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This paper develops an interdisciplinary space architecture optimization framework to analyze the tradeoff on in-situ resource utilization options, identify technology gaps, evaluate the benefits of in-situ resource utilization, and optimize the design of infrastructure for Mars human space exploration scenarios and mission profiles. It performs trade studies from the perspective of space logistics, which takes into account the interplanetary transportation, infrastructure deployment, in-situ resource utilization system operation, and logistics of the produced resources. Our method considers space architecture design and operation from the subsystem level to capture the coupling between in-situ resource utilization technologies and in-space architecture elements for space resource logistics. A case study involving a multi-mission human Mars exploration campaign is performed to evaluate the effectiveness of existing and proposed in-situ resource utilization technology concepts and system designs. The results can provide us with a better understanding of the benefits and costs of different in-situ resource utilization technologies for interplanetary space transportation. A sensitivity analysis is also conducted to understand the impacts of lunar and near-Earth-object's in-situ resource utilization systems on Mars missions. The results of this analysis can help decision-makers determine and optimize the roadmap for in-situ resource utilization technology development.

To build a sustainable and affordable space transportation system for human space exploration, the design and deployment of space infrastructures are critical; one attractive and promising infrastructure system is the in-situ resource utilization (ISRU) system. The design analysis and trade studies for ISRU systems require the consideration of not only the design of the ISRU plant itself but also other infrastructure systems (e.g., storage, power) and various ISRU architecture options (e.g., resource, location, technology). This paper proposes a system-level space infrastructure and its logistics design optimization framework to perform architecture trade studies. A new space infrastructure logistics optimization problem formulation is proposed that considers infrastructure subsystems' internal interactions and their external synergistic effects with space logistics simultaneously. Since the full-size version of this proposed problem formulation can be computationally prohibitive, a new multi-fidelity optimization formulation is developed by varying the granularity of the commodity type definition over the network graph; this multi-fidelity formulation can find an approximation solution to the full-size problem computationally efficiently with little sacrifice in the solution quality. The proposed problem formulation and method are applied to a multi-mission lunar exploration campaign to demonstrate their values., 34 pages, 3 figures, a former version was presented at the AIAA Propulsion and Energy Forum 2019

Numerous high-thrust and low-thrust space propulsion technologies have been developed in the recent years with the goal of expanding space exploration capabilities; however, designing and optimizing a multi-mission campaign with both high-thrust and low-thrust propulsion options are challenging due to the coupling between logistics mission design and trajectory evaluation. Specifically, this computational burden arises because the deliverable mass fraction (i.e., final-to-initial mass ratio) and time of flight for low-thrust trajectories can can vary with the payload mass; thus, these trajectory metrics cannot be evaluated separately from the campaign-level mission design. To tackle this challenge, this paper develops a novel event-driven space logistics network optimization approach using mixed-integer linear programming for space campaign design. An example case of optimally designing a cislunar propellant supply chain to support multiple lunar surface access missions is used to demonstrate this new space logistics framework. The results are compared with an existing stochastic combinatorial formulation developed for incorporating low-thrust propulsion into space logistics design; our new approach provides superior results in terms of cost as well as utilization of the vehicle fleet. The event-driven space logistics network optimization method developed in this paper can trade off cost, time, and technology in an automated manner to optimally design space mission campaigns., 38 pages; 11 figures; Journal of Spacecraft and Rockets (Accepted); previous version presented at the AAS/AIAA Astrodynamics Specialist Conference, 2018

This paper develops a network optimization formulation for dynamic campaign-level space mission planning. Although many past space missions have been designed mainly from a mission-level perspective, a campaign-level perspective will be important for future space exploration. In order to find the optimal campaign-level space transportation architecture, a mixed-integer linear programming (MILP) formulation with a generalized multi-commodity flow and a time-expanded network is developed. Particularly, a new heuristics-based method, a partially static time-expanded network, is developed to provide a solution quickly. The developed method is applied to a case study containing human exploration of a near-Earth object (NEO) and Mars, related to the concept of the Flexible Path. The numerical results show that using the specific combinations of propulsion technologies, in-situ resource utilization (ISRU), and other space infrastructure elements can reduce the initial mass in low-Earth orbit (IMLEO) significantly. In addition, the case study results also show that we can achieve large IMLEO reduction by designing NEO and Mars missions together as a campaign compared with designing them separately owing to their common space infrastructure pre-deployment. This research will be an important step toward efficient and flexible campaign-level space mission planning.

Aerospace engineers use mass (e.g. IMLEO) as a reliable proxy for space mission costs in space system architecture and trade studies. However, in recent years, the true cost of human space exploration architectures is progressively being decoupled from IMLEO, mainly as a result of reusable rockets, adoption of ISRU and ISM, and a new emphasis on developing permanent infrastructure on other worlds. This thesis investigates the case for adopting embodied energy as a novel and more capable metric for the value and cost of in-space activities. Energy is the natural metric for work, and all in-space activities require costly direct and indirect energy sources. Embodied energy is an objective metric of cumulative past work, first developed by ecologists and economists in the 1970's and mainly used today to evaluate the lifecycle energy performance of buildings. The embodied energy expended in space logistics is proposed as the primary source of embodied energy for all in-space activities, coupling the proposed new method with currently accepted practice of mass minimization. Howard Odum's energy language, which charts flows of embodied energy from sources to producers, consumers and sinks, is adapted for use in the design of an early industrial outpost on Mars. A case study of seven scenaria for this simple Mars outpost over 20 and 40 years, all with identical IMLEO but widely varying embodied energies, is used to demonstrate how embodied energy leads to superior system-wide architectural insights in the design of sustainable, permanent human outposts on other worlds. An early finding is that lifetime embodied energy cost reductions increase with the time horizon and the up-front investment in ISRU and ISM capabilities. Future work based on lifetime embodied energy may result in new approaches for the simultaneous optimization of lifetime emplaced and logistical masses, lifetime energy efficiency and other figures of merit for long term system performance. The proposed Lifetime Embodied Energy metric supports the development of improved methods and tools for the system design of human outposts on other worlds. Improved system design may in turn contribute to the outposts' sustainable growth in an organic manner, and shorten the time between their establishment and Earth independence.

Simple logistics strategies such as “carry-along” and Earth-based “resupply” were sufficient for past human space programs. Next-generation space logistics paradigms are expected to be more complex, involving multiple exploration destinations and in situ resource utilization. Optional in situ resource utilization brings additional complexity to the interplanetary supply chain network design problem. This paper presents an interdependent network flow modeling method for determining optimal logistics strategies for space exploration and its application to the human exploration of Mars. It is found that a strategy using lunar resources in the cislunar network may improve overall launch mass to low Earth orbit for recurring missions to Mars compared to NASA’s Mars Design Reference Architecture 5.0, even when including the mass of the in situ resource utilization infrastructures that need to be predeployed. Other findings suggest that chemical propulsion using liquid oxygen/liquid hydrogen, lunar in situ resource utilization water production, and the use of aerocapture significantly contribute to reducing launch mass from Earth. A sensitivity analysis of in situ resource utilization reveals that, under the given assumptions, local lunar resources become attractive at productivity levels above 1.8 kg / year / kg in the context of future human exploration of Mars., Jet Propulsion Laboratory (U.S.). Strategic University Research Partnerships Program

This paper reports on current habitability concepts for an Evolvable Mars Campaign (EMC) prepared by the NASA Human Spaceflight Architecture Team (HAT). For many years NASA has investigated alternative human Mars missions, examining different mission objectives, trajectories, vehicles, and technologies; the combinations of which have been referred to as reference missions or architectures. At the highest levels, decisions regarding the timing and objectives for a human mission to Mars continue to evolve while at the lowest levels, applicable technologies continue to advance. This results in an on-going need for assessments of alternative system designs such as the habitat, a significant element in any human Mars mission scenario, to provide meaningful design sensitivity characterizations to assist decision-makers regarding timing, objectives, and technologies. As a subset of the Evolvable Mars Campaign activities, the habitability team builds upon results from past studies and recommends options for Mars surface habitability compatible with updated technologies.

Human exploration missions under study are limited by the launch mass capacity of existing and planned launch vehicles. The logistical mass of crew items is typically considered separate from the vehicle structure, habitat outfitting, and life support systems. Although mass is typically the focus of exploration missions, due to its strong impact on launch vehicle and habitable volume for the crew, logistics volume also needs to be considered. NASA's Advanced Exploration Systems (AES) Logistics Reduction and Repurposing (LRR) Project is developing six logistics technologies guided by a systems engineering cradle-to-grave approach to enable after-use crew items to augment vehicle systems. Specifically, AES LRR is investigating the direct reduction of clothing mass, the repurposing of logistical packaging, the use of autonomous logistics management technologies, the processing of spent crew items to benefit radiation shielding and water recovery, and the conversion of trash to propulsion gases. Reduction of mass has a corresponding and significant impact to logistical volume. The reduction of logistical volume can reduce the overall pressurized vehicle mass directly, or indirectly benefit the mission by allowing for an increase in habitable volume during the mission. The systematic implementation of these types of technologies will increase launch mass efficiency by enabling items to be used for secondary purposes and improve the habitability of the vehicle as mission durations increase. Early studies have shown that the use of advanced logistics technologies can save approximately 20 m(sup 3) of volume during transit alone for a six-person Mars conjunction class mission.

The Space Launch System (SLS) is the new NASA heavy lift launch vehicle and is scheduled for its first mission in 2017. The goal of the first mission, which will be uncrewed, is to demonstrate the integrated system performance of the SLS rocket and spacecraft before a crewed flight in 2021. SLS has many of the same logistics challenges as any other large scale program. Common logistics concerns for SLS include integration of discreet programs geographically separated, multiple prime contractors with distinct and different goals, schedule pressures and funding constraints. However, SLS also faces unique challenges. The new program is a confluence of new hardware and heritage, with heritage hardware constituting seventy-five percent of the program. This unique approach to design makes logistics concerns such as commonality especially problematic. Additionally, a very low manifest rate of one flight every four years makes logistics comparatively expensive. That, along with the SLS architecture being developed using a block upgrade evolutionary approach, exacerbates long-range planning for supportability considerations. These common and unique logistics challenges must be clearly identified and tackled to allow SLS to have a successful program. This paper will address the common and unique challenges facing the SLS programs, along with the analysis and decisions the NASA Logistics engineers are making to mitigate the threats posed by each.

A sustainable space logistics system for robotic and human exploration of the Moon, asteroids, Mars, and other deep space destinations has been identified. Following the key tenets of launch and in-space commonality, efficient in-space transportation, and phased capability development drives the overall cost of missions to the Moon, NEOs, Phobos, and the surface of Mars to fall within achievable budgets while ensuring that risks to the crew and mission are minimized. Using high power solar electric freighters to preposition all nontime critical cargo and using conventional LOX/H2 high thrust systems for crew transportation enables the use of smaller SLS class launch vehicles with great commonality across missions, distributing fixed launch costs across a broad customer base and dramatically reducing exploration costs. Both 300kW and 600kW SEP freighters are used for pre-placement of habitats, exploration equipment, and return vehicles at the destinations, allowing complete systems verification prior to crew Earth departure, significantly reducing the risks from the crewed portion of the mission. Missions are phased to spread development, production, and mission operations costs and enable incremental expansion of demonstrated exploration capabilities and modular infusion of new technologies, culminating in a human mission to the surface of Mars in 2033.

The NASA Advanced Exploration Systems (AES) Logistics Reduction and Repurposing (LRR) project strives to enable a largely mission-independent cradle-to-grave-to-cradle approach to minimize logistics contributions to total mission architecture mass. The goals are to engineer logistics materials, common crew consumables, and container configurations to meet the following five basic goals: 1. Minimize intrinsic logistics mass and improve ground logistics flexibility. 2. Allow logistics components to be directly repurposed for on-orbit non-logistics functions (e.g., crew cabin outfitting) thereby indirectly reducing mass/volume. 3. Compact and process logistics that have not been directly repurposed to generate useful on-orbit components and/or compounds (e.g., radiation shielding, propellant, other usable chemical constituents). 4. Enable long-term stable storage and disposal of logistics end products that cannot be reused or repurposed (e.g., compaction for volume reduction, odor control, and maintenance of crew cabin hygienic conditions). 5. Allow vehicles in different mission phases to share logistics resources. This paper addresses the work being done to meet the second goal, the direct repurposing of logistics components to meet other on-orbit needs, through a strategy termed Logistics to Living (L2L). L2L has several areas but can be defined as repurposing or converting logistical items (bags, containers, foam, components, etc.) into useful crew items or life support augmentation on-orbit after they have provided their primary logistics function. The intent is that by repurposing items, dedicated crew items do not have to be launched and overall launch mass is decreased. For non-LEO missions, the vehicle interior volume will be relatively fixed so L2L will enable this volume to be used more effectively through reuse and rearrangement of logistical components. Past work in the area of L2L has already conceptually developed several potential technologies [Howe, Howard 2010]. Several of the L2L concepts that have shown the most potential in the past are based on NASA cargo transfer bags (CTBs) or their equivalents which are currently used to transfer cargo to and from the ISS. A high percentage of all logistics supplies are packaging mass and for a 6-month mission a crew of four might need over 100 CTBs. These CTBs are used for on-orbit transfer and storage but eventually becomes waste after use since down mass is very limited. The work being done in L2L also considering innovative interior habitat construction that integrate the CTBs into the walls of future habitats. The direct integration could provide multiple functions: launch packaging, stowage, radiation protection, water processing, life support augmentation, as well as structure. Reuse of these CTBs would reduce the amount of waste generated and also significantly reduce future up mass requirements for exploration missions. Also discussed here is the L2L water wall , an innovative reuse of an unfolded CTB as a passive water treatment system utilizing forward osmosis. The bags have been modified to have an inner membrane liner that allows them to purify wastewater. They may also provide a structural water-wall element that can be used to provide radiation protection and as a structural divider. Integration of the components into vehicle/habitat architecture and consideration of operations concepts and human factors will be discussed. In the future these bags could be designed to treat wastewater, concentrated brines, and solid wastes, and to dewater solid wastes and produce a bio-stabilized construction element. This paper will describe the follow-on work done in design, fabrication and demonstrations of various L2L concepts, including advanced CTBs for reuse/repurposing, internal outfitting studies and the CTB-based forward osmosis water wall.

This paper provides a summary of the 2007 Mars Design Reference Architecture 5.0 (DRA 5.0) [1], which is the latest in a series of NASA Mars reference missions. It provides a vision of one potential approach to human Mars exploration, including how Constellation systems could be used. The strategy and example implementation concepts that are described here should not be viewed as constituting a formal plan for the human exploration of Mars, but rather provide a common framework for future planning of systems concepts, technology development, and operational testing as well as potential Mars robotic missions, research that is conducted on the International Space Station, and future potential lunar exploration missions. This summary of the Mars DRA 5.0 provides an overview of the overall mission approach, surface strategy and exploration goals, as well as the key systems and challenges for the first three concepts for human missions to Mars.1,2

Space logistics is the science of planning, creating, and sustaining effective and affordable infrastructure, supply chain management, and maintenance to support space operations throughout the solar system. In information and entertainment, global commerce, navigation and communication, weather and environmental monitoring, surveillance and intelligence, and science and exploration, space connects the world and the flow of information across space becomes the lynchpin and focal point of any true advances in space logistics campaign planning and simulation. For the new era of human space exploration, new tools that surpass the existing Gantt and PERT chart approaches are needed as we transition from the Space Shuttle to Constellation while simultaneously balancing potential changes in priorities. At the National Aeronautics and Space Administration’s Marshall Space Flight Center (and including the Michoud Assembly Facility), a new tool has emerged which combines the benefits of both the Gantt and PERT charts with the power of the internet and the ability to orchestrate resources that excel using their own familiar tools. It is called Vdot (coined after the first derivative of velocity, or acceleration) and is a COTS software product. The process management methodology that Qualis Corporation has demonstrated with this tool has the potential to revolutionize space logistics campaign planning and simulation.

This paper summarizes the current state of the art in interplanetary supply chain modeling and discusses SpaceNet as one particular method and tool to address space logistics modeling and simulation challenges. Fundamental upgrades to the interplanetary supply chain framework such as process groups, nested elements, and cargo sharing, enabled SpaceNet to model an integrated set of missions as a campaign. The capabilities and uses of SpaceNet are demonstrated by a step-by-step modeling and simulation of a lunar campaign.

Fulfilling NASA’s Vision for Space Exploration will demand an extended presence in space at distances from our home planet that exceed our current experience in space logistics and maintenance. The ability to perform repairs in lieu of the customary Orbital Replacement Unit (ORU) process where a faulty part is replaced will be elevated from contingency to routine to sustain operations. The use and cost effectiveness of field repairs for ground based operations in industry and the military have advanced with the development of technology in new materials, new repair techniques and new equipment. The unique environments, accessibility constraints and Extra Vehicular Activity (EVA) issues of space operations will require extensive assessment and evolution of these technologies to provide an equivalent and expected level of assurance to mission success. Challenges include the necessity of changes in design philosophy and policy, extremes in thermal cycling, disruptive forces (such as static charge and wind entrainment) on developed methods for control of materials, dramatically increased volatility of chemicals for cleaning and other compounds due to extremely low pressures, the limits imposed on dexterity and maneuverability by current EVA equipment and practices, and the necessity of unique verification methodology. This paper describes these challenges in and discusses the effects on the established ground techniques for repair. The paper also describes the leading repair methodology candidates and their beneficial attributes for resolving these issues with the evolution of technology.

As NASA looks ahead to next-generation human space exploration, it is essential to consider the cost of operations and support in order to ensure the development of affordable programs. The life-cycle costs of future exploration ventures can be reduced by focusing on the interplanetary logistics strategy. By leveraging proven supply chain management techniques from the military and commercial sectors and applying them to the unique challenges of human space exploration, space logistics can be streamlined, and mission affordability and robustness can be increased. This paper describes a modeling framework for space logistics which enables description, evaluation, and optimization of various types of logistics strategies. The framework is embodied in SpaceNet, a discrete event simulation and optimization software program.

Space agencies around the world are gearing up for new human space exploration missions. In order to ensure that such programs are sustainable, it is worthwhile to examine the lessons learned from past experiences with space logistics and supply chain management. This paper offers an overview of the current state of the art in logistics management for space exploration focused on information systems, and highlights some emerging technologies that have the potential to significantly improve both the study and operation of space logistics systems.

The objective of this paper is to demonstrate a methodology for designing and evaluating the operational planning for interplanetary exploration missions. A primary question for space exploration mission design is how to best design the logistics required to sustain the exploration initiative. Using terrestrial logistics modeling tools that have been extended to encompass the dynamics and requirements of space transportation, an architectural decision method has been created. The model presented in this paper is capable of analyzing a variety of mission scenarios over an extended period of time with the goal of deflning interesting architectural scenarios for space logistics. This model can be utilized to evaluate difierent logistics trades, such as a possible establishment of a push-pull boundary, which can aid in commodity pre-positioning. The results of this implementation are presented for a lunar campaign using estimated surface demands for exploration.

The application of standard logistics analysis to military activities in space is discussed. Consideration is given to space-system segmentation, orbital placement, orbital maneuvers, and space assembly and maintenance options. It is argued that plans for a normalized space infrastructure should consider the total space support requirements and not be based on just the needs of a particular system. >

NASA's Space Station maintenance planning and analysis (MP&A)study is a step in the overall Space Station program to define optimum approaches for on-orbit maintenance planning and logistics support. The approach used in the MP&A study and the analysis process used are presented. Emphasis is on maintenance activities and processes that can be accomplished on orbit within the known design and support constraints of the Space Station. From these analyses, recommendations for maintainability/maintenance requirements are established. The ultimate goal of the study is to reduce on-orbit maintenance requirements to a practical and safe minimum, thereby conserving crew time for productive endeavours. The reliability, availability, and maintainability and operations performance evaluation modes used were assembled and developed as part of the MP&A study and are described. A representative space station system design is presented to illustrate the analysis process. >

As a tool for construction and refinement of the on-orbit maintenance system to sustain the International Space Station Alpha (ISSA), the Mission Operations Directorate (MOD) developed an end to-end on-orbit maintenance process flow. This paper discusses and demonstrates that process flow. This tool is being used by MOD to identify areas which require further work in preparation for MOD's role in the conduct of on-orbit maintenance operations.

It has been said that Continual Improvement (CI) is difficult to apply to service oriented functions, especially in a government agency such as NASA. However, a constrained budget and increasing requirements are a way of life at NASA Kennedy Space Center (KSC), making it a natural environment for the application of CI tools and techniques. This paper describes how KSC, and specifically the Space Shuttle Logistics Project, a key contributor to KSC's mission, has embraced the CI management approach as a means of achieving its strategic goals and objectives. An overview of how the KSC Space Shuttle Logistics Project has structured its CI effort and examples of some of the initiatives are provided.

This paper describes the NASA/JSC Research Technology Opportunity Program (RTOP) activity to assess the supportability of space systems throughout their life cycles. Supportability analyses for space systems present unique attributes and problems. The OSMOSSYS (Object oriented Simulation of Maintenance and Operations for Space Systems) was developed using object-oriented design concepts to provide NASA an analysis tool which addresses the question `Will a proposed space facility be able to successfully perform the missions for which it is designed?' This model integrates the complete configuration of the system including the reliability and maintainability characteristics of each component, the logistics support, and the mission operations of the facility to assess the success rate of the planned mission(s). Two parallel design processes are being utilized; developing core modules utilizing C++, and incorporating as much code and ideas as possible from existing NASA models. The space station was used as a test case to demonstrate the applicability of the model.

The Space Station Freedom program and the process used to develop an assembly sequence are overviewed, with special attention given to the outcome of the recent restructuring activity and the positive impact it had on the Space Station design and the assembly sequence. The many technically complex and challenging aspects of the assembly sequence planning are examined, including the launch vehicle integration, the spacecraft systems capability development, and the availability of resources. It is shown that the restructuring reduced the size and the complexity of the Space Station, while the increase of ground integration through the use of preintegrated truss and shortened modules offers a reduced program risk and reduced demands on the STS.

The design and functions of ALEPS (Automated Logistics Element Planning System) is a computer system that will automate planning and decision support for Space Station Freedom Logistical Elements (LEs) resupply and return operations. ALEPS provides data management, planning, analysis, monitoring, interfacing, and flight certification for support of LE flight load planning activities. The prototype ALEPS algorithm development is described.

The implications of logistics and operations on the manual control of spacecraft docking are discussed. The results of simulation studies to investigate fuel and time cost tradeoffs are reviewed and discussed. Comparisons of acceleration control and pulse control are presented to evaluate the effects of astronauts being instructed to use pulse mode for fuel conservation. The applications of the findings to moon and Mars missions are addressed.

The key roles played in the on-orbit maintenance of Space Station Freedom by mission controllers working in the Space Station Control Center are discussed. Responsibilities ranging from planning and procedure development to training and real-time support are addressed. The organization of the Mission Operations Directorate is described.

The development of a 'front-end' Integrated Logistics Support (ILS) strategic concept and a Supportability Index Model (SIM) for incorporation into future SEI engineering efforts is discussed. The ILS objectives and support strategy are examined. The SIM mission phases, which evaluates those items determined to be the most crucial for each mission phase in terms of a measure of supportability effectiveness, are summarized and the SIM data development and initial model results are reviewed.

The concept of the NASA Shuttle Logistics Depot (NSLD) developed for the Space Shuttle Orbiter Program is described. The function of the NSLD at Cape Canaveral is to perform the acceptance and diagnostic testing of the Shuttle's space-rated line-replaceable units and shop-replaceable units (SRUs). The NSLD includes a comprehensive electronic automatic test station, program development stations, and assorted manufacturing support equipment (including thermal and vibration test equipment, special test equipment, and a card SRU test system). The depot activities also include the establishment of the functions for manufacturing of mechanical parts, soldering, welding, painting, clean room operation, procurement, and subcontract management.

The paper addresses the challenges inherent in establishing an outpost on the planet Mars. For background purposes, the unique, remote Martian environment and the developmental phases of a settlement in such an environment are discussed. Challenges are identified in terms of surface systems and operations. Due to its importance to habitability, the life support system (LSS) is highlighted with various options identified. Operations for the Mars outpost, earth-based and local, are characterized by a decentralized concept. The challenge of integrating logistics analysis early in system design and operations strategy is also addressed. In order to understand and reduce the system and operations challenges, the application of terrestrial and lunar testbeds is explained.

Equipment maintenance and logistics strategies followed on the R/S Thompson, an oceanographic research vessel, are described, and parallels are drawn between the problems and solutions of an oceanographic expedition and those of a space station mission. Presumably oceanic expeditions, which have been conducted for over 150 years, have developed effective methods of equipment maintenance. Similarities are found in relative budget and equipment maintenance problems, but few similarities are found in solutions to these problems. It is speculated that the high relative cost of on-orbit work is responsible, and that development of significantly more effective component level fault diagnosis equipment and repair equipment could enable application of oceanographic equipment maintenance strategies, enhancing safety and speeding laboratory work while giving significant cost reduction.

Development of an efficient and cost effective operational logistics system for the Space Station will require logistics planning early in the program's design and development phase. This paper will focus on Integrated Logistics Support (ILS) Program techniques and their application to the Space Station program design, production and deployment phases to assure the development of an effective and cost efficient operational logistics system. The paper will provide the methodology and time-phased programmatic steps required to establish a Space Station ILS Program that will provide an operational logistics system based on planned Space Station program logistics support.

Space construction systems made feasible by an operational Space Shuttle are discussed with a view toward assembly, installation and construction support equipment. The level of construction capability will be reflected in the number of launches to accomplish a certain mission, either in terms of the mission time line or on the density of packaging in the Orbiter payload bay. It is noted that the development of construction support equipment in zero-gravity simulations should be the most productive initial activity. Crew EVAs, as well as the beam builder, cherrypicker and power distribution buses are covered in detail.

This paper describes some of the issues involved in converting a prototype of a large-scale discrete event simulation written in SIMSCRIPT II.5 and FORTRAN into Ada. Specific features provided by SIMSCRIPT that needed to be created in Ada are discussed. Preliminary conclusions regarding the use of both languages for large-scale simulations are then prersented.

This paper describes the overall logistics scenario which reflects the present design configurations and operational concepts as derived from the COLUMBUS phase B activities and results of considerations of coherence with other European Space Elements, e.g. Herrnes, and identifies the required resupply infrastructure, covering the range from provision or off-line repair of units at a manufacturers site via ground/orbit transport to on-orbit storage, until utilization in a servicing activity.

The Logistics Asset Tracking System (LATS) devised by NASA contains data on Space Shuttle LRUs that are daily updated to reflect such LRU status changes as repair due to failure or modification due to changing engineering requirements. The implementation of LATS has substantially increased personnel responsiveness, preventing costly delays in Space Shuttle processing and obviating hardware cannibalization. An evaluation is presented of LATS achievements in the direction of an integrated logistical support posture.

The Desktop Resource Leveling Model (DRLM) has been developed as a tool to rapidly structure and manipulate accommodation, schedule, and funding profiles for any kind of experiments, payloads, facilities, and flight systems or other project hardware. The model creates detailed databases describing 'end item' parameters, such as mass, volume, power requirements or costs and schedules for payload, subsystem, or flight system elements. It automatically spreads costs by calendar quarters and sums costs or accommodation parameters by total project, payload, facility, payload launch, or program phase. Final results can be saved or printed out, automatically documenting all assumptions, inputs, and defaults.