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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Interplanetary mission design handbook. Volume 1, part 3: Earth to Jupiter ballistic mission opportunities, 1985-2005

Graphical data necessary for the preliminary design of ballistic missions to Jupiter are provided. Contours of launch energy requirements, as well as many other launch and Jupiter arrival parameters, are presented in launch date/arrival date space for all launch opportunities from 1985 through 2005. In addition, an extensive text is included which explains mission design methods, from launch window development to Jupiter probe and orbiter arrival design, utilizing the graphical data in this volume as well as numerous equations relating various parameters.

Sergeyevsky, A. B.↗
NASA NTRS1982

Energetic-ion acceleration and transport in the upstream region of Jupiter: Voyager 1 and 2

Long-lived upstream energetic ion events at Jupiter appear to be very similar in nearly all respects to upstream ion events at Earth. A notable difference between the two planetary systems is the enhanced heavy ion compositional signature reported for the Jovian events. This compositional feature has suggested that ions escaping from the Jovian magnetosphere play an important role in forming upstream ion populations at Jupiter. In contrast, models of energetic upstream ions at Earth emphasize in situ acceleration of reflected solar wind ions within the upstream region itself. Using Voyager 1 and 2 energetic ( approximately 30 keV) ion measurements near the magnetopause, in the magnetosheath, and immediately upstream of the bow shock, the compositional patterns are examined together with typical energy spectra in each of these regions. A model involving upstream Fermi acceleration early in events and emphasizing energetic particle escape in the prenoon part of the Jovian magnetosphere late in events is presented to explain many of the features in the upstream region of Jupiter.

Baker, D. N.↗
NASA NTRS1983

The C-12/C-13 ratio in Jupiter from the Voyager infrared investigation

An analysis of the v(4) band of CH4 in the spectra recorded by the Voyager 1 IRIS experiment has yielded a C-12/C-13 ratio in Jupiter that is 160 plus 40 or minus 55, or 1.8 plus 0.4 or minus 0.6 times the terrestrial value. It is noted that while no plausible theory predicts such a difference between the C-12/C-13 ratio values of Jupiter and the inner solar system, values of this ratio in the solar neighborhood 4.5 million years ago, inferred from recent interstellar medium measurements, are compatible with the present determination in Jupiter. The Jovian, rather than the terrestrial value, would then be representative of the carbon isotope ratio in the primitive solar nebula.

Courtin, R.↗
NASA NTRS1983

Voyager orbit determination at Jupiter

This paper summarizes the Voyager 1 and Voyager 2 orbit determination activity extending from encounter minus 60 days to the Jupiter encounter, and includes quantitative results and conclusions derived from mission experiences. The major topics covered include an identification and quantification of the major orbit determination error sources and a review of salient orbit determination results from encounter, with emphasis on the Jupiter approach phase orbit determination. Special attention is paid to the use of combined spacecraft-based optical observations and earth-based radiometric observations to achieve accurate orbit determination during the Jupiter encounter approach phase.

Campbell, J. K.↗
NASA NTRS1982

Near-infrared mapping spectrometer for investigation of Jupiter and its satellites

In the late 1980s, the investigation of the Jupiter system will be continued with the aid of the Galileo spacecraft, which is to be placed in orbit around the planet. The Near-Infrared Mapping Spectrometer (NIMS) is one of several instruments which will be employed in connection with the study of Jupiter and its satellites. The NIMS combines spectroscopic and imaging capabilities. It represents, therefore, a new concept in remote sensing planetary experiments. Information provided by NIMS will be supplemented by results obtained with the aid of the Galileo Solid State Imager (SSI). In the SSI, very high spatial resolution is obtained, but limited spectral information is available. One of the goals of the Galileo mission is related to the investigation of the chemical composition and physical state of Jupiter's satellites, taking into account Io, Europa, Ganymede, and Callisto. Another primary aim involves the study of the Jovian atmosphere, giving attention to chemical composition, atmospheric structure, clouds, energy balance, and atmospheric motions.

Aptaker, I. M.↗
NASA NTRS1983

Lorentz forces on the dust in Jupiter's ring

The paths of dust particles in the Jovian ring are investigated using a numerical integration program, including the acceleration due to gravity and the Lorentz and drag accelerations arising from the motions of the charged dust through the Jovian plasma. It is determined that the orbit of a 2.5 micron radius spherical dust particle with a density of 2 g/cu cm -10V will become significantly perturbed. The ring will tend to warp northwards near 130-160 deg longitude, with the maximum excursion of the Jupiter ring grains equalling about 0.1 deg (consistent with a distance of 220 km above the equatorial plane). It is found that either the particles are larger or the voltages on them less than what has been determined by previous investigators, while the plasma near the ring may be considerably cooler than was estimated. Calculations show that particles of 0.3 micron with -10 V potentials are spread from 1.68-1.98 of the radius of Jupiter and inclined up to 7 deg out of the equatorial plane. The paths of these particles do not follow Keplerian orbits, and the particle positions are not symmetric about the equatorial plane. Particles of 0.4 micron radius have less asymmetric orbits than 0.3 micron particles, while particles less than 0.2 micron are perturbed into Jupiter cloudtops within a few tens of hours.

Consolmagno, G. J.↗
NASA NTRS1983

Force balance in the magnetospheres of Jupiter and Saturn

Spacecraft measurements of the plasma populations and magnetic fields near Jupiter and Saturn have revealed that large magnetospheres surround both planets. Magnetic field measurements have indicated closed field line topologies in the dayside magnetospheres of both planets while plasma instruments have shown these regions to be populated by both hot and cold plasma components convected azimuthally in the sense of planetary rotation. By using published data from the Voyager Plasma Science (PLS), Low Energy Charged Particle (LECP), and Magnetometer (MAG) instruments, it is possible to investigate the validity of the time stationary MHD momentum equation in the middle magnetospheres of Jupiter and Saturn. At Saturn, the hot plasma population is negligible in the dynamic sense and the centrifugal force of the cold rotating plasma appears to balance the Lorentz force. At Jupiter, the centrifugal force balances about 25 percent of the Lorentz force. The remaining inward Lorentz force is balanced by pessure gradients in the hot, high-beta plasma of the Jovian magnetodisk.

Mcnutt, R. L., Jr.↗
NASA NTRS1983

Energetic ion acceleration and transport in the upstream region of Jupiter - Voyager 1 and 2

Long-lived upstream energetic ion events at Jupiter appear to be very similar in nearly all respects to upstream ion events at earth. A notable difference between the two planetary systems is the enhanced heavy ion compositional signature reported for the Jovian events. This compositional feature has suggested that ions escaping from the Jovian magnetosphere play an important role in forming upstream ion populations at Jupiter. In contrast, models of energetic upstream ions at earth emphasize in situ acceleration of reflected solar wind ions within the upstream region itself. Using Voyager 1 and 2 energetic ion measurements near the magnetopause, in the magnetosheath, and immediately upstream of the bow shock, the compositional patterns are examined together with typical energy spectra in each of these regions. Characteristic spectral changes are found late in ion events observed upstream of the bow shock at the same time that heavy ion fluxes are enhanced and energetic electrons are present. A model involving upstream Fermi acceleration early in events and emphasizing energetic particle escape in the prenoon part of the Jovian magnetospehre late in events is presented to explain many of the features in the upstream region of Jupiter.

Baker, D. N.↗
NASA NTRS1983

Trapped particle absorption by the Ring of Jupiter

The interaction of trapped radiation with the ring of Jupiter is investigated. Because it is an identical problem, the rings of Saturn and Uranus are also examined. Data from the Pioneer II encounter, deductions for some of the properties of the rings of Jupiter and Saturn. Over a dozen Jupiter magnetic field models are available in a program that integrates the adiabatic invariants to compute B and L. This program is to label our UCSD Pioneer II encounter data with the most satisfactory of these models. The expected effects of absorbing material on the trapped radiation are studied to obtain the loss rate as a function of ring properties. Analysis of the particle diffusion problem rounds out the theoretical end of the ring absorption problem. Other projects include identification of decay products for energetic particle albedo off the rings and moons of Saturn and a search for flux transfer events at the Jovian magnetopause.

Fillius, W.↗
NASA NTRS1984

Chorus-related electrostatic bursts at Jupiter and Saturn

Analyses of the wideband plasma wave data obtained by Voyagers 1 and 2 at Jupiter and Saturn have revealed electrostatic bursts similar to those recently discovered at earth in association with whistler-mode chorus. In all three magnetospheres the bursts are characterized by sporadic emissions near or slightly below the electron plasma frequency with bandwidths ranging from 10 percent to more than 50 percent of the center frequency. The events found at Jupiter occur in the middle magnetosphere during both the dayside as well as the early morning passes. At Saturn, the bursts occurred in the outer regions of the magnetosphere during the dayside pass. In each of the events analyzed, evidence exists for modulation of the electrostatic bursts by a low frequency wave, presumably chorus. One of the observations gained at Jupiter includes the detection of a low-frequency band at the proper frequency for chorus. Detailed waveform analysis confirms that this band does, indeed, modulate the electrostatic bursts. Based on the present understanding of the terrestrial observations it is believed that the electrostatic bursts are generated by an electron beam trapped in Landau resonance with the chorus. Previously announced in STAR as N83-37042

Reinleitner, L. A.↗
NASA NTRS1984

Periodic intensity variation in (SIII) 9531 A emission from the Jupiter plasma torus

The intensity variation of (SIII) 9531 A line emission from the hot plasma torus of Jupiter was measured from Kitt Peak National Observatory during April 1982, using a scanning Fabry-Perot spectrometer with a field of view 2 R(J) in diameter, centered at 6 R (J) on the centrifugal equator. During the observational period, which covered 43 rotations of Jupiter, the intensities showed a periodic variation consistent with a zone of enhanced emission approximately 90 deg in longitude rotating with a period of 10.2 hours, or 2.8 percent longer than Jupiter's rotational period.

Roesler, F. L.↗
NASA NTRS1984

Very large array observations of Jupiter's nonthermal radiation

The VLA has been used at 18 and 20 cm to obtain observational data on Jupiter at all rotational aspects in all four Stokes parameters, yielding maps of the total, linearly polarized and circularly polarized intensity with a resolution of 0.25 Jupiter radii. These maps reveal such previously undetected phenomena as an emission feature close to the planetary surface north and south of each of the two main radiation peaks. The emission from 1.8 to about 3 Jupiter radii from the planet's center is sharply confined to the magnetic equator.

De Pater, I.↗
NASA NTRS1984

Galileo Jupiter approach orbit determination

Orbit determination characteristics of the Jupiter approach phase of the Galileo mission are described. Predicted orbit determination performance is given for the various mission events that occur during Jupiter approach. These mission events include delivery of an atmospheric entry probe, acquisition of probe science data by the Galileo orbiter for relay to earth, delivery of an orbiter to a close encounter of the Galilean satellite Io, and insertion of the orbiter into orbit about Jupiter. The orbit determination strategy and resulting accuracies are discussed for the data types which include Doppler, range, optical imaging of Io, and a new Very Long Baseline Interferometry (VLBI) data type called Differential One-Way Range (DOR).

Miller, J. K.↗
NASA NTRS1984

Direct evidence for solar wind control of Jupiter's hectometer-wavelength radio emission

Observations of the solar wind close to Jupiter by the Voyager 1 and Voyager 2 spacecraft in 1978 and 1979 are compared with the hectometer-wavelength radio emission from the planet. A significant positive correlation is found between variations in the solar wind plasma density at Jupiter and the level of Jovian radio emission output. During the 173-day interval studied for the Voyager 2 data the radio emission displayed a long-term periodicity of about 13 days, identical to that shown by the solar wind density at Jupiter and consistent with the magnetic sector structure association already proposed for ground-based observations of the decameter-wavelength emission.

Desch, M. D.↗
NASA NTRS1985

Photometric Analysis of Jupiter-illuminated Images of Io

Several sequences of the dark (Jupiter-illuminated) side of Io obtained during the Voyager 2 encounter present opporunity for understanding several problems relating to the surface composition of Io. The existence or absence of SO2 condensates on the night side is a sensitive indicator of an SO2 atmosphere. Preliminary analysis of the night side Io images suggests localized brightenings of approximately 25% may exist. Examination of the night side images represents an even more sensitive indicator for pure sulfur. Between 60 and 130 degrees (the minimum nighttime and maximum daytime temperatures, respectively), the relative spectral reflectance for yellow sulfur observed in the Voyager green and clear filters decreases by 25%. This decrease should be detectable on the nightside images. A search of the Voyager 2 Jupiter-illuminated images yielded a single pair of green and clear images. In these images one hemisphere of Io is Sun-illuminated and the other is Jupiter illuminated. Geologically similar regions of Io are being selected to obtain average color ratios of specific geologic units for both day and night sides.

Buratti, B. J.↗
NASA NTRS1984

Direct evidence for solar wind control of Jupiter's hectometer-wavelength radio emission

Observations of the solar wind close to Jupiter, by the Voyager 1 and Voyager 2 spacecraft in 1978 and 1979, are compared with the hectometer wavelength radio emission from the planet. A significant positive correlation is found between variations in the solar wind plasma density at Jupiter and the level of Jovian radio emission output. During the 173-day interval studied for the Voyager 2 data, the radio emission displayed a long term periodicity of about 13 days, identical to that shown by the solar wind density at Jupiter and consistent with the magnetic sector structure association already proposed for groundbased observations of the decameter wavelength emission.

Desch, M. D.↗
NASA NTRS1985

Laboratory simulations of PH3 photolysis in the atmospheres of Jupiter and Saturn

The effects of pressure, temperature, light wavelength and intensity, and components of the atmosphere of the Jovian planets on the photolysis of PH3 were experimentally studied. The products of the photolysis, P2H4 and red phosphorus, exhibited little variation when the irradiation experiments were performed under conditions prevalent in Jupiter's atmosphere. No quenching of PH2 radicals by the levels of hydrocarbons present in the Jovian atmosphere was noted. The high partial pressure of hydrogen present on Jupiter should have no effect on the course of the photolysis. The low temperatures on Jupiter and Saturn may result in some condensation of P2H4, but P2H4 had sufficient vapor pressure in the experimental studies at 157 K to be slowly converted to red phosphorus. The products of PH3 photolysis were the same whether a 147, 184.9, or 206.2 nm monochromatic light source or a xenon lamp with a broad spectral output was used.

Ferris, J. P.↗
NASA NTRS1985

Infrared polar brightening on Jupiter. III - Spectrometry from the Voyager 1 IRIS experiment

Spectra from the Voyager 1 IRIS experiment confirm the existence of enhanced infrared emission near Jupiter's north magnetic pole in March 1979. The spectral characteristics of the enhanced emission are consistent with a Planck source function. A temperature-pressure profile is derived for the region near the north magnetic pole, from which quantitative abundance estimates of minor species are made. Some species previously detected on Jupiter, including CH3D, C2H2, and C2H6, have been observed again near the pole. Newly discovered species, not previously observed on Jupiter, include C2H4, C3H4, and C6H6. All of these species except CH3D appear to have enhanced abundances at the north polar region with respect to midlatitudes. Upper limits are determined for C4H2 and C3H8. The quantitative results are compared with model calculations based on ultraviolet results from the IUE satellite. The plausibility of the C6H6 identification is discussed in terms of the literature on C2H2 polymerization. The relation of C6H6 to cuprene is also discussed.

Kim, S. J.↗