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Fused silica reflecting heat shields for outer planet entry probesThe development of slip-cast fused silica is discussed as a heat shield designed to meet the needs of outer-planet entry probes. The distinguishing feature of silica is its ability to reflect the radiation imposed by planetary-entry environments. This reflectivity is particularly sensitive to degradation by the presence of trace amounts of contaminants introduced by the starting materials or by processing. The microstructure of a silica configuration also significantly influences the reflectivity and other thermomechanical properties. The processing techniques attendant on controlling microstructure while maintaining purity are discussed. The selection of a starting material of essential purity precludes the use of purified natural quartz and requires the use of synthetic fused silica. The silica is characterized in a limited combined heating test environment. The surface mass loss is controlled by liquid runoff from a relatively low-temperature melt layer; the reflectance is basically maintained and the material achieves a surprisingly high heat of ablation.
Document ID
19750049685
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Congdon, W. M.
(Martin Marietta Aerospace Denver, Colo., United States)
Peterson, D. L.
(NASA Ames Research Center Thermal Protection Branch, Moffett Field, Calif., United States)
Date Acquired
August 8, 2013
Publication Date
May 1, 1975
Subject Category
Nonmetallic Materials
Report/Patent Number
AIAA PAPER 75-732
Meeting Information
Meeting: American Institute of Aeronautics and Astronautics, Thermophysics Conference
Location: Denver, CO
Start Date: May 27, 1975
End Date: May 29, 1975
Sponsors: American Institute of Aeronautics and Astronautics
Accession Number
75A33757
Funding Number(s)
CONTRACT_GRANT: NAS2-7912
Distribution Limits
Public
Copyright
Other

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