Three methods of measuring the normal spectral, total normal and total hemispherical emissivity of opaque solid materials are described. Spectral emissivity measurements are performed at approximately ambient temperature and encompass the wavelength interval .4 to 25 microns. Total hemispherical emissivity measurements cover the temperature range 0 C to 600 C. Results of the emissivity measurements, of various materials, as performed with each of the systems, are presented. (Author).

Progress in Astronautics and Aeronautics, Volume 18: Thermophysics and Temperature Control of Spacecraft and Entry Vehicles is a selection of technical papers based on two American Institute of Aeronautics and Astronautics meetings, namely, The Thermophysics Specialist Conference, held in Monterey, California on September 13-15, 1965 and the Third Aerospace Sciences Conference, held in New York on January 1966. This book covers the most important problems of thermophysical research and technology. This volume is composed of six parts encompassing 42 chapters. Part I contains papers on the thermal radiation properties of solids, including measuring techniques for solar reflectance and infrared emittance determination, and a paper on radiative transfer. Part II deals with the lunar and planetary thermal environment and includes research papers on emissivities, reflectivities, and polarization by planetary atmospheres and planetary surfaces. Part III discusses the effects of the space environment on the optical properties of thermal control surfaces. This part also presents results of flight experiments with sensors of environmental effects and flight experience with thermal coatings of satellites. Part IV covers the thermophysical measurements of ablative materials and with the char layers formed during the actual vehicle entry period or during laboratory simulation tests. Part V looks into the two comparatively areas of thermophysics, namely, the thermal similitude (thermal modeling) and interface resistance of joints under space conditions. Part VI summarizes the practical experience in thermal design gained on spacecraft flights. Thermophysicists, space engineers and designers, and research workers who are interested in thermophysical technology will find this book invaluable.