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Viewing 70801 to 70830 of 109592
1991-07-01
Technical Paper
911445
U. Laux, B. Behrens, H.P. Hafkemeyer, B. Miedza
The paper describes the thermal control and life support design and related system aspects of the COLUMBUS Free-Flyer. The specific requirements for the FreeFlyer thermal control and environmental control and life support are mainly driven by the particular performance to be provided in single mission phases by the overall operational life requirement of 30 years for the whole Free-Flyer flight configuration and the possibility for repair and maintenance in orbit by the different operating modes of the Resource Module as autonomous or composite configuration by the complex and partially different interfaces with HERMES and the Space Station Freedom. During the Resource Module exchange at the Space Station Freedom the Pressurized Module is deactivated and thermally controlled by a heater system supplied with power by the space station. After attachment of the new Resource Module the internal servicing will be performed.
1991-07-01
Technical Paper
911446
Silvio Dolce, Massimo Antonacci, Michele Trichilo
Columbus Pressurised Modules (APM permanently attached to Space Station Freedom and MTFF free flyer) will support the scientific experiments and commercial space exploitation requiring manned interaction and intervention (APM) or infrequent servicing/resupply by flight crew (MTFF) in a low gravity environment. This paper is based on the activities performed during the early stages of Columbus Phase C/D and presents: the Active Thermal Control design solutions including the architecture of the fluid loops, the fluid loops monitoring and control philosophy and the fluid loops components and design features; the Passive Thermal Control design solutions including MLI, anticondensation, heaters concept and thermo-optical properties selection.
1991-07-01
Technical Paper
911448
Giuseppe D. Racca, Wolfgang Hahn
The intensive endeavor of the human, to do research work and to test in the low earth orbit, results in complex orbital platforms. These space based platforms are either permanent or retrievable. This is the case of the European Retrievable Carrier (EURECA), a free-flying reusable platform that is launched and retrieved by the NSTS Orbiter. The first EURECA mission will be primarily a microgravity mission specifically for material processing and life science payloads. The thermal control system of EURECA has to ensure the correct environment for the carrier and the payload, throughout all mission phases, by means of passive and active means. The passive means consist of various multi-layer insulations, surface finishing, conducting straps. Electrical heaters work, in conjunction with the active cooling loop, to keep the spacecraft temperature at adequate level. The cooling loop consists of a single phase Freon 114 pumped loop, with two radiators in parallel.
1991-07-01
Technical Paper
911447
Jost Munder, Manfred Bader, Peter Moeller
The thermal control subsystem of the Columbus Resource Module has to cope with an unusual variety of orbit attitudes, mission modes and configurations. A short overview over the past RM thermal concepts is given and the present thermal design is described in detail. A passive concept with extensive use of heatpipes configured as network is baselined. The low available heater power in conjunction with the significant dissipation variations of th NiH2 batteries require there a very effective heat rejection control concept. A new regulation concept has been selected which allows to switch off up to 75% of the battery radiator area by use of Liquid Trap Heatpipes. The verification concept which does not use system level testing is briefly described.
1991-07-01
Technical Paper
911450
R. Orlando, P. Osella, M. Ferrera
This paper provides a comprehensive description of the present status of the Water Pump Subassembly (WPSA) that will be part of the Active Thermal Control System of the Pressurized Modules of Columbus, the Attached Laboratory (PM4) and the PM2 of the Man Tended Free Flyer. Description of major components of the Subassembly are presented along with the results of trade-offs performed and rationals for concept selection.
1991-07-01
Technical Paper
911449
Massimiliano Bottacini, Antonio Moscatelli, Claudio Ferro
The aim of this paper is to present the Hermes Thermal Control Concept which constitutes the reference baseline for the phase 2 of the Hermes program. The technical solutions based on active and passive means, are dictated by a variety of requirements including temperature and heat flux limits, mass & power minimization, availability of space for accommodation of TCS devices. Furthermore thecomplex mission profile (including atmospheric flight and several modes of operation o002d;orbit) and the configuration of the space-vehicle, require the adoption of a particularly flexible thermal control. The ATCS (Active Thermal Control Section) is based on a dual loop concept, using both water and Freon R114 cooling loops for heat collection from the various sources, heat transportation and heat rejection through dedicated devices.
1991-07-01
Technical Paper
911437
David E. Burchfield, Leigh Evans, William Niu, Itamar Bodek, Daniel J. Ehntholt
Abstract Space Station Freedom presents challenges in water contamination and in the preconcentration of trace contaminants for subsequent analysis. Terrestrial methodologies for the trace level determination of mercury, alcohols, and phenols have been evaluated against levels of detection, complexity, and phase separation requirements. Microgravity compatible modifications of standard methods have been developed and tested. A total mercury sensor, employing solid phase sorption of mercury metal from the analyte followed by determination at a gold film electrode, has been breadboarded and shows a minimum level of detection of less than 0.5ppb. The system uses sodium borohydride as a reagent to facilitate mercury reduction and the decomposition of organomercury compounds. Phenols are determined using a modification of the VOC methodology previously described followed by GC/MS analysis; detection levels below 1ppb have been achieved.
1991-07-01
Technical Paper
911436
Clifford D. Jolly, Elden L. Jeffers
Development of components to optimize on-line, gravity-independent measurement of Total Organic Carbon (TOC) in water to low ppb levels are being investigated for incorporation into water quality monitor hardware. A simple, flow- through device termed a reagentless separator has been designed for zero gravity operation that removes inorganic carbon from solution without using corrosive liquid acids. Flow-through, solid-phase TOC and Total Inorganic Carbon (TIC) functional check modules are being developed for replacement of liquid reagent calibration standards. Standard modules that impart 10 mg/1 TOC to product water have been demonstrated. Preliminary results indicate that expendable liquid reagents can be eliminated from the Process Water Quality Monitor (PCWQM) resulting in enhanced simplicity, safety, reliability, and significantly reduced hardware volume. Components and system operating parameters are described.
1991-07-01
Technical Paper
911438
Randolph W. Schweickart, Sandra E. Carr, Paul D. Mudgett
The measurement of ionic contaminants in samples from the potable water system on Space Station Freedom is one of the basic functions of the Crew Health Care System (CHeCS). The U. S. Environmental Protection Agency has identified ion chromatography as the analytical method of choice for measurement of anions and cations in water as described in USEPA method numbers 300.0 and 300.7, respectively. For this reason, ion chromatography was the technology initially identified to perform the ion contaminant monitoring function in the CHeCS Water Quality Subsystem. Subsequently, mass, size, and maintenance restrictions have led to a reevaluation of method options. Capillary electrophoresis (CE) has emerged as one of the more promising alternatives. CE is inherently microgravity compatible and uses an order of magnitude less reagent volume than ion chromatography. The major drawback to CE is its present state of development.
1991-07-01
Technical Paper
911442
Gary T. Runge
Abstract Some of the new garments being developed for advanced fighter pilot's personal equipment will increasingly insulate the pilot, adding to the potential for discomfort and thermal stress. Two of these garments, 1) a counter pressure vest, and 2) a chemical and biological warfare suit, were investigated to determine their effect on pilot comfort. Both garments increase the number of layers of clothing worn by the pilot. This inhibits the transfer of heat, as well as the passage of water vapor, which reduces the cooling effect of perspiring. A combined physiological and cockpit model was used to determine pilot temperatures and perspiration rates. Flow velocities at the pilot were also considered in evaluating pilot comfort. In addition to traditional methods of air cooling the pilot, an advanced personal equipment cooling concept was investigated.
1991-07-01
Technical Paper
911441
Fred Aboosaidi, Matthew J. Warfield, Dipankar Choudhury
Two three-dimensional cabin airflow configurations have been the subject of experimental and analytical testing to establish the validity and role of computational fluid dynamics (CFD) tools in the design of cabin airflow distribution systems. The CFD tools considered here are two separate Navier-Stokes computer codes which have been used for a number of applications, including those in the present study. A correlative study of a detailed air supply nozzle configuration has been examined to further understand its flow characteristics and to establish a procedure for examining cases with large size scale differences. The comparison of experimental results with the numerical simulations in the two cases is generally quite good, leading to an increased confidence in the application of CFD methods within the cabin airflow distribution system design arena.
1991-07-01
Technical Paper
911361
Kenneth J. Schlager
Significant needs exist for on-line real-time monitoring of water quality and hydroponic plant nutrients in regenerative life support systems. Toxic metals and organic pollutants in recirculated water are more effectively controlled by on-line monitoring. Biomass production of various crops may be enhanced by optimal control of plant nutrients. A new on-line fiber optic spectrometer is in development that uses a combination of ultraviolet-visible absorption measurements in combination with liquid atomic emission spectra to assay a wide variety of chemical compounds and ions in solution. Problems created by interfering, overlapping spectra are solved through the use of pattern recognition methods for multicomponent chemical analysis. This analytical instrument has been successfully applied to the analysis of 15-component plant nutrient solutions.
1991-07-01
Technical Paper
911359
Bob M. Thornton, James B. Schultz, Edson A. Worden
Design and implementation of a computer aided test and a knowledge base/object oriented database for Space Station Freedom is discussed. Described within the paper is the design and development of “C”/SQL language software and programmable logic needed to acquire data and provide system control functions. Creation of a user interface for an intelligent report generator, a database of test anomalies with interactive alarming and an expert system for system trouble-shooting is outlined.
1991-07-01
Technical Paper
911355
Francis A. Cucinotta, John W. Wilson, Lawrence W. Townsend, Judy L. Shinn, Robert Katz
Solar particle events (SPE) are typically dominated by high-energy, low-linear energy transfer (LET) protons. Biological damage to astronauts during an SPE is expected to include a large contribution from high LET target fragments produced in nuclear reactions in tissue. We study the effects of nuclear reactions on integral LET spectra, behind typical levels of spacecraft and body shielding, for the historically largest flares using the high-energy transport code, BRYNTRN in conjunction with several biological damage models. The cellular track model of Katz provides an accurate description of cellular damage from heavy ion exposure. The track model is applied with BRYNTRN to provide an LET decomposition of survival and transformation rates for solar proton events.
1991-07-01
Technical Paper
911351
Lisa C. Simonsen, John E. Nealy, Herbert H. Sauer, Lawrence W. Townsend
Several large solar proton events occurred in the latter half of 1989. For a moderately shielded spacecraft in free space, the potential exposure would have been greatest for the flare which occurred between October 19 to 27, 1989. This flare was comparable to the large flare event of August 1972. The temporal variations of the proton energy spectra at approximately 1 AU were monitored by the GOES-7 satellite. These data, recorded and processed at the NOAA-Boulder Space Environment Laboratory, provide the opportunity to analyze dose rates and cumulative doses which might be incurred by astronauts in transit to, or on, the moon. Of particular importance in such an event is the time development of exposure in the early phases of the flare, for which dose rates may range over many orders of magnitude in the first few hours. Consequently, special attention is given to the early time variation of the dose rate.
1991-07-01
Technical Paper
911345
Guna Selvaduray, Curtis Lomax
Fusible heat sinks are a possible source for thermal regulation of space suited astronauts. Historically, water has been the material of choice. Identification of alternative materials with greater thermal storage capability could enable both an extension of time between recharging, as well as a reduction in size. An extensive database search was undertaken to identify candidate materials with liquid solid transformations over the temperature range of -18°C (0°F) to 5°C (40°F); and 1215 candidates were identified. Based on available data, 59 candidate materials with thermal storage capability, ΔH values higher than that of water were identified. This paper presents the methodology utilized in the study, including the decision process used for materials selection. Future work will concentrate on measurement of thermodynamic data of the most promising materials so that the reliability of the data can be improved.
1991-07-01
Technical Paper
911343
James J. Kantara
The study investigates a Space Station Freedom (SSF) Central Thermal Bus (CTB) radiator array orientation profile that will meet the SSF 82.5 KW heat rejection requirement while maintaining radiator angular velocities under 45 deg/minute. The radiator orientation along with the amount of environmental absorbed heat and heat rejection capabilities without any consideration for the radiators exceeding the recommended maximum angular velocities were initially determined. The environments investigated were the minimum environment, alternate minimum environment, maximum environment, and a -80°F (-62.20°C) sink temperature environment. The collective data from the above environments were then used in order to recommend a radiator orientation profile that, under transient conditions, would meet the heat rejection requirements while maintaining the radiator angular velocities under 45 deg/minute, and prevent the ammonia in the panels from freezing.
1991-07-01
Technical Paper
911342
Brian E. Ames, Patricia A. Petete
The “restructured” baseline has eliminated many options for Active Thermal Control System (ATCS) growth for Space Station Freedom (SSF). Modular addition of baseline technology to increase heat rejection will be extremely difficult. The system design and the available real estate no longer accommodate this type of growth. As the station matures during its thirty years of operation, a demand of up to 165 kW of heat rejection can be expected. The baseline configuration will be able to provide 82.5 kW at Eight Manned Crew Capability (EMCC). A promising technology that could increase heat rejection by the necessary 82.5 kW is the heat pump. This paper provides a preliminary feasibility assessment of the application of a vapor compression heat pump to the ATCS.
1991-07-01
Technical Paper
911341
David H. Walker, Glenn I. Deming
Abstract Foster-Miller, Inc., is currently developing a heat pump system to produce hot water for crew hygiene on future manned space missions. The heat pump utilizes waste heat sources and a nonazeotropic working fluid in a highly efficient cycle. The potential benefits include a reduction in peak power draw from 2 to 5 kW for electric cartridge heaters, to just over 100W for the heat pump. As part of the heat pump development program, a unique high efficiency compressor was developed to maintain lubrication in a zero-gravity environment. Initial testing has resulted in measured COPs of 8.5.
1991-07-01
Technical Paper
911338
John Tandler
An integrated simulation model is described which characterizes the dynamic interaction of the energy transport subsystems of Space Station Freedom for given orbital conditions and for a given set of power and thermal loads. Subsystems included in the model are the Electric Power System (EPS), the Internal Thermal Control System (ITCS), the External Thermal Control System (ETCS), and the cabin Temperature and Humidity Control System (THC) (which includes the avionics air cooling, cabin air cooling, and inter-module ventilation systems). Models of the subsystems were developed in a number of system-specific modeling tools and validated. The subsystem models are then combined into integrated models to address a number of integrated performance issues involving the ability of the integrated energy transport system of Space Station Freedom to provide power, controlled cabin temperature and humidity, and equipment thermal control to support operations.
1991-07-01
Technical Paper
911333
Gerald J. Creager, Charles W. Lloyd
To aid planning for the storage of supplies onboard Space Station Freedom, an estimate was made of the amount of intravenous (IV) fluids required to support a patient who has suffered a medical emergency for a period of up to 10 days. Six different medical scenarios were evaluated, and the volume of IV fluids required for each scenario was estimated. Up to 220 liters of fluid would be required to support a patient for all of the scenarios. When optimizing the volumes to support any single scenario, a total of 123 liters is required. Use of a water polishing system to produce sterile water for injection from potable supplies and on-station formulation of IV fluids results in a smaller mass and volume requirement for the Fluid Therapy Subsystem than carrying prepackaged bags of fluid.
1991-07-01
Technical Paper
911328
William F. Dempster
Biosphere 2 is a large closed ecological system nearing completion in Arizona. Various subsystems are critical to the operation and the approach to redundancy and back-up systems for synergistic advantages is described in several instances.
1991-07-01
Technical Paper
911390
Stephen R. Ellis, Mitchell Tyler, Won S. Kim, Lawrence Stark
Abstract Two experiments were conducted examining three-dimensional pursuit tracking when operators of teleoperation simulations are faced with misalignment between the display and control frames of reference. Targets on the experimental displays moved irregularly in three dimensions and were tracked by subjects using either two 2-axis joysticks and a panel-mounted perspective display or, in a separate experiment, a hand-mounted, 6 degree-of-freedom electro-magnetic sensor and a head-mounted, virtual image, stereoscopic display. Analysis of the components of the tracking errors in the perspective display experiment showed that components of the error due to misalignment of the perspective projection may be linearly separated from those associated with the mismatch between display and control coordinate systems. We observed evidence from both experimental conditions that the tracking improved with several hours practice.
1991-07-01
Technical Paper
911391
Sheldon M. Ebenholtz
Four parameters of the visual system, i.e., far point, resting vergence, resting focus, and near point are described along with a variety of adaptable oculomotor systems. The conditions productive of adaptation of the vestibulo-ocular response (VOR), optokinetic response (OKR), accommodation, vergence, and other systems are discussed in relation to certain characteristics of teleoperator displays. Since adaptation shares a common set of antecedents with asthenopia (eye strain) and motion sickness, the possibility of illness, including ataxia, from exposure to teleoperator displays also will be discussed. It is likely that visual effort or stress is related to the degree to which the oculomotor control system departs from its resting level in order to maintain clear, single and stable vision.
1991-07-01
Technical Paper
911392
Ian P. Howard
Abstract Any stereoscopic imagery system must maintain the images in horizontal, vertical and torsional alignment. Humans maintain torsional alignment by rotating the eyes around the visual axes - a response known as cyclovergence. We have produced the first measurements of the dynamics of human cyclovergence and have shown that cyclovergence compensates well for low amplitude, low frequency torsional misalignments of binocular images. We have also shown that cyclovergence is driven more by cyclorotations of horizontal lines than of vertical lines. Teleoperated systems should emulate this strategy because vertical disparities code slant in depth and should therefore by retained, whereas horizontal disparities arise only from misalignment of images and should therefore by nulled. We have found that objective measurements of cyclovergence compare well with those obtained by a psychophysical nonius procedure.
1991-07-01
Technical Paper
911393
Antal K. Bejczy
A dual-arm Advanced Teleoperation System (ATOPS) was developed at JPL to demonstrate and evaluate performance capabilities of computer and sensing aided teleoperation. This paper gives a brief overview of the system and briefly describes some of the generic and application oriented performance experiments together with the major results. A major conclusion is that the new advanced technical features of the system should be properly integrated with or interfaced to the natural features of human operators in order to produce an improved overall system and task performance capability.
1991-07-01
Technical Paper
911386
Ralph A. Toscano
Since its inception, the space program has relied heavily upon stitched and cemented fabric goods in fabricating its space suits, and these items have performed satisfactorily. However, with the requirements for future Extra Vehicular Activity, (EVA), missions, and the planning of activities such as the construction of Space Station, Lunar and Martian exploratory missions, its has become apparent through papers given on future space suit design1,2, that some of the fabric portions of space suits may well be replaced with hard goods. This being the case, NASA and other aerospace organizations, have been giving serious thought to designs that utilize either limited hard goods or entire hard suits.
1991-07-01
Technical Paper
911382
Trista A. Niemann, Christine H. Lorenz, Steven W. Peterson, Alvin M. Strauss
The task of evaluating and designing space gloves requires accurate biomechanical characterization of the hand. The availability of magnetic resonance (MR) imaging has created new opportunities for in vivo analysis of physiological phenomena such as the relationship between circulation and fatigue. An MR imaging technique originally proposed to quantitatively evaluate cerebral perfusion has been modified to evaluate the capillary microcirculation in hand muscles. An experimental protocol was developed to acquire perfusion-weighted images in the hand before and after various levels of exercise. Preliminary results on the feasibility of applying the MR imaging technique to the study of microcirculation and fatigue in the hand are presented. The potential of this method for space glove testing and design is also discussed.
1991-07-01
Technical Paper
911389
Andrew Liu, Gregory Tharp, Michitaka Hirose, Lawrence Stark
Abstract We discuss three factors that could alter human operators' perception of a remote worksite and adversely affect their task performance. First, we discuss the effect of image degradation on task performance. Our experimental results are similar to corresponding visual psychophysical experimental results, suggesting that the psychophysical results might be helpful for predicting the performance under other viewing conditions. The second factor is the control of the different viewing parameters. Dynamic control could be disorienting, but if the parameters are fixed, the operator might not feel telepresent. The interface through which the parameters are controlled also requires careful consideration and we discuss the advantages of using a helmet-mounted display. The third factor, the display update rate, can be affected by hardware limitations, transmission delays, or long rendering times.