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Engineering topics
Publications and source records attributed to O'Donnell, T..
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A wide range of deep space science missions are planned by NASA for the future. Many of these missions are being planned under strict cost caps and advanced technologies are needed in order to enable these challenging mssions. Because of the wide range of thermal environments the spacecraft experience during the mission, advanced thermal control technologies are the key to enabling many of these missions.
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A number of studies on materials technologies for the Space Infrared Telescope Facility (SIRTF) intended to enhance SIRTF mission performance are reviewed. Particular attention is given to dewar support straps, dewar structural materials, infrared black coatings, optical mirror materials, cryogenic properties data base, contamination control, and thermal control materials/coatings. It is noted that the alternative to baseline materials offer potential for substantial improvements in reliability, weight, and lifetime.
Future NASA missions such as the Great Observatories of the 21st Century, will require high dimensional stability (i.e., the system's ability to retain geometrical properties related to the system's performance) which will have to be maintained with micron to nanometer accuracy over the 5 to 10 years of mission lifetime. This paper examines the thermodynamic and other mechanisms which limit the dimensional stability of a space system. It is shown that the space system's performance will be limited below 0.1 per million dimensional stability.
Standardized techniques for outgassing tests are developed and set forth for use in the screening of materials for aerospace instruments with cooled sensors, optics, and/or detectors. Materials for optical instruments are discussed in terms of molecular outgassing, and material-outgassing test results are presented which relate to several test conditions. The existing outgassing standard is found to be inadequate, and revised outgassing standards related to four application levels are given. The test protocols are designed for the development of materials for optical instruments that operate in environments with temperatures below 20 C. Consideration is also given to potential molecular contamination in the space environment and to outgas screening of instruments with a variety of sensor/optics/detector temperatures. The standards are designed for use with existing outgassing-test data as well as contamination analyses relating to the instrument being tested.