New Frontiers in the Solar System An Integrated Exploration Strategy (2003) / Chapter Skim
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4 Giant Planets: Keys to Solar System Formation
4 Giant Planets: Keys to Solar System Formation
Pages 92-117
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From page 93... ...
may have migrated inward or outward' ejecting some objects from the solar system' pushing some into their parent stars md swallowing others. Smaller thm stars' which have their own nuclear furnaces' the gist pawed rennin ~~S percent of the planetary mass of the solar system.
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From page 94... ...
That might explain He difference between He fee giants, Uranus md Neptune' md the gas giants' Jupiter md Saturn. Gist planets form faster ~ the orbits of Jupiter md Saturn' where the density of the solar nebula is large md collisions are more frequent.
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From page 95... ...
~ other words' preeipi~tion of helium has not yet produced significant depletion on Jupiter. This raises questions Bout the in~rpre~tion of Voyager remo~-sensing observations for both Jupiter md Saturn.
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From page 96... ...
Important Questions for Origins and Evolution Importmt questions about the origin md evolution of gimt plme~ em be divided into Dose speeif~eally relying to the solar systems give md, more generally, Lose relating to extrasolar planets md brown dwarfs. Importmt questions for the solar systems gist planets include the following: How did He gist planets form: Does Jupiter have ~ roek-iee cored What are the elemental compositions of the gist plme~9 What are the internal structures md dummies of He gimt plmets: What are the orbital evolutionary pays of the gimt plmets: For extrasolar gist plme~ md brown dwarfs' He impor~t questions are these: Around what types of stars are gist plmets found: Are multiple Lint plme~ common in seller systems: .
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From page 97... ...
The methods of inference are the same for my planet; the interiors of He gist plme~ are relatively urn own only because near-surface day are relatively sparse compared with day for the ~rrestria1 plme~. The distinction between interior Id Ionosphere is largely ~ operational one ~ the gimt plme~, Id Be two domains are proudly more intimately coupled in He gist planets than in Be Arrest plmets precisely because He gists lack ~ conventional surface.~~i Interior Stru~um Present models of gist planet interiors are contained by observed properties, including planetary mass' radius' shape, rotation period, hey flow, gravitations moments' magnetic moments' Id elemental composition.
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From page 98... ...
The clouds of Jupiter md Saturn are thought to comprise Area distinct layers' composed of ammonia ~ the top' ammonium hydrosulfide in the middle' arid ~ wa~r-solution cloud ~ the bosom. Analogous cloud decks may also exit ~ ~e ice giar~ts, Urar~us arid Neptune, with ~e addition of ~ methar~e cloud ~ high altitudes arid perhaps ~ hydrogen-sulf~de cloud rather Bars ~ ammonia cloud just below.
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From page 99... ...
The Galileo orbiter observations of water-rich convective storms ~soeia~d with lighting md eyelonie shear zones have shed new light on Be role of moist convection in the maintenance of Tonal jets on Jupiter; ~us' knowing the abundance of water is ~ major objective for Jovian me~orology.2i The Tonal jets are visually prominent ~ Be gas gibes Jupiter md Spurn md less so ~ the fee gists Uranus md Neptune.~~~5 At Jupiter' Tonal wind speeds (~ the cloud level) are greatest ~ the boundaries between Be lighter~olored <~ones', of upwelling warmer atmosphere md Be darker~olored < |
From page 100... ...
ELey Question Importers questions about ~e interiors arid atmospheres of Diary ply include ~e following. In~`ors Atmospheres What is the nature of convection in Tiara Claret interiors How does the composition vary with depth What is the nature of phase ~ar~sitions within the Diary plar~e~9 How is energy ~ar~spor~d through the deep Ionospheres Do radiative layers exists How md where are plar~e~ry magnetic fields generated: What energy source maintains the Tonal winds' md how do they v~ with depth: What role does wear md moist convection play: How md why does atmospheric temperature vary win depth latitude' md longitude: What physical md chemical processes eonhol He atmospheric composition md the formation of clouds md he layers: How does the aurora affect the global composition, temperature' md hue formation: What produces the intrigue vertical structure of gimt planet ionospheres: At what rate does ex~rna1 material enter gist planet atmospheres, md where does this material come from: What em organic chemist in gimt planet atmospheres tell us about the atmosphere of early Earth md He origin of life: Future Di~tiom The most importmt directions for research on the interiors md atmospheres of gist plme~ for He next decade are identified as follows: ~ ~so~g Jfi~-~ str~re of t~ gore ~ ~d maniac f ~4 to ei~m t~ ~rsmnor s~re ~d t~ mec~s~sms of energy trouper; ma~-fie~ grenerat~o~ ~d convection wean Jug.
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From page 101... ...
The diversity of present-day disk structures ~ the gist planets offers glimpses into Be various sages of solar system formation md other astrophysical processes. At first glance it is less ~m obvious that studies of planets rings will tell us Aching about ashophysiea1 disks because of Be grew mismatch in Be relevant sp~ia1 md temporal scales on which they operate.
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From page 102... ...
Plump The gimt planets have redefined our concept of planetary magnetospheres. Unlike the ~rreshia1 planet magnetospheres (Ear~ md Mercury)
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From page 103... ...
PLANETS joS FIGURE 4.2 Jupi~r,~ va~ magneto sphere as image from ~ distance of 10 million km by the ion ~d ncukal-~tom Emery Card the Gemini spacecraft during its Jupiter flyby in De~m~r 2000. Also shown, mhemati~lly, is Jupi~r5s magnetic field ~~, to ~1~, the to torus ~d Jupiter itself.
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From page 104... ...
Cassini observations ~ Saturn are thus ~ Critical complement to those of Galileo ~ Jupiter. llot~ion is aIso ~ dominant factor in Me magnetospheres of Uranus md Neptune' but win qualitatively new dummies resuking from We extraordinarily large magnetic dipole tilt males (~0 md 470' respectively)
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From page 105... ...
Rings ~ What are Me current physical properties (size distribution' shapes, strength md nature of aggregations) of particles in the various rings md of distinct regions within the rings: What are the most important meehmisms for ring evolution on long md short time scales: ~ What are Me underlying kinematics md dummies of the various ring systems: How do self-gravity' viscosity' ballistic bmsport' md collisions inbreed What is the chemical composition of He various rings md of distinct regions within the rings: ~ What is He current mass flux into the various ring systems: What are the current size, mass' Melodic, md composition distributions of He influx population: How did these eke with time: What are the influences of He magnetospherie md plasma environments of the various rings: - What do the differences among ring systems tell us about differences in ring progenitors mdior differences in initial md subsequent processes: - What is the relationship between local ring properties md those properties observable by remote sensing: What do planetary rings teach us about nebulas around other stars: ~ What is the nature of the eleetrod~amie coupling between major satellites md He ionospheres of their plme~9 ~ How do He to plasma torus md analogous structures ~ other plme~ convert plme~ry rotations energy into electromagnetic radiation over ~ wide rake of frequencies: ~ How are mauler momentum transfer md other globe magnetospherie processes revealed through aurora1 emission features: ~ What is He specie md comport structure of centrifugally driven plasma transport in ~ ro~tion-domina~d magnetosphere: How md where is He Jovian planetary wind generated: Does Saturn have ~ plme~ry wind: How does the Jovian pulsar work: Do other gist planets exhibit pulsar behavior: ~ What role does electromagnetic angular momentum transfer' as observed in gist planet magnetospheres' have in solar system formation:
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From page 106... ...
The nature of this process is rarities to understanding not only He magnetospheres of Jupiter md Saturn but also ~ much larger class of astrophysical objects. Ordin~ plasma particle md field measurement ~ low altitudes md high magnetic latitudes ~ Jupiter would revolutionize our understanding of this process.
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From page 107... ...
Wear is also impor~t to He meteorology of gist planets, as it is on Earth. The Galileo probe penetrated below the Jovian clouds, but the composition was still varying when He probe reached id maximum depth ~ 24 bars.
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From page 108... ...
However' Earth-b~ed ~leseopie observations are ~ essential complement to in situ studies ~ Jupiter md Saturn md are the only source of such information for Uranus md Neptune in the next decade. Three-dimensiona1 distributions of atmospheric composition' temperature, aerosols, winds' md aurora1 emissions
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From page 109... ...
~~ PLANETS jop FIGURE 4.5 Minim rear Alum doubled as ~ radio ~lewopc to Hollow chew images showing the variations in Jupi~r~s trapped radiation beds over ~ lO-hour period. The radio emission has ~ wavelength of 2.2 cm and original from cleckons trapped in Jupiter5s inane made tic field.
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From page 110... ...
It cart arid should ~ launched in this decade. For the longer Arms ~e party he identified ~ single large-class mission ~~ addresses most of the key questions for art ice diary ~ Neptune orbiter win multiple enLy probes.
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From page 111... ...
Enabling teehnolo gies for ~ Neptune Orbiter with Probes mission (see below) include nuclear elee~ie propulsion md power sources' enhanced telemetry' improved hem shields' lightweight instruments for entry probes, md possibly aeroeapture.
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From page 113... ...
~ ~ 4-= ~ O ~ ~ O O ~ ~ O ~ HA - , ~ -m ~ ~ ~ ~ S _ _ ~ ~ — S His shy MOD b ° do ~ ~ e US ~ o ~ ~ ~ ~ -A _ A =~ .
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From page 114... ...
satum R`~g 065~r On ~ Saturn Ring Observer mission' advanced propulsion would be used to hover clom above the ring plural for longhorn study of collisions arid over microphysica1 processes. Ur~ 0761~r why Probes The science objectives arid payload of ~ Urar~us Orbiter win Probes mission would be similar to those of ~e Neptune Orbiter with Proms mission.
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From page 115... ...
Space-based telescopes also have ~ more nearly continuous dub cycle. Plar~ry scientists mud ~ included in early plarming arid development to ensure thy space ~lemopes have instrument md tracking capabilities thy serve solar system research objectives.
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From page 116... ...
The maintenance md refurbishing of the I1lTF for this purpose is ~ continuing priority. Maximizing the science return from both in situ md Earth-b~ed observations requires ~ robust concurrent program of dam Physic md modeling efforts.
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From page 117... ...
s Wired Speeds Obtair~ed by Tracking Clouds ire Voyeur Image)
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