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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

High solar intensity radiometer

Silicon solar cells are used to measure visible radiant energy and radiation intensities to 20 solar constants. Future investigations are planned for up to 100 solar constants. Radiometer is small, rugged, accurate and inexpensive.

Jack, J. R.↗
NASA NTRS1972

Zone radiometer measurements on a model rocket exhaust plume

Radiometer for analytical prediction of rocket plume-to-booster thermal radiation and convective heating is described. Applications for engine combustion analysis, incineration, and pollution control by high temperature processing are discussed. Illustrations of equipment are included.

Source record↗
NASA NTRS1972

High intensity solar cell radiometer

Device can be employed under high intensity illumination conditions such as would occur in a close-solar-approach space mission or in monitoring high intensity lamps. Radiometer consists of silicon solar cells with thin semi-transparent coatings of aluminum deposited on the front surfaces to permit transmission of small percentage of light and reflect the remainder.

Brandhorst, H. W.↗
NASA NTRS1971

Silicon solar cells as a high-solar-intensity radiometer

The characteristics of a conventional, 1- by 2-cm, N/P, gridded silicon solar cell when used as a radiometer have been determined for solar intensity levels to 2800 mW/sq cm (20 solar constants). The short-circuit current was proportional to the radiant intensity for levels only to 700 mW/sq cm (5 solar constants). For intensity levels greater than 700 mW/sq cm, it was necessary to operate the cell in a photoconductive mode in order to obtain a linear relation between the measured current and the radiant intensity. When the solar cell was biased with a reverse voltage of -1 V, the measured current and radiant intensity were linearly related over the complete intensity range from 100 to 2800 mW/sq cm.

Spisz, E. W.↗
NASA NTRS1971

Altimeter and radiometer for a Venus orbiter mission

The concept, constraints, and capabilities of a radar altimeter type contour mapper for a Venus orbiter mission are presented. The system was developed for the proposed planetary explorer universal bus concept. A system with a height precision of 30meters over a surface area of 7200 square kilometers is achieved. Using this system and the orbit proposed in the orbiting bus concept, the northern hemisphere of Venus is mapped in one Venus day. The radar receiver system, is used in a radiometer mode to obtain a map of the diurnal and logitudinal variations of the Venus surface temperature with a resolution of 3.0 degrees Kelvin.

Bryan, J. W.↗
NASA NTRS1972

Polarization effects with a combined radar-radiometer

Described is a unique microwave sensor. The device uses a coherent X-band radar, a radiometer at the same wavelength and an antenna with a polarization that can be varied electronically. This microwave sensor was developed to acquire polarization signature information about various surfaces in both the active and passive mode simultaneously. One application for the sensor is expected to be the location and identification of plant life.

Martin, D.↗
NASA NTRS1971

Usefulness of the infrared heterodyne radiometer in remote sensing of atmospheric pollutants.

The application of narrow-band optical receivers to the problem of sensing atmospheric pollution is discussed. The emission/absorption lines of many major atmospheric pollutant molecules overlap the operating frequency bands of CO2 laser and CO laser heterodyne receivers. Several remote pollution sensing systems which are based upon utilization of these spectral overlaps are described, and an analysis of their potential is presented. The possibility of using other lasers (e.g.: the PbSnTe tunable diode laser) as local oscillators is also considered. Results of laboratory experiments with a CO2 laser heterodyne radiometer are presented.

Menzies, R. T.↗
NASA NTRS1972

Radiometer for remote sounding of the upper atmosphere.

The pressure-modulated carbon dioxide radiometer is a new kind of instrument capable of making temperature soundings in the 40-80-km region of the earth's atmosphere. It is intended to be mounted on a polar-orbiting satellite, where it will give global coverage of the upper atmosphere in a region that is not well understood at present but that is, as rocket soundings show, clearly the seat of many interesting and vigorous phenomena. The new technique employs a cell containing carbon dioxide as a filter. The pressure and hence transmission of this cell is periodically modulated, resulting in the selection of thermal radiation from the strong lines in the spectrum of atmospheric carbon dioxide. This radiation originates at levels in the atmosphere where the pressure is low. The energy grasp of the device is large enough to give high sensitivity.

Taylor, F. W.↗
NASA NTRS1971

International comparison of radiometers - Techniques and results.

Description of an international comparison of radiometers made on May 10 through 14, 1971, with 24 instruments, each one representing the calibration standard of a different country or a major laboratory. All were pyranometers, viewing the sun and sky, thus bypassing the conventional method of transferring the standard from Angstrom pyrheliometers. This is the first time that pyranometers from all around the globe have been brought together in order to verify the scale on which to report solar radiation data. A highly accurate data collection system measured simultaneously the output of each instrument and that of a reference standard at 20-sec intervals. Over 300,000 radiometric signals were recorded under varying atmospheric conditions, as well as data on turbidity, temperature, and other relevant parameters. Computer programs were developed for overnight analysis of the data and distribution to participants on the following day. Among major findings are that instruments of different types and independent calibration such as those of Eppley, U. S. A., World Radiation Center, Switzerland, and Melbourne, Australia, show better agreement than anticipated, that certain national standards have to be revised by as much as 16% and that the cosine factor is highly dependent on the type of instrument.

Thekaekara, M. P.↗
NASA NTRS1972

Objective analysis of sea-level winds and pressures derived from simulated observations of a satellite radar-radiometer and actual conventional data.

A computer-based procedure is developed that combines a field of simulated satellite-derived wind speeds with a limited amount of conventional surface data so as to recover the surface pressure field and the vector wind field over the North Pacific Ocean. Wind speeds are determined from an objective analysis of high spatial density ship observations in order to simulate the anticipated output of a proposed satellite-mounted radar-radiometer system. The simulated speeds are combined with the conventional network for various spatial distributions of ship data. The average rms departure of sea-level pressure fields analyzed by deleting from 75-94% of the available ship observations from the maximum data analysis is from 3.0-4.0 mb. Comparison of the wind components implied by the isobaric patterns to those of the withheld ship observations yields average rms differences of from 8.7-9.4 kt for a range of 75-94% data deletion.

Druyan, L. M.↗