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  • 1
    Publication Date: 2016-06-07
    Description: Issues regarding the use of optical fiber thermometers to control heater settings in a microgravity vacuum furnace are addressed. It is desirable to use these probes in environments such as the International Space Station, because they can be operated without re-calibration for extended periods. However, the analysis presented in this paper shows that temperature readings obtained using optical fiber thermometers can be corrupted by emissions from the fiber when extended portions of the probe are exposed to elevated temperatures.
    Keywords: Optics
    Type: The Tenth Thermal and Fluids Analysis Workshop; NASA/CP-2001-211141
    Format: application/pdf
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  • 2
    Publication Date: 2019-06-28
    Description: Future missions to Mars will require a communications system to link activities on the Martian surface with each other and with mission controllers on Earth. A conceptual design is presented for an aerosynchronous communications satellite to provide these links. The satellite provides the capability for voice, data/command, and video transmissions. The mission scenario assumed for the design is described, and a description of a single aerosynchronous satellite is explained. A viable spacecraft design is then presented. Communication band selection and channel allocation are discussed. The communications system conceptual design is presented along with the trades used in sizing each of the required antennas. Also, the analyses used to develop the supporting subsystem designs are described as is the communications impact on each subsystem design.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TP-2942 , L-16580 , NAS 1.60:2942
    Format: application/pdf
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  • 3
    Publication Date: 2019-06-28
    Description: The global change technology initiative calls for a geostationary platform for Earth science monitoring. One of the major science instruments is the high frequency microwave sounder (HFMS) which uses a large diameter, high resolution, high frequency microwave antenna. This antenna's size and required accuracy dictates the need for a segmented reflector. On-orbit disturbances may be a significant factor in its design. A study was performed to examine the effects of the geosynchronous thermal environment on the performance of the strongback structure for a proposed antenna concept for this application. The study included definition of the strongback and a corresponding numerical model to be used in the thermal and structural analyses definition of the thermal environment, determination of structural element temperature throughout potential orbits, estimation of resulting thermal distortions, and assessment of the structure's capability to meet surface accuracy requirements. Analyses show that shadows produced by the antenna reflector surface play a major role in increasing thermal distortions. Through customization of surface coating and element expansion characteristics, the segmented reflector concept can meet the tight surface accuracy requirements.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TP-3016 , L-16739 , NAS 1.60:3016
    Format: application/pdf
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  • 4
    Publication Date: 2019-07-13
    Description: Issues regarding the use of optical fiber thermometers to control heater settings in a microgravity vacuum furnace are addressed. It is desirable to use these probes in environments such as the International Space Station, because they can be operated without re-calibration for extended periods. However, the analysis presented in this paper shows that temperature readings obtained using optical fiber thermometers are corrupted due to emissions from the fiber when extended portions of the probe are exposed to elevated temperatures.
    Keywords: Instrumentation and Photography
    Type: Thermal and Fluids Analysis (TFAWS99) Workshop; Sep 13, 1999 - Sep 17, 1999; Huntsville, AL; United States
    Format: application/pdf
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  • 5
    Publication Date: 2019-07-13
    Description: Copper-water heat pipes are commonly used for thermal management of electronics systems on earth and aircraft, but have not been used in spacecraft thermal control applications to date, due to the satellite industry's requirement that any device or system be successfully tested in a microgravity environment prior to adoption. Recently, Advanced Cooling Technologies Inc., (ACT), NASA Marshall Space Flight Center, and the International Space Station office at NASA's Johnson Space Center demonstrated flight heritage in Low-Earth Orbit. The testing was conducted aboard the International Space Station (ISS) under the Advanced Passive Thermal eXperiment (APTx) project. The heat pipes were embedded in a high conductivity (HiK "TM") aluminum base plate and subject to a variety of thermal tests over a temperature range of -10 to 38 C for a ten-day period. Results showed excellent agreement with both predictions and ground tests. In addition, novel hybrid wick aluminum-ammonia heat pipes are developed to handle heat flux requirements for spacecraft thermal control applications. The 5-10 W/cm2 heat density limitation of aluminum-ammonia grooved heat pipes has been a fundamental limitation in the current design for space applications. The recently demonstrated 50W/cm2 capability of the hybrid high heat flux heat pipes provides a realistic means of managing the high heat density anticipated for the next generation space designs.
    Keywords: Engineering (General)
    Type: M17-6329 , International Heat Pipe Conference (IHPC); Jun 10, 2018 - Jun 14, 2018; Pisa; Italy|International Heat Pipe Symposium (IHPS); Jun 10, 2018 - Jun 14, 2018; Pisa; Italy
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