Engineering topics

Terrile, R. J.

Publications and source records attributed to Terrile, R. J..

42 records · Page 3

NASA NTRS1979

Infrared images of Jupiter at 5-micrometer wavelength during the Voyager 1 encounter

A coordinated program to observe Jupiter at high spatial resolution in the 5-micrometer wavelength region was undertaken to support Voyager 1 imaging and infrared radiation experiment targeting. Jupiter was observed over a 5-month period from Palomar and Mauna Kea observatories. The frequency of observations allowed the selection of interesting areas for closer Voyager examination and also provided good short-term monitoring of variations in cloud morphology. Significant global changes in the 5-micrometer distribution are seen over this time period.

Terrile, R. J.↗

NASA NTRS1978

Multiple frequency sounding of a Jovian cloud

A thermal asymmetry displayed in Pioneer 10 45-micron IR radiometric data between the rising and setting limbs of the Jovian South Equatorial Belt (SEB) between -5.0 and -7.0 deg latitude is examined. A high correlation is found between the longitudinal asymmetry of the SEB at 45 microns and the appearance of Jupiter in 5-micron radiation. It is shown that there was a cooler 'obscuring' cloud within the SEB latitude region which correlates highly with the location of relatively reduced intensities at 45 microns. The cloud-top temperature is estimated on the basis of simultaneous 5- and 45-micron observations

Orton, G. S.↗

NASA NTRS1977

Crater evolutionary tracks

The technique proposed in the present paper for studying planetary surface processes is based on the measurement of crater rim height, h, depth, d, and diameter, D. The h/d and d/D ratios provide a quantitative description of crater morphology as well as a quantitative method for assessing the relative importance of competing crater modification processes (since h, d, and D change as a crater is degraded by surface processes, and h/d and d/D change with time). Different classes of processes produce distinctive evolutionary tracks on an h/d versus d/D diagram. Tracks for three general classes of crater modification (processes adding material to the crater; processes redistributing the material within the crater vicinity; and processes removing the material from the crater vicinity) are calculated, and h/d and d/D ratios for craters on the earth, moon, and Mars are compared.

Schubert, G.↗

NASA NTRS1977

Infrared imaging of Jupiter in the 8-14-micrometer spectral region

High-spatial-resolution images of Jupiter were produced on the Hale 200-in. telescope. A programmable wobbling secondary was used to raster-scan the planet with 64 by 64 1-arcsec pixels. Images were made with broadband (8-14 microns) and several 1- and 2-micron-wide filters. All images reveal a belt-and-ozone structure similar to visible photographs. Belts in the broadband data appear to be about 2 K hotter than zones, but contrast varies markedly in different parts of the 8-14-micron spectral region. The lowest belt-zone contrast is found in the hydrogen-opacity-dominated region at 12.5 microns, while images at 9.5 microns exhibit the greatest contrast. Isolated areas are observed to be as much as 4 K hotter than surrounding areas at 9.5 microns. This large contrast is probably due to variations in the distribution of the ammonia clouds in the upper atmosphere.

Terrile, R. J.↗

NASA NTRS1977

The vertical cloud structure of Jupiter from 5 micron measurements

From 5-micron high-spatial-resolution images of Jupiter, flux-frequency histograms of the equatorial region show a trimodal distribution of brightness temperatures. Combined with limb-darkening measurements, a three-layer cloud model for Jupiter is developed. The highest, coldest clouds, apparently homogeneous and displaying relatively little limb darkening, cover the zones. These clouds are not present over the belts, allowing observational access to deeper regions. The belts appear heterogeneous: small, localized hot areas show enhanced limb darkening, while much of the belt is distinctly cooler and exhibits shallower limb darkening. These belt properties can be explained by a cool emitting layer superposed upon a hot, dense cloud deck.

Terrile, R. J.↗

NASA NTRS1974

Five-micron pictures of Jupiter

Several hundred five-micron 'video' pictures of Jupiter, with 1-sec resolution, made during September, October, and December 1973 and compared with color photographs, are shown to exhibit direct, detailed correlations with the darker 'purple' features. Forty-four of these pictures were made just before the Pioneer-10 encounter.

Westphal, J. A.↗