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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Holographic interferometry

Holographic interferometry application to laser NDT of objects with nonoptical surfaces, describing techniques and industrial uses

Wuerker, R. F.↗
NASA NTRS1972

Very long baseline interferometry

Some astronomical results, obtained by very long baseline interferometry, on quasi-stellar sources are reported. Data cover variations in optical luminosity, radio brightness variations, and observations of quasi-stellar nuclei.

Clark, T.↗
NASA NTRS1972

Fabrication and testing of scatter plates for interferometry

Scatter plate interferometry has become a reliable method of measuring surface configurations of telescope mirrors and other optical components. The scatter plate used in an instrument should be of optimum quality if the surface it is being used to measure is to be of high accuracy. Tests were performed and results show that, although many scatter plates would function, few were of the optimum quality necessary. These few were of the 180 grit group, using 35- and 30-s exposures, which are figures derived from calculations.

Pour, J. J., Sr.↗
NASA NTRS1973

Very long baseline interferometry

S-band stations with dual tracking capability have been used to gather double differential very long baseline interferometry data on Apollo 16 and Apollo 17. This was accomplished by simultaneously receiving both monochromatic radio signal emissions at each of two separated receiving stations, transmitting these data to a central processing facility, and calculating the differences between Doppler angular rates to determine the motion of the lunar roving vehicle.

Salzberg, I. M.↗
NASA NTRS1973

The application of VLB interferometry to earth measurements

Results of a four-phase development of capability in very long-baseline interferometry (VLBI) at the Smithsonian Astrophysical Observatory (SAO) are summarized. The objectives of the VLBI program at SAO are to: (1) develop the capability to collect, process, and analyze VLBI data; (2) determine experimentally the accuracy now attainable with VLBI and, within the constraints imposed by this accuracy, initiate a program of VLBI observations for geophysical applications; (3) identify all significant error sources and devise means for eliminating or correcting these errors; and (4) develop a long range plan for applying VLBI techniques to a program of earth physics measurements.

Michelini, R. D.↗
NASA NTRS1972

Very long baseline interferometry observations of radio emissions from geostationary satellites.

Review of the results of very long baseline interferometry (VLBI) observations of L-band emissions of the ATS-5 geostationary satellite, performed over a transcontinental baseline in 1970, as part of a more comprehensive program using radio stars as sources. Although the data were not sufficient to demonstrate fully the capability of the method for determining the orbital elements of a satellite and its inertial position, the analysis of the ATS observations show the presence of interference fringes related to the modulation waveform emitted by the satellite and to the various motions of the satellite. The measured VLBI time delays are in agreement with the geometry of the observations and with the instrumental delay, both determined independently.

Michelini, R. D.↗
NASA NTRS1973

Study of exothermic processes in shock ignited gases by the use of laser shear interferometry.

The paper reports on the measurements of maximum exothermic power pulses attainable from a given chemical system. Experimental tests involved the use of a shock tube technique whereby the exothermic process of combustion was controlled by reflected shock so that it occurred under virtually inviscid flow conditions, the data having been obtained at a resolution commensurate with the actual rate of chemical reaction. Experimental observations were made by means of a novel method of laser shear interferometry. Chemical systems treated in this manner comprised of mixtures of stoichiometric hydrogen-oxygen with 80 and 90% argon, while the measurements covered the full permissible range of initial thermodynamic conditions.

Meyer, J. W.↗
NASA NTRS1973

Tracking the Apollo Lunar Rover with interferometry techniques.

Apollo 16 and 17 Lunar Rover position history while transporting astronauts over the lunar surface has been determined to a resolution of better than 1 m and uncertainties of less than 25 m utilizing a specialized very-long baseline interferometry (VLBI) tracking technique. This paper describes the technique, discusses the National Aeronautics and Space Administration worldwide tracking system used to obtain data, discusses the data, and presents results.

Salzberg, I. M.↗
NASA NTRS1973

Radio interferometry depth sounding. II.

Experimental results from an analog scale model and from field tests on two glaciers using radio-frequency interferometry (RFI) are interpreted on the basis of previously described theoretical results. The RFI technique is found to be a practical method with which to study layering in low-loss dielectrics. Three parameters of the upper layer can be estimated from the data: the dielectric constant, the loss tangent, and an estimate of the thickness to a reflector. The method is an inexpensive way to sound ice sheets less than a few hundred meters thick, and could be used to study low-loss layers on the moon.

Rossiter, J. R.↗