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At least 1,081 records · Page 60
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NASA NTRS1972

A self-consistent model for Jupiter's radiation belts

The solar wind is assumed to be a sufficient source for the radiation belts of Jupiter, with radial diffusion as the process for getting the solar wind fluxes into the inner regions of the radiation belts. The process of a radial diffusion source is combined with pitch-angle diffusion losses to estimate an upper limit to the proton and electron fluxes. The upper limit to the integral proton and electron fluxes in the outer zone scale as L to the -6th power throughout the outer zone, assuming that the magnetic moment is conserved. It is important that these fluxes are above the stably trapped flux levels in the outer regions of the belts; the instability will work because the energies of the particles are above the critical value required.

Thorne, R. M.↗
NASA NTRS1972

Wave propagation in the magnetosphere of Jupiter

A systematic procedure is developed for identifying the spatial regimes of various modes of wave propagation in the Jupiter magnetosphere that may be encountered by flyby missions. The Clemmow-Mullaly-Allis (CMA) diagram of plasma physics is utilized to identify the frequency regimes in which different modes of propagation occur in the magnetoplasma. The Gledhill model and the Ioannidis and Brice model of the magnetoplasma are summarized, and configuration-space CMA diagrams are constructed for each model for frequencies from 10 Hz to 1 MHz. The distinctive propagation features, the radio noise regimes, and the wave-particle interactions are discussed. It is concluded that the concentration of plasma in the equatorial plane makes this region of vital importance for radio observations with flyby missions. Local radio noise around the electron cyclotron frequency will probably differ appreciably from its terrestrial counterpart due to the lack of field-line guidance. Hydromagnetic wave properties at frequencies near the ion cyclotron frequency and below will probably be similar to the terrestrial case.

Liemohn, H. B.↗
NASA NTRS1972

Note on the origin of Jupiter's magnetic field

The effect of the coriolis force was examined for stability of rotating hydromagnetic systems. It is shown that the effect of this force is to inhibit the onset of instability which leads to convective motion in these systems. The possibility of the existence of a dynamo process in Jupiter's interior is discussed, taking into account the effect of the coriolis force.

Sakurai, K.↗
NASA NTRS1972

Models for the atmospheres of Jupiter and Saturn

Numerical models of the atmospheres of Jupiter and Saturn have been created for use in the development of design criteria for space vehicles intended to investigate these plants. These models provide a basis for the assessment of entry heating, the transmission and emission of radiation, and structural and aerodynamic interactions. The model atmospheres are based on data and analyses published in the literature through 1970. The composition is duscussed, and the relative amounts of each molecular species are tabulated for nominal and extreme cases. The structure of the atmospheric regions is discussed, and the principal features of one nominal and two limiting models for each planet are indicated. The models are illustrated by pressure-temperature profiles which also display the major cloud layers.

Divine, N.↗
NASA NTRS1971

JOSE, Jupiter orbiting spacecraft: A systems study, volume 1

A brief summary of the mechanical properties of Jupiter is presented along with an organizational outline of the entire JOSE program. Other aspects of the program described include: spacecraft design, mission trajectories, altitude control, propulsion subsystem, on-board power supply, spacecraft structures and environmental design considerations, and telemetry.

Source record↗
NASA NTRS1972

Search for X rays from the planet Jupiter.

Actively collimated balloon-borne scintillation counters employing a special phoswich anticoincidence technique were flown a total of 5 times from Palestine, Texas. Jupiter was observed for a total of 133 min, and an upper limit to the flux of X rays present at the observation time is .016 X rays/sq cm sec in the energy range 30-100 keV. Three separate calculations are made to estimate the flux of Jovian X rays at the earth. These estimates range from .000000001 to .1 X rays/sq cm sec in the energy range 30-100 keV. It is concluded that, since there was no decametric emission at the time of the flight and there had been no significant solar activity for several days prior to the flight, no X rays were being generated at the time of the observation.

Hurley, K. C.↗
NASA NTRS1972

Lunar and Planetary Laboratory studies of Jupiter. II.

Discussion of Jovian belts, zones and atmospheric features as identified by an analysis of photographs of the planet at the Laboratory. The topics include the circulation of the Jovian atmosphere, the rotation periods of zones and belts, the Great Red Spot shown by methane photographs, and some high altitude photographs of terrestrial atmospheric conditions. Hypothetical mechanisms controlling the atmospheric conditions on Jupiter are considered.

Kuiper, G. P.↗
NASA NTRS1972

Does Io's ionosphere influence Jupiter's radio bursts.

Goldreich and Lynden-Bell's theory of Jupiter's Io-correlated decametric radiation sets a lower limit to Io's conductivity, high enough to carry the current associated with the radiated power. Dermott's analysis of conductivities of rocks and ice shows no such conductivity at Io's temperature. However, we show that if Io has even a small atmosphere, say of methane as suggested by Binder and Cruikshank, or of argon or nitrogen, it will have an ionosphere with adequate conductivity to meet the above criterion. A requirement for higher conductivity was found by Goldreich and Lynden-Bell on the basis of motion of magnetic lines past Io. This requirement appears to us unnecessary in view of experiments which prove that motion of the lines is not the source of the electromotance.

Webster, D. L.↗
NASA NTRS1972

Methods and approximations for the computation of transmission profiles in the v4 band of methane in the atmosphere of Jupiter.

This note discusses the validity of certain band models and scaling approximations for computing transmissions in the v4 band of methane along inhomogeneous paths in the atmosphere of Jupiter. It is shown that Goody's random band model approximates the results of a rigorous numerical line-by-line calculation of the transmission profile of a Jovian model atmosphere.

Taylor, F. W.↗
NASA NTRS1972

Jupiter - Its Red Spot and disturbances in 1970-1971.

Photographic observations of Jupiter and its Red Spot between Dec. 11, 1970, and Oct. 12, 1971, are reported. The Red Spot had a mean rotation period of 9 hr 55 min 38.5 sec, the shortest to be observed since the apparition of 1931-1932. The outstanding event of the apparition was an outburst of activity in the South Equatorial Belt which was similar in many ways to the great disturbance of 1928.

Reese, E. J.↗
NASA NTRS1972

Photographic observations of the occultation of Beta Scorpii by Jupiter

The occultation of the multiple star Beta Scorpii by Jupiter was observed visually and photographically from the Bosscha Observatory in Lembang (Java), Indonesia, on May 13, 1971. The photographs recorded the dimming of the stars as the light was differentially refracted by the Jovian atmosphere, and gave support to a scale height greater than 8 km. Measurement of the position of the brightest component at Beta Scorpii during ingress shown refraction of approximately 1.4 sec before becoming unobservable.

Larson, S. M.↗
NASA NTRS1972

Gravity thrust Jupiter orbiter trajectories generated by encountering the Galilean satellites.

A trajectory design philosophy is introduced for Jupiter orbiter missions that is based on the gravity thrust concept developed for interplanetary trajectories. This is accomplished by utilizing the moving gravitational fields of the four Galilean satellites. A general theorem, applicable to any existing planetary satellite system, is developed to show how the effects of small satellite perturbations can be magnified by incorporating multiple revolutions between encounters.-

Minovitch, M. A.↗
NASA NTRS1972

The Pioneer Jupiter magnetic control program.

The Pioneer Jupiter spacecraft was required to have a sufficiently small magnetic field that accurate interplanetary-magnetic field measurements would not be compromised. In order to control the magnetic field throughout the program a running account of spacecraft magnetic fields was maintained by means of a periodically updated magnetic model. This model was used to make economic tradeoffs in subsystem magnetic moments within the allowed magnetic budget. The program was culminated with a measurement of the magnetic field of the spacecraft. A description of the magnetic tests and a comparison with estimates made with the magnetic model are also presented.

Sanders, N. L.↗
NASA NTRS1973

Observations of 7.9-micron limb brightening on Jupiter.

Gillett et al. (1969) observed that the brightness temperature in the strong 7.7-micron CH4 band was higher than at the neighboring wavelengths (where the absorption was expected to be less) in the Jovian spectrum from 2.8 to 13 microns. This observation was interpreted as being caused by a temperature inversion in the upper atmosphere of Jupiter. This interpretation is checked by measuring the variation of the brightness temperature from the center to the limb of the disk, and is confirmed by the observation of limb brightening, rather than the usual limb darkening, at a certain wavelength within the 7.7-micron CH4 band.

Gillett, F. C.↗
NASA NTRS1972

An evolutionary calculation of Jupiter.

A preliminary evolutionary calculation has been made for a stellar object of 0.001 solar mass composed of pure hydrogen. The star undergoes the gravitational contraction from an initial radius of 35 times the present radius of Jupiter (Rj). We assume the interior to be in convective equilibrium throughout the evolution. The evolution has been followed for 1 b.y. at which time R = 2.8 Rj and the central temperature is 18,000 K.

Grossman, A. S.↗
NASA NTRS1973

Theory of decametric radio emissions from Jupiter.

It is suggested that the Jovian decametric emissions (DAM) originate in a cyclotron instability of weakly relativistic electrons trapped in the Jovian magnetic field. The resulting radiation has a group velocity in the magnetospheric plasma which may be of order 100 km/sec, and thus takes much more time to escape the magnetosphere than if the group velocity were at or near the speed of light. Therefore, the asymmetry of the Io phase with respect to sources east and west of the Earth-Jupiter line does not imply an asymmetric beaming of DAM; it is caused by the delay the waves experience in traversing the magnetosphere. The frequency drifts of milli- and decasecond bursts are also explained.

Wu, C. S.↗
NASA NTRS1973

On convection and gravitational layering in Jupiter and in stars of low mass.

Neutral helium is probably insoluble in metallic hydrogen below some critical temperature. When Jupiter has cooled sufficiently, helium droplets can form, grow, and fall under gravity, leading to chemical separation and gravitational layering in spite of rapid convection. Applications to cool stars are discussed.

Salpeter, E. E.↗