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  • 1
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    Moderate lift-to-drag aeroassist (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Significant performance benefits are realized via aerodynamic braking and/or aerodynamic maneuvering on return from higher altitude orbits to low Earth orbit. This approach substantially reduces the mission propellant requirements by using the aerodynamic drag, D, to brake the vehicle to near circular velocity and the aerodynamic lift, L, to null out accumulated errors as well as change the orbital inclination to that required for rendezvous with the Space Shuttle Orbiter. Broad concept evaluations were performed and the technology requirements and sensitivities for aeroassisted OTV's over a range of vehicle hypersonic L/D from 0.75 to 1.5 were systematically identified and assessed. The aeroassisted OTV is capable of evolving from an initial delivery only system to one eventually capable of supporting manned roundtrip missions to geosynchronous orbit. Concept screening was conducted on numerous configurations spanning the L/D = 0.75 to 1.5 range, and several with attractive features were identified. Initial payload capability was evaluated for a baseline of delivery to GEO, six hour polar, and Molniya (12 hours x 63.4 deg) orbits with return and recovery of the aeroassist orbit transfer vehicle (AOTV) at LEO. Evolutionary payload requirements that were assessed include a GEO servicing mission (6K up and 2K return) and a manned GEO mission (14K roundtrip).
    Keywords: LAUNCH VEHICLES AND SPACE VEHICLES
    Type: NASA. Lewis Research Center OTV Propulsion Issues; p 69-84
    Format: application/pdf
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  • 2
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    Telerobotic assembly of space station truss structures (1987)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: Discussed here are methods of assembling the space station's structure utilizing only telerobotic devices, i.e.: (1) an approximately anthropomorphic telerobot with two dextrous arms; (2) the Shuttle Remote Manipulator System (SRMS); and (3) various material handling machines. Timelines and task recommendations for autonomous operations are also included. Also described are some experimental results comparing two manipulator control devices.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Jet Propulsion Lab., California Inst. of Tech., Proceedings of the Workshop on Space Telerobotics, Volume 1; p 45-53
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  • 3
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    Tests of Lead-bronze Bearings in the DVL Bearing-testing Machine (1940)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The lead-bronze bearings tested in the DVL machine have proven themselves very sensitive to load changes as in comparison with bearings of light metal. In order to prevent surface injuries and consequently running interruptions, the increase of the load has to be made in small steps with sufficient run-in time between steps. The absence of lead in the running surface, impurities in the alloy (especially iron) and surface irregularities (pores) decreases the load-carrying capacity of the bearing to two or three times that of the static load.
    Type: NACA-TM-943
    Format: application/pdf
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  • 4
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    System technology analysis of aeroassisted orbital transfer vehicles - Moderate lift/drag (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The utilization of procedures involving aerodynamic braking and/or aerodynamic maneuvering on return from higher altitude orbits to low-earth orbit makes it possible to realize significant performance benefits. The present study is concerned with a number of mission scenarios for Aeroassisted Orbital Transfer Vehicles (AOTV) and the impact of potential technology advances in the performance enhancement of the class of AOTV's having a hypersonic lift to drag ratio (L/D) of 0.75 to 1.5. It is found that the synergistic combination of a hypersonic L/D of 1.2, an advanced cryopropelled engine, and an LH2 drop tank (1-1/2 stage) leads to a single 65,000 pound shuttle, two-man geosynchronous mission with 2100 pounds of useful paylod. Additional payload enhancement is possible with AOTV dry weight reductions due to technology advances in the areas of vehicle structures and thermal protection systems and other subsystems.
    Keywords: ASTRODYNAMICS
    Type: AIAA PAPER 83-2108
    Format: text
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  • 5
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    Modeling Global Water Use for the 21st Century: Water Futures and Solutions (WFaS) Initiative and Its Approaches (2016)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: To sustain growing food demand and increasing standard of living, global water use increased by nearly 6 times during the last 100 years, and continues to grow. As water demands get closer and closer to the water availability in many regions, each drop of water becomes increasingly valuable and water must be managed more efficiently and intensively. However, soaring water use worsens water scarcity conditions already prevalent in semi-arid and arid regions, increasing uncertainty for sustainable food production and economic development. Planning for future development and investments requires that we prepare water projections for the future. However, estimations are complicated because the future of the world's waters will be influenced by a combination of environmental, social, economic, and political factors, and there is only limited knowledge and data available about freshwater resources and how they are being used. The Water Futures and Solutions (WFaS) initiative coordinates its work with other ongoing scenario efforts for the sake of establishing a consistent set of new global water scenarios based on the shared socio-economic pathways (SSPs) and the representative concentration pathways (RCPs). The WFaS "fast track" assessment uses three global water models, namely H08, PCR-GLOBWB, and WaterGAP. This study assesses the state of the art for estimating and projecting water use regionally and globally in a consistent manner. It provides an overview of different approaches, the uncertainty, strengths and weaknesses of the various estimation methods, types of management and policy decisions for which the current estimation methods are useful. We also discuss additional information most needed to be able to improve water use estimates and be able to assess a greater range of management options across the water-energy-climate nexus.
    Keywords: Earth Resources and Remote Sensing
    Type: GSFC-E-DAA-TN29988 , Geoscientific Model Development (e-ISSN 1991-9603); 9; 1; 175-222
    Format: text
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  • 6
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    Advanced Power Transmission Technology (1983)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Technology overviews, advanced transmission concepts, rolling-element bearing technology, traction drive technology, spiral bevel gear technology, and spur gear technology are discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CP-2210 , E-817 , NAS 1.55:2210 , AVRADCOM-TR-82-C-16 , Jun 09, 1981 - Jun 11, 1981; Cleveland, OH; United States
    Format: application/pdf
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  • 7
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    Effects of the space flight environment on man's immune system. II - Lymphocyte counts and reactivity. (1972)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The present studies were undertaken to assess the effects of the environment of space flights on the cellular division of the human immune system. Peripheral blood absolute lymphocyte counts were determined at various preflight and postflight intervals for the 21 crewmen of Apollo Missions 7-13. Mean lymphocyte numbers tended to exhibit a delayed significant but fluctuating increase shortly after recovery, although a variety of responses was seen in individual astronauts. The in vitro reactivity of lymphocytes, reflected by RNA and DNA synthesis rates by unstimulated and PHA-stimulated lymphocytes tissue-cultured preflight and postflight from the same participants, was found to remain within previously established normal ranges. These results indicate that functional integrity of cellular immune potential as reflected by in vitro techniques is maintained during this spaceflight experience.
    Keywords: BIOSCIENCES
    Type: Aerospace Medicine; 43; Oct. 197
    Format: text
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  • 8
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    Scientific Rationale for Saturn's in Situ Exploration (2014)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Remote sensing observations meet some limitations when used to study the bulk atmospheric composition of the giant planets of our solar system. A remarkable example of the superiority of in situ probe measurements is illustrated by the exploration of Jupiter, where key measurements such as the determination of the noble gases abundances and the precise measurement of the helium mixing ratio have only been made available through in situ measurements by the Galileo probe. This paper describes the main scientific goals to be addressed by the future in situ exploration of Saturn placing the Galileo probe exploration of Jupiter in a broader context and before the future probe exploration of the more remote ice giants. In situ exploration of Saturn's atmosphere addresses two broad themes that are discussed throughout this paper: first, the formation history of our solar system and second, the processes at play in planetary atmospheres. In this context, we detail the reasons why measurements of Saturn's bulk elemental and isotopic composition would place important constraints on the volatile reservoirs in the protosolar nebula. We also show that the in situ measurement of CO (or any other disequilibrium species that is depleted by reaction with water) in Saturn's upper troposphere may help constraining its bulk O/H ratio. We compare predictions of Jupiter and Saturn's bulk compositions from different formation scenarios, and highlight the key measurements required to distinguish competing theories to shed light on giant planet formation as a common process in planetary systems with potential applications to most extrasolar systems. In situ measurements of Saturn's stratospheric and tropospheric dynamics, chemistry and cloud-forming processes will provide access to phenomena unreachable to remote sensing studies. Different mission architectures are envisaged, which would benefit from strong international collaborations, all based on an entry probe that would descend through Saturn's stratosphere and troposphere under parachute down to a minimum of 10 bar of atmospheric pressure. We finally discuss the science payload required on a Saturn probe to match the measurement requirements.
    Keywords: Space Sciences (General)
    Type: GSFC-E-DAA-TN21252 , Planetary and Space Science (ISSN 0032-0633); 104; 29-47
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  • 9
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    Scientific Rationale of Saturn's In Situ Exploration (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Remote sensing observations meet some limitations when used to study the bulk atmospheric composition of the giant planets of our solar system. A remarkable example of the superiority of in situ probe measurements is illustratedby the exploration of Jupiter, where key measurements such as the determination of the noble gases abundances and the precise measurement of the helium mixing ratio have only been made available through in situ measurements by the Galileo probe. This paper describes the main scienti-c goals to be addressed by the future in situ exploration of Saturn placing the Galileo probe exploration of Jupiter in a broader context and before the future probe exploration of the more remote ice giants. In situ exploration of Saturn's atmosphere addresses two broad themes that are discussedthroughout this paper : rst, the formation history of our solar system and second, the processes at play in planetary atmospheres. In this context, we detail the reasons why measurements of Saturn's bulk elemental and isotopiccomposition would place important constraints on the volatile reservoirs in the protosolar nebula. We also show that the in situ measurement of CO (or any other disequilibrium species that is depleted by reaction with water) in Saturn's upper troposphere may help constraining its bulk OH ratio. We compare predictions of Jupiter and Saturn's bulk compositions from different formation scenarios, and highlight the key measurements required to distinguish competing theories to shed light on giant planet formation as a common process in planetary systems with potential applications to mostextrasolar systems. In situ measurements of Saturn's stratospheric and tropospheric dynamics, chemistry and cloud-forming processes will provide access to phenomena unreachable to remote sensing studies. Dierent mission architectures are envisaged, which would benet from strong international collaborations, all based on an entry probe that would descend through Saturn's stratosphere and troposphere under parachute down to a minimum of 10 bars of atmospheric pressure. We rally discuss the science payload required on a Saturn probe to match the measurement requirements.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN19065 , Planetary and Space Sciences Journal; 104; A; 29-47
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  • 10
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    Design studies of continuously variable transmissions for electric vehicles (1981)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Preliminary design studies were performed on four continuously variable transmission (CVT) concepts for use with a flywheel equipped electric vehicle of 1700 kg gross weight. Requirements of the CVT's were a maximum torque of 450 N-m (330 lb-ft), a maximum output power of 75 kW (100 hp), and a flywheel speed range of 28,000 to 14,000 rpm. Efficiency, size, weight, cost, reliability, maintainability, and controls were evaluated for each of the four concepts which included a steel V-belt type, a flat rubber belt type, a toroidal traction type, and a cone roller traction type. All CVT's exhibited relatively high calculated efficiencies (68 percent to 97 percent) over a broad range of vehicle operating conditions. Estimated weight and size of these transmissions were comparable to or less than equivalent automatic transmission. The design of each concept was carried through the design layout stage.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-81642 , DOE/NASA/10444-12 , E-588 , SAE Congr.,; Feb 23, 1981 - Feb 27, 1981; Detroit, MI; United States
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