Galileo probe interpretation indicating a neutrally stable layer in the Jovian troposphere

AbstractRemote sensing observations suffer significant limitations when used to study the bulk atmospheric composition of the giant planets of our Solar System. This impacts our knowledge of the formation of these planets and the physics of their atmospheres. A remarkable example of the superiority of in situ probe measurements was illustrated by the exploration of Jupiter, where key measurements such as the determination of the noble gases’ abundances and the precise measurement of the helium mixing ratio were only made available through in situ measurements by the Galileo probe. Here we describe the main scientific goals to be addressed by the future in situ exploration of Saturn, Uranus, and Neptune, placing the Galileo probe exploration of Jupiter in a broader context. An atmospheric entry probe targeting the 10-bar level would yield insight into two broad themes: i) the formation history of the giant planets and that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. An atmospheric probe could represent a significant ESA contribution to a future NASA New Frontiers or flagship mission to be launched toward Saturn, Uranus, and/or Neptune.

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In-Situ Chemical and Isotopic Measurements of the Atmosphere of Jupiter

Highlights of Astronomy ◽

10.1017/s1539299600019596 ◽

1998 ◽

Vol 11 (2) ◽

pp. 1057-1064

Author(s):

P.R. Mahaffy ◽

S.K. Atreya ◽

H.B. Niemann ◽

T.C. Owen

Keyword(s):

Mass Spectrometer ◽

Atmospheric Composition ◽

Mixing Ratios ◽

Major Species ◽

Lateral Mixing ◽

Detailed Composition ◽

Different Depths ◽

Galileo Probe ◽

Spectrometer Data

AbstractInsights into both the detailed composition of Jupiter’s atmosphere and unexpected local meteorological phenomena were revealed by in-situ measurements from the Galileo Probe Neutral Mass Spectrometer taken on December 7, 1995. Measurements of the neutral atmospheric composition from a pressure of 0.5 bar to approximately 21 bar revealed the mixing ratios of the major species helium and hydrogen as well as numerous minor constituents including methane, water, ammonia, ethane, ethylene, propane, hydrogen sulfide, neon, argon, krypton, and xenon. This instrument measured the isotope ratios3He/4He, D/H, and13C/12C as well as the isotopes of neon, argon, krypton, and xenon. A summary is given of progress that has been made in refining preliminary estimates of the abundances of condensable volatiles and noble gases as a result of an ongoing laboratory study using a nearly identical engineering unit. The depletion of simple condensable species to depths well below their expected condensation levels is explained by a local downdraft in the region of the probe entry. The mass spectrometer data suggests that different species may recover at different depths and this may be due to lateral mixing of Jovian air.

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Galileo: Close-up Views of Jupiter’s Dynamic Atmosphere

Highlights of Astronomy ◽

10.1017/s1539299600014350 ◽

2002 ◽

Vol 12 ◽

pp. 602-605 ◽

Cited By ~ 1

Author(s):

Ashwin R. Vasavada

Keyword(s):

Near Infrared ◽

Moist Convection ◽

Entry Site ◽

Zonal Jets ◽

Night Side ◽

New Ideas ◽

Water Cloud ◽

Galileo Probe ◽

Auroral Phenomena

AbstractThe Galileo spacecraft’s Solid State Imager (SSI) has been returning mosaics of Jupiter since 1996. The combination of high spatial resolution, broad spectral range, and short mosaic time steps has revealed a dynamic, vertically extended cloud structure not detectable by Voyager. These data have stimulated new analyses of major features such as zonal jets, the Great Red Spot, White Ovals, and the Galileo Probe entry site. Near-infrared images have provided fundamental constraints on the vertical structure of clouds and hazes, including the first imaging of a water cloud. Results from night side imaging include an extensive search for lightning, the first matching of lightning events to day side storm clouds, and the first spectral and spatial measurements of visible-wavelength auroral phenomena (not discussed here, see Vasavada et al. 2000). The identification of several tall, energetic storm systems at specific latitudes has led to new ideas about the role of moist convection in Jupiter’s atmospheric energetics.

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Turbulent dispersion in a stable layer with a quadratic exchange coefficient

Boundary-Layer Meteorology ◽

10.1007/bf00116118 ◽

1987 ◽

Vol 39 (3) ◽

pp. 207-218 ◽

Cited By ~ 4

Author(s):

R. E. Robson

Keyword(s):

Turbulent Dispersion ◽

Exchange Coefficient ◽

Stable Layer

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Chemistry of the Solar System Revealed in the Interiors of the Giant Planets

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311025026 ◽

2011 ◽

Vol 7 (S280) ◽

pp. 249-260 ◽

Cited By ~ 1

Author(s):

Jonathan I. Lunine

Keyword(s):

Solar System ◽

Microwave Radiometer ◽

Giant Planets ◽

Isotopic Ratios ◽

Data Sets ◽

Terrestrial Water ◽

Galileo Probe ◽

Probe Mission ◽

Juno Mission

AbstractThe giant planets of our solar system contain a record of elemental and isotopic ratios of keen interest for what they tell us about the origin of the planets and in particular the volatile compositions of the solid phases. In situ measurements of the Jovian atmosphere performed by the Galileo Probe during its descent in 1995 demonstrate the unique value of such a record, but limited currently by the unknown abundance of oxygen in the interior of Jupiter–a gap planned to be filled by the Juno mission set to arrive at Jupiter in July of 2016. Our lack of knowledge of the oxygen abundance allows for a number of models for the Jovian interior with a range of C/O ratios. The implications for the origin of terrestrial water are briefly discussed. The complementary data sets for Saturn may be obtained by a series of very close, nearly polar orbits, at the end of the Cassini-Huygens mission in 2016-2017, and the proposed Saturn Probe. This set can only obtain what we have for Jupiter if the Saturn Probe mission carries a microwave radiometer.

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A Granular Dynamic Model for the Degradation of Material

Journal of Tribology ◽

10.1115/1.1705666 ◽

2004 ◽

Vol 126 (3) ◽

pp. 606-614 ◽

Cited By ~ 39

Author(s):

N. Fillot ◽

I. Iordanoff ◽

Y. Berthier

Keyword(s):

Dynamic Model ◽

Normal Pressure ◽

Two Dimensional ◽

Third Body ◽

Stable Layer ◽

Sliding Speed ◽

Particle Detachment ◽

Physicochemical Interactions

The work presented here is a model of the degradation of a material (by particle detachment), based on a two dimensional granular dynamic model designed to study the flows of third body particles inside a contact. As the detached particles (third body) cannot exit the contact, the detachments stop after a certain time and a stable layer of third body can be seen. It is shown that the thickness of this stable layer depends both on the conditions applied (normal pressure and sliding speed) and the physicochemical interactions between the detached particles. Such investigations provide better understanding of the mechanism leading to the degradation of material.

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