Physical characteristics Mars

1 physical characteristics

1.1 internal structure
1.2 surface geology
1.3 soil
1.4 hydrology

1.4.1 polar caps


1.5 geography , naming of surface features

1.5.1 map of quadrangles
1.5.2 impact topography
1.5.3 volcanoes
1.5.4 tectonic sites
1.5.5 holes


1.6 atmosphere

1.6.1 aurora


1.7 climate

physical characteristics

mars approximately half diameter of earth surface area less total area of earth s dry land. mars less dense earth, having 15% of earth s volume , 11% of earth s mass, resulting in 38% of earth s surface gravity. red-orange appearance of martian surface caused iron(iii) oxide, or rust. can butterscotch; other common surface colors include golden, brown, tan, , greenish, depending on minerals present.

internal structure

like earth, mars has differentiated dense metallic core overlaid less dense materials. current models of interior imply core radius of 1,794 ± 65 kilometers (1,115 ± 40 mi), consisting of iron , nickel 16–17% sulfur. iron(ii) sulfide core thought twice rich in lighter elements earth s. core surrounded silicate mantle formed many of tectonic , volcanic features on planet, appears dormant. besides silicon , oxygen, abundant elements in martian crust iron, magnesium, aluminum, calcium, , potassium. average thickness of planet s crust 50 km (31 mi), maximum thickness of 125 km (78 mi). earth s crust averages 40 km (25 mi).

surface geology

mars terrestrial planet consists of minerals containing silicon , oxygen, metals, , other elements typically make rock. surface of mars composed of tholeiitic basalt, although parts more silica-rich typical basalt , may similar andesitic rocks on earth or silica glass. regions of low albedo suggest concentrations of plagioclase feldspar, northern low albedo regions displaying higher normal concentrations of sheet silicates , high-silicon glass. parts of southern highlands include detectable amounts of high-calcium pyroxenes. localized concentrations of hematite , olivine have been found. of surface covered finely grained iron(iii) oxide dust.

geologic map of mars (usgs, 2014)

although mars has no evidence of structured global magnetic field, observations show parts of planet s crust have been magnetized, suggesting alternating polarity reversals of dipole field have occurred in past. paleomagnetism of magnetically susceptible minerals similar alternating bands found on earth s ocean floors. 1 theory, published in 1999 , re-examined in october 2005 (with of mars global surveyor), these bands suggest plate tectonic activity on mars 4 billion years ago, before planetary dynamo ceased function , planet s magnetic field faded.

it thought that, during solar system s formation, mars created result of stochastic process of run-away accretion of material protoplanetary disk orbited sun. mars has many distinctive chemical features caused position in solar system. elements comparatively low boiling points, such chlorine, phosphorus, , sulphur, more common on mars earth; these elements pushed outward young sun s energetic solar wind.

after formation of planets, subjected so-called late heavy bombardment . 60% of surface of mars shows record of impacts era, whereas of remaining surface underlain immense impact basins caused events. there evidence of enormous impact basin in northern hemisphere of mars, spanning 10,600 8,500 km (6,600 5,300 mi), or 4 times size of moon s south pole – aitken basin, largest impact basin yet discovered. theory suggests mars struck pluto-sized body 4 billion years ago. event, thought cause of martian hemispheric dichotomy, created smooth borealis basin covers 40% of planet.

artist s impression of how mars may have looked 4 billion years ago

the geological history of mars can split many periods, following 3 primary periods:

noachian period (named after noachis terra): formation of oldest extant surfaces of mars, 4.5 3.5 billion years ago. noachian age surfaces scarred many large impact craters. tharsis bulge, volcanic upland, thought have formed during period, extensive flooding liquid water late in period.
hesperian period (named after hesperia planum): 3.5 between 3.3 , 2.9 billion years ago. hesperian period marked formation of extensive lava plains.
amazonian period (named after amazonis planitia): between 3.3 , 2.9 billion years ago present. amazonian regions have few meteorite impact craters, otherwise quite varied. olympus mons formed during period, lava flows elsewhere on mars.

geological activity still taking place on mars. athabasca valles home sheet-like lava flows created 200 mya. water flows in grabens called cerberus fossae occurred less 20 mya, indicating equally recent volcanic intrusions. on february 19, 2008, images mars reconnaissance orbiter showed evidence of avalanche 700-metre-high (2,300 ft) cliff.

soil


exposure of silica-rich dust uncovered spirit rover

the phoenix lander returned data showing martian soil alkaline , containing elements such magnesium, sodium, potassium , chlorine. these nutrients found in soils on earth, , necessary growth of plants. experiments performed lander showed martian soil has basic ph of 7.7, , contains 0.6% of salt perchlorate.

streaks common across mars , new ones appear on steep slopes of craters, troughs, , valleys. streaks dark @ first , lighter age. streaks can start in tiny area, spread out hundreds of metres. have been seen follow edges of boulders , other obstacles in path. commonly accepted theories include dark underlying layers of soil revealed after avalanches of bright dust or dust devils. several other explanations have been put forward, including involve water or growth of organisms.

hydrology

liquid water cannot exist on surface of mars due low atmospheric pressure, less 1% of earth s, except @ lowest elevations short periods. 2 polar ice caps appear made largely of water. volume of water ice in south polar ice cap, if melted, sufficient cover entire planetary surface depth of 11 meters (36 ft). permafrost mantle stretches pole latitudes of 60°. large quantities of water ice thought trapped within thick cryosphere of mars. radar data mars express , mars reconnaissance orbiter show large quantities of water ice @ both poles (july 2005) , @ middle latitudes (november 2008). phoenix lander directly sampled water ice in shallow martian soil on july 31, 2008.

photomicrograph opportunity showing gray hematite concretion, nicknamed blueberries , indicative of past existence of liquid water

landforms visible on mars suggest liquid water has existed on planet s surface. huge linear swathes of scoured ground, known outflow channels, cut across surface in 25 places. these thought record of erosion caused catastrophic release of water subsurface aquifers, though of these structures have been hypothesized result action of glaciers or lava. 1 of larger examples, ma adim vallis 700 km (430 mi) long, greater grand canyon, width of 20 km (12 mi) , depth of 2 km (1.2 mi) in places. thought have been carved flowing water in mars s history. youngest of these channels thought have formed few million years ago. elsewhere, particularly on oldest areas of martian surface, finer-scale, dendritic networks of valleys spread across significant proportions of landscape. features of these valleys , distribution imply carved runoff resulting precipitation in mars history. subsurface water flow , groundwater sapping may play important subsidiary roles in networks, precipitation root cause of incision in cases.

along crater , canyon walls, there thousands of features appear similar terrestrial gullies. gullies tend in highlands of southern hemisphere , face equator; poleward of 30° latitude. number of authors have suggested formation process involves liquid water, melting ice, although others have argued formation mechanisms involving carbon dioxide frost or movement of dry dust. no partially degraded gullies have formed weathering , no superimposed impact craters have been observed, indicating these young features, possibly still active. other geological features, such deltas , alluvial fans preserved in craters, further evidence warmer, wetter conditions @ interval or intervals in earlier mars history. such conditions require widespread presence of crater lakes across large proportion of surface, there independent mineralogical, sedimentological , geomorphological evidence.

composition of yellowknife bay rocks. rock veins higher in calcium , sulfur portage soil (curiosity, apxs, 2013).

further evidence liquid water once existed on surface of mars comes detection of specific minerals such hematite , goethite, both of form in presence of water. in 2004, opportunity detected mineral jarosite. forms in presence of acidic water, demonstrates water once existed on mars. more recent evidence liquid water comes finding of mineral gypsum on surface nasa s mars rover opportunity in december 2011. believed amount of water in upper mantle of mars, represented hydroxyl ions contained within minerals of mars s geology, equal or greater of earth @ 50–300 parts per million of water, enough cover entire planet depth of 200–1,000 m (660–3,280 ft).

on march 18, 2013, nasa reported evidence instruments on curiosity rover of mineral hydration, hydrated calcium sulfate, in several rock samples including broken fragments of tintina rock , sutton inlier rock in veins , nodules in other rocks knorr rock , wernicke rock. analysis using rover s dan instrument provided evidence of subsurface water, amounting as 4% water content, down depth of 60 cm (24 in), during rover s traverse bradbury landing site yellowknife bay area in glenelg terrain. in september 2015, nasa announced had found conclusive evidence of hydrated brine flows on recurring slope lineae, based on spectrometer readings of darkened areas of slopes. these observations provided confirmation of earlier hypotheses based on timing of formation , rate of growth, these dark streaks resulted water flowing in shallow subsurface. streaks contain hydrated salts, perchlorates, have water molecules in crystal structure. streaks flow downhill in martian summer, when temperature above −23 degrees celsius, , freeze @ lower temperatures.

researchers believe of low northern plains of planet covered ocean hundreds of meters deep, though remains controversial. in march 2015, scientists stated such ocean might have been size of earth s arctic ocean. finding derived ratio of water deuterium in modern martian atmosphere compared ratio on earth. amount of martian deuterium 8 times amount exists on earth, suggesting ancient mars had higher levels of water. results curiosity rover had found high ratio of deuterium in gale crater, though not high enough suggest former presence of ocean. other scientists caution these results have not been confirmed, , point out martian climate models have not yet shown planet warm enough in past support bodies of liquid water.

polar caps

mars has 2 permanent polar ice caps. during pole s winter, lies in continuous darkness, chilling surface , causing deposition of 25–30% of atmosphere slabs of co2 ice (dry ice). when poles again exposed sunlight, frozen co2 sublimes. these seasonal actions transport large amounts of dust , water vapor, giving rise earth-like frost , large cirrus clouds. clouds of water-ice photographed opportunity rover in 2004.

the caps @ both poles consist (70%) of water ice. frozen carbon dioxide accumulates comparatively thin layer 1 metre thick on north cap in northern winter only, whereas south cap has permanent dry ice cover 8 metres thick. permanent dry ice cover @ south pole peppered flat floored, shallow, circular pits, repeat imaging shows expanding meters per year; suggests permanent co2 cover on south pole water ice degrading on time. northern polar cap has diameter of 1,000 km (620 mi) during northern mars summer, , contains 1.6 million cubic kilometres (380,000 cu mi) of ice, which, if spread evenly on cap, 2 km (1.2 mi) thick. (this compares volume of 2.85 million cubic kilometres (680,000 cu mi) greenland ice sheet.) southern polar cap has diameter of 350 km (220 mi) , thickness of 3 km (1.9 mi). total volume of ice in south polar cap plus adjacent layered deposits has been estimated @ 1.6 million cubic km. both polar caps show spiral troughs, recent analysis of sharad ice penetrating radar has shown result of katabatic winds spiral due coriolis effect.

the seasonal frosting of areas near southern ice cap results in formation of transparent 1-metre-thick slabs of dry ice above ground. arrival of spring, sunlight warms subsurface , pressure subliming co2 builds under slab, elevating , rupturing it. leads geyser-like eruptions of co2 gas mixed dark basaltic sand or dust. process rapid, observed happening in space of few days, weeks or months, rate of change rather unusual in geology – mars. gas rushing underneath slab site of geyser carves spiderweb-like pattern of radial channels under ice, process being inverted equivalent of erosion network formed water draining through single plughole.

geography , naming of surface features




a mola-based topographic map showing highlands (red , orange) dominating southern hemisphere of mars, lowlands (blue) northern. volcanic plateaus delimit regions of northern plains, whereas highlands punctuated several large impact basins.



these new impact craters on mars occurred sometime between 2008 , 2014, detected orbit

although better remembered mapping moon, johann heinrich mädler , wilhelm beer first areographers . began establishing of mars s surface features permanent , more precisely determining planet s rotation period. in 1840, mädler combined ten years of observations , drew first map of mars. rather giving names various markings, beer , mädler designated them letters; meridian bay (sinus meridiani) feature .

today, features on mars named variety of sources. albedo features named classical mythology. craters larger 60 km named deceased scientists , writers , others have contributed study of mars. craters smaller 60 km named towns , villages of world populations of less 100,000. large valleys named word mars or star in various languages; small valleys named rivers.

large albedo features retain many of older names, updated reflect new knowledge of nature of features. example, nix olympica (the snows of olympus) has become olympus mons (mount olympus). surface of mars seen earth divided 2 kinds of areas, differing albedo. paler plains covered dust , sand rich in reddish iron oxides once thought of martian continents , given names arabia terra (land of arabia) or amazonis planitia (amazonian plain). dark features thought seas, hence names mare erythraeum, mare sirenum , aurorae sinus. largest dark feature seen earth syrtis major planum. permanent northern polar ice cap named planum boreum, whereas southern cap called planum australe.

mars s equator defined rotation, location of prime meridian specified, earth s (at greenwich), choice of arbitrary point; mädler , beer selected line first maps of mars in 1830. after spacecraft mariner 9 provided extensive imagery of mars in 1972, small crater (later called airy-0), located in sinus meridiani ( middle bay or meridian bay ), chosen definition of 0.0° longitude coincide original selection.

because mars has no oceans , hence no sea level , zero-elevation surface had selected reference level; called areoid of mars, analogous terrestrial geoid. 0 altitude defined height @ there 610.5 pa (6.105 mbar) of atmospheric pressure. pressure corresponds triple point of water, , 0.6% of sea level surface pressure on earth (0.006 atm). in practice, today surface defined directly satellite gravity measurements.

map of quadrangles

for mapping purposes, united states geological survey divides surface of mars thirty quadrangles , each named prominent physiographic feature within quadrangle. quadrangles can seen , explored via interactive image map below.

the thirty cartographic quadrangles of mars, defined united states geological survey. quadrangles numbered prefix mc mars chart. click on quadrangle name link , taken corresponding article. north @ top; 0°n 180°w / 0°n 180°w / 0; -180 @ far left on equator. map images taken mars global surveyor.






impact topography

bonneville crater , spirit rover s lander

the dichotomy of martian topography striking: northern plains flattened lava flows contrast southern highlands, pitted , cratered ancient impacts. research in 2008 has presented evidence regarding theory proposed in 1980 postulating that, 4 billion years ago, northern hemisphere of mars struck object one-tenth two-thirds size of earth s moon. if validated, make northern hemisphere of mars site of impact crater 10,600 8,500 km (6,600 5,300 mi) in size, or area of europe, asia, , australia combined, surpassing south pole–aitken basin largest impact crater in solar system.

fresh asteroid impact on mars @ 3°20′n 219°23′e / 3.34°n 219.38°e / 3.34; 219.38. these before , after images of same site taken on martian afternoons of march 27 , 28, 2012 respectively (mro)

mars scarred number of impact craters: total of 43,000 craters diameter of 5 km (3.1 mi) or greater have been found. largest confirmed of these hellas impact basin, light albedo feature visible earth. due smaller mass of mars, probability of object colliding planet half of earth. mars located closer asteroid belt, has increased chance of being struck materials source. mars more struck short-period comets, i.e., lie within orbit of jupiter. in spite of this, there far fewer craters on mars compared moon, because atmosphere of mars provides protection against small meteors , surface modifying processes have erased craters.

martian craters can have morphology suggests ground became wet after meteor impacted.

volcanoes

viking 1 image of olympus mons. volcano , related terrain approximately 550 km (340 mi) across.

the shield volcano olympus mons (mount olympus) extinct volcano in vast upland region tharsis, contains several other large volcanoes. olympus mons 3 times height of mount everest, in comparison stands @ on 8.8 km (5.5 mi). either tallest or second-tallest mountain in solar system, depending on how measured, various sources giving figures ranging 21 27 km (13 17 mi) high.

tectonic sites

valles marineris (2001 mars odyssey)

the large canyon, valles marineris (latin mariner valleys , known agathadaemon in old canal maps), has length of 4,000 km (2,500 mi) , depth of 7 km (4.3 mi). length of valles marineris equivalent length of europe , extends across one-fifth circumference of mars. comparison, grand canyon on earth 446 km (277 mi) long , 2 km (1.2 mi) deep. valles marineris formed due swelling of tharsis area, caused crust in area of valles marineris collapse. in 2012, proposed valles marineris not graben, plate boundary 150 km (93 mi) of transverse motion has occurred, making mars planet possibly two-tectonic plate arrangement.

holes

images thermal emission imaging system (themis) aboard nasa s mars odyssey orbiter have revealed 7 possible cave entrances on flanks of volcano arsia mons. caves, named after loved ones of discoverers, collectively known 7 sisters . cave entrances measure 100 252 m (328 827 ft) wide , estimated @ least 73 96 m (240 315 ft) deep. because light not reach floor of of caves, possible extend deeper these lower estimates , widen below surface. dena exception; floor visible , measured 130 m (430 ft) deep. interiors of these caverns may protected micrometeoroids, uv radiation, solar flares , high energy particles bombard planet s surface.

atmosphere


the tenuous atmosphere of mars visible on horizon

mars lost magnetosphere 4 billion years ago, possibly because of numerous asteroid strikes, solar wind interacts directly martian ionosphere, lowering atmospheric density stripping away atoms outer layer. both mars global surveyor , mars express have detected ionised atmospheric particles trailing off space behind mars, , atmospheric loss being studied maven orbiter. compared earth, atmosphere of mars quite rarefied. atmospheric pressure on surface today ranges low of 30 pa (0.030 kpa) on olympus mons on 1,155 pa (1.155 kpa) in hellas planitia, mean pressure @ surface level of 600 pa (0.60 kpa). highest atmospheric density on mars equal found 35 km (22 mi) above earth s surface. resulting mean surface pressure 0.6% of of earth (101.3 kpa). scale height of atmosphere 10.8 km (6.7 mi), higher earth s, 6 km (3.7 mi), because surface gravity of mars 38% of earth s, effect offset both lower temperature , 50% higher average molecular weight of atmosphere of mars.

the atmosphere of mars consists of 96% carbon dioxide, 1.93% argon , 1.89% nitrogen along traces of oxygen , water. atmosphere quite dusty, containing particulates 1.5 µm in diameter give martian sky tawny color when seen surface. may take on pink hue due iron oxide particles suspended in it.

potential sources , sinks of methane (ch

4) on mars

methane has been detected in martian atmosphere concentration of 30 ppb; occurs in extended plumes, , profiles imply methane released discrete regions. in northern midsummer, principal plume contained 19,000 metric tons of methane, estimated source strength of 0.6 kilograms per second. profiles suggest there may 2 local source regions, first centered near 30°n 260°w / 30°n 260°w / 30; -260 , second near 0°n 310°w / 0°n 310°w / 0; -310. estimated mars must produce 270 tonnes per year of methane.

methane can exist in martian atmosphere limited period before destroyed—estimates of lifetime range 0.6–4 years. presence despite short lifetime indicates active source of gas must present. volcanic activity, cometary impacts, , presence of methanogenic microbial life forms among possible sources. methane produced non-biological process called serpentinization involving water, carbon dioxide, , mineral olivine, known common on mars.

escaping atmosphere on mars (carbon, oxygen, , hydrogen) maven in uv

the curiosity rover, landed on mars in august 2012, able make measurements distinguish between different isotopologues of methane, if mission determine microscopic martian life source of methane, life forms reside far below surface, outside of rover s reach. first measurements tunable laser spectrometer (tls) indicated there less 5 ppb of methane @ landing site @ point of measurement. on september 19, 2013, nasa scientists, further measurements curiosity, reported no detection of atmospheric methane measured value of 6999180000000000000♠0.18±0.67 ppbv corresponding upper limit of 1.3 ppbv (95% confidence limit) and, result, conclude probability of current methanogenic microbial activity on mars reduced.

the mars orbiter mission india searching methane in atmosphere, while exomars trace gas orbiter, launched in 2016, further study methane decomposition products, such formaldehyde , methanol.

on december 16, 2014, nasa reported curiosity rover detected tenfold spike , localized, in amount of methane in martian atmosphere. sample measurements taken dozen times on 20 months showed increases in late 2013 , 2014, averaging 7 parts of methane per billion in atmosphere. before , after that, readings averaged around one-tenth level.

ammonia tentatively detected on mars mars express satellite, relatively short lifetime, not clear produced it. ammonia not stable in martian atmosphere , breaks down after few hours. 1 possible source volcanic activity.

in september 2017, nasa reported radiation levels on surface of planet mars temporarily doubled, , associated aurora 25-times brighter observed earlier, due massive, , unexpected, solar storm in middle of month.

aurora

in 1994, european space agency s mars express found ultraviolet glow coming magnetic umbrellas in southern hemisphere. mars not have global magnetic field guides charged particles entering atmosphere. mars has multiple umbrella-shaped magnetic fields in southern hemisphere, remnants of global field decayed billions of years ago.

in late december 2014, nasa s maven spacecraft detected evidence of widespread auroras in mars s northern hemisphere , descended approximately 20–30 degrees north latitude of mars s equator. particles causing aurora penetrated martian atmosphere, creating auroras below 100 km above surface, earth s auroras range 100 km 500 km above surface. magnetic fields in solar wind drape on mars, atmosphere, , charged particles follow solar wind magnetic field lines atmosphere, causing auroras occur outside magnetic umbrellas.

on march 18, 2015, nasa reported detection of aurora not understood , unexplained dust cloud in atmosphere of mars.

climate

of planets in solar system, seasons of mars earth-like, due similar tilts of 2 planets rotational axes. lengths of martian seasons twice of earth s because mars s greater distance sun leads martian year being 2 earth years long. martian surface temperatures vary lows of −143 °c (−225 °f) @ winter polar caps highs of 35 °c (95 °f) in equatorial summer. wide range in temperatures due thin atmosphere cannot store solar heat, low atmospheric pressure, , low thermal inertia of martian soil. planet 1.52 times far sun earth, resulting in 43% of amount of sunlight.

if mars had earth-like orbit, seasons similar earth s because axial tilt similar earth s. comparatively large eccentricity of martian orbit has significant effect. mars near perihelion when summer in southern hemisphere , winter in north, , near aphelion when winter in southern hemisphere , summer in north. result, seasons in southern hemisphere more extreme , seasons in northern milder otherwise case. summer temperatures in south can 30 k (30 °c; 54 °f) warmer equivalent summer temperatures in north.

mars has largest dust storms in solar system. these can vary storm on small area, gigantic storms cover entire planet. tend occur when mars closest sun, , have been shown increase global temperature.

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