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  • 1
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    Outgassing considerations for composites in space applications (1994)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Composites have been increasingly used in the construction of spacecraft. However, unlike metals, composites must be used with particular discretion in space applications because of their outgassing properties. For example, the outgas materials may cause serious contamination problems and affect the performance of delicate instruments. This paper presents an overview of the testing procedure and acceptance criteria for outgassing selection of spacecraft materials. Since composites can contain and absorb moisture which will outgas in space as water vapor, the test results of moisture absorption and desorption of a composite material are discussed also.
    Keywords: COMPOSITE MATERIALS
    Type: Environmental, Safety, and Health Considerations: Composite Materials in the Aerospace Industry; p 209-218
    Format: application/pdf
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  • 2
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    Hygrothermal properties of composites (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The testing procedure and acceptance criteria for outgassing selection of materials to be used in spacecraft has been reviewed. Outgassing testing should be conducted according to ASTM Standard E 595-90. In general, materials with CVCM less than or equal to 0.10% and TML less than or equal to 1.00% are acceptable for space applications. Next, test data on several types of graphite-epoxy composite materials are presented over time at various relative humidity levels at room temperature for moisture absorption, and under vacuum at several temperatures for moisture desorption (outgassing). The data can be accurately represented by simple equations which are useful for materials characterization. Finally, a laser dilatometer systems of extremely high sensitivity and accuracy was assembled and used to measure the coefficient of thermal expansion (CTE) of several types of graphite-epoxy structures, culminating in the ability to perform loading and thermal expansion tests on a prototype optical bench.
    Keywords: Composite Materials
    Type: NASA-TM-104637 , NAS 1.15:104637 , GSFC-96B00089
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  • 3
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    Analysis of Yttrium-Barium-Copper-Oxide by x ray diffraction and mechanical characterization (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The efforts in developing high-temperature superconductor (HTSC) YBa2Cu3O7 electrical leads are to benefit future NASA missions that will carry payloads with sensitive instruments operating at cryogenic temperatures. Present-day leads made of copper or magnesium are responsible for as much as 50 percent of the parasitic heat load on cryogenic systems. A reduction of this load could be achieved by replacing the conventional materials with HTSC ceramic electrical leads. Superconductor quality has become a concern in the industry, as has the development of effective evaluation methods. The factors that need to be examined for these materials include material purity, mechanical properties, and superconducting ability below the critical temperature. We applied several methods to study these factors: thermogravimetric analysis, x-ray diffraction, tensile testing, and laser-generated ultrasound. Our objectives were to determine the average tensile strength and Young's modulus of the HTSC material and to compare them to those values for copper and manganin.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TM-104562 , NAS 1.15:104562 , REPT-92A01664
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  • 4
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    Constellation-X Cylinder Figuring and Polishing Studies (2001)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: In support of Goddard's Constellation-X mandrel manufacturing effort a series of fabrication experiments are being performed to determine a best approach. Currently, polishing immediately after diamond turning, produces a RMS surface roughness of 0.31 nm, on a nickel plated aluminum mandrel. Studies currently under way will incorporate an abrasive figuring step followed by a polishing operation. The current diamond turning, figuring and polishing procedures will be described and the results presented.
    Keywords: Optics
    Type: SPIE Conference; Jul 29, 2001 - Aug 03, 2001; San Diego, CA; United States
    Format: text
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  • 5
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    Design, Implementation, and Performance of the Astro-H Soft X-Ray Spectrometer Aperture Assembly and Blocking Filters (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The calorimeter array of the JAXA Astro-H (renamed Hitomi) soft x-ray spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV. The properties that made the SXS array a powerful x-ray spectrometer also made it sensitive to photons from the entire electromagnetic band as well as particles. If characterized as a bolometer, it would have had a noise equivalent power of 〈4 10(exp 18) W/((Hz)(exp 0.5)). Thus, it was imperative to shield the detector from thermal radiation from the instrument and optical and UV photons from the sky. In addition, it was necessary to shield the coldest stages of the instrument from the thermal radiation emanating from the warmer stages. These needs were addressed by a series of five thin-film radiation-blocking filters, anchored to the nested temperature stages, that blocked long-wavelength radiation while minimizing x-ray attenuation. The aperture assembly was a system of barriers, baffles, filter carriers, and filter mounts that supported the filters and inhibited their potential contamination. The three outer filters also had been equipped with thermometers and heaters for decontamination. We present the requirements, design, implementation, and performance of the SXS aperture assembly and blocking filters.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN66167 , Journal Astronomical Telescopes, Instruments, and Systems; 4; 1; 011215
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  • 6
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    Automated Figuring and Polishing of Replication Mandrels for X-Ray Telescopes (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In support of the Constellation X mission the Optics Branch at Goddard Space Flight Center is developing technology for precision figuring and polishing of mandrels used to produce replicated mirrors that will be used in X-Ray telescopes. Employing a specially built machine controlled in 2 axes by a computer, we are doing automated polishing/figuring of 15 cm long, 20 cm diameter cylindrical, conical and Wolter mandrels. A battery of tests allow us to fully characterize all important aspects of the mandrels, including surface figure and finish, mid-frequency errors, diameters and cone angle. Parts are currently being produced with surface roughnesses at the .5nm RMS level, and half-power diameter slope error less than 2 arcseconds.
    Keywords: Optics
    Type: SPIE Optifab; May 19, 2003 - May 22, 2003; Rochester, NY; United States
    Format: text
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  • 7
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    The Design, Implementation, and Performance of the Astro-H SXS Aperture Assembly and Blocking Filters (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The calorimeter array of the JAXA Astro-H (renamed Hitomi) Soft X-ray Spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV, enabling essential plasma diagnostics. The properties that make the SXS array a powerful x-ray spectrometer also make it sensitive to photons from the entire electromagnetic band, and particles as well. If characterized as a bolometer, it would have a noise equivalent power (NEP) of less than 4x10(exp -18) W/(Hz)0.5(exp 0.5). Thus it was imperative to shield the detector from thermal radiation from the instrument and optical and UV photons from the sky. Additionally, it was necessary to shield the coldest stages of the instrument from the thermal radiation emanating from the warmer stages. Both of these needs are addressed by a series of five thin-film radiation-blocking filters, anchored to the nested temperature stages, that block long-wavelength radiation while minimizing x-ray attenuation. The aperture assembly is a system of barriers, baffles, filter carriers, and filter mounts that supports the filters and inhibits their potential contamination. The three outer filters also have been equipped with thermometers and heaters for decontamination. We present the requirements, design, implementation, and performance of the SXS aperture assembly and blocking filters.
    Keywords: Instrumentation and Photography
    Type: GSFC-E-DAA-TN33295 , SPIE Astronomical Telescopes + Instrumentation; Jun 26, 2016 - Jul 01, 2016; Edinburgh, Scotland; United Kingdom
    Format: application/pdf
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