A photometric function for diffuse reflection by particulate materials

A photometric function is proposed to describe the diffuse reflection of radiation by particulate materials. Both multiple scattering and the dominant effects of particle shadowing are included and the function is verified by comparisons with the photometries of laboratory surfaces. Brightness measurements of planetary and other diffusely scattering surfaces can be used to calculate the brightness for geometries other than those used in the measurements and for which the Minnaert function does not apply. The measurements also can be directly related to such surface characteristics as particle size, single-particle albedo, and compactness

Simulated LM static reflectivity data, for site P-2-6

Simulated lunar module static reflectivity data for site P-2-

A preliminary study of ester oxidation on an aluminum surface using chemiluminescence

The oxidation characteristics of a pure ester (trimethyolpropane triheptanoate) were studied by using a chemiluminescence technique. Tests were run in a thin-film micro-oxidation apparatus with an aluminum alloy catalyst. Conditions included a pure oxygen atmosphere and a temperature range of 176 to 206 C. Results indicated that oxidation of the ester (containing 10 to the minus 3 power M diphenylanthracene as an intensifier) was accompanied by emission of light. The maximum intensity of light emission (I sub max) was a function of the amount of ester, the concentration of intensifier, and the test temperature. The induction period or the time to reach one-half of maximum intensity (t sub 1/2) was an inverse function of test temperature. Decreases in light emission at the later stages of a test were caused by depletion of the intensifier

Removal of acid gases and oxides of nitrogen from space cabin atmospheres

Removal of acid gases and oxides of nitrogen from spacecraft cabin atmospheres at ambient temperature

Values of the photometric parameters of Mars and their interpretation

Photometric data for the Martian disk obtained by Thorpe from television-camera pictures taken by Mariner 9 were used to derive values for the parameters in the photometric function. The photometric function can be applied to Mars and to the design of cameras for photography of Mars. Values of the parameters are for one wavelength only, 0.56 micros and are average or effective values for the Martian disk. The values derived were interpreted to provide semi-quantitative information on the soil. The results do not disagree with other indications that the effective mean diameter of the surface particles is about 400 micros. Another result is that the mean intercenter spacing of adjacent particles may be about 4/3 of the mean diameter

Enabling lunar and space missions by laser power transmission

Applications are proposed for laser power transmission on the Moon. A solar-pumped laser in lunar orbit would beam power to the lunar surface for conversion into either electricity or propulsion needs. For example, lunar rovers could be much more flexible and lighter than rovers using other primary power sources. Also, laser power could be absorbed by lunar soil to create a hard glassy surface for dust-free roadways and launch pads. Laser power could also be used to power small lunar rockets or orbital transfer vehicles, and finally, photovoltaic laser converters could power remote excavation vehicles and human habitats. Laser power transmission is shown to be a highly flexible, enabling primary power source for lunar missions

The photometry of flat, basaltic surfaces

A photometer was developed and successfully operated to obtain photometric measurements on several flat, particulate surfaces of basalt for coplanar scattering geometries. The test materials were two size ranges each of two different basalts with significantly different albedos. The measurements include a range of phase angles from 30 to 80 degrees and were obtained by varying the angles of incidence and emission such that the phase angle remained constant. The data were used elsewhere in the verification of the Meador-Weaver photometric function and are presented here in the form of Minnaert plots. In this form the data offered the first support for the accuracy of the Meador-Weaver photometric function because of a deviation of the data from a straight line trend at larger departures from the mirror point geometry. This trend is predicted by the Meador-Weaver function but not by the Minnaert function. The failure of photometric data to support the Minnaert function was not evident in earlier measurements because of the restriction of planetary data to small departures from the mirror point geometry and to small values of the phase angle

Investigation of Oxidation Profile in PMR-15 Polyimide using Atomic Microscope (AFM)

Nanoindentation measurements are made on thermosetting materials using cantiever deflection vs. piezoelectric scanner position behavior determined by AFM. The spring model is used to determine mechanical properties of materials. The generalized Sneddon's equation is utilized to calculate Young's moduli for thermosetting materials at ambient conditions. Our investigations show that the force-penetration depth curves during unloading in these materials can be described accurately by a power law relationship. The results show that the accuracy of the measurements can be controlled within 7%. The above method is used to study oxidation profiles in Pl\1R-15 polyimide. The thermo-mechanical profiles ofPNIR-15 indicate that the elastic modulus at the surface portion of the specimen is different from that at the interior of the material. It is also shown that there are two zones within the oxidized portion of the samples. Results confirm that the surface layer and the core material have substantially different properties