New Frontiers in the Solar System An Integrated Exploration Strategy (2003) / Chapter Skim
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3 Mars: The Evolution of an Earth-like Planet
3 Mars: The Evolution of an Earth-like Planet
Pages 66-91
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From page 67... ...
Mariner ~ revealed towering volcanoes' polar caps' md reheels apparently euthy water. Systematic observations of Be surface md atmosphere by Viking led to ~ huge increase in our knowledge of the breads of martim geologic history md the dummies of the current climax.
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From page 68... ...
For example' He discovery of localized, very strong remnant magnetism in its ancient crust suggest ~~ early Mars had ~ active dynamo md ~ strong magnetic field. If this was He ease, it would have shielded He plmet from biologically harmful solar And cosmic)
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From page 69... ...
War vapor md ice crystals are premnt in the atmosphere, arid wear ice is almost certainly present within ~e martim regolith ~ high latitudes arid ~ the surface in polar regions. At increasing depth' where ~e rock is warmer as ~ result of the ply geothermal gradient liquid wear may be presmt in pore spaces.2 To dew ~ single mt of robotic studies he searched for exam life on Mars: ~e Viking life-de~tion experiments' which were desired to ~st for organisms ~~ used ~ Air carbon sours eider carbon dioxide or orchid molecules.
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From page 70... ...
FIGURE 3.2b Travertine deposits ~ the hlincrva Terrace, M~noth Hot Sprinted Ycllowstone Nation Park. Such deposits are intimately asocial with microbial communities, aspects of which are commonly preserve in the kavertine ~posits.
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From page 71... ...
We have direct observations of four exposed martim wear reservoirs, which include water vapor in He a~osphere, water fee in the atmosphere' seasonal water fee deposits ~ the surface' md permanent water fee deposits ~ the polar caps. Of He four' He martim polar caps are by far the most massive.
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From page 72... ...
Marty of them questions are motivated by geomorphic evidence such as runoff charmers' outflow charmers' arid other features ~~ have been in~rpre~d to merry ~~ liquid wear may have been present periodically on ~e surface of Mars in past epochs.~8 The recent MOS Mars Orbiter Camera arid Mars Orbital Lamr Altimeter observations have provided evidence for large ch~els ~~ once flowed from ~e southern highlands to Me nor~ern lowl~ds'i~ widespread mcient layering inferred by some to be of mdimm~ry origin,2° md small gullies on order walls that are considered to be evidence for recent erosion by fluids (Figure 3.3~.~i Atmosphere Our knowledge of the composition of ~e Mars Ionosphere is band on measurements of minor gases such as neon, krypton, md xenon md ratios of common isotopes in the ambient Exosphere 06Arp8Ar' i267~' i6Ofi7O' i6Ofi8O, i4Nii5N, thigh) by ~e Viking descent mass spechome~r, ground-based md airborne spectroscopy, md laboratory analysis of atmospheric gams captured in the vitreous components of martim memories.
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From page 73... ...
The image is 2.3 km wide ~d illumination is from the upper left. Mars Global Surveyor, Mars Orbiter Camera.
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From page 74... ...
Multidecade telescopic records of grew dust storms, multiyear surface pressure records acquired ~ the Viking larding sired multiyear orbiter observations of the appearar~e of ~e seasonal md residual polar caps, md large Derisions in ahnospheric wear make it clear thy the climax of Mars exhibit distinct Derisions from one year to the next (in~r~ua1 char~ges)
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From page 75... ...
75 FIGURE 3.4 The Mars Orbiter Emery on Mars Global Surveyor imaged the alternating layers of bright and dark mamria1 comprising the North Polar Cap. This image of one of the dark lanes crossing the cap reveals inferno layering.
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From page 76... ...
The moment of inertia depends on He distribution of density within ~ planet' md only ~ limited range of rock compositions have ~ given density. ~ Mars had ~ magnetic field in the past but Here is no present global field' ~ shown by high-amplitude magnetic mom alies detected in the southern highlands of Mars by He Mars Global Surveyor.28 ~ Crusta1 Slickness variations are fairly smooth across He dichotomy boundary between the northern md southern hemispheres of Mars; thus, ~ impact origin for He low-lying northern hemisphere is not favored.29 The crush thickness result are consistent with ~ plate tectonic hypothesis' but Hey do nof confirm that idea.
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From page 77... ...
Morphologic features creed by ruling water md, apparently, by Wading bodies of water em be seen on Mars. Fluvia1 features range in size from the Mint outflow reheels to valley networks to recently identified small' young eh~els.~5 Features indicative of siding bodies of wear range from putative shoreline features in the northern hemisphere' perhaps due to ~ ocem,36 to deltaie md in~aerater sediments' to finely layered bedding Sediments deposited in siding bodies of wear are high-privily sites for the preservation of fossils md hiosignatures.37 Mmy of the valley networks terminate in erasers, while Me outflow reheels primarily debouched to the northern plains.
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From page 78... ...
Is HEW FR0~ IN =E SOLAR MUM FIGURE 3.5 This wi~-~gle view from the Mars Orbiter Emery on Mars Global Surveyor shows the martian volcanoes ~raunius Tholus (~awe: ~d Ur~ius Tholus ,(uppe0. The prawns of impel craters on the' vol~ocs.
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From page 79... ...
ELey Question (questions with po~ntia1 for ~ paradigm-al~ring discovery with respect to the structure md evolution of Mars include ~e folowing: What rock Ins comprise ~e crust of Mars: ~ What are the nature md origin of Marks crusty magnetisms Questions with po~tia1 for ~ pivotal scientific discovery are ~ follows: What is the degree of internal activity in Marsh What is the size of the Martian cores arid is it partly or wholly liquids What was He origin arid fad of the Mars dynamo: What is the absolute chronology of the plar~et~ How does the oxidation sate of the Mars crust vary win depth Future Di~tiom Importmt directions for He future relating to Mars is structure md evolution include the following: A long-lived network of seismic stations is needed on Mars for determining the structure' properties, md aetivily of id interior.
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From page 80... ...
KEY MEASUREMENT OBJECTIVES On the basis of the current sate of Mars science reflected in this chapter as well as in other recent NO md NASA documents,39~40 the most importmt measurement objectives for hears have been identified md prioritized. The top priority is to obtain day to answer He question Did life ever arise on Hurst This panel concurs win He conclusions of earlier N1~C panels thy ~ definitive answer to this question em only be obtained via He study of samples returned to Ear~.4i Returned samples would also serve to support ~ number of other high-priority studies bearing on He climate md weathering history md geologic evolution of He planet.
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From page 81... ...
9 How has the atmosphere char~d over time Wh~ is the radi~ior1 environmerrt at the surfam of h5ars Wh~ is the r~:~ture of we:~ther or~ h4ars Clim~e Cordrol Wh~ is the ir~erarmua1 variatili~ of climate Wh~ has beer~ the long-term clima~ history of the plar~et~ Upper Atmosphere ~d Plasma Er~viror~mer~ Wh~ are the d~amics of the upper atmosphere Wh~ are the hot atom ~ur~d~ ~ s ~d e soape fluxes Wh~ are the ior~ esoape fluxes~ Wh~ are the ma~etic field cor~figur:~tior~9 Wh~ are the proms~s cor~trollir~g the ionospheric ener~tics o 00 o O O O O 00 0 00 0 00 0 00 0 O O O O O O O O O O O O 00 o o o o O O O o o o o o o O O O o o O O O ~ O ~ O O 00 00 O O NOTE: ~ the columr~ titled 1lP~1 Recommer~dir~g>~> solid ciroles i~r~ify the que~ions th~ eachpar~1 recommer~d for ~u~. The columr~ labeled 1lIr~olusion ir~ h~issions>> shows which missior~s will address these que~ions, solid ciroles si~ify missior~s th~ will cor~nka~ on e:~ch scien~ obje~ive' ~d oper~ ciroles si~ify ~ les~r 1~1 of ~er~ion to th~ obje~ive.
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From page 82... ...
In summary' ~e measurement objectives ~~ the Mars Parted has identified include ~e following: ~ Definitive measurements to ~st for the presence of extant or extinct life, or the geochemica1 arid organic chemical evidence for past biological activity. These measurements will require highly sophi~ic^d equipment procedures, arid sample proportion techniques not currently available' nor likely to be available in ~e foreseeable future' for in situ experimmts.
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From page 83... ...
Mars lapper Atmosphere Orbiter The need for ~ orbits mission to study He upper atmosphere of hears is identified above (see the section < |
From page 84... ...
Central to this debug is the question of sample return, on which there are two points of view. The firm view is thy the costs of sample return will be high in terms of the spaceport resources md ir~frashueture needed to handle' house, md analyze the samples.
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From page 85... ...
, arid by ~ fear thy without ~ clear commitment to sample return He hap will never achieve this goal arid will lose support. The choice of which paw to take is not necessarily ~ either-or proposition.
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From page 86... ...
, md ~ de~rmin~ion of this ratio in near-surface materials may constrain the time of Heir formation. Compositional md isotopic analysis of surface minerals' weathering rinds' md sedimentary deposits will establish He role of liquid wear md processes such as weathering The corresponding measurement on volatiles released from near-surface materials are likely to be more heterogeneous md may provide fossils of past atmospheric md chemical conditions ~~ allow the past climate to be better understood.
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From page 87... ...
Knowing the bulk composition of Mars is importers for understanding the origin of the planets. Seismology cart tell us whiner the core is ~1 solid, all liquid' or part solid arid part liquid (~ is Earths cores' which has ~ direct arid profound bearing on our understanding of plar~etary dynamos arid Me present-day lack of ~ Mars global magnetic field.
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From page 88... ...
It will be ess~tia1 for precursor missions to MS1l to incorporate Me teeing of essential technologies. Sample return md ~ long-lived surface network will require sophisticated ins~umm~tion for science md operations.
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From page 89... ...
Support for future robotic arid possible m~ed missions to Mars will require ~ long clim~ologica1 baseline. The long baseline' partially obtained with ground-~md arid HST telescopic date will also con~ibu~ to art understanding of the wear cycles between the atmosphere, regolith' arid polar caps, as well as spatially resolved dam on Jollily cycles of whorl carbon dioxide' carbon monoxide, arid ozone.
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From page 90... ...
Rowl~ds' Ad S.`T. Borg 11~tema1 Structure Ad Early Thermal Evolution of hears from Mars Global Surveyor Topography Ad Gravity>~>Sc~e 287: 1783-1793' 2000.
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From page 91... ...
shears Explor~ior~ Program Sciertific Goals' Objectives' ~~estig~ior~' Ad Priorities>~' Demmber 2000> irk Poor Explore Mary JPL 0 ~ -7> Jet Propulsion L~or~ory' Par Calif.> 2001.
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