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Fanale, F. P.

Publications and source records attributed to Fanale, F. P..

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Io's surface - Its phase composition and influence on Io's atmosphere and Jupiter's magnetosphere

The evidence and interpretations pertaining to the surface phase composition of Io and the mechanisms by which Io's surface influences its atmosphere are discussed. The mechanism by which Io's surface and/or atmosphere supplies neutral and ionic species to the region around the satellite and ultimately to the Jovian magnetosphere is also discussed. A model is suggested in which the global SO2 gas abundance is primarily controlled by buffering in the brightest, coldest regions. The net SO2 flux across the disk is limited by regional cold trapping on high albedo regions and possibly by the resistance of a tenuous non-SO2 residual atmosphere. The continuing migration of SO2 toward cooler regions and those lacking SO2 sources is opposed by SO2 destruction and planetary ejection processes, including sputtering, thus preventing buildup of thick, ubiquitous SO2 coverage.

Fanale, F. P.↗
NASA NTRS1981

IO - Could SO2 condensation/sublimation cause the sometimes reported post-eclipse brightening

It is shown that each of the three quantifiable brightening characteristics (i.e., amplitude, time-scale /half-life/, and temporal variability) suggests that brightening of Io may be due to condensation and sublimation of SO2 frost. This is concentrated within a region that encompasses both the subsolar points at the time of entrance into and emergence from eclipse, and volcanic sources. Qualitatively and intuitively, an SO2 frost hypothesis is found to provide good possibilities for explaining any variations in Io's ability to brighten, which may occur on a time scale of years.

Fanale, F. P.↗
NASA NTRS1980

Io - Longtudinal distribution of sulfur dioxide frost

A longitudinal variation in the distribution of SO2 frost on Io is examined. Twenty spectra of Io (0.26 to 0.33 micrometer) are presented and a strong ultraviolet absorption is found shortward of 0.33 micrometer. The abundance of frost is greatest at orbital longitudes 72 to 137 degrees. Longitudes 250 to 323 degrees are least abundant in SO2. Comparisons are made with a Voyager color relief map, which suggest that SO2 frost is in greatest concentration in the white areas of Io and other sulfurous materials are in greatest concentration in the red areas.

Nelson, R. M.↗
NASA NTRS1980

SO2 frost - UV-visible reflectivity and Io surface coverage

The reflectance spectrum in the range 0.24-0.85 microns of SO2 frost is measured in light of the discovery of SO2 gas in the atmosphere of Io and the possible discovery of the frost on its surface. Frost deposits up to 1.5 mm thick were grown in vacuum at 130 K and bi-directional reflectance spectra were obtained. Typical SO2 frost is found to exhibit very low reflectivity (2-5%) at 0.30 microns, rising steeply at 0.32 microns to attain a maximum reflectivity (75-80%) at 4.0 microns and uniformly high reflectivity throughout the visible and near infrared. Comparison with the full disk spectrum of Io reveals that no more than 20% of the surface can be covered with optically thick SO2 frost. Combinations of surface materials including SO2 frost which can produce the observed spectrum are indicated.

Nash, D. B.↗
NASA NTRS1980

Rings of Uranus - Proposed model is unworkable

A model of Uranus's rings proposed by Van Flandern (1979) is discussed. According to the proposed model, Uranus's rings are the gaseous tails of unobserved small satellites. The hypothesis raises a number of objections, e.g., a gaseous torus must have a minor diameter of thousands, not tens, of kilometers; very large densities are required to produce the postulated angles of refraction; and making up the mass losses, even with a generous lifetime, would use up quite a large body in a few million years.

Hunten, D. M.↗
NASA NTRS1979

Mars - CO2 adsorption and capillary condensation on clays: Significance for volatile storage and atmospheric history

Results on the adsorbate-adsorbent system CO2-nontronite are reported at 230, 196, and 158 deg K, covering the range of subsurface regolith temperature on Mars. A three-part regolith-atmosphere-cap model reveals that cold nontronite, and expanding clays in general, are far better but far more complex CO2 adsorbers than cold pulverized basalt. In addition, the layered terrain, and possibly the adjacent debris mantle, contains about 2% or more by mass of atmosphere-exchangeable CO2 and the total regolith inventory of available adsorbed CO2 is estimated to be 400 g/ sq cm.

Fanale, F. P.↗
NASA NTRS1979

Significance of absorption features in Io's IR reflectance spectrum

This paper shows that the presence of SO2 may have important implications for Io's atmosphere and transient phenomena. It is suggested that any abundant metal-containing compounds, such as halides or sulfides, are spectrally bland in the wavelength region from 2.0 to 5.0 microns.

Fanale, F. P.↗
NASA NTRS1979

Localized deposition and sputtering of Jovian ionospheric sodium on Io

Because of relative motion between the innermost Galilean satellite Io and Jupiter's ionosphere, a current is drawn from the ionosphere that can be a source of both deposition on, and sputtering from, the surface of Io. It is shown that the ions in this current strike Io in a localized region in the quadrant bounded by a line connecting Io and Jupiter and a tangent line extended in the direction of Io's orbital motion. If these ions are the principal source of sodium that is sputtered from Io, then this current provides a simple explanation of the observation of a localized area from which sodium ions escape from Io. The geometry of this current may also affect the optical surface of Io. Several experimental tests are suggested that can determine the compatibility of this hypothesis with the directly observable properties of Io's surface.

Hill, T. W.↗
NASA NTRS1978

Mars - The role of the regolith in determining atmospheric pressure and the atmosphere's response to insolation changes

A quantitative model for atmosphere-regolith exchange of CO2 on Mars is presented. The model, based on new laboratory measurements of CO2 adsorption on ground rock at 158, 175, 196, and 231 K for CO2 pressures from 1.0 to 80 mbar, is consistent with Viking observations, while models involving a massive residual CO2 cap and no long-term atmosphere-regolith CO2 exchange are not consistent. The model indicates: (1) the atmosphere-plus-cap system is buffered on a long-term basis by exchangeable CO2 adsorbed in the regolith; (2) if the atmosphere-plus-cap system suddenly disappeared, the system would eventually be almost completely restored by reequilibration with the regolith; (3) exchange with the adsorbed phase in the regolith has greatly restricted O-18 enrichment of the atmosphere; (4) the layered terrain primarily represents current periodic pressure increases; and (5) pressures of 100-300 nbar might have existed during the early history of the planet.

Fanale, F. P.↗
NASA NTRS1978

Mars - Regolith adsorption and the relative concentrations of atmospheric rare gases

Laboratory measurements of Kr and Xe adsorption on samples of ground montmorillonite, limonite and basalt at -77 C have been performed. Results suggest that (1) most degassed martian Xe could be adsorbed on a regolith with a large effective surface area, and (2) if this is the case the elemental composition of martian nonradiogenic rare gas (counting that in the regolith) may be virtually identical to that of ordinary chondrites.

Fanale, F. P.↗
NASA NTRS1978

Mars - The role of the regolith in volatile storage and atmospheric evolution

Earth-based observations of the optical properties of Mars, laboratory alteration experiments, Mariner 9 data, and Viking lander observations are reviewed which indicate the existence of hydrated minerals on the Martian surface. The problem of estimating the total inventory of H2O, CO2, and other volatiles that may be stored in the Martian regolith is discussed, and morphological evidence is cited which supports the possible occurrence of hard-frozen permafrost in some areas on Mars. Physical adsorption of CO2 in the Martian regolith is considered, buffering of atmospheric pressure by regolith-atmosphere reequilibration is examined, and the problem of the exceedingly low inventory of Ar-36 in the Martian atmosphere is investigated. The possibility is considered that earth's degassing history may have had a larger component of long-diffusion-path degassing from a large hot body while the Martian surface inventory may have received a proportionately greater contribution from volatization of accreting particles.

Fanale, F. P.↗
NASA NTRS1977

Report of the Terrestrial Bodies Science Working Group. Volume 9: Complementary research and development

Topics discussed include the need for: the conception and development of a wide spectrum of experiments, instruments, and vehicles in order to derive the proper return from an exploration program; the effective use of alternative methods of data acquisition involving ground-based, airborne and near Earth orbital techniques to supplement spacraft mission; and continued reduction and analysis of existing data including laboratory and theoretical studies in order to benefit fully from experiments and to build on the past programs toward a logical and efficient exploration of the solar system.

Fanale, F. P.↗
NASA NTRS1977

Io's surface composition - Observational constraints and theoretical considerations

Observations of line emission from neutral and ionic species in the Io-surrounding cloud, reflectance studies and theoretical considerations suggest Io's surface is unlike that of any other body in the solar system. The cloud has a peculiar composition which we show is probably not due to cloud/surface fractionation. Io's surface may be largely covered with an endogenically produced mixture of S and dehydrated salts, or by accretion-fractionated compounds modified by charge particle bombardment.

Fanale, F. P.↗