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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 235 records · Page 13
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NASA NTRS1978

Saturn orbiter dual probe mission

The described Saturn orbiter dual probe mission and spacecraft combines three systems into a multi-purpose Saturn exploration package. The spacecraft consists of: (1) Saturn orbiter; (2) Saturn probe; and (3) Titan probe or lander. This single spacecraft provides the capability to conduct in situ measurements of the Saturn and Titan atmospheres, and, possibly the Titan surface, as well as a variety of remote sensing measurements. The remote sensing capabilities will be used to study the surfaces, interiors and environments of Saturn's satellites, the rings of Saturn, Saturn's magnetosphere, and synoptic properties of Saturn's atmosphere.

Rudd, R. P.↗
NASA NTRSDate not supplied

Enriching Heavy Noble Gases in Titan Atmosphere by Cryogenic Condensation

Titan is an extraordinary moon belonging to Saturn. It presents a dense atmosphere with a surface pressure approximately 1.45 times that of Earth’s. The relative abundance of noble gases and their isotopes can elucidate extant geochemical processes and inform past and future planetary evolution. The GCMS on the Hyugens probe sampled the dense atmosphere of Saturn’s Titan in 2005 and did not detect Kr or Xe at ppb concentrations. Several chemical pathways have been considered as mechanisms to account for the depletion of these heavy nobles. However, our understanding remains incomplete without in situ detection. Thus, we investigate spaceflight cryogenic enrichment for Kr and Xe. The thermodynamic processes would be capable of substantially amplifying these gases at femtomole concentrations, in anticipation of future atmospheric surveys on Titan.

condensation↗
NASA NTRS1986

Saturn: A unique magnetosphere/ionosphere/ring interaction

Latitudinal variations in images of Saturn's disk, upper atmospheric temperatures, and ionospheric electron density anomalies found in magnetic conjugacy with features in Saturn's ring plane are discussed. It is suggested that latitudinal variations are the result of a variable influx of water, transported along magnetic field lines from sources in Saturn's ring plane. Two such sources with optical counterparts in the inner B ring can be readily attributed to an electromagnetic erosion process that transports water in the form of high charge to mass ratio particles (ions or submicron grains with 1 electron charge) along magnetic field lines from the ring plane to Saturn's atmosphere. Another is attributed to erosion of the icy satellite Enceladus and the associated E ring.

Converney, J. E. P.↗
NASA NTRS1993

Infrared spectroscopy of Jupiter and Saturn

Infrared spectroscopy provides unique insights into the chemistry and dynamics of the atmospheres of Jupiter, Saturn, and Titan. In 1991 we obtained data at J, H, K, and M and made repeated observations of Titan's albedo as the satellite orbited Saturn. The J albedo is 12% +/- 3% greater than the albedo measured in 1979; the H and K albedos are the same. There was no evidence for variations at any wavelength over the eastern half of Titan's orbit. We also obtained low resolution (R=50) spectra of Titan between 3.1 and 5.1 microns. The spectra contain evidence for CO and CH3D absorptions. Spectra of Callisto and Ganymede in the 4.5 micron spectral region are featureless and give albedos of 0.08 and 0.04 respectively. If Titan's atmosphere is transparent near 5 microns, its surface albedo there is similar to Callisto's. In 1992 and 1993 we obtained further spectroscopic data of Titan with the UKIRT CGS4 spectrometer. We discovered two unexpected and unexplained spectral features in the 3-4 micron spectrum of Titan. An apparent emission feature near the 3 micron (nu sub 3) band of methane indicated temperatures higher than known to be present in Titan's upper stratosphere and may be caused by unexpected non-LTE emission. An absorption feature near 3.47 microns may be caused by absorption in solid grains or aerosols in Titan's clouds. The feature is similar but not identical to organics in the interstellar matter and in comets.

Knacke, Roger F.↗
NASA NTRS1989

Ultraviolet spectrometer observations of Neptune and Triton

Results from the occultation of the sun by Neptune imply a temperature of 750 + or - 150 kelvins in the upper levels of the atmosphere (composed mostly of atomic and molecular hydrogen) and define the distributions of methane, acetylene, and ethane at lower levels. The ultraviolet spectrum of the sunlit atmosphere of Neptune resembles the spectra of the Jupiter, Saturn, and Uranus atmospheres in that it is dominated by the emissions of H Lyman alpha (340 + or - 20 rayleighs) and molecular hydrogen. The extreme ultraviolet emission in the range from 800 to 1100 angstroms at the four planets visited by Voyager scale approximately as the inverse square of their heliocentric distances. Weak auroral emissions have been tentatively identified on the night side of Neptune. Airglow and occultation observations of Triton's atmosphere show that it is composed mainly of molecular nitrogen, with a trace of methane near the surface. The temperature of Triton's upper atmosphere is 95 + or - 5 kelvins, and the surface pressure is roughly 14 microbars.

Broadfoot, A. L.↗
NASA NTRS1985

Photochemistry and clouds of Jupiter, Saturn and Uranus

Photochemistry of ammonia, methane, phosphine, hydrogen sulfide, methylamine, hydrogen cyanide and carbon monoxide in the atmospheres of Jupiter, Saturn and Uranus is discussed. Condensation of ammonia, ammonium hydrosulfide, water, methane, ethane and acetylene below and near the tropopause of these planets is formulated. Whenever necessary, new calculations are included. Candidates for the upper atmospheric hazes, and the reddish-brown chromosphore in the clouds of Jupiter and Saturn are discussed.

Atreya, S. K.↗
NASA NTRS1987

The excitation of the far ultraviolet electroglow emissions on Uranus, Saturn, and Jupiter

Data from Voyager 2 observations of FUV electroglow in the sunlit atmospheres of Jupiter, Saturn, and Uranus are compiled in tables and graphs and analyzed theoretically, and an excitation mechanism is proposed. This mechanism is based on local acceleration of photoelectrons and ions by the electric field (consisting of field-aligned potentials) due to an ionospheric dynamo. Anomalous resistivity and plasma instabilities induced by field-aligned currents in the ionosphere are invoked to explain the field-aligned potentials, and the processes which might give rise to such currents are further explored.

Clarke, John T.↗
NASA NTRS1990

Outer planets; Proceedings of Symposium 4 and the Topical Meeting of the 27th COSPAR Plenary Meeting, Espoo, Finland, July 18-29, 1988

Various papers on the magnetospheres, atmospheres, satellites, and rings of the outer planets are presented. Individual topics addressed include: thermal plasma in outer planet magnetospheres, neutral gas-plasma interaction in the Io plasma torus, satellite-plasma interactions, comparison of planetary magnetic fields, energization process of trapped particles in outer planets, remote sensing of planetary plasma, comparison of the deep atmospheres of the giant planets, seasonal thermal structure of giant planet atmospheres, CCD imaging of Neptune at methane-band wavelengths, physical parameters for the Uranus atmosphere, Uranus photochemistry, Uranus electroglow production, vibrationally excited H2 in Saturn's upper atmosphere, Titan, origin of outer planet satellite systems, microphysical modeling of Titan's aerosols, tectonics of icy satellites, geological evolution of Ganymede, photometric techniques for atmosphereless solar system bodies, the new rings, narrow rings, and time variability of the Jovian system.

Johnson, T. V.↗
NASA NTRS1986

Saturn - A unique magnetosphere/ionosphere/ring interaction

Latitudinal variations in images of Saturn's disc, upper atmospheric temperatures, and ionospheric electron density anomalies are found in magnetic conjugacy with - i.e., magnetically linked to - features in Saturn's ring plane. It is suggested that these latitudinal variations are the result of a variable influx of water, transported along magnetic field lines from sources in Saturn's ring plane. Two such sources with optical counterparts in the inner B ring can be readily attributed to an electromagnetic erosion process that transports water in the form of high charge to mass ratio particles (ions or submicron grains with 1 electron charge) along magnetic field lines from the ring plane to Saturn's atmosphere. Another is attributed to erosion of the icy satellite Enceladus and the associated E ring.

Connerney, J. E. P.↗
NASA NTRS1977

Study of alternative probe technologies

A number of implied technologies for a deep probe mission was examined; i.e., one that would provide the capability to scientifically examine planetary atmospheres at the 1000 bar level. Conditions imposed by current Jupiter, Saturn, and Uranus atmospheric models were considered. The major thrust of the measurements was to determine lower atmosphere composition, even to trace constituents of one part per billion. Two types of instruments having the necessary accuracy to meet the science objectives were considered and integrated into a deep probe configuration. One deep probe option that resulted was identified as a Minimum Technology Development approach. The significant feature of this option is that only three technology developments are required to enable the mission, i.e., (1) science instrument development, (2) advanced data processing, and (3) external high pressure/thermal insulation. It is concluded that a probe designed for a Jupiter mission could, with minor changes, be used for a Saturn or Uranus mission.

Source record↗
NASA NTRS1980

Outer planet investigations using a CCD camera system

Problems related to analog noise, data transfer from the camera buffer to the storage computer, and loss of sensitivity of a two dimensional charge coupled device imaging system are reported. To calibrate the CCD system, calibrated UBV pinhole scans of the Saturn disk were obtained with a photoelectric area scanning photometer. Atmospheric point spread functions were also obtained. The UBV observations and models of the Saturn atmosphere are analyzed.

Price, M. J.↗
NASA NTRS1990

Stellar and Jovian vortices

The characteristics of 'Jovian' vortices (the large vortices observed in the atmospheres of Jupiter, Saturn, Neptune) are summarized, and the existence of similar structures in the atmospheres of stars is considered theoretically. The problem of vortex maintenance is addressed, including potential vorticity, numerical simulations of Jovian vortices, and cyclones and anticyclones; the Great Red Spot of Jupiter is described on the basis of Voyager data; the evidence for convective generation of vertical vorticity in the sun is examined; the possibly vortical nature of the large spots of RS CVn stars is discussed; and models of spots on rapidly rotating hot stars are surveyed.

Dowling, T. E.↗
NASA NTRS2010

Saturn's Equatorial Oscillation: Evidence of Descending Thermal Structure from Cassini Radio Occultations

Ground-based and Cassini CIRS thermal-infrared data have characterized the spatial and temporal characteristics of an equatorial oscillation in Saturn's middle atmosphere above the 100-mbar level. The CIRS data indicate a vertical pattern of alternating warm and cold anomalies at the equator. From the thermal wind equation this implies a concomitant reversal of zonal winds with attitude, relative to the cloud-top winds, with peak-to-peak amplitude approximately 200 meters per second. The ground-based observations do not having the altitude range or vertical resolution of the CIRS observations, but they cover several years and indicate an oscillation cycle of 1 years, roughly half of Saturn's year. Equatorial oscillations in Earth's middle atmosphere have primarily exhibited either quasi-biennial or semi-annual "periodicities," and both types have been extensively observed and modeled. They exhibit a vertical pattern of alternating warmer and cooler zonal-mean temperatures and zonal winds analogous to that described above for Saturn. Moreover, the pattern of winds and temperatures descends with time. Momentum deposition by damped vertically propagating easterly and westerly waves is thought to play a key role in forcing both types of oscillation, and it can plausibly account for the descent. Here we report the direct observation of this descent in Saturn's equatorial atmosphere from Cassini radio occultation soundings in 2005 and 2009. The retrieved temperatures are consistent with a descent of 0.6 x the pressure scale height over this time period. The descent rate is related to the magnitude of the wave forcing, radiative damping, and induced meridional circulations. A simple calculation implies that vertical wave fluxes of zonal momentum approximately 0.05 square meters per square second could account for the observed vertical descent on Saturn, which is comparable to the magnitude of the wave fluxes associated with the terrestrial quasi-biennial oscillation.

Flasar, F. M.↗
NASA NTRS1976

NASA environmental design criteria

Environmental Design Criteria Monographs have been published to give the designer of spacecraft and the planner of space missions the best information which is currently available concerning the environmental conditions existing in various areas of outer space. Information is provided concerning the solar electromagnetic radiation, the earth's atmosphere, the earth albedo, the earth's trapped radiation belts, the Mars' atmosphere, the Venus atmosphere, the surface of Mars, the planet Jupiter, the planet Mercury, the planet Saturn, Titan's atmosphere, and the assessment and control of the magnetic fields of a spacecraft.

Mills, S. A.↗
NASA NTRS1983

Radio scintillations observed during atmospheric occultations of Voyager: Internal gravity waves at Titan and magnetic field orientations at Jupiter and Saturn

The refractive index of planetary atmospheres at microwave frequencies is discussed. Physical models proposed for the refractive irregularities in the ionosphere and neutral atmosphere serve to characterize the atmospheric scattering structures, and are used subsequently to compute theoretical scintillation spectra for comparison with the Voyager occultation measurements. A technique for systematically analyzing and interpreting the signal fluctuations observed during planetary occultations is presented and applied to process the dual-wavelength data from the Voyager radio occultations by Jupiter, Saturn, and Titan. Results concerning the plasma irregularities in the upper ionospheres of Jupiter and Saturn are reported. The measured orientation of the irregularities is used to infer the magnetic field direction at several locations in the ionospheres of these two planets; the occultation measurements conflict with the predictions of Jovian magnetic field models, but generally confirm current models of Saturn's field. Wave parameters, including the vertical fluxes of energy and momentum, are estimated, and the source of the internal gravity waves discovered in Titan's upper atmosphere is considered.

Hinson, D. P.↗
NASA NTRS1993

Laboratory studies of low temperature rate coefficients: The atmospheric chemistry of the outer planets

The objectives are to measure laboratory rate coefficients for key reactions of hydrocarbon molecules and radicals at low temperatures, which are relevant to the atmospheric photochemistry of Saturn, Jupiter, and Titan. Upcoming NASA planetary missions, such as Cassini, will probe the atmosphere of Titan in more detail, offering an excellent opportunity to test kinetic models and to establish fiducial standards for using kinetic models to interpret various parameters of the outer planets. Accurate low temperature kinetic data, which are presently lacking, may require crucial revisions to the rates of formation and destruction and are of utmost importance to the success of these efforts. In this program, several key reactions of ethynyl radicals (C2H) with acetylene (C2H2), methane (CH4), and oxygen (O2), down to temperatures of 170 K were successfully investigated. The experimental apparatus developed in our laboratory for measuring reaction kinetics at low temperatures consists of a laser photolysis/infrared probe laser setup. The rate measurements are carried out as a function of (low) temperature with a transverse flow cell designed specifically for these studies. A 193 nm argon fluoride pulsed excimer laser is used to photolyze a suitable precursor molecule, such as acetylene to produce C2H, and a high resolution, tunable infrared F-center laser (2.3-3.35 mu m) probes the transient concentrations of the radical species directly in absorption to extract the kinetic rate coefficients.

Leone, Stephen R.↗
NASA NTRS1986

Photometry from Voyager 2 - Initial results from the Uranian atmosphere, satellites, and rings

The results of Voyager 2 photopolarimetry (PPS) surveys of Uranus, the ring system, occultation experiments and observations of the Uranian moons are reported. Dual-channel photometry and polarimetry data obtained of the atmosphere at various emission and phase angles are delineated and compared with characteristics of the Saturn and Jupiter atmospheres. The results of temperature, UV absorption and density profile calculations are also discussed. Extensive ring dimensional data, based on two occultation experiments, are provided in tabular form noting that the rings contain no dust. Finally, the geometric albedos of the five major moons and the phase curve of the moon Titania are presented. The latter data indicate that Titanian surface features are not the result of recent events such as volcanism or ice slurry outflows.

Lane, A. L.↗
NASA NTRS1973

Mission Planning for Pioneer Saturn/Uranus Atmospheric Probe Missions

Mission planning for a series of atmospheric probe missions to Saturn and Uranus using a modified Pioneer spacecraft launched in 1979 and 1980 was examined. The operational options and the associated systems requirements consistent with the major scientific goals and spacecraft constraints of the missions is summarized. It is feasible to obtain in-situ atmospheric measurements in the atmosphere of Saturn and Uranus down to a pressure level of 10 bars using a common probe and spacecraft design. Spacecraft can be launched to both objectives with an adequate launch window in 1979 and 1980 using a Titan/Centaur launch vehicle with a TE-364-4 upper stage. Other scientific objectives can be accomplished by the flyby spacecraft. Encounters with the satellite Titan and RF occultations of Saturn, the ring system of Saturn, and Uranus can be obtained.

Swenson, B. L.↗