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At least 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Performance of the HIRS/2 instrument on TIROS-N

The High Resolution Infrared Radiation Sounder (HIRS/2) was developed and flown on the TIROS-N satellite as one means of obtaining atmospheric vertical profile information. The HIRS/2 receives visible and infrared spectrum radiation through a single telescope and selects 20 narrow radiation channels by means of a rotating filter wheel. A passive radiant cooler provides an operating temperature of 106.7 K for the HgCdTe and InSb detectors while the visible detector operates at instrument frame temperature. Low noise amplifiers and digital processing provide 13 bit data for spacecraft data multiplexing and transmission. The qualities of system performance that determine sounding capability are the dynamic range of data collection, the noise equivalent radiance of the system, the registration of the air columns sampled in each channel and the ability to upgrade the calibration of the instrument to maintain the performance standard throughout life. The basic features, operating characteristics and performance of the instrument in test are described. Early orbital information from the TIROS-N launched on October 13, 1978 is given and some observations on system quality are made.

Koenig, E. W.↗
NASA NTRS1983

Results of the 1982 NASA/JPL balloon flight solar cell calibration program

The 1982 solar cell calibration balloon flight was successfully completed on July 21, meeting all objectives of the program. Twenty-eight modules were carried to an altitude of 36.0 kilometers. The calibrated cells can now be used as reference standards in simulator testing of cells and arrays.

Downing, R. G.↗
NASA NTRS1984

Results of the 1984 NASA/JPL balloon flight solar cell calibration program

The 1984 solar cell calibration balloon flight was successfully completed on July 19, meeting all objectives of the program. Thirty-six modules were carried to an altitude of 36.0 kilometers. The calibrated cells can now be used as reference standards in simulator testing of cells and arrays.

Downing, R. G.↗
NASA NTRS1983

A pyroloysis technique for determining microamounts of hydrogen in lunar soil using the helium ionization detector

A method has been developed which will determine hydrogen in sub-milligram samples of lunar soil. It consists of heating the sample in a pyroprobe followed by the gas chromatographic determination of hydrogen using the helium ionization detector. Using a 7 foot, 1/8 OD stainless steel column packed with Carbosieve S, 120/140 mesh, hydrogen was well-separated from the other gases released from lunar soil. Standards of hydrogen in helium were used for calibration. The limit to detection under the conditions used was about 2 ng. The method was linear from 2 ng to 270 ng. The method was checked using some actual lunar samples. Results were typical of those obtained for lunar soils using other methods.

Bustin, R.↗
NASA NTRS1986

Results of the 1985 NASA/JPL balloon flight solar cell calibration program

The 1985 solar cell calibration balloon flight was successfully completed on July 12, 1985, meeting all objectives of the program. Fifty-seven modules were carried to an altitude of 115,000 ft (35.0 km). The calibrated cells can now be used as reference standards in simulator testing of cells and arrays.

Anspaugh, B. E.↗
NASA NTRS1986

Results of the 1986 NASA/JPL Balloon Flight Solar Calibration Program

The 1986 solar cell calibration balloon flight was successfully completed on July 15, 1986, meeting all objectives of the program. Thirty modules were carried to an altitude of 118,000 ft (36.0 km). The calibrated cells can now be used as reference standards in simulator testing of cells and arrays.

Anspaugh, B. E.↗
NASA NTRS1986

Portable high speed photometry systems for observing occultations

Ring orbit studies for Uranus have been particularly fruitful because of the ability, through occultations, to obtain data of high spatial resolution at the rate of 1 to 2 times per year. The occultation program at M.I.T. involves: (1) identifying the scientific questions that can be answered by occultation events, (2) predicting the zone of visibility for the useful events, (3) maintaining and improving a set of portable high-speed photometric systems, (4) obtaining the observations, and (5) reducing the data and interpreting the results. Two stellar occultations by Uranus occurred in May 1985, and were observed with a network of large telescopes that encompassed the Northern and Southern Hemispheres. Portable quartz-oscillator time standards were used at all observatories, and were calibrated before and after each event. Observations obtained form Cerro Tololo and McDonald Observatories of the 4 May and 24 May 1985 occultations by the Uranian rings clearly show a companion to the delta ring on both the immersion and emersion traces. The occultation by Ceres that occurred on 12 November 1984 was observed. Preliminary results give a mean diameter of 933 + or - 10 km, which implies a geometric albedo, Pv = 0.07 + or - 0.01 and a density 2.7 + or - 0.3 gm cu/cm. Hence Ceres is likely composed of silicate material throughout.

Elliot, J. L.↗
NASA NTRS1988

Results of the 1988 NASA/JPL balloon flight solar cell calibration program

The 1988 solar cell calibration balloon flight was successfully completed on August 7, 1988, meeting all objectives of the program. Forty-eight modules were carried to an altitude of 118,000 ft (36.0 km). The calibrated cells can now be used as reference standards in simulator testing of cells and arrays.

Anspaugh, B. E.↗
NASA NTRS1989

Results of the 1989 NASA/JPL balloon flight solar cell calibration program

The 1989 solar cell calibration balloon flight was successfully completed on August 9, 1989, meeting all objectives of the program. Forty-two modules were carried to an altitude of 118,000 ft (36.0 km). The calibrated cells can now be used as reference standards in simulator testing of cells and arrays.

Anspaugh, B. E.↗
NASA NTRS1994

Thermalite Apparatus

Thermalite is portable apparatus that nondestructively determines thermal-diffusion properties of specimen. Based on heat-pulse method; it applies pulse of heat to specimen, then computes relevant thermal properties of specimen from time-resolved measurements of thermal response of specimen to heat pulse. Apparatus is self-contained and calibrated and tested with stored thermal pattern as standard. Used to assess flaw in specimen.

Heyman, Joseph S.↗
NASA NTRS1993

Test results from LAGEOS-2 optical characterization using pulsed lasers

The Laser Geodynamic Satellite-2 (LAGEOS-2) has undergone extensive optical testing at NASA Goddard Space Flight Center during 1989. The techniques included measuring the far field diffraction pattern using cw and pulsed lasers. In the pulsed measurement technique, response of the satellite was studied by measuring the far-field diffraction pattern (FFDP) as a function of pulsewidth, wavelength, polarization, position in the FFDP, detector/processing techniques, and satellite orientation. The purpose of the pulsed laser testing was two-fold: (1) to characterize the satellite optical response with the detector and signal processing electronics currently used in most SLR stations using the portable laser ranging standard, and (2) to characterize the satellite response for various conditions using the highest bandwidth optical detector (streak camera) available for the next generation of satellite laser ranging (SLR) technology. The portable ranging standard employed multiple measurement devices and an optical calibration scheme to eliminate range-dependent and amplitude-dependent systematics. These precautions were taken to eliminate/minimize instrumental errors and provide maximum accuracy. For LAGEOS orbit (6000 Km), ground stations are located 34 to 38 Mu radians off the axis of the return signal from the satellite; therefore, an optical mask was used to restrict the field of view (FOV) of detection to this annular region of the FFDP. The two measurement techniques were implemented using an aperture sharing scheme and complemented each other by providing mutual verification.

Varghese, Thomas K.↗
NASA NTRS1992

Activities of NIST (National Inst. of Standards and Technology)

The Radiometric Physics Division of the NIST is responsible for the national standards in radiation thermometry, spectroradiometry, photometry, and spectrophotometry; dissemination of these standards by providing measurement services to customers requiring calibrations of the highest accuracy; and conducting fundamental and applied research to develop the scientific basis for future measurement services. Its relevance to EOS/TIR calibration includes calibrating unknown blackbody for radiance using a well-characterized NIST blackbody source by matching the radiant fluxes with an IR radiometer. The TIR Round Robin is used to verify the calibration of the sources that are used for the absolute radiometric calibration of the individual EOS sensors.

Source record↗
NASA NTRS1994

Computerized Ultrasonic Testing System (CUTS) for in-process thickness determination

A Computerized Ultrasonic Testing System (CUTS) was developed to measure, in real-time, the rate of deposition and thickness of chromium plated on the inside of thick steel tubes. The measurements are made from the outside of the tubes with the ultrasonic pulse-echo technique. The resolution of the system is 2.5 micron. (0.0001 in.) and the accuracy is better than 10 micron (0.0004 in.). The thickness is measured using six transducers mounted at different locations on the tube. In addition, two transducers are mounted on two reference standards, thereby allowing the system to be continuously calibrated. The tube temperature varies during the process, thus the input from eight thermocouples, located at the measurement sites, is used to calculate and compensate for the change in return time of the ultrasonic echo due to the temperature dependence of the sound velocity. CUTS is applicable to any commercial process where real-time change of thickness of a sample has to be known, with the advantage of facilitating increased efficiency and of improving process control.

Frankel, J.↗
NASA NTRS1990

Linear Calibration of Radiographic Mineral Density Using Video-Digitizing Methods

Radiographic images can provide quantitative as well as qualitative information if they are subjected to densitometric analysis. Using modern video-digitizing techniques, such densitometry can be readily accomplished using relatively inexpensive computer systems. However, such analyses are made more difficult by the fact that the density values read from the radiograph have a complex, nonlinear relationship to bone mineral content. This article derives the relationship between these variables from the nature of the intermediate physical processes, and presents a simple mathematical method for obtaining a linear calibration function using a step wedge or other standard.

Martin, R. Bruce↗
NASA NTRS1990

Linear Calibration of Radiographic Mineral Density Using Video-Digitizing Methods

Radiographic images can provide quantitative as well as qualitative information if they are subjected to densitometric analysis. Using modem video-digitizing techniques, such densitometry can be readily accomplished using relatively inexpensive computer systems. However, such analyses are made more difficult by the fact that the density values read from the radiograph have a complex, nonlinear relationship to bone mineral content. This article derives the relationship between these variables from the nature of the intermediate physical processes, and presents a simple mathematical method for obtaining a linear calibration function using a step wedge or other standard.

Martin, R. Bruce↗
NASA NTRS2000

Laboratory Study of Water Surface Roughness Generation by Wave-Current Interaction

Within the framework of this project, the blocking of waves by inhomogeneous currents was studied. A laboratory experiment was conducted in collaboration with Steven R. Long at the linear wave tank of the NASA Air-Sea Interaction Facility, Wallops Island, VA during May 1999. Mechanically-generated waves were blocked approximately 3m upstream from the wave paddle by an opposing current. A false bottom was used to obtain a spatially varying flow field in the measurement section of the wave tank. We used an imaging slope gauge, which was mounted directly underneath the sloping section of the false tank bottom to observe the wave field. For a given current speed, the amplitude and the frequency of the waves was adjusted so that the blocking occurred within the observed footprint. Image sequences of up to 600 images at up 100 Hz sampling rate were recorded for an area of approximately 25cm x 25cm. Unlike previous measurements with wave wire gauges, the captured image sequences show the generation of the capillary waves at the blocking point and give detailed insight into the spatial and temporal evolution of the blocking process. The image data were used to study the wave-current interaction for currents from 5 to 25 cm/s and waves with frequencies between 1 and 3 Hz. First the images were calibrated with regard to size and slope. Then standard Fourier techniques as well the empirical mode decomposition method developed by Dr. Norden Huang and Dr. Steven R. Long were employed to quantify the wave number downshift from the gravity to the capillary regime.

Klinke, Jochen↗
NASA NTRS2001

The Evolution of CTB-109

The subject grant is for the analysis of XMM observations of the galactic supernova remnant CTB-109. As of the writing of this report, the XMM observations have not been conducted yet. We have begun gaining experience with the XMM analysis SW and calibration files so that we can more quickly analyze our data once they become available. We have downloaded the latest version of the XMM standard analysis SW (SAS 5.1). We have downloaded some of the public calibration datasets and started manipulating them using the SAS SW.

Plucinsky, Paul↗
NASA NTRS2002

Simulated Space Vacuum Ultraviolet (VUV) Exposure Testing for Polymer Films

Vacuum ultraviolet (VUV) radiation of wavelengths between 115 and 200 nm produced by the sun in the space environment can cause degradation to polymer films producing changes in optical, mechanical, and chemical properties. These effects are particularly important for thin polymer films being considered for ultra-lightweight space structures, because, for most polymers, VUV radiation is absorbed in a thin surface layer. NASA Glenn Research Center has developed facilities and methods for long-term ground testing of polymer films to evaluate space environmental VUV radiation effects. VUV exposure can also be used as part of sequential simulated space environmental exposures to determine combined damaging effects. This paper will describe the effects of VUV on polymer films and the necessity for ground testing. Testing practices used at Glenn Research Center for VUV exposure testing will be described including characterization of the VUV radiation source used, calibration procedures traceable to the National Institute of Standards and Technology (NIST), and testing techniques for VUV exposure of polymer surfaces.

Dever, Joyce A.↗