(Grant AF-AFOSR-0180-87; AF Proj. 2313) (AD-A209884; AFOSR-89-0815TR) Avail: NTIS HC A03/MF A01 CSCL 06/4 Research on several interrelated topics is described. These projects are focused on the analysis of feature and conjunction detection, models of selective attention, and curve tracing. One project examines the effects of a heterogeneous background on feature search. Another assesses spatial factors (such a target-distractor separation) in the detection of targets defined in terms of simple features. A third project has the goal of developing methods for determining the extent to which processing is serial or parallel. A fourth represents initial efforts to determine whether conjoined features are represented in retinotopic or spatiotopic maps. A fifth explores top-down and bottom-up factors in visual search. A sixth makes use of an inhibitory priming method to test early-and late-selection models of selective attention. Finally, a project is reported in which the operation of visual curve tracing GRA is studied. A01 CSCL 05/8 Avail: NTIS HC A02/MF This report describes a number of experiments related to the effects of mental imagery and other high-level cognitive tasks on the spontaneous activity of the brain. The basic procedure involves narrowly bandpassing the magnetoencephalogram (MEG), computing the average response to a stimulus or event within that bandpass, and computing the variance around the average. The variance at any point in time subsequent to the stimulus is a measure of mean square field (power). Power in the alpha band (8 to 12 Hz) was found to show a prominent change in level subsequent to presentation of form. Simply watching the form results in a dip in alpha power, but when subjects attempt to determine if the form had been seen previously, the duration of the reduction in alpha power increases significantly, and is correlated with reaction time (RT). In an experiment subjects tried to form an image of an object represented by a visually presented word, or to find a rhyming word. The latter task did not produce a change in activity of visual cortex, while the same words produced a profound change in activity cortex during imaging. Acoustically presented words were also found to produce changes in MEG activity. GRA Design considerations for a heterodyne spatial tracking system utilizing pupil-plane processing techniques and its advantages over traditional focal-plane processing are described. Noise performance bounds, optimal and suboptimal local oscillator distributions, pull-in performance, and applications other than spatial tracking are discussed. Experimental verification of a one-axis closed-loop tracking system is presented. GRA N89-28210# Psychology. New York Univ., New York. Dept. of Physics and VISUALIZING AND RHYMING CAUSE DIFFERENCES IN ALPHA SUPPRESSION Report, 1 Mar. 1988 - 28 Feb. 1989 Lloyd Kaufman, M. Glanzer, Y. Cycowicz, and S. J. Williamson 12 May 1989 5 p (Contracts F49620-88-K-0004; F49620-86-C-0141; AF Proj. 2313) (AD-A210005; AFOSR-89-0962TR) Avail: NTIS HC A02/MF A01 CSCL 06/4 Alpha rhythms of the EEG are strongest at the occipital regions of the head, and the visual cortex is apparently a major contributor. It has been suggested that visual cortex is involved in forming and processing mental images. The purpose of this experiment is to determine if a task that involves visualizing objects represented by words produces changes in alpha rhythms of the MEG that differ from changes associated with finding rhymes of the same or related verbal stimuli. By hypothesis, the visual areas of the cortex play a less prominent role in the latter task than they do in the visualizing task. This inference is consistent with the finding that visual imagery is accompanied by attenuation of the alpha rhythm over the occipital scalp, in the proximity of visual cortex cognitive factors, such as memorization and classification of words, affects the pattern of alpha blockage across the occipital and parietal area, but this does not establish that visual cortex per se is involved. Subjects responded by forming mental images of the objects represented by the words. The event related potentials associated with presentation of the words were larger in amplitude than they were when the subjects silently pronounced words that rhymed with the stimuli instead of forming mental images. This effect was more evident at occipital electrodes than it was at other locations. There may well be differential suppression of alpha activity depending on the degree to which visual resources are engaged in various mental tasks, such as imaging. 53 BEHAVIORAL SCIENCES GRA N89-28211*# Good Samaritan Hospital and Medical Center, Portland, OR. Dept. of Neuro-otology. AGE-RELATED CHANGES IN HUMAN VESTIBULO-OCULAR REFLEXES: SINUSOIDAL ROTATION AND CALORIC TESTS R. J. Peterka, F. O. Black, and M. B. Schoenhoff 1989 15 p (Grant NAG9-117) (NASA-CR-185857; NAS 1.26:185857) Avail: NTIS HC A03/MF A01 CSCL 05H The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) were characterized in 216 human subjects ranging in age from 7 to 81 years. The object of this cross-sectional study was to determine the effects of aging on VOR dynamics, and to identify the distributions of parameters which describe VOR responses to caloric and to sinusoidal rotational stimuli in a putatively normal population. Caloric test parameters showed no consistent trend with age. Rotation test parameters showed declining response amplitude and slightly less compensatory response phase with increasing age. The magnitudes of these changes were not large relative to the variability within the population. The age-related trends in VOR were not consistent with the anatomic changes in the periphery reported by others which showed an increasing rate of peripheral hair cell and nerve fiber loss in subjects over 55 years. The poor correlation between physiological and anatomical data suggest that adaptive mechanisms in the central nervous system are important in maintaining the VOR. Author Postural control was measured in 214 human subjects ranging in age from 7 to 81 years. Sensory organization tests measured the magnitude of anterior-posterior body sway during six 21 s trials in which visual and somatosensory orientation cues were altered (by rotating the visual surround and support surface in proportion to the subject's sway) or vision eliminated (eyes closed) in various combinations. No age-related increase in postural sway was found for subjects standing on a fixed support surface with eyes open or closed. However, age-related increases in sway were found for conditions involving altered visual or somatosensory cues. Subjects older than about 55 years showed the largest sway increases. Subjects younger than about 15 years were also sensitive to alteration of sensory cues. On average, the older subjects were more affected by altered visual cues whereas younger subjects had more difficulty with altered somatosensory Author cues. N89-28213*# R. J. Peterka, F. O. Black, and M. B. Schoenhoff 1989 16 P (NASA-CR-185856; NAS 1.26:185856) Avail: NTIS HC A03/MF A01 CSCL 05H The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) were characterized in 216 human subjects ranging in age from 7 to 81 years. The object of this cross-sectional study was to determine the effects of aging on VOR and OKR reflex dynamics, and to identify the distributions of parameters which describe VOR and OKR responses to pseudorandom stimuli in a putatively normal population. In general, VOR and OKR response parameters changed in a manner consistent with declining function with increasing age. For the VOR this was reflected in declining response amplitudes, although the magnitude of the decline was small relative to the variability of the data. For the OKR the lag time of the response, probably associated with the time required for visual information processing, increased linearly with age at a rate of about 1 ms per year. Author 629 p (ESA-SP-288; ISSN-0379-6566; ETN-89-95012) Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars Environmental control and life support systems; heat transport systems; orbital systems thermal control; atmosphere management; EVA; analysis methods; satellite thermal control; liquid management and habitability; cryogenics; in-orbit performance and testing; thermal control technology; and reentry and thermal protection systems were discussed. For individual titles, see N89-28215 through N89-28297. Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The space station environmental control and life support system (ECLSS) and internal thermal control system (ITCS) are outlined. The ECLSS is composed of six subsystem groups: the temperature humidity control, the atmosphere control and supply, the air revitalization, water reclamation and management, fecal waste management, and the fire detection and suppression subsystems. The ITCS consists of all WP01 elements of passive and active thermal measures. The ECLSS and ITCS provide services for the permanently orbiting pressurized modules as well as the pressurized and unpressurized logistics carriers. All internal cooling of the permanent orbital elements are provided via internal active fluid loops within the elements utilizing water as the transport media. Cabin and equipment cooling are provided by forced air flow and coldplate heat sinks. An active cooling loop is provided in the laboratory module to accommodate experiments and other payloads. Coatings and insulation are used in conjunction with the active components to passively limit heat losses/gains. The most challenging ECLSS new technology issues relate to oxygen and water recovery. Closure of the oxygen loop requires the use of regenerative CO2 removal and concentration techniques, CO2 reduction to convert the CO2 to water with a waste by-product, and the electrolysis of water to produce breathing oxygen for water recovery. ESA N89-28216# Entwicklungsring Nord, Bremen (Germany, F.R.). U. Laux, B. Behrens, and R. Lawson In ESA, Third European 22-54) Thermal Control and Life Support Systems of the Columbus flight configurations, the Attached Pressurized Module (APM), the Man Tended Free Flyer (MTFF) and the Polar Platform (PPF) are described. The overall APM and MTFF Environmental Control and Life Support System (ECLSS) is strongly affected by the interfaces to the International Space Station (ISS) and Hermes. It is proposed to centralize particular ECLSS functions of both the APM and MTFF for reasons of cost, mass, power, and complexity reduction and to operate the MTFF-ECLSS in a power saving mode during the free flying phase. Rejection of the APM generated heat is performed totally by the ISS, whereas the MTFF Thermal Control is fully autonomous in the free flying and Hermes servicing phase. The preferred MTFF orientation, which is driven by the very stringent microgravity requirement, is in conflict with the heat rejection capabilities of the TCS. ESA N89-28217# Aerospatiale Usines de Toulouse (France). H. Lacaze, P. Bisiaux, and C. Rodiere In ESA, Third European 22-54) Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The status of the Hermes, the thermal protection subsystem, thermal control subsystem, and environmental control and life support subsystem is outlined. Each one contributes to the thermal control of some part of the vehicle and is therefore influenced by the two others. Due to severe constraints coming from the launcher performances, the Hermes mass budget is critical and renders necessary elaborate design studies and use of advanced techniques for most component parts. ESA N89-28218# Dornier System G.m.b.H., Friedrichshafen (Germany, EUROPEAN LIFE SUPPORT SYSTEMS FOR SPACE H. Preiss In ESA, Third European Symposium on Space Thermal Control and Life Support Systems Dec. 1988 p 39-44 (For primary document see N89-28214 22-54) Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The environmental control and life support systems (ECLSS) for Columbus and Hermes are described, and the ECLSS requirements for European missions to Mars, the Moon, and an LEO station are outlined. It is argued that to meet these demands, international cooperation is necessary. ESA 22-54) Copyright N89-28214 Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The Columbus environmental control and life support system (ECLSS) is compared with the Spacelab ECLSS. The individual Columbus ECLSS equipment characteristics are identified, stating whether they are identical, modified, and advanced or completely new compared to the Spacelab capabilities. Although the basic ECLSS functions of Columbus are similar to those of Spacelab there are considerable differences in design and performance between the two systems. These differences are mainly caused by two factors. The first one is the mission duration characterized by the in orbit life time of the module and the uninterrupted attendance of one crew before change of shift. The second one is the required full automatic operation capability caused by the 180 days free flying and unmanned period of the Man-Tended Free Flyer. ESA N89-28220# Dornier System G.m.b.H., Friedrichshafen (Germany, THE DEFINITION STATUS OF THE ENVIRONMENTAL Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The systems engineering needs of regenerative physicochemical atmosphere revitalization is discussed from the qualitative point of view, and a procedure that can be used to quantify the prospective merits of competing designs at an early stage in their development cycle is described. This procedure involves the preparation of energy and multicomponent material balances, the derivation of weight penalties for various power generation/supply and heat rejection technologies, the calculation of equivalent weights versus duration of mission and the use of spreadsheets to analyze the sensitivity of results when input data such as the weight of flight qualified equipment is subject to uncertainty. The methodology can be applied to other systems including water management and future biological options on manned space missions. N89-28222# (Belgium). ESA Centre d'Etude de l'Energie Nucleaire, Mol MELISSA: A MICRO-ORGANISMS-BASED MODEL FOR CELSS M. Mergeay, W. Verstraete, G. Dubertret, M. Lefort-Tran, C. dollars The MELISSA was conceived as a microorganism based ecosystem, being a simplified, model of a future biological life support system for manned missions. The driving element is the reprocessing of edible biomass from waste, CO2, and minerals with the direct use of sunlight as a source of energy for biological photosynthesis. A four compartments ecosystem is selected allowing the closure of the material loop around a central food and O2 reprocessing compartment by the growth of the filamentous cyanobacterium SPIRULINA. Nitrates, CO2, and minerals required by SPIRULINA are produced by the other microbial compartments, namely an anaerobic digestion system and a nitrifying compartment. The anaerobic digestion system includes a thermophilic solubilization and fermentation compartment (CLOSTRIDIA) followed by a second light dependent compartment, colonized by RHODOBACTER, removing the soluble organics (mainly fatty acids) and leaving the minerals requested by SPIRULINA, and producing a biomass of high food value. Nitrification of ammonium from the anaerobic step to nitrate for SPIRULINA, is performed by NITROBACTERIA, with a very low biomass production, in the fourth compartment. For a consumer added to the loop, MELISSA ensures food and oxygen recycling through complete carbon, nitrogen, sulfur Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The C23A system (automatic culture chambers in artificial atmosphere) was used in respiratory studies on a small animal, Triturus Walt I.I. The multiplexed analyzers allow use of the same analyzer for several different applications, e.g., respirometry, or atmosphere. This method permits to decrease weight and reduce the number of gas calibrations. Similarly the design of the computing system anticipates the full separation between automation in space and control-command on ground. ESA N89-28224# Dornier System G.m.b.H., Friedrichshafen (Germany, TWO-PHASE HEAT TRANSPORT SYSTEMS: CRITICAL H. Kreeb and R. Siepmann In ESA, Third European Symposium Within the preparatory support technology program for COLUMBUS a mechanically pumped two-phase heat transport system is developed. A preparatory study recommended system based on a parallel arrangement of evaporator cold plates and heat exchangers, condenser units, and a conventional mechanical pump. Important characteristics of this system include the controlled flooding of the condensers with liquid to achieve temperature control and the ability to use the evaporators also as condensers to permit heat load sharing between payload elements. In order to meet Columbus-requirements the system is specified to work at a maximum heat load of 10 to 20 kW at a nominal temperature of 20 C. The working medium is freon R 114. The design of the overall system, the breadboard development of the critical components, and the planned test-bed verification are outlined. ESA N89-28225# R. S. Bhatti, S. VanOost, and C. J. Savage (European Space N89-28214 Dec. 1988 22-54) Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The general objectives, the design concept, and the potential performances of the two-phase capillary pumping loop (CPL) as a heat transportation system are reviewed. Results obtained on the first breadboard CPL model are reported with comparison of predicted against tested performances. ESA N89-28226# Entwicklungsring Nord, Bremen (Germany, F.R.). DESIGN AND TEST OF A TWO-PHASE COLDPLATE R. Mueller In ESA, Third European Symposium on Space Thermal Control and Life Support Systems p 89-95 Dec. 1988 primary document see N89-28214 22-54) (For Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The design and the results of a performance test for a two phase cold plate are presented. The cold plate consists of 7 parallel aluminum evaporator tubes and a 50 x 50 cm mounting plate. The evaporator tubes are equipped with capillary circumferential grooves and an internal structure to separate liquid and vapor. The cold plate is suitable for application in mechanically, as well as capillary pumped loops. In the test the heat transport limit of the evaporator tubes, i.e., the dryout of their circumferential grooves, was evaluated. The test was conducted in the mechanically pumped mode using ammonia as a working fluid. It demonstrates the feasibility of the selected design of the cold plate evaporator tubes. Heat flux limits ranging from 2.4 and 10.7 W/sq cm and heat transfer coefficients between 0.14 and 1.35 W/sq cm-K are were measured for the different evaporator tubes. ESA N89-28227# Minelectrotechprom, Moscow (USSR). M. D. Parfentiev In ESA, Third European Symposium on Space Thermal Control and Life Support Systems Dec. 1988 p 97-101 (For primary document see N89-28214 22-54) Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars Results of studies on noncondensable gas (NCG) distribution in condensation zones of low temperature heat pipes (LTHP) and estimates of its effect on distribution of both localized heat flows and localized heat-exchange coefficients as well as LTHP was temperature profile in condensation zone are described. Based on visual studies on vapor-gas mixture distribution in LTHP condensation zone, a NCG distribution model is proposed which considers distribution irregularities both in axial and radial directions. Using the accepted NCG distribution model as the base, the heat balance equation for a condenser wall component which considers variable thermal resistance of a NCG layer was obtained. N89-28228# Tokyo Univ., Sagamihara (Japan). ESA K. Oshima and N. Izutsu In ESA, Third European Symposium on Space Thermal Control and Life Support Systems Dec. 1988 p 103-108 (For primary document see N89-28214 22-54) Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars Heat pipe systems utilizing phase changing heat transfer concepts are introduced, including micro heat pipes, a separate type heat pipe heat exchanger, and heat pipe turbines. Inside these heat pipes, contrary to the conventional thermosyphon, evaporation and condensation processes are heavily influenced by the surface tension effect. This effect is also dominant in heat pipes operating under microgravity in space. Similarity parameters concerning these phenomena are discussed. Laboratory experiments as well as numerical simulations of the flows relating to evaporative heat transfer were carried out. It is found that heat transfer by the evaporation process is decreased in such conditions. ESA N89-28229# Minelectrotechprom, Moscow (USSR). A. D. Lobanov and A. A. Parentieva In ESA, Third European Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars Results of studies and application of a heat pipe quality control method applicable in the pipe series production (and introduced) into the heat pipe production process and on installing the heat pipes on cooled and controlled temperature instruments and equipment, with no pipes disconnected from these instruments, are described. A heat short time action (heat flux density ranges from unities to tens of W/sq m and time interval, from unities to tens of seconds) is applied upon an envelope of a working fluid filled and sealed heat pipe locally, that is on its small section (an area of 1 sq m) and the pipe envelope temperature increase at the heat short time action input section is registered during its effect time or a shorter period. It is possible to determine a heat pipe parameter controlled by making comparison with an increase in temperature premeasured at a reference device subjected to a similar effect. The method is used to check working fluid availability in a heat pipe, to test noncondensible gas absence (or presence of its given amount) therein. The method markedly accelerates heat pipe rejection and improve quality control reliability (one heat ESA pipe requires only 30 sec for its testing). N89-28230# National Aerospace Lab., Emmeloord (Netherlands). DEVELOPMENT OF A SENSOR FOR HIGH-QUALITY A. A. M. Delil and J. F. Heemskerk In ESA, Third European Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars Based on a tradeoff of quality monitoring concepts, a dedicated quality sensor for two phase mixtures was developed, based on the axial capacitance principle. Its theoretically demonstrated feasibility as quality and wetting sensor was experimentally confirmed by experiments using liquid layer simulating plastic sheets and annular air/liquid flow. Experiments in a two-phase freon test loop show the sensor to be an accurate, fast responding, sensitive instrument. It was accepted for further development as a component of the two-phase heat transport system developed by the European Space Agency. Performance figures, obtained by calibrations in a freon 114 loop, are given. Recommendations for future work and applications are indicated. ESA In ESA, Third European Symposium B. Poulain and S. Aucel on Space Thermal Control and Life Support Systems p 127-134 Previously announced as N89-23511 document see N89-28214 22-54) Dec. 1988 (For primary Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The impact of the requirements of the Columbus program such as long life time and servicing on system architecture and subsequently on thermal control systems (TCS) design is discussed. Based on these requirements two completely different approaches were selected for polar platform (PPF) and resources module (RM) architectures. The system architecture/TCS approach used for the PPF (individual TCS of ORU) led to an optimized TCS in terms of mass and performance (i.e., launch cost) having nevertheless certain penalties: on power budget (improvements are possible); The (acceptable). RM system and on servicing architecture/TCS approach (centralized TCS) is optimized with respect to servicing operations and power budget but has penalties on TCS mass and performance. These penalties are compensated by global savings at MTFF level. One of the prime drivers leading to the difference between the two approaches is the use of Hermes as servicing vehicle for RM and not for PPF (additional constraint on RM). Although the TCS performances are quite different, the mass selected designs of both spacecraft are the best compromises which could be achieved at system level. ESA N89-28232# Erno Raumfahrttechnik G.m.b.H. Bremen (Germany, REDUNDANCY CONCEPT FOR THE COLUMBUS C18 B. Behrens, C. Bunkenborg, W.-D. Ebeling, and U. Laux In ESA, Third European Symposium on Space Thermal Control and Life Support Systems Dec. 1988 p 135-140 (For primary document see N89-28214 22-54) Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The Columbus Man-Tended Free Flyer (MTFF) thermal control system (TCS) is described. The redundancy philosophy for TCS is discussed and the resulting thermal control concept presented. Effects of the failure tolerance requirements on the overall MTFF thermal control architecture as well as the arrangement of subsystem units within the MTFF for thermal control reasons is considered. Reliability analyses are outlined. For operating the MTFF at a required reliability level of 0.93 for nominal payload support for 180 days, the items aboard are classified in three criticality categories. Therefore various required failure tolerances have to be provided by an appropriate redundancy concept for each of these criticality categories. N89-28233# Aeritalia S.p.A., Turin (Italy). THERMAL CONTROL OF COLUMBUS PRESSURIZED MODULES ESA C18 S. Dolce, M. Trichilo, and F. Berardi In ESA, Third European Symposium on Space Thermal Control and Life Support Systems Dec. 1988 p 141-147 (For primary document see N89-28214 22-54) Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The thermal control architecture of Columbus Pressurized Modules (PM); tradeoffs and design activities performed up to the present phase CO; and the baseline design solutions at loop and at component level are discussed. Active thermal control architecture consists of: module internal water loops collecting heat from directly interfacing P/L's and S/S's, avionic and cabin air loops; space station external freon loop (PM2 only) providing removal and transportation of water loop heat loads to the heat rejection system; based thermal bus providing removal and rejection of docked element water loops heat loads; and loop control and monitoring functions provided by modulating pumps and valves, temperature, pressure, and flow sensors interfacing with an intelligent control unit. Passive thermal control architecture consists of: MLI to insulate the modules and limit heat leaks, gains; coatings to provide the required thermo-optical properties; and internal insulation to avoid condensation. N89-28234# ESA Aeritalia S.p.A., Turin (Italy). DESIGN CONCEPTS FOR HERMES THERMAL CONTROL c18 C. Ferro, G. Gianfiglio, and L. Costamagna In ESA, Third European Symposium on Space Thermal Control and Life Support Systems Dec. 1988 p 149-156 (For primary document see N89-28214 22-54) Copyright Avail: NTIS HC A99/MF A01; ESA Publications Div., ESTEC, Noordwijk, Netherlands, 80 Dutch guilders or 45 US dollars The Hermes spaceplane configuration and the possible mission profile are discussed with regard to the major thermal requirements. The design approach and the optimization criteria are described, highlighting procedures for the overall mass minimization. The design concept is illustrated for the ATCS (Active Thermal Control Section) and the PTCS (Passive Thermal Control Section). The ATCS performances mainly rely on the adoption of fluid loops (dual option), collecting and transporting heat loads from the thermal sources to the sink devices. The possible architectures of |