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The inability of available situation displays to provide a decelerating instrument approach capability to a hover led to a flight research program in which control-command information was displayed for three degrees of freedom. The test aircraft (NASA's CH-46C in-flight simulator) was stabilized with high-gain attitude command system. Using this system, the pilot was able to decelerate the aircraft to a hover while simultaneously following a 6 deg glidepath. Although these tests demonstrate the potential of this concept, a number of factors, including adequate integration of command and situation information, were identified as affecting pilot acceptance of the system.

The Department of Defense has made progress in modernizing its procurement of weapon systems. Modernization has identified a need to address Federal and military standards and specifications for parts, materials, and processes that represent many de facto national standards. The aerospace industry is proposing a transition to commercial specifications that meet the needs of Acquisition Reform. This paper reviews the history and benefits of modernization and describes the transition process.

For an optimum design, the weight, energy consumption, and operational flexibility of the traction drive system for a lunar roving vehicle must be considered along with the power supply, motor, and power train. Other problems considered in this paper include: environment and motor dissipation; motor type (a-c or d-c) and commutation if d-c; motor controller (switching of large currents); delivery of torque at varying speeds; the power train; use of regenerative braking and conservation of energy; and power supply voltage variation. These problems are studied in the light of certain general system specifications, which fall into weight, performance, and environment categories. Tradeoff studies are considered for purposes of optimization in each of these areas. Special consideration is given to the controller and system design as it pertains to regenerative braking and the conservation of energy.

NASA's plans to implement the Vision for Space Exploration include extensive human-robot cooperation across an enterprise spanning multiple missions, systems, and decades. To make this practical, strong enterprise-level interface standards (data, power, communication, interaction, autonomy, and physical) will be required early in the systems and technology development cycle. Such standards should affect both the engineer and operator roles that humans adopt in their interactions with robots. For the engineer role, standards will result in reduced development lead-times, lower cost, and greater efficiency in deploying such systems. For the operator role, standards will result in common autonomy and interaction modes that reduce operator training, minimize workload, and apply to many different robotic platforms. Reduced quantities of spare hardware could also be a benefit of standardization.

Currently the U.S. is sponsoring production of radioisotope thermoelectric generators (RTGs) for the Cassini mission to Saturn; the SP-100 space nuclear reactor power system for NASA applications; a thermionic space reactor program for DoD applications as well as early work on nuclear propulsion. In an era of heightened public concern about having successful space ventures it is important that a full understanding be developed of what it means to “flight qualify” a space nuclear system. As a contribution to the ongoing work this paper reviews several qualification programs, including the general-purpose heat source radioisotope thermoelectric generators (GPHS-RTGs) as developed for the Galileo and Ulysses missions, the SNAP-10A space reactor, the Nuclear Engine for Rocket Vehicle Applications (NERVA), the F-1 chemical engine used on the Saturn-V, and the Space Shuttle Main Engines (SSMEs). Similarities and contrasts are noted.

Advanced water processors being developed for NASA's Exploration Initiative rely on phase change technologies and/or biological processes as the primary means of water reclamation. As a result of the phase change, volatile compounds will also be transported into the distillate product stream. The catalytic reactor assembly used in the International Space Station (ISS) water processor assembly, referred to as Volatile Removal Assembly (VRA), has demonstrated high efficiency oxidation of many of these volatile contaminants, such as low molecular weight alcohols and acetic acid, and is considered a viable post treatment system for all advanced water processors. To support this investigation, two ersatz solutions were defined to be used for further evaluation of the VRA. The first solution was developed as part of an internal research and development project at Hamilton Sundstrand (HS), and is based primarily on ISS experience related to the development of the VRA.

Advanced life support systems require computer controls which deliver a high degree of reliability and autonomy and meet life support criteria. Such control systems must allow crewmembers on long-term missions to perform their scientific and engineering duties while minimizing interactions with life support systems. Control systems must be the “brains” of life support systems providing air, water, edible biomass, and recycling services. They must establish and maintain life support components in an optimized manner, providing self-sufficient infrastructures independent of Earth-based resupply. The CELSS (Controlled Ecological Life Support System) Breadboard Project has implemented such a computerized component of a future mission. The Universal Networked Data Acquisition and Control Engine (UNDACE) is the software interface between humans and hardware controlling plant growth experiments.

A lab-scale testbed for screening and characterizing the chemical specificity of commercial “off-the-shelf” (COTS) polymer adsorbents was built and tested. COTS polymer adsorbents are suitable candidates for future trace contaminant (TC) control technologies. Regenerable adsorbents could reduce overall TC control system mass and volume by minimizing the amounts of consumables to be resupplied and stored. However, the chemical specificity of these COTS adsorbents for non-methane volatile organic compounds (NMVOCs) (e.g., methanol, ethanol, dichloromethane, acetone, etc) commonly found in spacecraft is unknown. Furthermore, the effect of humidity on their filtering capacity is not well characterized. The testbed, composed of a humidifier, an incubator, and a gas generator, delivers NMVOC gas streams to conditioned sorbent tubes.

The Technology Test Bed and Hydrogen Cold Flow facilities at NASA’s Marshall Space Flight Center (MSFC) in Huntsville, Alabama provide unique testing capabilities for the aerospace community. Located at the Advanced Engine Test Facility (AETF), these facilities are operated and maintained by MSFC Propulsion Laboratory personnel. They provide a systems and components level testing platform for validating new technology concepts and advanced systems design and for gaining a better understanding of test article internal environments. A discussion follows of the particular capabilities of each facility to provide a range of testing options for specific test articles.

Selecting the appropriate atmosphere for a spacecraft and mission is a complicated problem. NASA has previously used atmospheres from Earth normal composition and pressure to pure oxygen at low pressures. Future exploration missions will likely strike a compromise somewhere between the two, trying to balance operation impacts on EVA, safety concerns for flammability and health risks, life science and physiology questions, and other issues. Life support systems and internal thermal control systems are areas that will have to respond to changes in the atmospheric composition and pressure away from the Earth-like conditions currently used on the International Space Station. This paper examines life support and internal thermal control technologies currently in use or in development to find what impacts in design, efficiency and performance, or feasibility might be expected.

Unlike a terrestrial electric utility which can purchase power from a neighboring utility, the Space Station Freedom (SSF) has strictly limited energy resources; as a result, source control, system monitoring, system protection and load management are essential to the safe and efficient operation of the SSF Electric Power System (EPS). These functions are being evaluated in the DC Power Management and Distribution (PMAD) Testbed which NASA LeRC has developed at the Power System Facility (PSF) located in Cleveland, Ohio. The testbed is an ideal platform to develop, integrate, and verify power system monitoring and control algorithms. State Estimation (SE) is a monitoring tool used extensively in terrestrial electric utilities to ensure safe power system operation.

A palladium catalytic oxidizer is being developed to remove plant-generated oxygen from a closed plant growth chamber, replacing the oxygen with carbon dioxide gas and water vapor. The device will provide a relatively simple means of preventing oxygen build-up within the chamber. It may also be used to simulate man-in-the-loop at whatever scale is desired. Discussion is provided on how the device fits in with the development of the closed plant growth environmental chamber in the short term and with controlled ecological life support systems (CELSS) development in the longer term. Alternative means of oxygen removal are compared. The results of preliminary kinetics testing is presented.

The purpose of the Permeable Membrane Experiment is to gather flight data on three areas of membrane performance that are influenced by the presence of gravity. These areas are: (1) liquid/gas phase separation, (2) gas bubble interference with diffusion through porous membranes and (3) wetting characteristics of hydrophilic membrane surfaces. These data are important in understanding the behavior of membrane/liquid/gas interfaces where surface tension forces predominate. The data will be compared with 1-g data already obtained and with predicted microgravity behavior. The data will be used to develop designs for phase separation and plant nutrient delivery systems and will be available to the life support community for use in developing technologies which employ membranes. A conceptual design has been developed to conduct three membrane experiments, in sequence, aboard a single Complex Autonomous Payload (CAP) carrier to be carried in the Shuttle Orbiter payload bay.

Particle trajectory and ice shape calculations were made for the Energy Efficient Engine (E₃) using the LEWICE3D Version 3 software. The particle trajectory and icing computations were performed using the new "block-to-block" collection efficiency method which has been incorporated into the LEWICE3D Version 3 software. The E₃ was developed by NASA and GE in the early 1980s as a technology demonstrator and is representative of a modern high bypass turbofan engine. The E₃ flow field was calculated using the NASA Glenn ADPAC turbomachinery flow solver. Computations were performed for the low pressure compressor of the E₃ for a Mach .8 cruise condition at 11,887 meters assuming a standard warm day for three drop sizes and two drop distributions typically used in aircraft design and certification. Particle trajectory computations were made for water drop sizes of 5, 20 and 100 microns.

For reasons of safety as well as cost, increasingly lengthy space missions at unprecedented distances from Earth in the 21st century will require reductions in consumables and increases in the autonomy of spacecraft life support systems. Advanced life support technologies can increase mission productivity and enhance science yield by achieving reductions in the mass, volume, and power required to support human needs for long periods of time in sterile and hostile environments. Current investment in developing advanced life support systems for orbital research facilities will increase the productivity of these relatively near-term missions, while contributing to the technology base necessary for future human exploration missions.

The process of reducing a physical system to a mathematical representation is a prevalent task mutual to all fields of analysis. Sometimes the system of equations, or mathematical model as commonly known, will be modified on a trial and error basis to make the model respond in some predetermined fashion or react so as to match behavioral data obtained from the actual physical system. This paper presents a survey of activities to produce logically based schemes to generate mathematical models by making use of experimentally derived information. Primary attention is given to modeling of mechanical structures for purposes of dynamic analysis. Emphasis is given to current effort at Goddard and in particular to the recent studies designed to verify the practical effectiveness of a specific modeling scheme. Strengths and weaknesses of the various modeling schemes are discussed.

The development from program inception of major Apollo spacecraft systems is reviewed. Those subsystems which required significant advances in current technology are highlighted, and important system development derived from Project Mercury and the Gemini Program is discussed where pertinent. The overall approach to satisfaction of mission requirements in the Apollo spacecraft is outlined in relation to the manned lunar landing. The paper illustrates that all mission-critical systems were designed with a high degree of reliability and redundancy because of the limited flight frequency, the denial of inflight maintenance, and the absence of an inflight rescue capability. For the lunar module, the first true spacecraft, significant unknowns that faced spacecraft designers could not be effectively resolved in any of the earth-orbit flight programs.

Future lunar science and exploration missions will involve the use of pressurized rovers for long duration lunar surface missions. Designs for pressurized rovers are being studied by NASA and the industry. This paper presents some results of work currently underway on the development of a rover simulator in the context of a new pressurized rover concept. A motion base simulator will play a vital role in generating rover vehicle design and performance requirements. A simulator based on a modular simulation (MODSIM) architecture, has been under study and development since 1991. The MODSIM approach will provide benefits of flexibility of modification, low cost, phased scheduling and ease of supportability when compared with more traditional simulator architectures. A lunar rover simulator based on MODSIM will help rover vehicle engineers to be productive through all phases of simulator development.

Large launch vehicle systems are examined in terms of design and operating characteristics and potential applications. A brief history of the development of Saturn V is followed by a discussion of potential cost-saving simplifications. Potentially attractive intermediate payload derivatives of Saturn V and the use of a nuclear third stage are considered along with potential missions. New concepts and technology discussed include low-cost expendable, partially reusable, and fully reusable systems in which the launch vehicle and spacecraft are integral. The need for, and desired characteristics of, a reusable “space shuttle” system are indicated and a brief description of alternate approaches to obtaining this system are presented.

A new technique is proposed for computing particle concentrations and fluxes with Lagrangian trajectories. This method calculates particle concentrations based on the volume of a parcel element, or cloud, at the flux plane compared against the initial volume and is referred to as the Lagrangian Parcel Volume (LPV) method. This method combines the steady-state accuracy of area-based methods with the unsteady capabilities of bin-based methods. The LPV method results for one-dimensional (1D) unsteady flows and linear two-dimensional (2D) steady flows show that a quadrilateral element shape composed of a single parcel (with four edge particles) is capable of accurately predicting particle concentrations. However, nonlinear 2D flows can lead to concave or crossed quadrilaterals which produce significant numerical errors.