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Young, A. T.

Publications and source records attributed to Young, A. T..

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

The Martian atmosphere - Mariner 9 television experiment progress report.

Atmospheric phenomena appearing in the Mariner 9 television pictures are discussed in detail. The surface of the planet was heavily obscured by a global dust storm during the first month in orbit. Brightness data during this period can be fitted by a semi-infinite scattering and absorbing atmosphere model with a single-scattering albedo in the range 0.70-0.85. This low value suggests that the mean radius of the particles responsible for the obscuration was at least 10 microns. By the end of the second month, this dust storm had largely dissipated, leaving a residual optical depth of about 0.1. Much of the region north of 45 deg N was covered by variable clouds comprising the north polar hood.

Leovy, C. B.↗
NASA NTRS1972

On the temperature distribution in a planetary atmosphere.

Criteria for the appearance of a double maximum in the absorption spectra are derived. A very oversimplified model atmosphere which consists of two isothermal layers of gas is considered. The model involves the presence of two absorption cells in series, in front of a light source that has a higher temperature than either of the cells. The possibility that the double maximum is due to a quantum-mechanical interaction is studied. It is concluded that the effect reported by Kaplan (1962) was due to noise, and that it is impossible to detect temperatures as high as 700 K in the atmosphere of Venus by means of ground-based observations of the 7820 A carbon dioxide band.

Young, L. D. G.↗
NASA NTRS1972

Mariner 9 - Image processing and products.

The purpose of this paper is to describe the system for the display, processing, and production of image data products created to support the Mariner 9 Television Experiment. Of necessity, the system was large in order to respond to the needs of a large team of scientists with a broad scope of experimental objectives. The desire to generate processed data products as rapidly as possible to take advantage of adaptive planning during the mission, coupled with the complexities introduced by the nature of the vidicon camera, greatly increased the scale of the ground image processing effort. This paper describes the systems that carried out the processes and delivered the products necessary for real-time and near-real-time analyses. References are made to the computer algorithms used for the different levels of decalibration and analysis.

Levinthal, E. C.↗
NASA NTRS1972

Observing Venus near the sun.

Discussion of the special requirements posed by telescopic observing near the sun. The sky brightness in the image plane must be kept to a minimum. Sunlight scattered from dust in the atmosphere or on the optical surfaces is the main difficulty, particularly at red and infrared wavelengths where Rayleigh scattering by air molecules is weak. Atmospheric dust is less troublesome at high altitudes and in dry climates than at low, humid sites. Excellent seeing is required, especially to get the thin crescent of Venus at inferior conjunction into the narrow slit of a spectrograph. The spectroscopic phase effect of Venus is discussed, and the procedures used to carry out observations near the sun are described in detail.

Young, A. T.↗
NASA NTRS1972

The Viking missions to Mars.

The Viking Project will launch two unmanned spacecraft to Mars in 1975 for scientific exploration with special emphasis on the search for life. Each spacecraft will consist of an orbiter and a lander. The landing site will be selected after the spacecraft is in orbit. Twelve investigations will be performed: three mapping experiments from the orbiter, one atmospheric experiment during the lander entry phase, seven analytical experiments on the surface of the planet, and one using the spacecraft radio and radar systems. The experiments on the surface will deal principally with biology, geology, and meteorology. Sixty-three scientists have been selected for the twelve teams.

Soffen, G. A.↗
NASA NTRS1972

Imaging experiment - The Viking Lander.

The Viking Lander Imaging System will consist of two identical facsimile cameras. Each camera has a high-resolution mode with an instantaneous field of view of 0.04 deg, and survey and color modes with instantaneous fields of view of 0.12 deg. Cameras are positioned one meter apart to provide stereoscopic coverage of the near-field. The Imaging Experiment will provide important information about the morphology, composition, and origin of the Martian surface and atmospheric features. In addition, lander pictures will provide supporting information for other experiments in biology, organic chemistry, meteorology, and physical properties.

Mutch, T. A.↗
NASA NTRS1971

Seeing and scintillation

Astronomical telescopes image motion, distortion and scintillation, examining atmospheric refractive index and density/temperature variation effects

Young, A. T.↗
NASA NTRS1971

Mariner Mars 1969 - Atmospheric results

Mars atmospheric data from Mariner flights, discussing north polar haze, bright surface features morphology, multiring structures and water vapor exchange

Leighton, R. B.↗
NASA NTRS1971

Seeing effects on occultation curves.

Evaluation of seeing effects on the light curve of a stellar occultation by the moon. Some theoretical studies of Fried (1966) and Hulett (1967) on the linear size of the downward-looking seeing disk are cited, showing that the seeing blur amounts to a few centimeters for a star in the zenith and that the linear blur must grow approximately as (sec z) to the 3/2 power. For most observations the seeing blur will not exceed 8 to 10 cm. The limitation on angular resolution imposed by this seeing effect is calculated.

Young, A. T.↗
NASA NTRS1970

Saturation of scintillation

Stellar scintillation saturation at large zenith angles, examining atmospheric dispersion and multiple scattering roles

Young, A. T.↗