to more than 5 billion; if that does happen than almost two-thirds of the world's population will be living and working in cities. Interestingly, 90 percent of that increase will occur in developing countries. The world's urban population is currently growing at four times the rate of the rural population. Such pressure means that either more land will be taken up by cities or that taller buildings will be required. And this increased building density could mitigate against passive design approaches such as natural ventilation. Recent studies in the Boundary Layer Wind Tunnel at James Cook University, Townsville Australia, have suggested one design approach that could be used to address these issues. Designers are making greater use of double facades on buildings (where there is a significant gap between the inside and outside cladding). Their adoption is often linked to a natural ventilation strategy for the overall building. The study demonstrated that if the cladding was sealed to the outside but open at the top and at each floor than an even negative (suction) pressure was developed over the face of the building inside the cladding. This finding is not recognised in the present literature. In addition, it has the further advantage that this pressure is independent of wind direction (often cited as one problem with most natural ventilation strategies). The study also looked at the impact of air wells and wind catchers or "hoods" over those air wells on the natural ventilation potential of buildings. This showed that even positive pressures were developed inside the air wells. This suggested that a combination of these two namely double facades and air wells with wind catchers could be the optimal solution for natural ventilation of the building. This paper outlines the potential of such an approach against a context of the continuing pressure on urban building densities.

CFD simulations of the wind speed conditions in passages between generic parallel building configurations are performed. CFD validation is conducted based on published wind tunnel data. The computational results agree well with the experimental data when an appropriate grid resolution is employed. The required grid resolution across the passage width appears to be a function of the passage width and the building influence scale. A grid resolution guideline is provided. Finally, the simulations and the measurement data are used to identify three different types of passage flow as a function of the dimensionless ratio of passage width to building influence scale.

A construction project begins with a work plan that includes a budget, a schedule, and an engineered approach designed to complete the project in the most effective manner. Effective project management requires controlling all aspects of a construction project: quality and quantity of work, costs, and schedules to guarantee the success of the project. Performance monitoring of the entire construction project is crucial. One way of measuring overall performance is by using an aggregate performance measure called Earned Value. Earned value is used to measure cost and schedule performance against a baseline plan. All work is planned, budgeted, and scheduled in time phased planned value increments constituting a cost and a schedule measurement baseline. Earned Value is mainly used to monitor the progress of work and compare accomplished work with planned work. A proposed new model based on wireless communications technologies, to track the progress of percentage completed in a construction project is being investigated in this paper. The model is based on Radio Frequency Identification (RFID) system. It will greatly increase productivity and efficiency, reduce labor hours and time required for tracking, and give more accurate result in estimation. This new technology includes an automated system of reading RFID tags placed on items that send out either a tracking number, or other information for that item, directly to the reader. Keeping track of the material used on site, based on the estimated quantity will permit making a better estimate of the amount of work done on a construction site.

This paper presents the results of a survey of the use of wireless and advanced information technology applications in the construction industry. Responses were recorded from 58 construction managers around the world. The results of the survey indicate that construction companies are beginning to employ tools like CAD, web portals and the Internet in their operations. However, it was also found that companies are not yet widely employing wireless technologies at remote offices or the field.

Much of the inhabited terrestrial underground consists of sands, clays, and gravel mixed with stones, tree roots, construction debris, and of course, utilities. While the sub-spaces on Moon and Mars do not yet contain utilities or construction debris, they are made up of material that could provide in-situ resources essential for sustaining human colonies on a short and long-term basis. For example, caves will protect humans from solar rays outside the safety of a lunar lander. Knowing about their existence and entry points, however, requires detailed information about the subsurface. Also, buildings need to be constructed on solid ground instead of covered over "sinkholes". Ice and oxygen or helium-rich ores will be other highly desirable substances. Ground penetrating radar promises to be an excellent technology to for supporting the search for such in-situ resources. It is being successfully used to investigate the terrestrial sub-space for various purposes. This paper will discuss its various applications, a novel data processing method applied to experimental tests performed in beach sand.

Wireless local area networks offer new opportunities to establish effective communication channels between the many production units on a construction site. Having managers, workers, operators, mobile construction equipment and even tools communicate with each other as well as with off-site resources would open new information arteries critical to advancing the lagging productivity in terrestrial construction. For the exploration, mining and construction on Moon and Mars, however, such communication networks will be imperative. In order to test the viability of wireless construction, researchers at the Construction Automation & Robotics Lab at NCSU outfitted a construction site with a wireless backbone network and installed several test applications. The main focus of this effort was to experiment with a Wi-Fi agent mediated information system able to protect a mobile crane from accidents. The paper presents key components of the experimental implementation before arguing the need for applying the tested concept to the operation of equipment fleets on the lunar or martian surface charged with exploring and constructing inhabitable colonies.

As we have learned from history, settlers in a new "land" depend on the effective use of ISRU in order to ensure a sustainable presence. Even explorers who tried to traverse large spaces on earth with plentiful provisions ended up being fed and saved by aborigines, natives of the land, who had learned to adapt to the environment within they lived. The importance of "harvesting" in-situ resources will permeate most everything that will have to be designed, planned, and built to support the exploration of space, similar to the British penal colonies established in Australia. This paper provides a comparison of issues faced by terrestrial colonies in colonial times with those faced while planning to "live-off-the-land" on the Moon and Mars. It is argued that the synergistic phenomenon of In-Situ-Resources (ISRs) as part of an interdependent whole will not only influence the establishment of any type of habitat, but also be one of the key elements penetrating the most effective design, construction, and support of human exploration efforts as well as the commercialization of space.

This paper reports results of collaboration between the Sasakawa International Center for Space Architecture (SICSA), Houston, USA and the Applied Computing and Mechanics Laboratory (IMAC), Lausanne, Switzerland. A design project has been initiated in response to growing international scientific research interest at Summit Station in Greenland and a requirement for better accommodation and support. Research at IMAC involves the study of intelligent cable-strut structures that are adaptable and self repairing. An architectural and engineering development approach as well as conceptual proposals for the Summit Station in Greenland for science research and operational support is proposed. The proposed facility in Greenland supports 50 people during the summer season and 25 people during the wintertime. Primary elements of the modular configuration include a triangular platform with two upper floors that is supported by three jacking columns. This approach means that structure can be adjusted to accommodate differential settlement of supports. An adaptable apron structure around the primary platform is used to modify the form of the underside of the platform to maintain predetermined clearance criteria between the structure and level below, thereby avoiding excessive snow accumulating around the building and minimizing drifting and scour underneath it (on Mars, dust storms might be the difficulty). A separate structure for a mechanical shop and power support is added to complete the initial configuration. Important priorities are to provide a high quality environment and to minimize development, construction and operational costs while optimizing safety, versatility, autonomy and human factors. Testing of a plywood model of the primary facility that was installed in Summit in May 2005 and a wind tunnel model at EPFL confirmed that if the structure was not sufficiently elevated, drifting could bury it. Important parameters are the shape of the building, the form of the bottom of the platform, snow accumulation points, snow drift distribution, wind direction, wind speed and distance between the structure and the snow surface.

The feasibility of conducting a human Mars mission is considered, assuming no heavy lift launch vehicle is available and minimal crew flight times are required. Propulsion options are evaluated and extrapolated, and an architecture is defined. A low-thrust cargo vehicle deploys Mars surface cargo, and also establishes propellant depots in orbit around Earth and Mars. Subsequently, a low-thrust crew vehicle departs, carrying insufficient propellant for the complete mission but obtaining additional propellant from the depots. Although the architecture enables one-way crew flight times of approximately 100 days, and does not require heavy lift, its complexity calls into question the practicality of such a mission.

The project featured in this paper is part of a larger research and design venture undertaken by the Sasakawa International Center for Space architecture (SICSA), Houston, in collaboration with SPACEHAB. The one year design project involved planning and design of various landers, rovers, and surface facilities required for a three year mission to Mars. This activity produced the design of a common module to serve as a logistic habitat or laboratory facility as evolutionary needs demand. The paper presents design parameters and architectural design options for this modular element. The purpose of the project is to: (1) Study the similarities and differences of lunar and Mars environments to propose a module that can serve as a habitat in both environments. (2) Study human function and performance issues in such extraterrestrial environments and estimate food, water and other basic requirements for the representative missions. (3) Provide design solutions that address the future evolutionary needs, weight and mass constraints presented by launch, landing and surface mobility/ deployment. This project was conducted in connection with SICSA's ongoing studies of facilities in general, and in support of SPACEHAB's Space Exploration Concept Evaluation and Refinement (CE&R) contract with NASA.

Planning for long-duration lunar and Mars exploration missions must provide appropriate human support accommodations to optimize crew comfort, health, morale and performance. This paper will present special habitability considerations using a proposed Mars Transfer Module to illustrate concepts for functional areas and equipment systems. Design concepts that efficiently and effectively utilize limited volumes and minimize launch mass are based on two main assumptions: 1. Shape of a single unit: the volume of regular boxy sleeping quarters can be optimized by ergonomic design so that an individual crewmember can perform diverse private activities inside the unit. 2. Configuration: the proposed combination and orientation of 8 sleeping quarters is compatible with use of a 4-standoff layout in 12-feet diameter module. The project addresses fundamental requirements for human habitation in a 0-G environment in an orbital Mars Transfer Module. Special emphasis is directed to crew sleeping quarters, including configuration, the lighting system, restraint and mobility devices, and privacy curtains.

This paper presents a design proposal for a crew descent/ascent vehicle to deliver crews to lunar/Mars surfaces, return them to lunar/Mars orbits to dock with the trans-Earth return vehicles, and reenter the Earth's atmosphere for a surface landing. The paper also presents a proposed lunar/Mars lander that utilizes a tether system that deploys during the final descent stage to softly place payloads on the surface with minimum rocket blast ejecta which could pose ballistic hazards to nearby facilities. The design approach baselines vehicles and landers that can be placed in LEO using Medium Lift Vehicles (MLVs) (15 MT by 12 ft. diameter payload capacities), and are scalable to utilize larger launchers if available.

The focus of this paper is a preliminary study intended as the first phase in the development of a pressurized rover conceptual design. NSBE Space has concluded that pressurized rovers will be necessary for any large scale lunar presence. Rover missions include both local transportation between the lunar base and lunar landers as well as surface expeditions away from the base focused around scientific research or commercial industry activities. The paper provides a brief assessment of design concepts for rover vehicle systems. This rover is a traditional configuration of a pressure vessel mounted above a drive mechanism, but is larger than many of the traditional concepts based on the MOSAP configuration, such as LUNOX.

NASA's 2004 Mars Exploration Rovers (MER) have greatly advanced our understanding of Mars and set new standards in surface exploration. The twin rovers "Spirit" and "Opportunity" have been the first Landers on Mars with a mobility enabling them to look what is hiding behind the horizon. That mobility is a great achievement but also poses new problems. Choosing an initial drive direction after landing is somewhat a gamble since "scientific sweet spots" might be lurking just behind the Rover's horizon in the opposite direction. Surface observations from orbit are much advanced since the times of Viking and have proven to be of great value in determining surface features that are both areas of high scientific interest and safe landing sites. However, the spatial resolution of orbital cameras is insufficient to resolve spots of potential scientific interest at meter and sub-meter scale. The famous Opportunity Ledge outcrop, hidden in a ~ 20 m diameter crater, might have been missed had Opportunity not performed its "hole in one" landing inside that very crater. To close that gap between resolution from orbital observations and the rover's view on future mobile Landers on Mars we propose a simple Mapping Balloon carrying a high-resolution stereo camera. Using the MER concept of a static landing platform from which the rover egresses, the Mapping Balloon would be attached to the landing platform to not compromise the mobility of the rover. The Mapping Balloon would rise up to 100 m above the surface enabling the stereo camera to characterize the landing site beyond the rover's horizon in 3D and at sub-meter scale. Such a map will also help with the precise localization of the landing site. Future human exploration will offer even greater mobility than MER or future robotic rovers. In that scenario the Mapping Balloon would also function as a beacon for orientation, guiding future explorers back to their habitat. It could also serve as radio relay should surface features obstruct direct communications with the habitat.

In view of the fact that NASA and ESA are both planning to set up a Lunar Base for long duration missions on our neighboring celestial body, collecting more information about the Moon will be inevitable — not only global information but also details of potential landing sites. On that purpose, several planetary scout missions will be conducted in the near future. The probes will carry robotic lunar landers as well as ground vehicles. Based on these contemplations, the REZ has started to develop a standardized Micro-Mission-System for future robotic missions to the Moon and Mars, consisting of landing stages, rovers, and orbiters for both missions to the Moon and Mars. Our first development will be a rover system for operations on the Moon.

In order to design space infrastructures of several type, location and dimension, precise design parameters should be prepared to respect the particular requirements of the space environment and the technological limitations at any given time. In this paper we want to list and analyse such design criteria ranging from production, transportation, safety and assembly functions as well as flexibility, modularity and expansion possibilities taking in due consideration economical and state of the art technological requirements. Following such parameters definition we also want to analyse how they can be utilized for infrastructures of various dimensions and scope ranging from early space station construction systems, such as the AstroHab to more complex settlements and finally for ultimate artificial planet assembly all proposed by the author.

The Vision for Space Exploration encompasses the development of a newer spacecraft, the Crew Exploration Vehicle (CEV) and recommends using a `System of Systems' spiral approach for exploration of Moon, Mars and beyond. The CEV and other supporting spacecrafts have been developed through the methodology of optimal conceptual design based on need analysis and hierarchical function structure generation method. This optimal design method has been merged with the spiral approach to ensure that technologies, architectures and configurations will evolve over a period of time and will be integrated together in order to have a sustained and affordable exploration program.

We present a new orbital space settlement design for 5,000 residents, "Kalpana One." The structure is a cylinder with a radius of 250m and a length of 550m. Cylinders minimize shielding mass per unit of 1g living area compared to other feasible shapes. Aligning the rotational axis along the solar system's north-south axis provides continuous natural light through transparent end caps without moving mirrors. Wobble control is provided by a combination of exterior teleoperated robots moving weights about and weights attached to cables on motorized winches. Ten tons of lunar regolith shielding per square meter is placed inside the hull requiring greater hull strength relative to older designs but eliminating a major failure mode. Emergency power is provided by body-mounted solar cells, but primary power comes from solar power satellites beaming energy to a body-mounted rectenna. Thermal rejection is provided by a disk of thermal arrays with 450m radius outward from the hull. The 1g living area in the hull is supplemented by internal cylinders at lower g-levels for industry, storage, agriculture, retirement communities and recreation.

Exploration of the universe is and will be an endless process. President Bush has issued a challenge for the phase covering the next 30 years, in other words a generation-long endeavor. We have been studying and exploring the heavens for millennia. The new factors are exploration by humans, the time-line for the next phase, and the ultimate goal of this next phase of human exploration and ultimate colonization of Mars. The Schriever Institute has chosen to focus on the latter; setting up a human colony on Mars and all that entails. That long perspective generates the need for an enduring and evolving architecture. The Schriever Institute looks to the ASCE to grasp the opportunity and take the lead in conceptualizing and developing the necessary architecture to support the Human Explorer in the decades to come. The Space colonies depend on the expertise of civil engineering within the ASCE community. We, at the Schriever Institute appreciate the opportunity to participate in and contribute to ASCE's efforts developing our Space Architecture. Moreover, the President raised the challenge at a time when we have a substantially rich technology base coupled with that of an expanding and emerging technology continuum. Given that heritage, we anticipate continuous discovery, invention, emerging technologies and applications to this imaginative and challenging endeavor. The new NASA Administrator, Michael Griffin, faces the usual challenges, however, let us, as a Nation, rise up to the opportunity and take the necessary steps required to make it a reality.

Present day construction and in its associated activities is an involved process due to the phenomenal increase in various facets of constructional activities. The complexity of the decision parameters adds new dimension in the decision making process for technology transfer. Thus, the need to rationalize the various inputs and optimize the construction planning practices becomes imperative. Several considerations that are qualitatively described by the terms such as high, medium, low, good, bad and satisfactory have an important bearing on the engineering aspects of projects and the structures therein. The subjective judgments implicit in these qualitative terms cannot be directly incorporated into the analysis and planning of engineering activities in a routine way through classical evaluation. The fuzzy set theory makes available a convenient and meaningful tool to the practising engineers to incorporate these seemingly vague but practically powerful factors in the several phases of a project life cycle. This paper reports a methodology for incorporating the fuzzy set concept into the procedural analysis of planning the buildings in challenging environments with or without proper weightages assigned for the qualitative factors. Intangible, non-quantitative and linguistic variables are considered for the evaluation process relatively in an easier way through this concept.

Areas mantled by boulder-rich alluvial deposits present particular difficulties in field exploration, subsurface characterization and foundation design. Lessons learned in the subsurface characterization and design of structures in bouldery alluvial terrains in the vicinity of southern California's San Jacinto Mountain Range offer insights into the investigation and design of structures in other boulder-rich terrestrial sites, as well as potential future building sites on the Moon and Mars.

Ever since Buckminster Fuller's futuristic design for US pavilion at Expo 67, the field of space design has showed itself as a noticeable domain in the field of architectural research and practice. The domain of space design has been concerned with practical issues such as mission planning, ergonomics, conceptualization of structures, orbital assembly processes (Astrotectonics), as well as the design of habitats to optimize human safety, comfort, adaptation, and productivity. On the other hand, there has been a growing interest in a related domain of architecture research; namely "Experimental Architecture". Experimental architecture promotes a type of experimentation that deals with the concept and perception of architecture itself. It operates outside the well-established rules and classifications of mere "problem-solving" architectural design activity. This domain is less concerned with the constraints of engineering and nature than in evoking a mood and opening new possibilities about what it means to inhabit a space. Experimental architecture is grounded in real-world conditions at the same time it pushes far beyond the boundaries of conventional architecture. This paper discusses a simple lesson learned from experimental architecture and suggests that experimental architecture makes powerful statements about the role and function of the new spaces that architects and engineers will design in the future. Many lessons from experimental architecture can be applied to address important planning and design challenges of space design. A brief history, development, theoretical backgrounds as well as examples of experimental architecture are presented here.

This study focuses on a sensitivity analysis of a Modulated Laser Analyzer for Combustion Products (MLA-CP) developed by SouthWest Sciences of Santa Fe, NM. The MLA-CP uses a single telecommunications-grade IR diode laser to scan several wavelengths and, using wavelength modulation spectroscopy (WMS), determine the concentrations of four target gases (CO₂, CO, HCCH, HCN) to a precision of parts per billion for HCN. The sensitivity analysis, conducted at the NASA-Johnson Space Center and the University of Colorado at Boulder, is designed to expose the MLA-CP to temperature and gas concentration conditions likely to be encountered in the spacecraft environment. This analysis will aid a greater trade study of microgravity fire detection systems in cooperation with the Microgravity Combustion Research Group at Glenn Research Center. The initial tests, conducted in July and August 2005, exposed the sample cell to known concentrations of gases, including breathing air, grade B nitrogen, ultra high purity nitrogen, and 1% carbon dioxide in a balance of nitrogen. Trials were conducted increasing the temperature as the gas was flowed through the cell. Additionally, overnight tests were conducted with ambient temperature conditions and environmental flows. Initial findings showed that the MLA-CP is extremely sensitive to temperature, temperature ranges, and rates of temperature change. Significant sources of error were identified as being inherent to the IR diode laser itself, in the form of unwanted optical interference fringes, or etalons.

Advanced composite material for strengthening and rehabilitation of Concrete structures are more frequently used these days mainly due to change in the serviceability parameters, refined analysis and design philosophies. However the Carbon Fiber Reinforced Polymers (CFRP) have many advantages as compared to other such material in terms of small additional weight, faster mode of application, less effect over the architectural components and no corrosion of material. In this research eight beams of size 7in x 12in (18 cm x 30 cm) and 9 feet (23 cm) span were cast such that six beams were retrofitted with CFRP strips of various dimensions and points of applications. The beams were tested under two point load and the results of retrofitted beams were compared with the beams with no CFRP. The results have shown considerable improvement in the flexural capacity of the retrofitted beams and corresponding decrease in the deflection for the same values of load. It has been observed that the geometry and area of retrofitting material has direct bearing on the improvement in the load carrying capacity of beams.

This paper addresses the analysis and experimental investigation of plymer matrix composite (PMC) panels utilized for seismic energy dissipation. The concepts rely on introducing considerable shear deformation at strategically located layers. The layers at which the shear deformation to take place, referred to here as the interface layers, are composed of a combination of solid viscoelastic material combined with honeycomb material. As part of this research, a series of experiments were performed to quantify the energy dissipation characteristics of the interface layer. The effects of thickness, loading rate, and the ratio of the volume fractions of the constituent materials are investigated. Utilizing the results obtained from material testing, three conceptual panel designs were tested to assess the over all energy dissipation in a structural system. Results obtained from the experimental program were used to further verify finite element models that were used to simulate the response of several structural systems retrofitted with the seismic energy dissipating panel concepts. A theree-dimensional (3D) nonlinear finite element analysis was carried out to evaluate the damping effective of added PMC panel with viscoelastic interface layers in the retrofitting of the Multidisciplinary Center for Earthquake Engineering Research (MCEER) demonstration hospital structure. An equivalent Kelvin model consisting of an elastic spring and a linear viscous damper combined in parallel is proposed for the PMC panel with viscoelastic interface layer. The retrofitted structure was subjected to MCEER west coast ground motions. Significant increase in the system damping was obtained with the added PMC panel. Both the modal strain energy method and logarithmic decrement method showed the PMC panel contributed 8% damping to the hospital structure. Time history analysis results showed the peak displacement and acceleration responses were reduced a lot and vibration damped out very quickly.

Fiber reinforced polymer (FRP) wrapping is used by bridge owners in several temporary (5 to 7 year) repairs to control delaminations in reinforced concrete (R/C) bridge columns. This paper describes results of a study where different concrete removal strategies with one layer of FRP wrapping were evaluated for their effectiveness in containing delaminations in reinforced concrete columns. Results indicated that FRP wrapping was effective for short-term (5 to 7 year) applications in confining the repaired/delaminated concrete columns and concrete removal strategies did not influence the durability during the six year monitoring duration.

An original model for impact analysis of elastic-plastic sandwich beams is presented, and the effect of sandwich damping is uniquely introduced in the analysis by considering the gradient of beam compliance. By incorporating the compliance (or stiffness) and compliance gradient of the sandwich beams to the equation of motion of the projectile, the standard mass-spring model for the sandwich system is uniquely recovered. Both the elastic and elastic-plastic impact processes are analyzed and compared with elastic model of no sandwich damping effect. The proposed impact model is validated with the elastic finite element analysis using LS-DYNA. A parametric study on the influences of velocity and mass of the projectile on the impact response of elastic and elastic-plastic sandwich beams is conducted, and it reveals the significant contribution of the sandwich damping and plasticity to the impact response.

In recent years, researchers have focused their study on many possible approaches to enhancing the seismic performance of structures. One promising solution which is receiving attention today is the application of Shape Memory Alloys (SMA). In this study, high seismic performance shear walls have been proposed to have SMA bars acting as a kind of structural bracing system at both sides of the shear walls to increase the ductility and the energy dissipation capacity of the low-rise shear walls. This paper presents the results of the reversed cyclic tests on low-rise shear walls with SMA bars. The height, width, and thickness of the designed shear walls were 1.0 m, 2.0 m and 0.12 m, respectively. SMA bars were provided in the directions of 25 degrees to the horizontal (from the top corner to the bottom corner of the wall). The steel ratio in both perpendicular directions of the shear walls was 0.24%. The main parameter used in the study is the type of SMA bars, namely Superelastic and Martensite SMA bars. The force-displacement hysteretic loops of the low-rise shear walls under reversed cyclic loading are presented. Test results show that the maximum shear strengths of the tested walls are affected by SMA bars. It was found that the shear wall with Martensite SMA bars has greater residual displacement. In contrast, the shear wall with Superelastic SMA bars has less residual displacement. At the ultimate state, one of the four Superelastic SMA bars buckled, resulting in less energy dissipation capacity than the expected value. How to prevent the buckling of SMA bars needs to be investigated in the near future.

The procedures for updating structural analytical model from modal test data based on different approaches including the traditional Modal Sensitivity Method, Neural Networks method and Genetic Algorithm are described, respectively. Some aspects of structural model updating such as the problem of incomplete modal test data and robustness of model refinement, as well as the factors affecting the computational efficiency and solution convergence, are considered. Merits and defects of these proposed methods are discussed by comparison of numerical results of a real 5-story steel frame from limited modal test data.

This paper investigates the self-rehabilitation properties of Intelligent Reinforced Concrete Structures (IRCS) with superelastic Shape Memory Alloys (SMAs). The concrete structure reinforced with superelastic shape memory alloys is intelligent in the sense that the structure possesses the self-rehabilitation capacity, which refers to that the structure can significantly reduces the width of its cracks induced by earthquakes or other disastrous events by taking advantage of the superelastic property of SMA reinforcements. In this study, SMA strands/cables, made of SMA wires, were developed for reinforcing concrete structures via post-tensioning. For comparison purposes, three reinforced concrete beam specimens were cast: an ordinary concrete beam containing only steel reinforcements and two concrete beams containing both superelastic SMA and steel reinforcements with different configurations. The post-tensioning method was used to reinforce the concrete beam using SMA strands and the three-point bending tests were conducted on these beams to induce severe cracks. The test results show that with a proper arrangement of steel and superelastic SMA reinforcements the specimen exhibits the self-rehabilitating capacity in the sense that the induced cracks can be closed by the superelastic SMA reinforcements upon removing of the load.

In this study, the dynamic behavior of a two-story building frame with Shape Memory Alloy (SMA) braces is determined experimentally in terms of its oscillatory response to earthquakes loadings. Two earthquake loadings representing the El Centro and Northridge earthquakes were generated and applied to the base of the building frame using a shake table. SMA wires, whose stiffness varies with applied current through them, were used to brace the building frame in order to control vibrations. Two types of current: constant current and pulse current were used to tune the system (2D frame) stiffness. The goal is to achieve increased damping capacity of the frame due to the martensite-austenite co-existing state. The effect of constant and pulse current on the system stiffness (i.e., deformation, acceleration) are analyzed to determine the optimum current values. For El Centro earthquake, the optimum value of the constant current is 1.8A for minimum displacement and oscillation of the system. Where as, the value of the constant current for minimization of the displacement and oscillation of the building frame is found to be 1.4A using the Northridge earthquake excitation. It is shown that the periodic pulse current used to stiffen the SMA brace is more effective than the constant current actuations. In this study, the effect of system stiffness on resonance frequency is also determined. Finally, the responses of the two-dimensional (2D) frames with and without bracing were compared. It is believed that the findings of this study will be useful in advance understanding of the behavior of building structures with SMA members under earthquake loadings.

A previously developed analytical formulation has been modified in order to accurately model the nonlinear, strain rate dependent deformation of polymeric materials, including the effects of hydrostatic stresses. State variable constitutive equations originally developed for metals have been modified in order to model the nonlinear, strain rate dependent deformation of polymeric materials. To account for the effects of hydrostatic stresses, which are significant in polymers, the classical J₂ plasticity theory definitions of effective stress and effective inelastic strain are appropriately modified. To account for the effects of temperature on the nonlinear, strain rate dependent deformation of polymers, the isothermal equations were still applied, but some of the material constants were allowed to vary with temperature. Preliminary efforts to model the nonlinear unloading observed in polymers indicated that the methods used to compute the value of a state variable which controls the inelastic flow must be modified to account for the nonlinear unloading. To verify the developed formulation, the room temperature shear and tensile deformation response of a representative polymer has been computed across a wide range of strain rates. The high strain rate (several hundred per second) torsion response, and the low strain rate (quasi-static) tensile and torsion response of the polymer has also been simulated. In all cases, the results computed using the developed constitutive equations correlate well with experimental data. Techniques which can be used to incorporate the model into the analysis of the strain rate dependent deformation of polymer matrix composites, through the use of micromechanics techniques, are also described.

A multiscale numerical procedure has been developed by implementing a 3D rate dependent inelastic micromechanics model within the nonlinear transient finite element code LS-DYNA to investigate high velocity impact of polymer matrix composite laminates. A recently developed strength of materials based 3D micromechanics model, incorporating a set of nonlinear, strain rate dependent constitutive equations for the polymer matrix, has been extended to model through the thickness normal stresses and transverse shear stresses that are critical during impact events. A progressive damage model is used to identify various failure modes associated with the penetration process. Good correlation has been obtained between predicted and experimental results.

A previously developed constitutive model has been modified in order to incorporate the unloading behavior into the nonlinear, strain rate dependent deformation analysis of polymer. To compute the inelastic strains in the polymer matrix, state variable based viscoplastic equations originally developed for metals are modified in order to account for the effects of hydrostatic stresses, which are significant in polymers. The unloading behavior is approximated linearly with a simple damage model with decreasing unloading young's modulus, in which the damage parameter is increasing with the increment of inelastic strain. This nonlinear, rate dependent polymer model is then implemented into LS-DYNA, an explicit transient dynamic finite element code, through the use of the user defined materials option (UMATs). Experimental and computed stress-strain curves under different strain rates are compared for one representative polymer under shear and tensile loading.

This article deals with techniques which have been developed to study the behavior of composite materials and structures under high speed ballistic impact conditions at the NASA Glenn Research Center (GRC) Ballistic Impact Facility. The techniques include launching systems, fixture methods, imaging systems and instrumentation systems.

Samples consisted of JSC-1 regolith simulant, melted purified sulfur and glass fiber hand-drawn from regolith were cast and tested in a four-point bend test. Stress and deflections of the control samples (without glass fibers) and samples containing 1% glass fibers by mass were made. The glass fibers made from melted JSC-1 simulant, were mainly produced by hand-draw process. Initial test results showed that the ultimate strength can significantly improve with the addition of fiber glass, derived from the lunar regolith simulant. Using a mathematical code created by Langley Research Center, the radiation shielding effectiveness of sulfur/regolith concrete and other composite materials were analyzed. The mathematical code is a good tool to compare the radiation shielding effectiveness of different materials. This comparison was presented in this paper.

In recent years, the application of high-performance FRP composites in construction industry has grown tremendously in several different directions. The composite materials have been used extensively in manufacturing stand-alone structural members such as beams, columns, and wall panels in cooling tower system, in strengthening and retrofitting the existing but deteriorating structures to prevent the corrosion of steel members and the spalling of concrete surface. Other application area under consideration include infrastructure and facility members for transmission towers, closed circuit television poles, sign posts, guardrails, bridge railings, and light-gage structural system. The primary purpose of this paper is to investigate an application of FRP composites in product development for utility and/or lighting fixture poles, highway sign post, and medium size of transmission tower elements. This kind of infrastructural system can be designed, constructed, and operated in many challenging environments on planet earth, in-space, and on other planetary bodies such as the moon and mars. The objectives of this investigation are: (a) to determine the bending and buckling strengths of various FRP poles using eigenvalue solution, (b) to evaluate and compare the ultimate strength and stress of the facility poles using three dimensions finite element computational analysis, and (c) to perform the parametric structural efficiency analysis for determining an optimum rigidity length ratio, a/l, between the variable length from the fixed end to the overall length of the pole. The results indicate that the rigidity length ratio, a/l, as well as the moment of inertia ratio, I_T / I_B, have significant influence on the performance of facility poles, The study also proves that the step pole used in analytical model is light weight than the convention tapered pole for particular configurations.

Graphite nanoplatelets were added to the matrices of carbon fiber/epoxy composites to determine the effect of particle loading on the microcrack mitigation capabilities of composite samples after exposure to cryogenic temperatures. Volumetric particle concentrations of zero, one, two, three, four, five, and ten percent were added to the epoxy resin during filament winding. Although most of the samples contained some microcracks after cryogenic cycling, the graphite nanoplatelets seemed to have prevented the microcracks from propagating further. After comparing the various graphite nanoplatelet loadings, the addition of ten volume percent demonstrated the most drastic decrease in the number of microcracks within the laminate.

Most telescopes designed today assume that, as the telescope is pointed at different locations on the celestial sphere, there will be some interactive human or computationally-activated mechanical adjustment for defocus or misalignment during routine use. As part of a collaboration between the University of New Mexico and the University of Texas at Austin, design of the second iteration of the CCD/Transit Instrument (CTI-II) is underway. With a one degree square scientific focal plane mosaic of charged coupled devices (CCDs) operated in the time-delay and integrate readout mode, the stationary, 1.8-m telescope will accomplish a multi-bandpass photometric and astrometric imaging survey of more than 300 square degrees of the sky. The structural design goal for CTI-II is to make the telescope as passive as possible, so that little or no physical human or computationally-activated mechanical adjustment is required during routine use. Because the telescope will never be repositioned during normal operations, structural deformations due to the earth's gravity will not vary during operation. We are designing the telescope so that its optical behavior will be as nearly as possible thermally invariant, and we are also attempting to minimize vibrations due to wind and ambient seismicity. The structural design philosophy, methodology, and provisions for thermally and optically tuning the telescope (hopefully an infrequent operation) are discussed.

A novel actuator failure detection algorithm is developed in this paper. An actuator failure is considered to occur when it produces an input to the structure that is different from the commanded input. In this paper, an error function, one for each actuator, is developed to monitor the working status of the examined actuator in real-time, regardless the status of other actuators. Non-zero signal profile in the error function indicates the time instant of failure of the examined actuator (for measurement noise free case). The coefficients of the error function are calculated directly from the healthy input data (from the examined actuator) and all outputs without having to identify the state-space model of the system. Thus the need to know the state-space model of the plant is bypassed in the presented direct approach. Experimental results from a NASA eight bay truss show that the direct method can successfully isolate and identify the failure of the examined actuator in real-time.

The focus in this paper is an analysis of existing state of the arts directed toward the development of the next generation of vibration damping materials/systems in aerospace engineering applications. However, our goal is novel damping material and design solutions for turbine fan blade applications. The research work concentrates on understanding fundamental phenomena related to nanoparticles/fibers/tubes-reinforced materials and coatings dynamics/damping so as to enable the efficient synthesis of these novel damping solutions. Some available damping behavior (strength and loss factor) of CNT-reinforced polymeric composite materials is compared in chronological order to show a progress.

An analytical model is being developed to predict the deployment rate of Elastic Memory Composites. The key components of this deployment rate model are the one dimension constitutive relationships of both the fiber and resin phases. The resin phase consists of a viscoelastic theromset epoxy resin with a reported glass transition temperature (T_g) of 71 degrees C. Since a typical deployment takes place within the temperature range from 23.9 degrees C to 79.4 degrees C, characterization at sample temperatures throughout this range was required. Due to the demanding nature of the planned creep experiments, significant effort was involved in the evaluation of the load frames and strain measurement devices to be used in these experiments. The strengths and weaknesses of each of these pieces of equipment will be presented. Following this evaluation, the final experimental setup included an MTS servo-hydraulic load frame / controller, and an MTS LX-300 Laser Extensometer. This load frame / controller combination provided the system responsiveness required by the creep method, while the laser extensometer provided a non-contact means of measuring strain across the wide range of temperatures sampled.

This paper proposes a smart passive damping system using MR dampers by introducing electromagnetic induction (EMI) system as an external power source to MR damper and verified the performance of smart passive damping system for mitigating the vibration of stay cables. The performances of smart passive damping system are compared with those of the linear viscous damper and the passive-mode MR damper.

Magnetorheological (MR) damper has received a great deal of attention in the recent years. A new mechanical model—double sigmoid is proposed based on the experimental study of MR damper, and it can accurately describe the hysteresis nonlinear properties of MR damper. A 3-storey frame-shear wall structure model with an asymmetric stiffness distribution is considered, and multiple MR dampers are used to control this test structure. The simulation model of this test structure is built according to the coupled translation and torsion response, with and without MR dampers, based on Matlab/Simulink and hardware/software resources of dSPACE. Then the shaking table experiment has been carried out in Dalian University of Technology. It is found that the coupled translation and torsion response is significantly mitigated with MR dampers under different earthquake excitations and various excitation levels.

A time domain method to directly separate system modes from spurious modes for close-mode structure with output-only data is presented in the paper. The time series analysis is often adopted for identifying structural dynamic characteristics in time domain with output-only data. However, the problems caused by spurious mode contradict its application to close-mode structures. According to the equivalent relationship between system equation of motion and state equation of output vector, the backward differential model of the correlation function is formulated with output-only data. Based on the location relationship between the unit circle and the eigen-values on the complex plane, a method to determine the system modes is proposed. The system modal parameters are then calculated by the system eigen-values and eigen-vectors of the characteristic matrix of the backward differential model. To verify the validity of the proposed method, numerical simulations of the Kabe's mass-spring model, which is a typical close-mode system, have been carried out with output-only data. The results indicate the feasibility of using the present method in the modal identification for close-mode structures with output-only data.

This paper focuses on the wind-induced vibration control of the Dalian International Trade Mansion by using Tuned Liquid Dampers (TLDs). The results show that the TLDs can effectively reduce the structural response amplitudes and enhance the comfortableness of the mansion.

The Global Positioning System (GPS) has been used in the health monitoring of large structures in recent years since it is weather independent, capable of autonomous operation, and does not require a line-of-sight between target points. But it is well known that there are various kinds of error sources impacting on high precision GPS positioning. In order to derive a relatively noise-free time series from the GPS results, an integrated method based on Adaptive Noise Cancelling (ANC) principles and wavelet de-noise method is presented. To verify the effectiveness of the method, an experiment is carried out, the data analysis results indicate that the adaptive noise canceller is a powerful signal decomposer, which can significantly mitigate multipath effects since multipath tends to exhibit the same pattern between consecutive days; wavelet filter is a suitable tool to separate random noise that cannot be filtered by adaptive noise cancellation method form signal. This kind of combination is superior to single filtering method.

Carbon nanotubes have been widely used in many applications and some of them are vibration damping and noise reducing materials. This research work concentrates on understanding fundamental phenomena related to damping behaviour of CNT-reinforced materials. In this paper the equilibrium equation of damping structure is described with FEM-based approach, compared with experiments and solved with the help of a numerical code.

An efficient algorithm is developed on the basis of considering the characteristic of mass concrete with high aggregate content ratio. All the same kind of random triangle fundamental aggregates are generated at one time, and then the two dimensional arbitrary shapes of aggregate can be generated by the method of random extension. The presented algorithm is superior to the common method, in which all aggregates are put one by one, and our algorithm avoids the defects of the latter algorithm, such as inefficiency of algorithm, low aggregate content etc. Corresponding software 2D-RAS is developed on the basis of this algorithm. Finally, the behavior of the three-grading concrete specimen under uniaxial tension is studied. The results indicate critical load capacity of the specimen with the random arbitrary shape aggregate is greater than that of the specimen with random circle aggregate.

Based on the theory of layered elastic systems mechanics, the stress of asphalt concrete bridge deck pavement structure systems under the action of wheel-loads is obtained and the main influence factors are considered in this paper. The numerical results of a bridge over Chongyang Reservoir is carried out by using the commercial finite element software ANSYS. The effects of various thickness and modulus of upper layer and lower layer on the mechanical indexes of pavement are analyzed. The theoretical and numerical results indicate that among the considered factors the elastic modulus of upper layer is the most important influencing the magnitude of the stress of asphalt concrete bridge deck pavement structure. The obtained results is hoped to provide the theoretical guide for the design and construction of asphalt concrete bridge deck pavement.

With complete computational micro-mechanics method, the whole failure process of uniaxial tension and compression specimen of three-grading concrete of Dongjiang arch dam is carried out. Monte Carlo simulation method is used to generate the random aggregate model, and the number of aggregate of different diameter is determined according to the actual gradation. The maximum tensile stress criterion and the linear Mohr-Coulomb criterion are adopted in the uniaxial tension and uniaxial compression specimen, respectively. The results indicate that concrete macro mechanical performance is much related with the composition of internal structure. The results also show that the interface is the weakest part, in which cracks under tension or yielding under compression is usually observed at first.

Contamination of aggregates with sulfate salts (especially gypsum) is a major problem in Middle East concrete construction. Fine aggregate has more detrimental effect due to its large surface area (fineness). An experimental work had carried out to investigate the behavior of high performance concrete exposed to internal sulfate attack in comparison with traditional concrete. Four sulfate contents (0.5, 1.5, 2.0, and 2.5 %) in fine aggregate were studied. Metakaolin was used as a pozzolanic material, which has proved itself as a good active one. Teasing program included compression, splitting, and ultrasonic pulse velocity tests. 168 cubes and 216 cylinders were cast throughout this program. The test period was extended to 210 days. The harmful effect (reduction in strength) of sulfate was obvious in early ages in contrast to external attack (as early as 7 days). The reduction in strength was continuous and higher in later ages and for higher SO₃ contents with reference to the mix with 0.5% SO₃. Test results showed that high performance concrete had lost strength, in such an environment, but it was more resistant than normal concrete and it may gain strength with age due to the pozzolanic action of metakaolin. The ultrasonic velocity results were positively proportional to strength development but with a slower rate of variation.

The ACI Committee 209 (ACI 209R- 97) had presented a model for prediction of concrete shrinkage. The included variables in this model are related to mix proportions, member geometry, curing method, and age of concrete. The predictions of this model had not pay adequate attention to the effect of the coarse aggregate on restraining shrinkage strain of concrete and overestimate the shrinkage half- time especially in hot climates. A parametric study was done to investigate the effect of variables other than those included in the ACI model (concrete and aggregate stiffness, aggregate volume, actual added water). Three types of normal-weight aggregate and one light-weight aggregate were included with two moisture conditions (dry and saturated). Teasing program included length change, compression, splitting tensile and static modulus of elasticity tests. The test period for shrinkage strain was extended to 150 days. A mathematical model based on dimensional analysis was built according to current experimental data. The predictions of this model stick close to the actual results (R²= 0.97) and it proves itself as a good tool to predict concrete shrinkage strains at anytime after curing is ceased. Another model was built to calculate shrinkage half-time. This factor is defined as the end of short-term age of concrete shrinkage. Finally, a proposed procedure for ultimate shrinkage prediction was suggested and it was verified reliable throughout statistical tests.

Optimization of structural weight is of particular importance for construction in space, moon, or mars since transportation of the structural elements to these sites is very costly. An optimized structure that satisfies the design requirements while utilizing minimum amount of material is especially suitable for construction in such remote areas and can result in significant savings in transportation costs. The Tabu Search method, a heuristic search technique, was selected for application to the structural weight optimization of skeleton structures. Further, a computer program was developed that uses Tabu Search for weight minimization of two-dimensional framed structures performing search, structural analysis, and structural design in an iterative manner. The program was used to optimize the weight of several frames of varying height including 3-story/3-bay, 9-story/5-bay, and 20-story/5-bay steel moment resisting frames. These frames had previously been designed to resist vertical and lateral loads. The same loads were used for the optimized weight design using the Tabu Search program. To improve efficiency of the method, several searches were performed with different search parameters and the duration of search was increased if needed. The program demonstrated its capability of optimizing the weight of these frames in a reasonable amount of time without requiring engineer interface during the search process. The search procedure was able to reduce the structural weight of these frames by 26.4%, 18.3%, and 25.5% respectively compared to their original design weights.

The piezoresistive behavior of cement based composites reinforced with conductive filler was investigated under uni-axial compression. The conductive filler contents used in this study were 3% and 6% (by weight of dry mix). The average 28 days compressive strength was 14.75 MPa and 11.00 MPa for the 3% and 6% composites respectively where the water-to-cement ratio was 1. Under compression, the specific electrical resistivity of the composites changed with applied stress, proving the piezoresistive nature of the composite. The specific electrical resistivity initially decreased with increasing stress but after a certain stress value (threshold change of resistivity), it increased with stress increase up to failure. The piezoresistivity parameters such as piezoresistivity coefficients and gage factors were quantified and found to be dependant on the filler content. Increasing the filler content to 6% increased the piezoresistivity coefficients and gage factor parameters. A constitutive model relating the change in the specific electrical resistivity to the applied compressive stress was used to predict the piezoresistive behavior of the composites. The model predicted the piezoresistive behavior of the composites.

Based on a strict and novel decomposition of deformation patterns of a sandwich beam under transverse loading, the flexural and indentation responses of sandwich beams are analyzed with consideration of elastic-plastic behavior of the crushable core material. The analytical model is capable of predicting the flexural response, indentation failure load, and indentation deformation. Some interesting phenomena, such as the global elastic-plastic hardening behavior and three distinct failure stages, are revealed using the present approach. Different from the existing plastic foundation model, a generic model for analyzing the flexural and indentation responses of the elastic-plastic sandwich beams is proposed, and it sheds new light on the effects of skin membrane and elastic-plastic core during indentation process.

A new model for the bending of a Bernoulli-Euler beam is developed using a modified couple stress theory. A variational formulation based on the total minimum potential energy principle is employed. The new model contains an internal material length parameter and can capture the size effect, unlike the classical Bernoulli-Euler beam model. The former reduces to the latter when the material length parameter is set to zero. As a direct application of the new model, a cantilever beam problem is solved. It is found that the rigidity of the cantilever beam predicted by the new model is larger than that predicted by the classical beam model. The difference between the deflections predicted by the two models is very significant when the beam thickness is small (below 10 μm), but is diminishing with the increase of the beam thickness. This demonstrates that the new model can indeed predict the size effect at the micron scale observed in bending tests.

The dynamic behaviors of long-span bridges due to near fault ground motions were analyzed by considering different cases, some factors were ranked in estimating their affections on bridge performance during earthquake.

On the basis of theoretical analysis and calculation, mainly for parts are involved in this paper: the effective stress analysis of soil deposit, the numerical response analysis of Pipe-Soil Spring System to effective seismic wave, the theoretical analysis of dynamic response of buried pipelines, upward floating response of buried pipelines are discussed.

This paper gets some material constants of elastic and plastic fatigue damage evolutionary equations from high and low cycle fatigue experiments of unnotched metal samples on the basis of fundamental principles of damage mechanics. Then, the finite element program ANSYS is used to simulate the development of crack of notched metal samples under high cycles of constant-amplitude stress and the distributions of elastic and plastic areas and so on. The whole variation of stress field, strain field and damage field are completely described. Finally, to compare it with the experimental results, the applicability and practicability of the model is appraised.

This paper focuses on an experimental investigation and theoretical analysis of different types of RC shear wall the profile steel strengths in two side columns and diagonal profile steel braces of walls subjected to applied repeated cyclic loads. Fifteen RC shear walls with different shear span ratio are tested and their aseismic charactertics are studied. The effect of profile steel bracings on failure property, bearing capacity, ductility and hysteretical characteristic of shear wall is investigated based on experimental results. It is shown that adding the profile steel braces on the boundary column and inner of walls can obviously enhance the ultimate strength of specimens and improve their aseismic characteristics.

The past decade has seen rapid advances in research, development, and application of optical fiber Bragg grating technology. Sensors based on this technology have special advantages of being lightweight and small in size, inert and corrosion resistant, immune to electromagnetic interference (EMI), easily multiplexed and multifunctional (they can measure strain, temperature, pressure, and vibration) and these advantages made fiber Bragg grating sensors promising candidates for structural health monitoring. This paper serves as a tutorial to introduce the basics about fiber optical sensors, in particular, fiber Bragg grating sensors, for structural health monitoring. The operating principles, types, major components, and merits of these sensors are presented in the paper. This paper will also review the-state-of-the-art of applications of fiber Bragg grating sensors for structural health monitoring.

In this paper a vibration suppression control system by piezoelectric actuators and sensors is presented for a one flexible link manipulators for space activities. This research is innovative because of the very high flexibility, stringent pointing requirements and a low first vibration frequency. In the last years there has been a large number of studies on the possible use of distributed actuators and sensors, in the framework of `smart' materials technology. Among the various available materials for smart structures actuators and sensors, lead zirconate titanate piezoceramics (PZT) patches are very attractive: they undergo mechanical stresses and strain when subjected to an applied electric field and, vice-versa, generate an electric field in response to mechanical stresses and strains. They are easy to bond to a structure, and their high stiffness makes it possible to induce high strain energy in the system. In fact it is possible to bond or even embed these materials into a passive traditional structure to perform both sensing and actuation functions, provided that appropriate placement and size is chosen for them. In this paper, a Linear Quadratic Regulator controller (LQR) for vibration suppression is used on both an aluminum link with bonded PZT patches and a carbon fiber link with embedded PZT patches. One test with aluminum link is conducted also with the link mounted on an Harmonic Drive motor. Some experimental tests of vibration suppression, to validate the proposed method, are presented. This experiment has been performed at the Spacecraft Robotics Laboratory of Naval Postgraduate School at Monterey, while the carbon fiber link were manufactured at Politecnico di Milano.

Significant research has been conducted in damage detection using dynamics-based technique. But simultaneously determining the presence, severity, and location of damage using the existing damage detection methods still faces some challenges. In this study, a new structural damage detection method called Local Damage Factor (LDF) is presented, and it is capable of determining the presence, severity, and location of a structural damage at the same time. By including the dynamic information of the local intact structure in the LDF method, the influence of structural nonlinearity, imperfection, and system noise is considered, so that the accuracy of damage detection is improved. The effectiveness of the LDF method in damage detection is evaluated using an experimental study of a 3-D steel frame structure, and the experimental results indicate that the method can effectively determine the presence, severity, and location of a saw cut crack in one of the pillars in the frame. The LDF method is effective in a way that it can eliminate the nonlinear severity effect of structure itself and ambient noise which are contained in the intact structure. As an implementation of the proposed technique in practice, damage detection of a wharf structure is presented using the LDF method, and the crack damage in one of concrete piles in the wharf is successfully detected. The successful detection of damage in the 3-D frame and the wharf demonstrates that the proposed local damage factor (LDF) technique can be effectively and efficiently used in damage detection. Further, in-situ damage detection of the wharf pile indicates that this proposed technique can be used to detect damage in large structures in the real time.

A light-rail transit (LRT) tunnel was mined in Austin Chalk (soft rock). A polypropylene-fiber-reinforced shotcrete liner was pneumatically placed against the rock. The liner thickness varies from 5 to 28 cm. Inspections by sounding revealed that some of the liner had delaminated from the rock. In order to perform structural diagnostics and health monitoring on the tunnel liner, a mapping procedure for the liner subsurface with ground penetrating radar was selected using non-contact antennas. This paper discusses the antenna deployment device and issues involved in using ground penetrating radar in the underground tunnel to map the subsurface of over 131,000 m² of fiber-reinforced shotcrete. In conclusion, it was determined that there are many factors involved that limit the use and application of ground penetrating radar in LRT tunnels.

In this paper, the experimentally measured data of two sensor systems (i.e., a surface-bonded piezoelectric sensor system and a non-contact scanning laser vibrometer (SLV) system) are studied, and three dynamics-based damage detection algorithms are evaluated. The curvature mode shapes are selected as a parameter to locate damage due to its sensitivity. The piezoelectric sensors directly acquire the curvature mode shapes of the structures, while the SLV measures the displacement mode shapes. The beam specimens are made of E-glass/epoxy composites, and several different types of damages are introduced in the beams (i.e., delaminations, impact and saw cut damage). This study provides a thorough assessment of the two sensor systems to damage detection of laminated composite beams and verify the validity of dynamics-based damage detection methodology for locating the local defects in composite structures.

In recent years, the impedance-based health monitoring technique has shown its promise in many applications. This technique makes use of the special properties of smart piezoelectric materials to identify the change of material properties due to the nucleation and progression of damage. A major advantage of this technique is that the procedure is nondestructive in nature and does not perturb the properties and performance of the materials and structures. This paper reports the results of applying the impedance-based nondestructive testing technique to the damage identification of composite laminates at cryogenic temperature. These materials have potential application for fuel tanks in future reusable launch vehicles and other applications. Special Single-Crystal Piezoceramic sensor/actuators are tested to assess their performance under a very wide range of temperature environments including cryogenic temperature. The results suggest that a linear relationship exists between the temperature and the measured data over a very wide range of temperatures. This relationship can be used to compensate the data collected in varying temperature environments and is an important tool for sensor data analysis.