Engineering topics

Hale, Robert R.

Publications and source records attributed to Hale, Robert R..

5 records

NASA NTRS1991

Reflectance stability analysis of Spectralon diffuse calibration panels

The Multi-angle Imaging SpectroRadiometer (MISR) plans to use deployable diffuse reflectance panels to provide periodic radiometric calibrations of its nine cameras while in-flight. Near-Lambertian reflectance characteristics are desirable to facilitate flat-field camera intercomparisons. Also required is panel spatial and spectral uniformity, and stability with time. Spectralon, a commercially available polytetrafluoroethylene (PTFE) compound, has been baselined in the MISR design. To assess the suitability of this material, a series of degradation tests were planned and implemented. These included UV vacuum exposure and proton bombardment tests which simulated the exposure levels to be encountered during the mission life. Proton levels are now considered too low to be of concern, but UV vacuum tests demonstrate sensitivity to material contamination. Material investigations have concluded that hydrocarbons are present in the bulk of the material, and that plastic packaging materials can introduce additional surface-layer contamination. It is found however, that these unwanted elements can be eliminated through vacuum pumping at elevated temperatures. Exposure to a UV source, while in vacuum, is again planned for a set of targets which have been vacuum baked. This will assess the stability of the pure PTFE form.

Bruegge, Carol J.↗

NASA NTRS1991

Reflective and refractive optical materials for earth and space applications; Proceedings of the Meeting, Orlando, FL, Apr. 4, 5, 1991

The present conference discusses beryllium mirror design and fabrication, production of aspheric beryllium optical surfaces by HIP consolidation, the control of thermally induced porosity for the fabrication of beryllium optics, fine-grained beryllium optical coatings, light-absorbing beryllium baffle materials, and advanced broadband baffle materials. Also discussed are radiation-resistant optical glasses, a catalog of IR and cryooptical properties of selected materials, durable metal-dielectric mirror coatings, the optical stability of diffuse reflectance materials, and optical filters for space applications.

Riedl, Max J.↗

NASA NTRS1989

Proceedings of the Second Noncontact Temperature Measurement Workshop

The state of the art in noncontact temperature measurement (NCTM) technology was reviewed and the NCTM requirements of microgravity materials processing community identified. The workshop included technical presentations and discussions which ranged from research on advanced concepts for temperature measurement to laboratory research and development regarding measurement principles and state-of-the-art engineering practices for NCTM methodology in commercial and industrial applications. Technical presentations were made concerning: NCTM needs as perceived by several NASA centers, recent ground-based NCT, research and development of industry, NASA, academia, and selected national laboratories, work-in-progress communication, and technical issues of the implementation of temperature measurement in the space environment to facilitate future U.S. materials science investigations.

Hale, Robert R.↗

NASA NTRS1989

Combustion process science and technology

An important and substantial area of technical work in which noncontact temperature measurement (NCTM) is desired is that involving combustion process research. In the planning for this workshop, it was hoped that W. Serignano would provide a briefing regarding the experimental requirements for thermal measurements to support such research. The particular features of thermal measurement requirements included those describing the timeline for combustion experiments, the requirements for thermal control and diagnostics of temperature and other related thermal measurements and the criticality to the involved science to parametric features of measurement capability including precision, repeatability, stability, and resolution. In addition, it was hoped that definitions could be provided which characterize the needs for concurrent imaging as it relates to science observations during the conduct of experimentation.

Hale, Robert R.↗

NASA NTRS1989

Space optical materials and space qualification of optics; Proceedings of the Meeting, Orlando, FL, Mar. 30, 31, 1989

The present conference on space optical materials discusses current metals and nonmetals-related processing R&D efforts, investigations of space optical effects, and the spaceborne qualification of optical components and systems. Attention is given to CVD SiC for optical applications, optical materials for space-based lasers, the high-efficiency acoustooptic and optoelectronic crystalline material Tl3AsSe3, HIPed Be for low-scatter cryogenic optics, durable solar-reflective surfacing for Be optics, thermal effects on Be mirrors, contamination effects on optical surfaces in the monolayer regime, and IR background signature survey experiment results. Also discussed are the contamination-control program for the EUE instrument, an optical multipass radiation system for the heating of levitated samples, optical sample-position sensing for electrostatic levitation, and the qualification of space lighting systems.

Hale, Robert R.↗