Engineering topics

Low, F. J.

Publications and source records attributed to Low, F. J..

At least 73 records · Page 4

NASA NTRS1975

Infrared orbital mapping of lunar features

A computer program has been developed which constructs second generation isothermal contour maps of the lunar surface from Apollo 17 Infrared Scanning Radiometer (ISR) data. The maps clearly show large-scale trends such as the lunar cooling curve and directionality of lunar emission. Direct evidence has been found for the downslope transport of lunar soil. Studies of features have led to a crater degradation sequence based on thermal contours. Unusual cold regions have been found which are not well understood.

Mendell, W. W.↗

NASA NTRS1974

A balloon-borne 1 meter telescope for far-infrared astronomy

The flight of a balloon-borne one-meter telescope for infrared astronomy in the wavelength interval of 40 to 240 microns is discussed. The gyro-stabilized telescope mapped the intensity of the far infrared radiation from NGC 7538, Mars, the Orion Nebula, and W3 with a resolution of one minute and from selected regions of these sources with a resolution of 30 seconds. The infrared detection is described and its capabilities are analyzed. The instrumentation, orientation system, and modes of observation of the telescope are defined.

Fazio, G. G.↗

NASA NTRS1974

Low-background air-infrared telescope for balloon-borne infrared astronomy

The design and performance of a far-infrared telescope are discussed. The instrument is twenty centimeters in diameter and has excellent operating characteristics at 100 microns. The principal features of the telescope are summarized. A diagram of the system is provided. The telescope completed two sucessful balloon flights in which the planets Mars and Saturn were used as calibration sources. Observations were made of the H2 regions W 3, Orion A, NGC 2024, and the bright infrared galaxy M 82.

Low, F. J.↗

NASA NTRS1974

High-resolution maps of H2 regions at far-infrared wavelengths

The first successful flight of a balloon-borne 1-m telescope for far-infrared (40 micron) astronomy occurred on 4 February 1974 (UT), from Palestine, Texas. During 6 h at float altitude, the gyrostabilized telescope mapped the intensity of far-infrared radiation from the H 2 regions Ori A and W3 with a resolution of 1 prime. Partial maps of these regions were made with a resolution of 0.5 prime. These sources were resolved into several components, some of which were previously unknown. Observations of Mars were used for calibration.

Fazio, G. G.↗

NASA NTRS1974

Infrared measurements of Uranus and Neptune

New measurements verify that Neptune is brighter than Uranus near 20 microns and show that both planets have increasing brightness temperature with decreasing wavelength between 34 and 22.5 microns. The observations are not compatible with existing models for the atmospheres of these planets.

Rieke, G. H.↗

NASA NTRS1974

A high-resolution map of the Orion Nebula region at far-infrared wavelengths

It is shown that the Kleinmann-Low nebula continues to radiate like a 70-deg-K blackbody at 69 microns, as it does at shorter wavelengths, but that most of the 69-micron flux from Ori A (M42) comes from an extended emission that roughly follows the free-free radio emission. Nearby sources also detected include the nebula M43 and the molecular cloud OMC-2.

Fazio, G. G.↗

NASA NTRS1974

Infrared photometry of Titan

A set of observations of Titan at wavelengths from 1.6 through 34 microns shows that Titan has a remarkably low albedo near 1.6 micron. Thermal flux observations for 10 years at 10.6 microns and for 5 years at 21 microns suggest that the thermal properties of Titan remained constant over this period and are independent of phase. Narrowband photometry between 17 and 25 microns does not indicate the presence of a structure characteristic of a hydrogen-rich atmosphere. An atmospheric model consistent with the observations is proposed for Titan.-

Low, F. J.↗

NASA NTRS1974

Continued development and application of far-infrared detection techniques

The development of a balloon gondola and pointing system are discussed which can be used with the low background far infrared telescope. Flight test progress of the new gondola is reported using a 3-axis system which would provide much greater capabilities. In this design both a polar and declination axis are use and are maintained in the proper orientation by a free handing (vertical) azimuth shaft.

Low, F. J.↗

NASA NTRS1974

Infrared observations of the planets

The planetary observations presented are divided into three parts: (1) infrared photometry at all wavelengths accessible from the ground; (2) high resolution infrared mapping of Jupiter with special emphasis at 5 microns; and (3) extensive infrared observations of Comet Kohoutek. Results are briefly summarized.

Low, F. J.↗

NASA NTRS1974

Far-infrared filters utilizing small particle scattering and antireflection coatings

High-transmission, low-pass scatter filters for blocking at wavelengths from 3.5 to 50 microns and single-layer antireflection coatings for optical materials used in the 25- to 300-micron region of the spectrum are described. The application of both techniques to liquid-He-cooled filters permits the construction of efficient low-pass and medium-width bandpass filters for use throughout the far infrared.

Armstrong, K. R.↗

NASA NTRS1974

Preliminary results of the Apollo 17 infrared scanning radiometer

The thermal emission of the lunar surface has been mapped by an infrared scanner from lunar orbit. Samples from approximately 250,000 scans reveal the full range of lunar temperatures from 80 to 400 K. The temperature resolution was 1 K with about plus or minus 2 K absolute precision. Spatial resolution was approximately 2 km over most of the horizon-to-horizon scan. The total mapped area amounted to approximately 30% of the lunar surface. The data currently available confirms the large population of nighttime thermal anomalies in western Oceanus Procellarum predicted by earth-based observations. Most of these 'hot spots' are associated with fresh impact features or boulder fields. Also seen in the data are 'cold spots' where the local nighttime temperature is depressed relative to the general soil background. Such regions exhibiting low surface conductivity are inferred to be relatively young, nonimpact features.

Mendell, W. W.↗

NASA NTRS1973

New techniques for far-infrared filters.

The techniques considered make it possible to construct high performance low-pass wide-band, and medium-band filters at wavelengths in the range from 25 to 300 micrometers. Short wavelength rejection without appreciable loss at long wavelengths is achieved by means of small particle scattering. Spectral definition in the far infrared is obtained by cooling one or more crystalline materials to liquid-He or liquid-nitrogen temperatures. The problem of reflection losses at the various surfaces is solved by a new antireflection coating technique.

Armstrong, K. R.↗

NASA NTRS1973

High-resolution maps of Jupiter at five microns.

The distribution of 5-micron radiation, emitted from a large number of discrete sources from Jupiter, was observed during the 1972 apparition. These sources are less bright than those observed by Westphal (1969). At least 50 discrete sources having brightness temperatures exceeding 227 K were revealed which were mainly located within three narrow-latitude bands. Strong correlation exists between the 5-micron brightness temperatures of Jovian features and their colors as recorded photographically.

Keay, C. S. L.↗

NASA NTRS1973

Ground-based observations at 34 microns.

Filtering techniques for a new photometric band from 28 to 40 microns are described together with the results of ground-based observations of planets, stars, and galactic nebulae conducted with 28- and 61-in. telescopes in this wavelength interval. The data indicate that high angular resolution and good sensitivity can be obtained at 34 microns from the ground. Some stars have very cold (less than 100 K) circumstellar dust shells or clouds. The Kleinmann-Low nebula in M42 is extremely bright at 34 microns, whereas the Ney-Allen nebula associated with the Trapezium stars is much weaker.

Low, F. J.↗

NASA NTRS1973

Far-infrared observations of galactic nuclei.

M82 (NGC 3034) and NGC 253 have been detected at wavelengths from 27 to 125 microns by using a 30-cm airborne IR telescope and a multiband photometer. Spectral power distribution curves are plotted for the galactic nuclei. Tables of obtained data are also given.

Harper, D. A., Jr.↗

NASA NTRS1973

Infrared scanning radiometer

The Apollo 17 infrared scanning radiometer (ISR) experiment for mapping lunar surface thermal emission is reported. The instrument, lunar surface coverage, and the data obtained are discussed.

Low, F. J.↗

NASA NTRS1972

Far-infrared brightness temperatures of the planets.

An airborne telescope operating in an altitude range from 45,000 to 50,000 feet together with a low-temperature germanium bolometer and six cooled filters were used in an investigation of the temperatures of the planets. The measurements conducted provide a basis for absolute calibration in the far infrared, confirm the high effective temperature and internal power of Jupiter, and give information on the far-infrared opacities and emissivities of the four bright planets.

Armstrong, K. R.↗

NASA NTRS1972

21-micron observations of H II regions.

The 21-micron contour map of M17 is similar to radio maps with three components. Measured flux densities give color temperatures of both 240 and 75 K for the two principal components of M17 and 44 to 63 K for Sgr B2, NGC 2024, and DR-21.

Lemke, D.↗