New Frontiers in the Solar System An Integrated Exploration Strategy (2003) / Chapter Skim
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2 Inner Solar System: Key to Habitable Worlds
2 Inner Solar System: Key to Habitable Worlds
Pages 38-65
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From page 39... ...
Through the study of over objects in the inner solar system' it is now understood that Each as ~ habitable plmet is the result of ~ series of stochastic event that occurred over id 4.~-billion-year history. The terrestrial or ``Ear~-like'' plme~ exhibit common geologic processes that bow reflect md determine Heir fate.
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From page 40... ...
By their very nature' several of He mod fundamental science investigations require commitment to ~ long-term integrated approach of observation' measurement Ad analysis. WHAT LED TO THE UNIQUE CHAlIACTEll OF OUR HOME PLANET' The factors leading to Earths unique eharae~ri~ies md' by extension' the unique characteristics of the other inner planets may be org~i~d as follows: The bulk compositions of the irmer plme~ Ad their derisions with disagree from the Sun; The internal structure Ad evolution of the core, crust' Ad mmile; The history Ad role of early impacts; Ad The history of water Ad other vol~iles Ad He evolution of inner planets' Ionospheres.
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From page 41... ...
_ act- ~i. ail.,;, Fig cloud aerosol size : and composition nea r- l ~ descent and ascent imaging elemental abundances and m in eral ogy from core sample surface mineral microscopy FIGURE 2.2 A slice imp Earths sister planet Venus illustrates the urn own nature of the structure and ~~ of the interior; the composition and history of materials at We surface; md the composition' circulation' and evolution of Me atmosphere.
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From page 42... ...
Samples of rocks from major unsampled terrains, primarily Be Soup Pole-AitkenDasin' are needed to determine ~ accurate deep erusta1 composition Id stratigraphy. I - ort~t cautions High-priorily investigations relating to bulk compositions of the inner planets Id Heir variation with disagree from He Sun are as follows: Determine elemental Id mineralogical surface compositions, Determine noble gas compositions of atmospheres' Determine oxygen isotopic compositions of He unaltered surface Id atmosphere, Id Determine interior (mmile)
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From page 43... ...
Instead' topography md the relative your of the Venusim surface indigen ~ major, possibly global, resurfacing thy may have occurred episodically.~7 Although Venus appears to have ~ iron core' the absence of ~ magnetic field suggest ~~ it does nof have ~ magnetic dynamo, perhaps eonsis~nt with its slow rotation. Limited Mariner 10 dam ~ Mercury indie ate the presence of ~ magnetic field with ~ magnetosphere capable of standing off the solar wind most of the time.
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From page 44... ...
However' because d~a are incomplete' it is not known if global melting md differentiation occurred on all of He ~rrestria1 plme~' or if impact basins Domingo the erustal structure of Mercury ~ they do on the Moon md to some extent on Mars. The history of volatiles md plme~ry atmospheres were also affected by impacts' both through implication by comets md rem oval of gases through impact erosion.
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From page 45... ...
, but the dam are insufficient to determine the egret evolutionary paths. Aecura~ measurement of hydrogen Ed isotopic abundances of noble gases Ed oxygen in the Biospheres soil, Ed rocks are required.
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From page 46... ...
Recent progress in studies of each' likely future directions for research' arid imports questions ~~ need to be addressed are outlined ~low. Proses That Stabilize Climate Venus, Earth, arid Mars have complex interactions between the surface, atmosphere' arid interior.
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From page 47... ...
What would Earth currently ~ like without play tectonics or without id protective magnetic fields The lack of play tectonics on the other ~rrestria1 ply the lack of ~ magnetic field ~ Venus arid ~e weak field ~ Mercury, arid the remnar~t magnetization of Mars allow us to explore `~al~rn~ive scenarios,' for the current shy of processes active on Earn md to underbred the relative significance of ~e interplay between volcanic activity arid atmospheric composition in generating md sustaining habitable environments. Recent Progress The hot interiors of planets drive tectonic arid volcar~ic processes such as plate Felonies.
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From page 48... ...
Magnetospheres cart help recycle ions into ~e neuba1 ahnosphere, but ~e efficiency of this process is urn own. Studies of ~e effects of ~e solar wind on ply win weak or no magnetic fields provide ~ basis for understar~ding how ex~rna1 processes affect atmospheric evolution.
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From page 49... ...
Recent progress in studies relying to each of these factors, together with likely future directions for research' are outlined below. Vulnernhility of Earthy Environment As Revealed by the Diverse Climates of the Inner Planed Mars is ~ small, frozen world, homily to life because of its thin atmosphere md harsh radiation environment.
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From page 50... ...
The Moon arid Mercury have very different histories compared with those of Venus arid Earth. The surface of Mercury has probably ~~n modified by contraction associated win the cooling of id large iron core arid possibly from stresses associated with the slowing of id spin ray over time, but the ex~nt of volcanism is urn own.
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From page 51... ...
Recent Progress Although the Moon is depleted of volatile elements' enrichments occur ~ Me surface: (1~ ~ the lunar poles' where hydrogen md perhaps other volatile species, possibly delivered by comet or other volatile-rich impaetors' have been trapped in cold' permanently shaded erasers; md (2) in ordinal surface regoli~, owing to implosion of solar wind.~° The po~tia1 production of propellant is signif~emt' because development eons for heavy lift launchers are high md have been viewed as stumbling blocks for planetary exploration strategies.
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From page 52... ...
As outlined in Be previous sections, samples afford Be mems to test specific hypotheses posed from orbital md lander missions. Most importantly, they provide day that emnof be overwise obtained' such as radiometrie ages for key surfaces md identification of isotopic md trace-element signatures of planets formation md evolution processes.
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From page 53... ...
Supporting llesear~h and Analysis A robust research md analysis (BOA) program is absolutely essential for maximizing the science return from missions to the inner planets.
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From page 54... ...
Although large missions to the inner planets are feasible md would terribly be of enormous value, He Irmer Plme~ Panel thinks that He timing of these two privily missions md He investment made would be well tuned to the current economic md political climate. Table 2.l summaries how these missions address key mienee questions diseussed above.
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From page 55... ...
Bock Po~-A`~ke~ Bm`n Sit ~~m (SPARSE. The next highly ranked mission for inner solar system exploration is understanding basin-forming processes arid impact chronology by returning samples from the Soup Pole-Ai~en Basin on ~e far side of the Moon.
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From page 58... ...
Are plme~ry Biospheres the remnant of gases that were originally solar in composition but Ben suffered massive hydrodynamic eseape,36 or did Hey acquire Biospheres from vol~iles ~~ had Trendy been differentiated~7 What was the role of impacts on Be ultimate compositions md evolution of Be ~rrestria1 plmets: Diserimin~ion between these events for each of the ironer plme~ is possible if noble gas isotopic ratios em be measured with ~ s~te-of-the-art neutral mass spectrometer. Previous spacecraft measurement have been inadequate to address these issues.
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From page 59... ...
Surface science experiment should include these: Near-infrared descent md lander cameras' win filers chosen to maximize surface~omposition information; ~ An instrument to measure He elemental geochemist of ~ surface sample' likely ~ x-ray fluorescence malywr or ~ new instrument utilizing technologies ~~ are currently being developed. This measurement will be done inside the lander on He surface; An imaging microscope to analyze the e ore sample during ascent; ~ An instrument to measure surface mineralogy.
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From page 60... ...
This mission is considered ~ medium~lass mission. The SPA-SR mission will address fundamental issues relevant to the impwt history of the inner planets arid the Ear~-Moon system md key remaining issues of lunar science.
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From page 61... ...
' to determine sources (solar wind' Biometry, meteoritic) md history (recent versus ancient)
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From page 62... ...
to determine interns structure' distribution of he~produeing elements, lateral md vertical heterogeneity of erupt md maples md He possible exis~ee of ~ ironrich core. Geophysical network science would address how small planetary bodies differentiate' how the bulk composition of the Moon is relend to He composition of Earth md how planetary compositions are relend to
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From page 63... ...
· ~ · . · ~ ~ ~ ~ r The inner solar system affords He opportunity to address broad objectives for understanding the history' current sates md po~ntia1 future of habitable planets.
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From page 64... ...
~ eomlusion' the inner planets hold fundamental clues to Be development of E~h-like plar~e~ in our solar sham md elsewhere. They provide Equable insights into He paths toward md Philip of hale environments.
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From page 65... ...
Khodakovsky' Cryochemical Studies ore Versus with the Leers from the Vega ~ Ad Vega ~ Probes>~' GO ~~er~o~l 23: 53-~> 1986.
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