Vicinity Of Jupiter Research Articles

Jovian Magnetosheath Turbulence Driven by Whistler

Jupiter’s magnetosheath is a natural yet complex laboratory for analyzing compressible plasma turbulence. Recent observations by the Juno mission provide a promising opportunity for the first time to reckon the energy cascade rate in the magnetohydrodynamic scales in the vicinity of Jupiter’s space. In the present work, a two-dimensional model is constructed for a whistler wave that is nonlinearly coupled with a wave magnetic field via ion density perturbation. The dynamics of whistler wave propagating in the direction of the magnetic field are derived within the limit of the two-fluid modeling approach. The magnetic field localization along with magnetic field spectra and spectral slope variations are estimated to realize the turbulence generation and energy cascade from large to small scales in the Jovian magnetosheath region. The simulated magnetic field spectrum in the wave number (in the unit of ion inertial length ρ i ) consists of turbulence in the inertial range with a spectral slope of −1.4 and a spectral knee at k ρ i = 1. Subsequently, the spectral slope increases to −2.6 and the spectrum becomes steeper. The simulated magnetic field spectrum in the wave number is further translated into the frequency domain using the whistler wave dispersion relation and by considering the Taylor frozen-in condition. The analytically estimated magnetic field spectrum slopes, i.e., −1.8 and −4.2 at low and high frequencies are further compared with recent Juno mission observations. The comparison further affirms the existence of Kolmogorov scaling, a spectral knee, and steepening in the spectrum at high frequencies. Furthermore, it is found that the two-fluid model can reasonably simulate the turbulence effects in Jovian magnetosheath in terms of magnetic field spectral distribution in wave number and frequency domains.

Simulations on the shielding performance of composite materials around Jupiter’s radiation belts

The radiation environment in the vicinity of Jupiter is extremely harsh. In this context, dominant high-energy electrons are the main cause of the total ionizing dose that seriously threatens the service life of electronic devices aboard spacecraft. In this study, we explore the shielding effect of aluminum–tantalum composite materials in the energy spectrum of the radiation environment of a probe orbiting Jupiter and the planet’s gravity assist orbit at the edge of the solar system by using Monte Carlo simulations. The results show that when the shielding material was sufficiently thick, the composite shield was superior to a shield composed of a single element. Moreover, the lower the apogee of the orbit around Jupiter was, the higher was the flux in the energy spectrum of the electrons, and it was advantageous to use a thin material in the composite shield in this case. As the thickness of the material increased, the mass ratio of Al in the optimal ratio of the Al–Ta composite material gradually increased. The results of this study provide a reference for designing strong shielding materials to protect against radiation in deep space exploration.

Monoenergetic neutrinos from WIMP annihilation in Jupiter

Weakly interacting massive particles (WIMPs) can be captured by the Sun and annihilate in the core, which may result in production of kaons that can decay at rest into monoenergetic 236 MeV neutrinos. Several studies of detection of these neutrinos at DUNE have been carried out. It has been shown that if the WIMP mass is below 4 GeV, then they will evaporate prior to annihilation, suppressing the signal. Since Jupiter has a cooler core, WIMPs with masses in the 1--4 GeV range will not evaporate and can thus annihilate into kaons which decay at rest into monoenergetic neutrinos. We calculate the flux of these neutrinos near the surface of Jupiter and find that it is comparable to the flux of neutrinos from the Sun at DUNE for masses above 4 GeV and substantially greater in the 1--4 GeV range. Of course, detecting these neutrinos would require a neutrino detector near Jupiter. Obviously, it will be many decades before such a detector can be built, but should direct detection experiments find a WIMP with a mass in the 1--4 GeV range, it may be one of the few ways to learn about the annihilation process. A liquid hydrogen time projection chamber might be able to get precise directional information and energy of these neutrinos (and hydrogen is plentiful in the vicinity of Jupiter). We speculate that such a detector could be placed on the far side of one of the tidally locked Amalthean moons; the moon itself would provide substantial background shielding and the surface would allow easier deployment of solar panels for power generation.

Strong whistler mode waves observed in the vicinity of Jupiter\u2019s moons

Understanding of wave environments is critical for the understanding of how particles are accelerated and lost in space. This study shows that in the vicinity of Europa and Ganymede, that respectively have induced and internal magnetic fields, chorus wave power is significantly increased. The observed enhancements are persistent and exceed median values of wave activity by up to 6 orders of magnitude for Ganymede. Produced waves may have a pronounced effect on the acceleration and loss of particles in the Jovian magnetosphere and other astrophysical objects. The generated waves are capable of significantly modifying the energetic particle environment, accelerating particles to very high energies, or producing depletions in phase space density. Observations of Jupiter’s magnetosphere provide a unique opportunity to observe how objects with an internal magnetic field can interact with particles trapped in magnetic fields of larger scale objects.

Method of interplanetary trajectory optimization for the spacecraft with low thrust and swing-bys

The method developed to avoid the complexity of solving the multipoint boundary value problem while optimizing interplanetary trajectories of the spacecraft with electric propulsion and a sequence of swing-bys is presented in the paper. This method is based on the use of the preliminary problem solutions for the impulsive trajectories. The preliminary problem analyzed at the first stage of the study is formulated so that the analysis and optimization of a particular flight path is considered as the unconstrained minimum in the space of the selectable parameters. The existing methods can effectively solve this problem and make it possible to identify rational flight paths (the sequence of swing-bys) to receive the initial approximation for the main characteristics of the flight path (dates, values of the hyperbolic excess velocity, etc.). These characteristics can be used to optimize the trajectory of the spacecraft with electric propulsion. The special feature of the work is the introduction of the second (intermediate) stage of the research. At this stage some characteristics of the analyzed flight path (e.g. dates of swing-bys) are fixed and the problem is formulated so that the trajectory of the spacecraft with electric propulsion is optimized on selected sites of the flight path. The end-to-end optimization is carried out at the third (final) stage of the research. The distinctive feature of this stage is the analysis of the full set of optimal conditions for the considered flight path. The analysis of the characteristics of the optimal flight trajectories to Jupiter with Earth, Venus and Mars swing-bys for the spacecraft with electric propulsion are presented. The paper shows that the spacecraft weighing more than 7150kg can be delivered into the vicinity of Jupiter along the trajectory with two Earth swing-bys by use of the space transportation system based on the "Angara A5" rocket launcher, the chemical upper stage "KVTK" and the electric propulsion system with input electrical power of 100kW.

The accretion of Uranus and Neptune by collisions among planetary embryos in the vicinity of Jupiter and Saturn

Modeling the formation of the ice giants Uranus and Neptune is a long-lasting problem in planetary science. Due to gas-drag, collisional damping, and resonant shepherding, the planetary embryos repel the planetesimals away from their reach and thus they stop growing (Levison et al. 2010). This problem persists independently of whether the accretion took place at the current locations of the ice giants or closer to the Sun. Instead of trying to push the runaway/oligarchic growth of planetary embryos up to 10-15 Earth masses, we envision the possibility that the planetesimal disk could generate a system of planetary embryos of only 1-3 Earth masses. Then we investigate whether these embryos could have collided with each other and grown enough to reach the masses of current Uranus and Neptune. Our results point to two major problems. First, there is typically a large difference in mass between the first and the second most massive core formed and retained beyond Saturn. Second, in many simulations the final planetary system has more than two objects beyond Saturn. The growth of a major planet from a system of embryos requires strong damping of eccentricities and inclinations from the disk of gas. But strong damping also favors embryos and cores to find a stable resonant configuration, so that systems with more than two surviving objects are found. In addition to these problems, in order to have substantial mutual accretion among embryos, it is necessary to assume that the surface density of the gas was several times higher than that of the minimum-mass solar nebula. However this contrasts with the common idea that Uranus and Neptune formed in a gas-starving disk, which is suggested by the relatively small amount of hydrogen and helium contained in the atmospheres of these planets. Only one of our simulations "by chance" successfully reproduced the structure of the outer Solar System.

Mapping potential-vorticity dynamics on Jupiter. II: the Great Red Spot from Voyager 1 and 2 data

Maps of Ertel potential vorticity on isentropic surfaces (IPV) and quasi-geostrophic potential vorticity (QGPV) on isobaric surfaces in the vicinity of Jupiter's Great Red Spot (GRS) are derived by making use of a combination of velocity measurements, derived from the tracking of cloud features in Voyager 1 and 2 images, and thermal measurements from the Voyager 1 IRIS instrument. The thermal data were obtained during Voyager 1's closest approach to Jupiter. IPV and QGPV in the vicinity of the GRS show a clearly isolated anticyclonic patch in the troposphere, with a suggestion of some spiral structure. The relationship of IPV and QGPV q with the corresponding isentropic or isobaric stream functionΨ near the GRS is not compatible with marginal stability with respect to Arnol'd's second stability theorem, and does not indicate a relaxed, maximum entropy structure except perhaps close to the tropopause. q(Ψ) in the upper troposphere and lower stratosphere for both Ertel and QGPV is reasonably well defined within the GRS and on a different branch to the ambient zonal flow, though is less well defined close to the cloud tops where local thermodynamic forcing may be significant. The profile in the upper troposphere is consistent with an isolated ‘free mode’ structure for which the air inside the GRS has a different dynamical origin to the atmosphere outside. Copyright © 2006 Royal Meteorological Society

Energetic particle observations in the vicinity of Jupiter: Cassini MIMI/LEMMS results

We report on energetic particle measurements from the Low Energy Magnetospheric Measurement System (LEMMS) on board the Cassini spacecraft during the Jupiter flyby (October 2000 to April 2001). Cassini passed Jupiter on its way to Saturn on the dusk flank of the magnetosphere and explored for the first time the dusk‐to‐midnight magnetosheath of the planet. The flyby period can be divided into three distinct regimes where energetic particle parameter changes are observed. The first period (October 2000 to 10 January 2001) covers the approach phase toward the planet, including bow shock crossings in and out of the magnetosheath as well as the closest approach. In this period, LEMMS responded on solar wind pressure pulses and recorded the passing of two interplanetary shocks. Hours before the first bow shock crossing, low‐energy particle intensity increases were observed, possibly with Jovian origin. Before the closest approach approach to the planet two inbound and one outbound bow shock crossings have been observed. The second period (9–10 January) is the period where Cassini briefly entered the magnetosphere twice at about 200 RJ. LEMMS data are only available during a large portion of the second encounter. Inside the magnetosphere the energetic electrons showed a bidirectional pitch angle distribution along the magnetic field, indicative of a closed magnetic field configuration predominantly in the north‐south direction. In addition, quasi‐periodic electron intensity variations with periods of ≈40 min were observed. The third period (January to April 2001) covers the distances between 205 and 800 RJ. The spacecraft was skimming along the bow shock boundary in the dusk‐to‐midnight sector. More than 44 inbound and outbound bow shock crossings have been observed. The most interesting magnetosheath encounter occurred between day 19 and day 28 at distances between 300 and 400 RJ. In that period, LEMMS observed strong intensification of MeV‐electron fluxes to values similar to those measured inside the magnetosphere as reported by Krupp et al. [2002]. Most of these increases in electrons were associated with sign changes in the north‐south component of the magnetic field. We interpret these observations in terms of magnetic dayside reconnection and particle leakage through the duskside magnetosheath.

The Dynamics of Cometary Orbits in Close Encounters with Jupiter. An Analysis of Encounter Durations

The duration of the encounters is analyzed. The encounters studied are divided into low- and high-velocity encounters according to the duration of the comet's presence in the vicinity of Jupiter. Examples of low-velocity (Russel 3, 1931–1941) and high-velocity (Honda–Mrkos–Paidushakova, 1935) encounters are given. The main characteristics of high- and low-velocity encounters are described.

Probabilistic models of the Jovian magnetopause and bow shock locations

New three‐dimensional models of the Jovian magnetopause and bow shock were derived by combining spacecraft observations with boundary characteristics inferred from a magnetohydrodynamic (MHD) simulation. The MHD simulation provides polynomial forms parameterized by solar wind dynamic pressure. Observations from Pioneer 10 and 11, Voyager 1 and 2, Ulysses, and Galileo were used to establish the probability that regions surrounding Jupiter fall inside or outside these boundary surfaces. The magnetopause location was found to have a bimodal probability distribution with the two most probable standoff distances at 63 RJ (σ = 4 RJ) and 92 RJ (σ = 6 RJ). The bow shock location distribution appears bimodal, but a single distribution function description cannot be ruled out at the 95% confidence level. The mean bow shock standoff distance is 84 RJ (σ = 16 RJ). Analysis of solar wind measurements near 5.2 AU (interplanetary magnetic field, dynamic pressure, and Alfvén Mach number) suggests that the bimodal distribution of boundary positions results at least in part from the bimodal distribution of solar wind parameters in the vicinity of Jupiter. The probability density distributions of these parameters within and between regions of disturbed solar wind, caused by corotating interaction regions and coronal mass ejections, are statistically distinct. Smaller variations were also observed in these parameters over the solar cycle.

Searching for comets encountering Jupiter. Second campaign observations and further constraints on the size of the Jupiter family population

The results from the second campaign of the search for comets in the vicinity of Jupiter are presented. As in the previous campaign, we find no comets. This result is used to calculate upper limits ...

Micron‐sized particles detected in the vicinity of Jupiter by the Voyager plasma wave instruments

Wideband waveform data obtained by the plasma wave instruments onboard the Voyager 1 and 2 spacecraft have been used to study micron‐sized dust particles in the vicinity of Jupiter. The technique used was developed during the fly by s of Saturn, Uranus, and Neptune, and makes use of the fact that a particle striking the spacecraft at 10–20 km/s causes a voltage pulse in the plasma wave receiver. The waveform of the voltage pulse is much different than the waveform of plasma waves and provides a highly reliable method of detecting micron‐sized dust particles. Although the dust impact rate observed in the vicinity of Jupiter is much lower than the rates at Saturn, Uranus, and Neptune, the particles are easily detectable. Approximately 1200 48‐second frames of wideband waveform data were examined in the vicinity of Jupiter. Dust impact signatures were found in approximately 20% of these frames. The peak impact rates are about 1 impact per second, and the peak number densities are about 10−5 m−3. Most of the impacts occurred near the equatorial plane at radial distances less than about 35 RJ from Jupiter. Analysis of the detection threshold indicates that the particles have masses greater than 10−11 g, which corresponds to particles with diameters of a few micrometers or larger.

UESAC — The Uppsala-ESO Survey of Asteroids and Comets

The Uppsala-ESO Survey of Asteroids and Comets was undertaken to find previously undetected comets in the vicinity of Jupiter. Over 15000 positions of moving objects have been detected on 74 plates obtained from the European Southern Observatory in Chile

Searching for Comets Encountering Jupiter: First Campaign

This paper reports results from a first search for previously undetected comets in the vicinity of Jupiter. Combining these with a model for the probability for finding a comet in this region we estimate the total number of comets in the Jupiter family. Thirty-six Schmidt plates were obtained at ESO in March and April 1992. We searched the plates down to a limiting nuclear B-magnitude of 13.8. No comet was found. This result, together with a model for the probability of finding a comet close to Jupiter, yields an upper estimate of the number of objects in the Jupiter family. If we assume that the comets are inactive at ∼5 AU from the Sun, we get a conservative estimate of N ( H B N < 13.8) < 210. We discuss the possible brightening due to activity and present estimates including this effect. By assuming a certain magnitude distribution, we then compare our results with previous attempts to estimate the total size of the Jupiter family. Although our estimates are still higher than previous values, our results are independent of the distribution of comets with perihelion distance. Ongoing and future searches with the same technique will further constrain the population size of the Jupiter family.

Results from Ulysses' Jupiter flyby

The joint European Space Agency/NASA Ulysses spacecraft flew through the Jovian system in early February for a gravity‐assist boost out of the ecliptic plane on its way to its primary mission exploring the polar regions of the Sun. While in the vicinity of Jupiter, Ulysses' nine field and particle experiments probed the Jovian magnetosphere. At a February 11 press conference at the Jet Propulsion Laboratory, Ulysses investigators presented the initial results from the flyby. The first set of scientific papers will be published in Science this summer.

Accretion in the inner nebula: The relationship between terrestrial planetary compositions and meteorites*

Abstract— The bulk compositions of the terrestrial planets are assessed. Venus and Earth probably have similar bulk compositions, but Mars is enriched in volatile elements. The inner planets are all depleted in volatile elements, as shown by K/U ratios, relative to most meteorites and the CI primordial values. Terrestrial upper mantle Mg/Si ratios are high compared with CI data. If they are representative of the bulk Earth, then the Earth accreted from a segregated suite of planetesimals that had non‐chondritic major element abundances. The CI meteorite abundances, despite aqueous alteration, match the solar data and provide the best estimate for the composition of the solar nebula, including the iron abundance. The widespread depletion of volatile elements in the inner solar nebula is most likely caused by heating related to early violent solar activity (e.g., T Tauri and FU Orionis stages) which, for example, drove water out to a “snow line” in the vicinity of Jupiter. The variation in composition among the meteorites and the apparent lack of mixing among the groups indicates accretion from narrow feeding zones. There appears to have been little mixing between meteorite and planetary formation zones, as shown by the oxygen isotope variations, lack of mixing of meteorite groups, and differences in K/U ratios. In summary, it appears that the final accretion of planets did not result in widespread homogenization, and that mixing zones were not more than about 0.3 A.U. wide. Although the composition of the Moon is unique, and its origin due to an essentially random event, its presence reinforces the planetesimal hypothesis and the importance of stochastic processes during planetary accretion in the inner solar system.

Proton aurora on Io

view Abstract Citations (5) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Proton aurora on Io. Pilcher, C. B. Abstract The Jovian satellite Io should exhibit substantial auroral activity due to interactions of the satellite's atmosphere with Jovian magnetospheric particles. Plasma sheaths that may form around the satellite will cause substantial proton aurorae on the Jupiter-facing hemisphere and electron aurorae on the outward-facing hemisphere. A sample calculation indicates that Doppler-shifted radiation from high-velocity hydrogen atoms (proton aurora) will be observable from a spacecraft in the vicinity of Jupiter. Emission near Lyman-alpha may be present at a level as much as 100 times that of the solar background reflected from Io's surface. Publication: The Astrophysical Journal Pub Date: July 1976 DOI: 10.1086/154531 Bibcode: 1976ApJ...207..646P Keywords: Auroras; Hydrogen Atoms; Io; Plasma Sheaths; Protons; Alpha Particles; Atmospheric Models; Earth Magnetosphere; Lyman Alpha Radiation; Lunar and Planetary Exploration full text sources ADS | Related Materials (1) Erratum: 1976ApJ...209..651P

Io's atmosphere and ionosphere: New limits on surface pressure from plasma models

We have studied charge particle impact as a mechanism for the production of Io's ionosphere. Pioneer 10 thermal plasma measurements and magnetospheric plasma models which explain the observed spatial distribution of neutral hydrogen and sodium atoms in the vicinity of Jupiter’s satellite Io imply electron fluxes of ∼1010 cm−2 sec−1. The fluxes and the temperature (∼100 eV) of this plasma suggest that electron impact ionizaion is the dominant process in forming the ionosphere of Io. It is found that the surface number density of the neutral species required to match the observed electron density profiles is ∼109 cm−3 or less. This value is two orders of magnitude lower than previous estimates.

Detection of ionized sulfur in the Jovian magnetosphere

Detection of a pair of emission lines at 6717 and 6730 A in the near vicinity of Jupiter is reported. It is proposed that the lines be identified with the forbidden doublet of S II. The astrophysical implications of this identification are discussed.

Observations of Jovian electron events in the vicinity of Earth

A number of quiet‐time enhancements in the intensity of interplanetary electrons over the range 0.22 ≲ E ≲ 2.5 MeV have been observed with the JHU/APL experiment on the earth orbiting near‐circular (∼ 32 by 38 Re) Explorer 47 (IMP‐7) spacecraft during 1973 and 1974. These quiet‐time increases last from ∼ 3 to ∼ 20 days and are observed both in the interplanetary medium and inside the magnetotail. The main features of the observations are as follows: (a) The increases occur during the first 200 days of 1973 and from day ∼ 20 to ∼ 230 in 1974. (b) The intensity onset is relatively slow (1 to 2 days) when compared to either solar electron events or magnetospheric electron bursts, (c) The electron energy spectrum is quite distinct from that of solar or magnetospheric electrons and is consistent with γ = 1.3±0.3 in a differential power law spectrum. (d) Significant anisotropies are present, several days after the onset of the increase. (e) Some distinct fluctuations appear in some of the intensity profiles, suggesting the presence of a modulated source. The appearance of these enhancements occurs during times when the earth could be magnetically connected to the magnetosphere of Jupiter, assuming typical solar wind velocities. Further, the energy spectrum is not unlike that observed by instrumentation on Pioneer 10 in the vicinity of Jupiter. On the basis of the above it is reasonable to suggest that the observed electrons may be of Jovian origin. The implications of these results are discussed, and it is suggested that interconnection between the interplanetary and Jovian magnetic field takes place. Using this concept, a length of the Jovian magnetotail of ∼4.6 AU is computed.