Mars Explored

8/21/2019 Mars Explored

1/83

/DEAR WIKIPEDIA READERS:/ To protect our independence, we'll never runads. We survive on donations averaging about $15. Now is the time weask. If everyone reading this right now gave $3, our fundraiser would bedone within an hour. Yep, that's about the price of buying an engineer acoffee. We're a small non-profit with costs of a top 5 website: servers,staff and programs. Companies like Google and Facebook employ thousandsof engineers. Wikipedia only has about 100. If Wikipedia is useful to

you, please take one minute to make a tax-deductible donation to keep itonline and ad-free another year. /Thank you./

One-time Monthly*$3 $5 $10 $20$30 $50 $100 $Credit Card PayPal Amazon Boleto PayPal (USD)

Problems donating?

| Other ways to give| Frequently asked questions| By donating, you are agreeing to our donor privacy policy.The Wikimedia Foundation is a nonprofit, tax-exempt organization.By donating, you are agreeing to our donor privacy policyand to sharing your information with the Wikimedia Foundation and itsservice providers in the U.S. and elsewhere. The Wikimedia Foundation isa nonprofit, tax-exempt organization.By donating, you are agreeing to our donor privacy policy

and to sharing your information with the Wikimedia Foundationand its service providers in the U.S. and elsewhere. *Recurring paymentswill be debited by the Wikimedia Foundation until you notify us to stop.We

ll send you an email receipt for each payment, which will include alink to easy cancellation instructions.

Mars

From Wikipedia, the free encyclopediaJump to: navigation , search


2/83

This article is about the planet. For other uses, see Mars(disambiguation) .Page semi-protected This is a featured article. Click here for more information.Mars Astronomical symbol of Mars The planetMars

A computer-generated image of Mars from real data^[caption 1]DesignationsPronunciation Listen^i / m rz /

Adjectives MartianOrbital characteristics ^[2]Epoch J2000 Aphelion

249.2 million km

1.6660 AU Perihelion

206.7 million km

1.3814 AUSemi-major axis

227,939,100 km

1.523679 AUEccentricity 0.0934Orbital period

686.971 d1.8808 Julian years

668.5991 sols Synodic period

779.96 days

2.135 Julian yearsAverage orbital speed

24.077 km/s

Mean anomaly 19.3564

Inclination 1.850 to ecliptic


3/83

>5.65 to Sun

s equator 1.67 to invariable plane ^[1]Longitude of ascending node

49.562Argument of perihelion

286.537Satellites 2Physical characteristicsMean radius

3389.50.2 km^[a] ^[3]Equatorial radius

3396.20.1 km^[a] ^[3]

0.533 EarthsPolar radius

3,376.20.1 km^[a] ^[3]

0.531 EarthsFlattening 0.005890.00015Surface area

144,798,500 km^2

0.284 EarthsVolume

1.631810^11 km^3 ^[4]

0.151 EarthsMass

6.418510^23 kg^[4]

0.107 EarthsMean density

3.93350.0004^[4] g/cmSurface gravity

3.711 m/s ^[4]

0.376 /g /Moment of inertia factor

0.36620.0017^[5] Escape velocity

5.027 km/sSidereal rotation period

1.025957 d


4/83

24^h 37^m 22^s ^[4] Equatorial rotation velocity

868.22 km/h (241.17 m/s)Axial tilt

25.19North pole right ascension

21^h 10^m 44^s

317.68143North pole declination

52.88650Albedo

0.170 (geometric )^[6]

0.25 (Bond )^[7]

Surface temp. min mean maxKelvin 130 K 210 K^[7] 308 KCelsius -143 C^[9] -63 C35 C^[10]

Apparent magnitude +1.6 to -3.0^[8] Angular diameter

3.525.1^[7] Atmosphere^[7] ^[14] Surface pressure

0.636 (0.40.87) kPa Composition

* (mole fractions )^[/citation needed /] * 95.97% carbon dioxide * 1.93% argon * 1.89% nitrogen * 0.146% oxygen * 0.0557% carbon monoxide * 210 ppm water vapor * 100 ppm nitric oxide * 15 ppm molecular hydrogen ^[11]

* 2.5 ppm neon * 850 ppb HDO * 300 ppb krypton * 130 ppb formaldehyde * 80 ppb xenon * 18 ppb hydrogen peroxide ^[12] * 10 ppb methane ^[13]

*Mars* is the fourth planet from the Sun andthe second smallest planet in the Solar System ,after Mercury . Named after the Roman god of war , it is often

described as the "Red Planet" because the iron oxide prevalent on its surface gives it a reddishappearance .^[15]


5/83

Mars is a terrestrial planet with a thin atmosphere ,having surface features reminiscent both of the impact craters of the Moon and the volcanoes,valleys, deserts, and polar ice caps of Earth. The rotational period andseasonal cycles of Mars are likewise similar to those of Earth, as is

the tilt that produces the seasons. Mars is the site of Olympus Mons, the second highest known mountain within the SolarSystem (the tallest on a planet), and of Valles Marineris, one of the largest canyons. The smoothBorealis basin in the northern hemisphere covers40% of the planet and may be a giant impact feature.^[16] ^[17] Mars has two moons , Phobos and Deimos , which are small and irregularlyshaped. These may be captured asteroids ,^[18] ^[19] similar to 5261 Eureka, a Martian trojan asteroid

.

Until the first successful Mars flyby in 1965 by /Mariner 4/, many speculated about the presence of liquid wateron the planet's surface. This was based on observed periodic variationsin light and dark patches, particularly in the polar latitudes, which appeared to be seas and continents; long, darkstriations were interpreted by some asirrigation channels for liquid water. These straight line features werelater explained as optical illusions , thoughgeological evidence gathered by unmanned missions suggests that Marsonce had large scale water coverage on its surface at some earlier stageof its life.^[20] In 2005, radar data revealed

the presence of large quantities of water ice at the poles^[21] and at mid latitudes.^[22] ^[23] The Marsrover /Spirit / sampled chemical compoundscontaining water molecules in March 2007. The /Phoenix/ lander directly sampled water ice inshallow Martian soil on July 31, 2008.^[24]

Mars is host to seven functioning spacecraft : five inorbit the /Mars Odyssey /, /Mars Express/, /Mars Reconnaissance Orbiter/, /MAVEN / and /Mars

Orbiter Mission / and two on the surface Mars Exploration Rover /Opportunity/ and the Mars Science Laboratory /Curiosity /. Defunctspacecraft on the surface include MER A /Spirit/ and several other inertlanders and rovers such as the /Phoenix/ lander, which completed itsmission in 2008. Observations by the /Mars Reconnaissance Orbiter/ have revealed possible flowingwater during the warmest months on Mars.^[25]In 2013, NASA's Curiosity rover discovered that Mars' soil containsbetween 1.5% and 3% water by mass (about two pints of water per cubic

foot or 33 liters per cubic meter, albeit attached to other compoundsand thus not freely accessible).^[26]


6/83

Mars can easily be seen from Earth with the naked eye, as can itsreddish coloring. Its apparent magnitude reaches -3.0,^[8] which is surpassed only byJupiter , Venus , the Moon, and the Sun.Optical ground based telescopes are typically limited to resolvingfeatures about 300 km (186 miles) across when Earth and Mars are closestbecause of Earth's atmosphere.^[27]

Contents

[hide ]

* 1 Physical characteristics o 1.1 Internal structure o 1.2 Surface geology o 1.3 Soil o 1.4 Hydrology + 1.4.1 Polar caps

o 1.5 Geography and 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 o 1.6 Atmosphere o 1.7 Climate * 2 Orbit and rotation * 3 Search for life * 4 Habitability * 5 Exploration missions

* 6 Astronomy on Mars * 7 Viewing o 7.1 Closest approaches + 7.1.1 Relative + 7.1.2 Absolute, around the present time * 8 Historical observations o 8.1 Ancient and medieval observations o 8.2 Martian "canals" o 8.3 Spacecraft visitation * 9 In culture

o 9.1 Intelligent "Martians" * 10 Gallery * 11 Moons * 12 See also * 13 Notes * 14 References * 15 External links

Physical characteristics

Earth compared with Mars.

File:Mars.ogvPlay mediaMars animation (00:40) showing major features.


7/83

Mars has approximately half the diameter of Earth. Itis less dense than Earth, having about 15% of Earth's volume and 11% ofthe mass . Its surface area is onlyslightly less than the total area of Earth's dry land.^[7] While Mars is larger and more massive than Mercury, Mercury has a higher density. This results in

the two planets having a nearly identical gravitational pull at thesurface that of Mars is stronger by less than 1%. The red orangeappearance of the Martian surface is caused by iron(III) oxide, more commonly known as hematite, or rust.^[28] It can also lookbutterscotch,^[29] and other common surfacecolors include golden, brown, tan, and greenish, depending onminerals.^[29]

Internal structure

Like Earth, this planet has undergone differentiation, resulting in a dense, metallic coreregion overlaid by less dense materials.^[30] Current models of the planet's interior imply a core region about1,794

65 kilometres (1,115

40 mi) in radius, consisting primarily ofiron and nickel with about 1617% sulfur.^[31] This iron sulfide core is partially fluid, and it has twice theconcentration of the lighter elements that exist at Earth's core. Thecore is surrounded by a silicate mantle thatformed many of the tectonic and volcanic features on the planet, but itnow appears to be dormant. Besides silicon and oxygen, the most abundantelements in the Martian crust are iron, magnesium, aluminum, calcium,

and potassium. The average thickness of the planet's crust is about50 km (31 mi), with a maximum thickness of 125 km (78 mi).^[32] Earth's crust, averaging 40 km (25 mi), is onlyone third as thick as Mars's crust, relative to the sizes of the twoplanets. The InSight lander planned for 2016 will use aseismometer to better constrain the models of theinterior.

Surface geology

Main article: Geology of Mars

Mars is a terrestrial planet that consists ofminerals containing silicon and oxygen ,metals , and other elements that typically make up rock. The surface of Mars is primarily composed oftholeiitic basalt ,^[33] although parts are more silica rich than typical basalt and may be similar to andesitic rocks on Earth or silica glass. Regions of low albedo show concentrations of plagioclase feldspar, with northern low albedo regionsdisplaying higher than normal concentrations of sheet silicates andhigh silicon glass. Parts of the southern highlands include detectable

amounts of high calcium pyroxenes . Localizedconcentrations of hematite and olivine have also been found.^[34] Much of the surface


8/83

is deeply covered by finely grained iron(III) oxide dust.^[35] ^[36]

Mars Geologic Map

(USGS ; 14 July 2014)(full / video).^[37] ^[38] ^[39]

Although Mars has no evidence of a current structured global magneticfield ,^[40] observations show that parts of the planet's crust have been magnetized,and that alternating polarity reversals of its dipole field haveoccurred in the past. This paleomagnetism ofmagnetically susceptible minerals has properties that are similar to the

alternating bands found on the ocean floors of Earth. One theory, published in 1999 and re examinedin October 2005 (with the help of the /Mars Global Surveyor/), is that these bands demonstrate platetectonics on Mars four billion years ago, before the planetary dynamo ceased to function and the planet's magnetic fieldfaded away.^[41]

During the Solar System's formation, Mars was created asthe result of a stochastic process ofrun away accretion out of the protoplanetary disk

that orbited the Sun. Mars has manydistinctive chemical features caused by its position in the SolarSystem. Elements with comparatively low boiling points, such aschlorine, phosphorus, and sulphur, are much more common on Mars thanEarth; these elements were probably removed from areas closer to the Sunby the young star's energetic solar wind .^[42]

After the formation of the planets, all were subjected to the so called"Late Heavy Bombardment ". About 60% ofthe surface of Mars shows a record of impacts from that era,^[43] ^[44] ^[45]

while much of the remaining surface is probablyunderlain by immense impact basins caused by those events. There isevidence of an enormous impact basin in the northern hemisphere of Mars,spanning 10,600 km by 8,500 km, or roughly four times larger than theMoon's South Pole Aitken basin, the largest impact basin yetdiscovered.^[16] ^[17] This theory suggests that Mars wasstruck by a Pluto sized body about four billion years ago.The event, thought to be the cause of the Martian hemispheric dichotomy, created the smooth Borealis basin that covers 40% of the planet.^[46] ^[47]

The geological history of Mars can be split into many periods, but thefollowing are the three primary periods:^[48]


9/83

^[49]

This Mars rock revealed its bluish gray interior to Mars ScienceLaboratory^[50]

* *Noachian period * (named after Noachis Terra ): Formation of the oldest extant surfaces of Mars, 4.5 billion years ago to 3.5 billion years ago. Noachian age surfaces are scarred by many large impact craters. The Tharsis bulge, a volcanic upland, is thought to have formed during this period, with extensive flooding by liquid water late in the period. * *Hesperian period * (named after Hesperia Planum ): 3.5 billion years ago to 2.93.3 billion years ago. The Hesperian period is marked by the formation of extensive lava plains. * *Amazonian period * (named after Amazonis

Planitia ): 2.93.3 billion years ago to present. Amazonian regions have few meteorite impact craters, but are otherwise quite varied. Olympus Mons formed during this period, along with lava flows elsewhere on Mars.

Some geological activity is still taking place on Mars. The AthabascaValles is home to sheet like lava flows up toabout 200 Mya . Water flows in the grabens called theCerberus Fossae occurred less than 20 Mya,indicating equally recent volcanic intrusions.^[51] On February 19, 2008, images from the /MarsReconnaissance Orbiter / showed

evidence of an avalanche from a 700 m high cliff.^[52]

Soil

Main article: Martian soil Exposure of silica rich dust uncovered by the /Spirit/ rover

The /Phoenix / lander returned data showingMartian soil to be slightly alkaline and containing elements such asmagnesium , sodium , potassium and chlorine . These nutrients arefound in gardens on Earth, and they are necessary for growth ofplants.^[53] Experiments performed by theLander showed that the Martian soil has a basic pH of 8.3, and may contain traces of the salt perchlorate .^[54] ^[55]

Streaks are common across Mars and new ones appear frequently on steepslopes of craters, troughs, and valleys. The streaks are dark at first

and get lighter with age. Sometimes, the streaks start in a tiny areawhich then spread out for hundreds of metres. They have also been seento follow the edges of boulders and other obstacles in their path. The


10/83

commonly accepted theories include that they are dark underlying layersof soil revealed after avalanches of bright dust or dust devils.^[56] Several explanations have been putforward, some of which involve water or even the growth oforganisms.^[57] ^[58]

Hydrology

Main article: Water on Mars Microscopic photo taken by /Opportunity /showing a gray hematite concretion ,indicative of the past presence of liquid water

Liquid water cannot exist on the surface of Mars due to low atmosphericpressure, except at the lowest elevations for short periods.^[59]

^[60] The two polar ice capsappear to be made largely of water.^[61] ^[62] The volume of water ice in the south polar icecap, if melted, would be sufficient to cover the entire planetarysurface to a depth of 11 meters.^[63] Apermafrost mantle stretches from the pole tolatitudes of about 60.^[61]

Large quantities of water ice are thought to be trappedwithin the thick cryosphere of Mars. Radar data from/Mars Express / and the /Mars Reconnaissance Orbiter/ show large quantities of water ice

both at the poles (July 2005)^[21] ^[64] and at mid latitudes (November 2008).^[22] The Phoenix lander directly sampled waterice in shallow Martian soil on July 31, 2008.^[24]

Landforms visible on Mars strongly suggest thatliquid water has at least at times existed on the planet's surface. Hugelinear swathes of scoured ground, known as outflow channels, cut across the surface in around 25 places.These are thought to record erosion which occurred during thecatastrophic release of water from subsurface aquifers, though some of

these structures have also been hypothesized to result from the actionof glaciers or lava.^[65] ^[66] One of the larger examples, Ma'adim Vallis is 700 km long and much bigger than the GrandCanyon with a width of 20 km and a depth of 2 km in some places. It isthought to have been carved by flowing water early in Mars'history.^[67] The youngest of thesechannels are thought to have formed as recently as only a few millionyears ago.^[68] Elsewhere, particularly on theoldest areas of the Martian surface, finer scale, dendritic networks ofvalleys are spread across significantproportions of the landscape. Features of these valleys and theirdistribution strongly imply that they were carved by runoff

resulting from rain or snow fall in early Marshistory. Subsurface water flow and groundwater sapping may play important subsidiary roles in some


11/83

networks, but precipitation was probably the root cause of the incisionin almost all cases.^[69]

Along crater and canyon walls, there are also thousands of features thatappear similar to terrestrial gullies . The gullies tendto be in the highlands of the southern hemisphere and to face theEquator; all are poleward of 30 latitude. A number of authors have

suggested that their formation process demands the involvement of liquidwater, probably from melting ice,^[70] ^[71] although others have argued for formationmechanisms involving carbon dioxide frost or the movement of drydust.^[72] ^[73] No partially degraded gullies have formed by weathering and nosuperimposed impact craters have been observed, indicating that theseare young features, possibly even active today.^[71]

Other geological features, such as deltas andalluvial fans preserved in craters, also argue

strongly for warmer, wetter conditions at some interval or intervals inearlier Mars history.^[74] Such conditionsnecessarily require the widespread presence of crater lakes across a large proportion of the surface, for which there is alsoindependent mineralogical, sedimentological and geomorphologicalevidence.^[75] Some authors have even goneso far as to argue that at times in the Martian past, much of the lownorthern plains of the planet were covered with a true ocean hundreds ofmeters deep, though this remains controversial.^[76]

Composition of "Yellowknife Bay" rocks rock veins are higher in calcium and sulfur than "Portage" soil APXSresults Curiosity rover (March, 2013).

Further evidence that liquid water once existed on thesurface of Mars comes from the detection of specific minerals such ashematite and goethite , both of which

sometimes form in the presence of water.^[77] Some of the evidence believed to indicate ancient water basins and flowshas been negated by higher resolution studies by the Mars ReconnaissanceOrbiter.^[78] In 2004, /Opportunity/ detected themineral jarosite . This forms only in the presence ofacidic water, which demonstrates that water once existed on Mars.^[79] More recent evidence for liquid water comesfrom the finding of the mineral gypsum on the surface byNASA's Mars rover Opportunity in December 2011.^[80] ^[81] Additionally, the study leader Francis McCubbin, a planetary scientistat the University of New Mexico in Albuquerque looking at hydroxals incrystalline minerals from Mars, states that the amount of water in the

upper mantle of Mars is equal to or greater than that of Earth at 50300parts per million of water, which is enough to cover the entire planetto a depth of 2001,000 m (6603,280 ft).^[82]


12/83

On March 18, 2013, NASA reported evidence from instrumentson the Curiosity rover of mineral hydration, likely hydrated calcium sulfate, in several rock samples including the broken fragments of "Tintina" rock

and "Sutton Inlier" rock as wellas in veins and nodules in other rocks like "Knorr" rock and "Wernicke" rock .^[83] ^[84] ^[85] Analysis using the rover's DAN instrument providedevidence of subsurface water, amounting to as much as 4% water content,down to a depth of 60 cm, in the rover's traverse from the /BradburyLanding / site to the /Yellowknife Bay/ area inthe /Glenelg / terrain.^[83]

Polar caps

Main article: Martian polar ice caps North polar early summer ice cap (1999)South polar midsummer ice cap (2000)

Mars has two permanent polar ice caps. During a pole's winter, it liesin continuous darkness, chilling the surface and causing the deposition of 2530% of the atmosphere into

slabs of CO_2 ice (dry ice ).^[86] When the poles are again exposed to sunlight,the frozen CO_2 sublimes , creatingenormous winds that sweep off the poles as fast as 400 km/h. Theseseasonal actions transport large amounts of dust and water vapor, givingrise to Earth like frost and large cirrus clouds .Clouds of water ice were photographed by the /Opportunity/ rover in 2004.^[87]

The polar caps at both poles consist primarily of water ice. Frozencarbon dioxide accumulates as a comparatively thin layer about one metrethick on the north cap in the northern winter only, while the south cap

has a permanent dry ice cover about eight metres thick.^[88] This permanent dry ice cover at thesouth pole is peppered by flat floored, shallow, roughly circular pits, which repeat imaging shows are expandingby meters per year; this suggests that the permanent CO_2 cover over thesouth pole water ice is degrading over time.^[89] The northern polar cap has a diameter of about1,000 kilometres during the northern Mars summer,^[90] and contains about 1.6 million cubic km of ice,which, if spread evenly on the cap, would be 2 km thick.^[91] (This compares to a volume of 2.85 million cubickm (km^3 ) for the Greenland ice sheet .) Thesouthern polar cap has a diameter of 350 km and a thickness of

3 km.^[92] The total volume of ice in the southpolar cap plus the adjacent layered deposits has also been estimated at1.6 million cubic km.^[93] Both polar caps show


13/83

spiral troughs, which recent analysis of SHARAD icepenetrating radar has shown are a result of katabatic winds that spiral due to the Coriolis Effect.^[94]^[95]

The seasonal frosting of some areas near the southern ice cap results inthe formation of transparent 1

metre

thick slabs of dry ice above theground. With the arrival of spring, sunlight warms the subsurface andpressure from subliming CO_2 builds up under a slab, elevating andultimately rupturing it. This leads to geyser like eruptions of CO_2 gas mixed with dark basaltic sand ordust. This process is rapid, observed happening in the space of a fewdays, weeks or months, a rate of change rather unusual in geology especially for Mars. The gas rushing underneath a slab to the site of ageyser carves a spider

like pattern of radial channels under the ice,the process being the inverted equivalent of an erosion network formed

by water draining through a single plughole.^[96] ^[97] ^[98] ^[99]

Geography and naming of surface features

Main article: Geography of Mars See also: Category:Surface features of MarsA MOLA based topographic map

showing highlands (red and orange) dominating the southern hemisphere ofMars, lowlands (blue) the northern. Volcanic plateaus delimit thenorthern plains in some regions, while the highlands are punctuated byseveral large impact basins.

Although better remembered for mapping the Moon, Johann Heinrich Mdler and Wilhelm Beer were the first "areographers". They began byestablishing that most of Mars's surface features were permanent and bymore precisely determining the planet's rotation period. In 1840, Mdlercombined ten years of observations and drew the first map of Mars.Rather than giving names to the various markings, Beer and Mdler simply

designated them with letters; Meridian Bay (Sinus Meridiani) was thusfeature "/a/".^[100]

Today, features on Mars are named from a variety of sources. Albedofeatures are named for classical mythology. Craters larger than 60 kmare named for deceased scientists and writers and others who havecontributed to the study of Mars. Craters smaller than 60 km are namedfor towns and villages of the world with populations of less than100,000. Large valleys are named for the word "Mars" or "star" invarious languages; small valleys are named for rivers.^[101]

Large albedo features retain many of the older names, but

are often updated to reflect new knowledge of the nature of thefeatures. For example, /Nix Olympica/ (the snows of Olympus) has become/Olympus Mons/ (Mount Olympus).^[102]


14/83

The surface of Mars as seen from Earth is divided into two kinds ofareas, with differing albedo. The paler plains covered with dust andsand rich in reddish iron oxides were once thought of as Martian"continents" and given names like Arabia Terra (/land of Arabia/) or Amazonis Planitia (/Amazonian plain/). The dark features were thought to be seas, hencetheir names Mare Erythraeum , Mare Sirenum and

Aurorae Sinus . The largest dark feature seen fromEarth is Syrtis Major Planum .^[103] The permanent northern polar ice cap isnamed Planum Boreum , while the southern cap iscalled Planum Australe .

Mars's equator is defined by its rotation, but the location of its PrimeMeridian was specified, as was Earth's (atGreenwich ), by choice of an arbitrary point; Mdlerand Beer selected a line in 1830 for their first maps of Mars. After thespacecraft Mariner 9 provided extensive imagery ofMars in 1972, a small crater (later called Airy 0 ),

located in the Sinus Meridiani ("Middle Bay" or"Meridian Bay"), was chosen for the definition of 0.0 longitude tocoincide with the original selection.^[104]

Since Mars has no oceans and hence no "sea level", a zero elevationsurface also had to be selected as a reference level; this is alsocalled the /areoid/^[105] of Mars,analogous to the terrestrial geoid . Zero altitude wasdefined by the height at which there is 610.5 Pa (6.105 mbar ) of atmospheric pressure.^[106] This pressure corresponds to the triple point of water, and it is about 0.6% of the sea level

surface pressure on Earth (0.006 atm).^[107] In practice, today this surface is defined directly from satellitegravity measurements.

Map of quadrangles

The following imagemap of the planet Mars is dividedinto the 30 quadrangles defined bythe United States Geological Survey^[108] ^[109] The quadrangles

are numbered with the prefix "MC" for "Mars Chart."^[110] Click on the quadrangle and you will be taken to thecorresponding article pages. North is at the top;WikiMiniAtlas0N 180W/ 0N 180W/ 0; 180is at the far left on the equator . The map imageswere taken by the Mars Global Surveyor .

Mars Quad MapAbout this image WikiMiniAtlas

0N 180W/ 0N 180W/ 0; 180


15/83

WikiMiniAtlas0N 0W/ 0N 0E/ 0; 0

WikiMiniAtlas

90N 0W/ 90N 0E/ 90; 0

MC 01 Mare Boreum

MC 02 Diacria

MC

03 Arcadia

MC 04 Mare Acidalium

MC 05 Ismenius Lacus

MC 06 Casius

MC

07 Cebrenia

MC 08 Amazonis

MC 09 Tharsis

MC 10 Lunae Palus

MC 11 Oxia Palus

MC

12 Arabia

MC 13 Syrtis Major

MC 14 Amenthes

MC 15 Elysium

MC 16

Memnonia

MC 17


16/83

Phoenicis

MC 18 Coprates

MC 19 Margaritifer

MC 20 Sabaeus

MC 21 Iapygia

MC 22 Tyrrhenum

MC

23 Aeolis

MC 24 Phaethontis

MC 25 Thaumasia

MC 26 Argyre

MC

27 Noachis

MC 28 Hellas

MC 29 Eridania

MC 30 Mare Australe

Impact topography

Bonneville crater and /Spirit/ rover's lander

The dichotomy of Martian topography isstriking: northern plains flattened by lava flows contrast with thesouthern highlands, pitted and cratered by ancient impacts. Research in2008 has presented evidence regarding a theory proposed in 1980postulating that, four billion years ago, the northern hemisphere ofMars was struck by an object one tenth to two thirds the size of Earth'sMoon . If validated, this would make the northern hemisphereof Mars the site of an impact crater 10,600 kmlong by 8,500 km wide, or roughly the area of Europe, Asia, and

Australia combined, surpassing the South PoleAitken basin as the largest impact crater inthe Solar System.^[16] ^[17]


17/83

Fresh asteroid impact on MarsWikiMiniAtlas320N 21923E/ 3.34N 219.38E/ 3.34; 219.38 /before//March 27 & /after//March 28, 2012 (MRO).^[111]

Mars is scarred by a number of impact craters: a total of 43,000 craterswith a diameter of 5 km or greater have been found.^[112] The largest confirmed of these is the Hellasimpact basin , a light albedo feature

clearly visible from Earth.^[113] Due to the smaller mass of Mars, theprobability of an object colliding with the planet is about half that ofthe Earth. Mars is located closer to the asteroid belt, so it has an increased chance of being struck bymaterials from that source. Mars is also more likely to be struck byshort

period comets , /i.e./, those that lie within theorbit of Jupiter.^[114] In spite of this, thereare far fewer craters on Mars compared with the Moon, because theatmosphere of Mars provides protection against small meteors. Somecraters have a morphology that suggests the ground became wet after themeteor impacted.^[115]

Volcanoes

Viking orbiter view of Olympus MonsMOLA colorized shaded relief map ofwestern hemisphere of Mars showing Tharsis bulge (shadesof red and brown). Tall volcanoes appear white.

Main article: Volcanism on Mars

The shield volcano Olympus Mons (/Mount Olympus/) is an extinct volcano in the vastupland region Tharsis , which contains several otherlarge volcanoes. Olympus Mons is roughly three times the height of MountEverest , which in comparison stands at just over8.8 km.^[116] It is either the tallest orsecond tallest mountain in the solar system, depending on how it ismeasured, with various sources giving figures ranging from about 21 to27 km high.^[117] ^[118]

Tectonic sites

The large canyon, Valles Marineris (Latin for


18/83

/Mariner Valleys/, also known as Agathadaemon inthe old canal maps), has a length of 4,000 km and a depth of up to 7 km.The length of Valles Marineris is equivalent to the length of Europe andextends across one fifth the circumference of Mars. By comparison, theGrand Canyon on Earth is only 446 km (277 mi) longand nearly 2 km (1.2 mi) deep. Valles Marineris was formed due to theswelling of the Tharsis area which caused the crust in the area of

Valles Marineris to collapse. In 2012, it was proposed that VallesMarineris is not just a graben , but also a plate boundarywhere 150 km of transverse motion has occurred,making Mars a planet with possibly a two plate tectonic arrangement.^[119] ^[120]

Holes

Images from the Thermal Emission Imaging System (THEMIS) aboard NASA's Mars

Odyssey orbiter have revealed seven possiblecave entrances on the flanks of the volcano Arsia Mons.^[121] Thecaves, named after loved ones of their discoverers, are collectivelyknown as the "seven sisters."^[122] Caveentrances measure from 100 m to 252 m wide and they are believed to beat least 73 m to 96 m deep. Because light does not reach the floor ofmost of the caves, perhaps they extend much deeper than these lowerestimates and widen below the surface. "Dena" is the only exception; itsfloor is visible and was measured to be 130 m deep. The interiors ofthese caverns may be protected from micrometeoroids, UV radiation, solarflares and high energy particles that bombard theplanet's surface.^[123]

Atmosphere

Main article: Atmosphere of Mars Mars escaping atmosphere carbon, oxygen , hydrogen (MAVEN; UV ;October 14, 2014).^[124]

Mars lost its magnetosphere 4 billion yearsago,^[125] so the solar wind interacts directly with the Martian ionosphere ,lowering the atmospheric density by stripping away atoms from the outerlayer. Both Mars Global Surveyor and MarsExpress have detected ionised atmospheric particles trailing off intospace behind Mars,^[125] ^[126] and this atmospheric loss will be studied by theupcoming MAVEN orbiter. Compared to Earth, the atmosphere of Mars is quite rarefied. Atmosphericpressure on the surface today ranges from alow of 30 Pa (0.030 kPa ) onOlympus Mons to over 1,155 Pa (1.155 kPa) in Hellas

Planitia , with a mean pressure at the surfacelevel of 600 Pa (0.60 kPa).^[127] Thehighest atmospheric density on Mars is equal to that found 35 km


19/83

(22 mi)^[128] above the Earth's surface. Theresulting mean surface pressure is only 0.6% of that of the Earth (101.3kPa). The scale height of the atmosphere is about10.8 km (6.7 mi),^[129] which is higher thanEarth's (6 km (3.7 mi)) because the surface gravity of Mars is onlyabout 38% of Earth's, an effect offset by both the lower temperature and50% higher average molecular weight of the atmosphere of Mars.

Tenuous atmosphere of Mars visible on thehorizon.

The atmosphere of Mars consists of about 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen andwater.^[7] ^[130] Theatmosphere is quite dusty, containing particulates about 1.5 m in diameter which give the Martian sky a tawny

color when seen from the surface.^[131]

Methane has been detected in the Martian atmosphere with a mole fraction of about 30 ppb ;^[13] ^[132] it occurs inextended plumes, and the profiles imply that the methane was releasedfrom discrete regions. In northern midsummer, the principal plumecontained 19,000 metric tons of methane, with an estimated sourcestrength of 0.6 kilogram per second.^[133] ^[134] The profiles suggest that there may betwo local source regions, the first centered near

WikiMiniAtlas30N 260W/ 30N 260W/ 30; 260and the second nearWikiMiniAtlas0N 310W/ 0N 310W/ 0; 310.^[133] It is estimated that Mars must produce 270tonnes per year of methane.^[133] ^[135]

The implied methane destruction lifetime may be as long as about 4 Earthyears and as short as about 0.6 Earth years.^[133] ^[136] This rapidturnover would indicate an active source of the gas on the planet.Volcanic activity, cometary impacts, andthe presence of methanogenic microbial life forms are among possible sources. Methanecould also be produced by a non biological process called/serpentinization /^[b] involving water, carbon dioxide, andthe mineral olivine , which is known tobe common on Mars.^[137]


20/83

Methane on Mars "potential sourcesand sinks" (November 2, 2012).

The Curiosity rover , which landed on Mars inAugust 2012, is able to make measurements that distinguish betweendifferent isotopologues of methane,^[138] but even ifthe mission is to determine that microscopic Martian life is the source

of the methane, the life forms likely reside far below the surface,outside of the rover's reach.^[139] The firstmeasurements with the Tunable Laser Spectrometer (TLS) indicated that there is less than 5 ppbof methane at the landing site at the point of the measurement.^[140] ^[141] ^[142] ^[143] OnSeptember 19, 2013, NASA scientists, from further measurements byCuriosity, reported no detection of atmospheric methane with a measured value of 0.18

0.67 ppbvcorresponding to an upper limit of only 1.3 ppbv (95% confidence limit)and, as a result, conclude that the probability of current methanogenic

microbial activity on Mars is reduced.^[144] ^[145] ^[146] The Mars Trace Gas Mission orbiter planned to launch in 2016 wouldfurther study the methane,^[147] ^[148] as well as its decomposition products such asformaldehyde and methanol .

Ammonia was also tentatively detected on Mars by the Mars Expresssatellite, but with its relatively short lifetime, it is not clear whatproduced it.^[149] Ammonia is not stable in theMartian atmosphere and breaks down after a few hours. One possiblesource is volcanic activity.^[149]

Climate

Main article: Climate of Mars

Dust storm on Mars.

November 18, 2012November 25, 2012

Opportunity and Curiosity rovers are noted.

Of all the planets in the Solar System, the seasons of Mars are the mostEarth like, due to the similar tilts of the two planets' rotationalaxes. The lengths of the Martian seasons are about twice those ofEarth's because Mars's greater distance from the Sun leads to theMartian year being about two Earth years long. Martian surfacetemperatures vary from lows of about -143 C (at the winter polarcaps)^[9] to highs of up to 35 C (in equatorialsummer).^[10] The wide range in temperatures is dueto the thin atmosphere which cannot store much solar heat, the lowatmospheric pressure, and the low thermal inertia

of Martian soil.^[150] The planet is also 1.52 times as far fromthe Sun as Earth, resulting in just 43% of the amount of sunlight.^[151]


21/83

If Mars had an Earth like orbit, its seasons would be similar to Earth'sbecause its axial tilt is similar to Earth's. Thecomparatively large eccentricity of theMartian orbit has a significant effect. Mars is near perihelion when it is summer in the southern hemisphere and winter in

the north, and near aphelion when it is winter in thesouthern hemisphere and summer in the north. As a result, the seasons inthe southern hemisphere are more extreme and the seasons in the northernare milder than would otherwise be the case. The summer temperatures inthe south can reach up to 30 kelvins warmer than theequivalent summer temperatures in the north.^[152]

Mars also has the largest dust storms in the SolarSystem. These can vary from a storm over a small area, to giganticstorms that cover the entire planet. They tend to occur when Mars isclosest to the Sun, and have been shown to increase the global

temperature.^[153]

Orbit and rotation

Main article: Orbit of Mars Mars is about 143 million miles from the Sun; its orbital period is 687(Earth) days

depicted in red

Earth's orbit in blue.

Mars's average distance from the Sun is roughly 230 million km (1.5 AU,or 143 million miles), and its orbital period is 687 (Earth) days. The

solar day (or sol ) on Mars is only slightlylonger than an Earth day: 24 hours, 39 minutes, and 35.244 seconds. AMartian year is equal to 1.8809 Earth years, or 1 year, 320 days, and18.2 hours.^[7]

The axial tilt of Mars is 25.19 degrees, which is similar to the axialtilt of the Earth.^[7] As a result, Mars hasseasons like the Earth, though on Mars, they are nearly twice as longgiven its longer year. Currently, the orientation of the north pole of Mars is close to the star Deneb.^[14] Mars passed an aphelion in March 2010^[154] and its

perihelion in March 2011.^[155] The next aphelion came in February 2012^[155] and the next perihelion came in January2013.^[155]

Mars has a relatively pronounced orbital eccentricity of about 0.09; of the seven other planetsin the Solar System, only Mercury shows greatereccentricity. It is known that in the past, Mars has had a much morecircular orbit than it does currently. At one point, 1.35 million Earthyears ago, Mars had an eccentricity of roughly 0.002, much less thanthat of Earth today.^[156] The Marscycle of eccentricity is 96,000 Earth years compared to the Earth's

cycle of 100,000 years.^[157] Mars also has amuch longer cycle of eccentricity with a period of 2.2 million Earthyears, and this overshadows the 96,000 year cycle in the eccentricity


22/83

graphs. For the last 35,000 years, the orbit of Mars has been gettingslightly more eccentric because of the gravitational effects of theother planets. The closest distance between the Earth and Mars willcontinue to mildly decrease for the next 25,000 years.^[158]

Search for life

Main articles: Life on Mars and Viking spacecraftbiological experiments Viking 1 Lander

sampling arm created deep trenches, scooping upmaterial for tests (Chryse Planitia ).

The current understanding of planetary habitability the ability of a world to develop andsustain life favors planets that have liquid water on their surface.

This most often requires that the orbit of a planet lie within thehabitable zone , which for the Sunextends from just beyond Venus to about the semi

major axis of Mars.^[159] Duringperihelion, Mars dips inside this region, but the planet's thin(low pressure) atmosphere prevents liquid water from existing over largeregions for extended periods. The past flow of liquid water demonstratesthe planet's potential for habitability. Some recent evidence hassuggested that any water on the Martian surface may have been too saltyand acidic to support regular terrestrial life.^[160]

The lack of a magnetosphere and extremely thin atmosphere of Mars are a

challenge: the planet has little heat transfer across its surface, poor insulation against bombardment of the solarwind and insufficient atmospheric pressure to retainwater in a liquid form (water instead sublimates to a gaseous state).Mars is also nearly, or perhaps totally, geologically dead; the end ofvolcanic activity has apparently stopped the recycling of chemicals andminerals between the surface and interior of the planet.^[161]

Curiosity rover self portrait at /"Rocknest"/ (October 31, 2012), with the rim of GaleCrater and the slopes of Aeolis Mons in the distance.

Evidence suggests that the planet was once significantly more habitablethan it is today, but whether living organisms everexisted there remains unknown. The Viking probes of the mid 1970s carried experiments designed to detect microorganismsin Martian soil at their respective landing sites and had positiveresults, including a temporary increase of CO_2 production on exposure

to water and nutrients. This sign of life was later disputed by somescientists, resulting in a continuing debate, with NASA scientistGilbert Levin asserting that Viking may have found


23/83

life. A re analysis of the Viking data, in light of modern knowledge ofextremophile forms of life, has suggested that theViking tests were not sophisticated enough to detect these forms oflife. The tests could even have killed a (hypothetical) life form.^[162] Tests conducted by the Phoenix Marslander have shown that the soil has a alkaline pH and it contains magnesium, sodium, potassium and

chloride.^[163] The soil nutrients may be ableto support life, but life would still have to be shielded from theintense ultraviolet light.^[164]

At the Johnson Space Center lab , somefascinating shapes have been found in the meteorite ALH84001 , which is thought to have originatedfrom Mars. Some scientists propose that these geometric shapes could befossilized microbes extant on Mars before the meteorite was blasted intospace by a meteor strike and sent on a 15 million year voyage to Earth.An exclusively inorganic origin for the shapes has also beenproposed.^[165]

Small quantities of methane and formaldehyde recently detected by Mars orbiters are both claimedto be possible evidence for life, as these chemical compounds would quickly break down in the Martianatmosphere.^[166] ^[167] Alternatively, these compounds may instead bereplenished by volcanic or other geological means, such asserpentinization .^[137]

Habitability

The German Aerospace Center discoveredthat Earth lichens can survive in simulated Marsconditions.^[168] The simulation basedtemperatures, atmospheric pressure, minerals, and light on data fromMars probes.^[168] An instrument called REMS is designed to providenew clues about the signature of the Martian general circulation,microscale weather systems, local hydrological cycle, destructivepotential of UV radiation, and subsurface habitability based onground atmosphere interaction.^[169] ^[170] It landed on Mars as part of /Curiosity/(MSL) in August 2012. Microorganisms make up 80% of Earth's

biomass.^[168]

Exploration missions

Main article: Exploration of Mars Panorama of Gusev crater , where /Spirit/rover examined volcanic basalts

In addition to observation from Earth, some of the latest Marsinformation comes from five active probes on or in orbit around Mars,

including three orbiters and two rovers. This includes 2001 Mars Odyssey,^[171] MarsExpress , Mars Reconnaissance Orbiter


24/83

, Opportunity rover, and Curiosity rover .

Dozens of unmanned spacecraft , including orbiters, landers , and rovers, have been sent to Mars by the SovietUnion , the United States ,

Europe , and Japan to study the planet'ssurface, climate, and geology. The public can request images of Mars viathe HiWish program .

The Mars Science Laboratory , named/Curiosity/, launched on November 26, 2011, reached Mars on August 6,2012 UTC . It is larger and more advanced than the MarsExploration Rovers, with a movement rate up to 90 m per hour.^[172] Experiments include a laser chemical sampler thatcan deduce the make up of rocks at a distance of 7 m.^[173] On February 10 the /Curiosity/ Mars rover obtained the first deep rock samples

ever taken from another planetary body, using its onboard drill.^[174]

On 24 September 2014, Mars Orbiter Mission nicknamed Mangalyaan launched by The Indian Space Research Organization has successfully reached theMars orbit. ISRO launched the Mars Orbiter Mission, Mangalyaan, on November 5, 2013, with the aim of analyzing theMartian atmosphere and topography. The Mars Orbiter Mission used aHohmann transfer orbit to escape Earth'sgravitational influence and catapult into a nine

month

long voyage toMars. The mission is the first successful Asian interplanetarymission.^[175]

Astronomy on Mars

Main article: Astronomy on Mars Phobos transits theSun (/Opportunity /; March 10, 2004).Comet Siding Spring to pass near Mars on October 19,

2014 (Hubble ; March 11, 2014).

With the existence of various orbiters, landers, and rovers, it is nowpossible to study astronomy from the Martian skies.While Mars's moon Phobos appears about one third the angular diameter of the full moon as it appears from Earth,Deimos appears more or less star like and appears only slightly brighterthan Venus does from Earth.^[176]

There are various phenomena, well known on Earth, that have beenobserved on Mars, such as meteors and auroras.^[177] A transit of the Earth asseen from Mars will occur on November

10, 2084.^[178] There are also transits ofMercury and transits of Venus, and the moons Phobos and Deimos are


25/83

of sufficiently small angular diameter thattheir partial "eclipses" of the Sun are best considered transits (seeTransit of Deimos from Mars ).^[179] ^[180]

On October 19, 2014, Comet Siding Spring is expectedto pass extremely close to Mars, so close that the coma

may envelop Mars.^[181] ^[182]

Comet Siding Spring Mars flyby on 19 October2014 (artist's concepts)POV: UniversePOV: CometPOV: Mars

Viewing

Animation of the apparent retrograde motion of Mars in 2003 as seen fromEarth

Because the orbit of Mars is eccentric, its apparent magnitude at opposition from the Sun can range from-3.0 to -1.4. The minimum brightness is magnitude +1.6 when the planetis in conjunction with the Sun.^[8] Mars

usually appears distinctly yellow, orange, or red; the actual color ofMars is closer to butterscotch , and the rednessseen is just dust in the planet's atmosphere; considering this, NASA's /Spirit/ rover has taken pictures of a greenish brown,mud colored landscape with blue grey rocks and patches of light redsand.^[183] When farthest away from the Earth,it is more than seven times as far from the latter as when it isclosest. When least favorably positioned, it can be lost in the Sun'sglare for months at a time. At its most favorable times at 15 or17 year intervals, and always between late July and late September Mars shows a wealth of surface detail to a telescope .Especially noticeable, even at low magnification, are the polar ice caps

.^[184]

As Mars approaches opposition, it begins a period of retrograde motion, which means it will appear to movebackwards in a looping motion with respect to the background stars. Theduration of this retrograde motion lasts for about 72 days, and Marsreaches its peak luminosity in the middle of this motion.^[185]

Closest approaches

Relative

The point at which Mars's geocentric longitude is 180 different from


26/83

the Sun's is known as opposition , which isnear the time of closest approach to the Earth. The time of oppositioncan occur as much as 8 days away from the closest approach. Thedistance at close approach varies between about 54^[186] and about 103 million km due to the planets'elliptical orbits, which causes comparable variation inangular size .^[187] The

last Mars opposition occurred on April 8, 2014 at a distance of about180 million km.^[188] The average timebetween the successive oppositions of Mars, its synodic period, is 780 days but the number of days between thedates of successive oppositions can range from 764 to 812.^[189]

As Mars approaches opposition it begins a period of retrograde motion, which makes it appear to movebackwards in a looping motion relative to the background stars. Theduration of this retrograde motion is about 72 days.

Absolute, around the present time

Mars oppositions from 20032018, viewed from above the ecliptic with theEarth centered

Mars made its closest approach to Earth and maximum apparent brightnessin nearly 60,000 years, 55,758,006 km (0.372719 AU; 34,646,400 mi), magnitude -2.88, on 27 August 2003 at 9:51:13 UT.This occurred when Mars was one day from opposition and about three days

from its perihelion , making Mars particularly easy tosee from Earth. The last time it came so close is estimated to have beenon September 12, 57 617 BC , the next timebeing in 2287.^[190] This record approach wasonly slightly closer than other recent close approaches. For instance,the minimum distance on August 22, 1924 was 0.37285 AU, and the minimum distance on August 24, 2208will be 0.37279 AU .^[157]

Historical observations

Main article: History of Mars observation

The history of observations of Mars is marked by the oppositions ofMars, when the planet is closest to Earth and hence is most easilyvisible, which occur every couple of years. Even more notable are theperihelic oppositions of Mars, which occur every 15 or 17 years and aredistinguished because Mars is close to perihelion, making it even closerto Earth.

Ancient and medieval observations

The existence of Mars as a wandering object in the night sky wasrecorded by the ancient Egyptian astronomers


27/83

and by 1534 BCE they were familiar with the retrograde motion of the planet.^[191] By the period of the Neo Babylonian Empire, the Babylonian astronomers were making regular records of thepositions of the planets and systematic observations of their behavior.For Mars, they knew that the planet made 37 synodic periods

, or 42 circuits of the zodiac, every 79 years.They also invented arithmetic methods for making minor corrections tothe predicted positions of the planets.^[192] ^[193]

In the fourth century BCE, Aristotle noted that Marsdisappeared behind the Moon during an occultation ,indicating the planet was farther away.^[194] Ptolemy , a Greek living in Alexandria,^[195] attempted to addressthe problem of the orbital motion of Mars. Ptolemy's model and hiscollective work on astronomy was presented in the multi volume

collection /Almagest /, which became the authoritativetreatise on Western astronomy for the nextfourteen centuries.^[196] Literature fromancient China confirms that Mars was known by Chinese astronomers by no later than the fourth century BCE.^[197] In the fifth century CE, the Indianastronomical text /Surya Siddhanta/ estimated the diameter of Mars.^[198] In the East Asian cultures,Mars is traditionally referred to as the "fire star" (), based onthe Five elements .^[199]

During the seventeenth century, Tycho Brahe measuredthe diurnal parallax of Mars that JohannesKepler used to make a preliminary calculation ofthe relative distance to the planet.^[200] Whenthe telescope became available, the diurnal parallax of Mars was againmeasured in an effort to determine the Sun Earth distance. This wasfirst performed by Giovanni Domenico Cassini in 1672. The early parallaxmeasurements were hampered by the quality of the instruments.^[201] The only occultation of Mars by Venus observed was that of October 13, 1590, seen by Michael

Maestlin at Heidelberg.^[202] In 1610, Mars wasviewed by Galileo Galilei , who was first to seeit via telescope.^[203] The first person to drawa map of Mars that displayed any terrain features was the Dutchastronomer Christiaan Huygens .^[204]

Martian "canals"

Map of Mars by Giovanni Schiaparelli

Mars sketched as observed by Lowell sometime before 1914. (South top)


28/83

Map of Mars from Hubble Space Telescope as seen near the 1999 opposition. (North top)Main article: Martian canal

By the 19th century, the resolution of telescopes reached a levelsufficient for surface features to be identified. A perihelic oppositionof Mars occurred on September 5, 1877. In that year, Italian astronomer

Giovanni Schiaparelli used a 22 cm(8.7 in) telescope in Milan to help produce the firstdetailed map of Mars. These maps notably contained features he called/canali/, which were later shown to be an optical illusion. These /canali/ were supposedly long, straightlines on the surface of Mars, to which he gave names of famous rivers onEarth. His term, which means "channels" or "grooves", was popularlymistranslated in English as "canals".^[205] ^[206]

Influenced by the observations, the orientalist Percival Lowell founded an observatory

which had a 30 cm and 45 cm telescope (11.8and 17.7 in). The observatory was used for the exploration of Marsduring the last good opportunity in 1894 and the following lessfavorable oppositions. He published several books on Mars and life onthe planet, which had a great influence on the public.^[207] The /canali/ were also found by otherastronomers, like Henri Joseph Perrotin and Louis Thollon in Nice , using oneof the largest telescopes of that time.^[208] ^[209]

The seasonal changes (consisting of the diminishing of the polar capsand the dark areas formed during Martian summer) in combination with the

canals lead to speculation about life on Mars, and it was a long heldbelief that Mars contained vast seas and vegetation. The telescope neverreached the resolution required to give proof to any speculations. Asbigger telescopes were used, fewer long, straight /canali/ wereobserved. During an observation in 1909 by Flammarion with an 84 cm (33 in) telescope, irregularpatterns were observed, but no /canali/ were seen.^[210]

Even in the 1960s articles were published on Martian biology, puttingaside explanations other than life for the seasonal changes on Mars.Detailed scenarios for the metabolism and chemical cycles for a

functional ecosystem have been published.^[211]

Spacecraft visitation

Foothills of Aeolis Mons ("Mount Sharp") (whitebalanced image ).Main article: Exploration of Mars

Once spacecraft visited the planet during NASA's

Mariner missions in the 1960s and 70s theseconcepts were radically broken. In addition, the results of the Vikinglife detection experiments aided an intermission in which the hypothesis


29/83

of a hostile, dead planet was generally accepted.^[212]

Mariner 9 and Viking allowed better maps of Mars to be made using thedata from these missions, and another major leap forward was the MarsGlobal Surveyor mission, launched in 1996and operated until late 2006, that allowed complete, extremely detailed

maps of the Martian topography, magnetic field and surface minerals tobe obtained.^[213]These maps are now available online, for example, at Google Mars. Mars Reconnaissance Orbiter and Mars Express continued exploring with new instruments, andsupporting lander missions.

In culture

Main articles: Mars in culture and Mars infiction Mars symbol.svg

Mars is named after the Roman god of war. In different cultures, Mars representsmasculinity and youth. Its symbol , a circle withan arrow pointing out to the upper right, is also used as a symbol forthe male gender.

The many failures in Mars exploration probes resulted in a satiricalcounter culture blaming the failures on an Earth Mars "Bermuda Triangle", a "Mars Curse

", or a "Great Galactic Ghoul" that feeds on Martian spacecraft.^[214]

Intelligent "Martians"

Main article: Mars in fiction

The fashionable idea that Mars was populated by intelligent Martians exploded in the late 19th century. Schiaparelli's "canali" observations combined with

Percival Lowell 's books on the subject putforward the standard notion of a planet that was a drying, cooling,dying world with ancient civilizations constructing irrigationworks.^[215]

Many other observations and proclamations by notable personalities addedto what has been termed "Mars Fever".^[216] In1899 while investigating atmospheric radio noise using his receivers inhis Colorado Springs lab, inventor Nikola Tesla observed repetitive signals that he later surmised might have been radiocommunications coming from another planet, possibly Mars. In a 1901interview Tesla said:

It was some time afterward when the thought flashed upon my mind that the disturbances I had observed might be due to an intelligent control. Although I could not decipher their meaning, it was


30/83

impossible for me to think of them as having been entirely accidental. The feeling is constantly growing on me that I had been the first to hear the greeting of one planet to another.^[217]

An 1893 soap ad playing on the popular idea that Mars was populated.

Tesla's theories gained support from Lord Kelvin who, while visiting the United States in 1902, was reported to have saidthat he thought Tesla had picked up Martian signals being sent to theUnited States.^[218] Kelvin "emphatically"denied this report shortly before departing America: "What I really saidwas that the inhabitants of Mars, if there are any, were doubtless ableto see New York, particularly the glare of the electricity."^[219]

In a /New York Times / article in 1901, Edward

Charles Pickering , director of theHarvard College Observatory , saidthat they had received a telegram from Lowell Observatory in Arizona that seemed toconfirm that Mars was trying to communicate with the Earth.^[220]

Early in December 1900, we received from Lowell Observatory in Arizona a telegram that a shaft of light had been seen to project from Mars (the Lowell observatory makes a specialty of Mars) lasting seventy minutes. I wired these facts to Europe and sent out neostyle copies through this country. The observer there is a careful, reliable man and there is no reason to doubt that the light existed.

It was given as from a well known geographical point on Mars. That was all. Now the story has gone the world over. In Europe it is stated that I have been in communication with Mars, and all sorts of exaggerations have spring up. Whatever the light was, we have no means of knowing. Whether it had intelligence or not, no one can say. It is absolutely inexplicable.^[220]

Pickering later proposed creating a set of mirrors in Texas, intended to signal Martians.^[221]

In recent decades, the high resolution mapping of the surface of Mars,culminating in Mars Global Surveyor ,

revealed no artifacts of habitation by "intelligent" life, butpseudoscientific speculation about intelligent life on Mars continuesfrom commentators such as Richard C. Hoagland. Reminiscent of the /canali/ controversy,some speculations are based on small scale features perceived in thespacecraft images, such as 'pyramids' and the 'Face on Mars'. Planetary astronomer Carl Sagan wrote:

Mars has become a kind of mythic arena onto which we have projected our Earthly hopes and fears.^[206]

Martian tripod illustration from the 1906 French edition of /The War ofthe Worlds/ by H.G. Wells.


31/83

The depiction of Mars in fiction has been stimulated by its dramatic redcolor and by nineteenth century scientific speculations that its surfaceconditions might support not just life but intelligent life.^[222] Thus originated a large number of sciencefiction scenarios, among which is H. G. Wells's /The War of the Worlds

/, published in 1898, in which Martiansseek to escape their dying planet by invading Earth. A subsequent USradio adaptation of /The War of the Worlds/ on October 30, 1938, by OrsonWelles was presented as a live news broadcast andbecame notorious for causing a public panic when many listeners mistookit for the truth.^[223]

Influential works included Ray Bradbury 's /TheMartian Chronicles /, in which humanexplorers accidentally destroy a Martian civilization, Edgar RiceBurroughs ' /Barsoom/ series

, C. S. Lewis ' novel /Out of theSilent Planet / (1938),^[224] and a number of Robert A. Heinlein stories before the mid sixties.^[225]

Author Jonathan Swift made reference to the moonsof Mars, about 150 years before their actual discovery by Asaph Hall, detailing reasonably accurate descriptions of theirorbits, in the 19th chapter of his novel /Gulliver's Travels/.^[226]

A comic figure of an intelligent Martian, Marvin the Martian

, appeared on television in 1948 as acharacter in the Looney Tunes animated cartoons of Warner Brothers ,and has continued as part of popular culture to the present.^[227]

After the Mariner and Viking spacecraft had returned pictures of Mars as itreally is, an apparently lifeless and canal less world, these ideasabout Mars had to be abandoned, and a vogue for accurate, realistdepictions of human colonies on Mars developed, the best known of whichmay be Kim Stanley Robinson 's /Mars/

trilogy . Pseudo

scientific speculations about theFace on Mars and other enigmatic landmarks spotted by space probes have meant that ancient civilizations continue to bea popular theme in science fiction, especially in film.^[228]

The theme of a Martian colony that fights for independence from Earth isa major plot element in the novels of Greg Bear aswell as the movie /Total Recall / (basedon a short story by Philip K. Dick ) and thetelevision series /Babylon 5 /. Some video games alsouse this element, including /Red Faction / and the/Zone of the Enders / series. Mars (and its

moons) were also the setting for the popular /Doom/ video game franchise and the later /MartianGothic /.


32/83

Gallery

*

Streaks on slopes in Acheron Fossae .

*

Avalanche down 700 m slope (north pole ).

*

Nanedi Valles inner channel.

*

Valles Marineris (/2001 Mars Odyssey /).

*

Mars

cave entrances (possible).

*

Mars suspected lava tube skylight.

*

Mars North Pole area.

Moons

Main articles: Moons of Mars , Phobos (moon) and Deimos (moon) Enhanced color HiRISE image of Phobos , showing aseries of mostly parallel grooves and crater chains, with its crater Stickney at rightEnhanced color HiRISE image of Deimos (not toscale), showing its smooth blanket of regolith .

Mars has two relatively small natural moons, Phobos (about 14 miles in diameter) and Deimos

(about 8 miles in diameter), which orbit close tothe planet. Asteroid capture is a long favored theory, but their originremains uncertain.^[229] Both satellites were


33/83

discovered in 1877 by Asaph Hall ; they are namedafter the characters Phobos (panic/fear) andDeimos (terror/dread), who, in Greekmythology , accompanied their father Ares, god of war, into battle. Mars was the Roman counterpart ofAres.^[230] ^[231] Inmodern Greek , though, the planet retains its

ancient name /Ares/ (Aris: /rh/).^[232]

F om t e su face of Ma s, t e motions of P obos and Deimos appeadiffe ent f om t at of ou own moon. P obos ises in t e west, sets int e east, and ises again in just 11 ou s. Deimos, being only justoutside sync

onous o

bit w

e

e t

e o

bitalpe iod would matc t e planet's pe iod of otation ises as expectedin t e east but slowly. Despite t e 30 ou o bit of Deimos, 2.7 dayselapse between its ise and set fo an equato ial obse ve , as it slowlyfalls be

ind t

e

otation of Ma

s.^[233]

O bits of P obos and Deimos (to scale)

Because t e o bit of P obos is below sync onous altitude, t e tidalfo ces f om t e planet Ma s a e g adually lowe ingits o bit. In about 50 million yea s, it could eit e c as into Ma s'su face o b eak up into a ing st uctu e a ound t e planet.^[233]

T e o igin of t e two moons is not well unde stood. T ei low albedo andca bonaceous c ond ite composition avebeen ega ded as simila to aste oids, suppo ting t e captu e t eo y.T e unstable o bit of P obos would seem to point towa ds a elatively ecent captu e. But bot ave ci cula o bits ,nea t e equato , w ic is unusual fo captu ed objects and t e equi edcaptu e dynamics a e complex. Acc etion ea ly in t e isto y of Ma s isalso plausible, but would not account fo a composition esemblingaste oids at e t an Ma s itself, if t at is confi med.

A t i d possibility is t e involvement of a t i d body o some kind ofimpact dis uption.^[234] Mo e ecent lines ofevidence fo P obos aving a ig ly po ous inte io ,^[235] and suggesting a composition containing mainlyp yllosilicates and ot e mine als known f omMa s,^[236] point towa d an o igin of P obos

f

om mate

ial ejected by an impact on Ma

s t

at

eacc

eted in Ma

tiano bit,^[237] simila to t e p evailing t eo y fo t e o igin of Ea t 's moon. W ilet e VNIR spect a of t e moons of Ma s esemble t ose ofoute belt aste oids, t e t e mal inf a ed spect a of P obos a e epo ted to be inconsistent wit c ond ites of any class.^[236]

Ma s may ave additional moons smalle t an 50100 mete s, and a dust ing is p edicted between P obos and Deimos.^[238]

See also

Book icon


34/83

* Book: Ma s * Book: Sola System

* C/2013 A1 a comet passing nea Ma s in 2014 * Colonization of Ma s * Composition of Ma s * Da ian calenda time-keeping system.

* Geodynamics on Ma s * Geology of Ma s * Ext

ate

est

ial life * Explo ation of Ma s * List of a tificial objects on Ma s * List of c

asmata on Ma

s * List of c ate s on Ma s * List of Ma s t ojan aste oids * List of mountains on Ma s * List of quad

angles on Ma

s * List of ocks on Ma s

* List of valles on Ma

s * Seasonal flows on wa m Ma tian slopes * Te afo ming of Ma s * 2007 WD5 aste oid nea -encounte wit Ma s Janua y 30, 2008. * Wate on Ma s

Notes

1. *Jump up ^ * Based on a /Ma s Global Su veyo / image mosaic (19992004). At left,

o og ap ic wate ice clouds a e suspended ove t e s ield volcanoes Olympus Mons , Alba Mons and t e T a sis Montes . T e no t pola summe (wate ) ice cap is at top, incised by C asma Bo eale . At lowe ig t, Valles Ma ine is st etc es east-west ove 4000 km. Da k a eas on t e ig t a e lacking in su face dust; t e b ig t a ea at t e lowe ig t limb is t e impact basin A gy e .

1. ^ Jump up to: ^/*a*/ ^/*b*/

^/*c*/ Best fit ellipsoid 2. *Jump up ^ * T e e a e many /se pentinization / eactions. Olivine is a solid solution between fo ste ite and fayalite w ose gene al fo mula is (Fe,Mg)_2 SiO_4 . T e eaction p oducing met ane f om olivine can be w itten as: /Fo ste ite + Fayalite + Wate + Ca bonic acid Se pentine + Magnetite + Met ane/ , o (in balanced fo m): 18Mg_2 SiO_4 + 6Fe_2 SiO_4 + 26H_2 O + CO_2 12Mg_3 Si_2 O_5 (OH)_4 + 4Fe_3 O_4 + CH_4

Refe ences

1. *Jump up ^ * "T e MeanPlane (Inva iable


35/83

plane) of t e Sola System passing t oug t e ba ycente " . 2009-04-03. Ret ieved 2009-04-10. (p oduced wit Solex 10 w itten by Aldo Vitagliano; see also inva iable plane )2. *Jump up ^ * Yeomans, Donald K. (2006-07-13). "HORIZONS Web-Inte face fo Ma s (Majo Body=499)"

. JPL Ho izons On-Line Ep eme is System . Ret

ieved 2007-08-08. Select "Ep eme is Type: O bital Elements", "Time Span: 2000-01-01 12:00 to 2000-01-02". ("Ta get Body: Ma s" and "Cente : Sun" s ould be defaulted to.) Results a e instantaneous osculating values at t

e p

ecise J2000 epoc .3. ^ Jump up to: ^/*a*/ ^/*b*/ ^/*c*/ Seidelmann, P. Kennet

; A

c

inal, B

ent A.; A'Hea

n, Mic

ael F. et al. (2007). "Repo t of t e IAU/IAG Wo king G oup on ca tog ap ic

coo

dinates and

otational elements: 2006". /Celestial Mec

anics and Dynamical Ast onomy/ *98* (3): 155180. Bibcode :2007CeMDA..98..155S . doi :10.1007/s10569-007-9072-y . edit 4. ^ Jump up to: ^/*a*/ ^/*b*/ ^/*c*/ ^/*d*/ ^/*e*/ Lodde s, Kat a ina; Fegley, B uce (1998). /T e planeta y scientist's companion/. Oxfo d Unive sity

P ess US. p. 190. ISBN 0-19-511694-1 .5. *Jump up ^ * Folkne , W. M. et al (1997). "Inte io St uctu e and Seasonal Mass Redist ibution of Ma s f om Radio T acking of Ma s Pat finde ". /Science/ *278* (5344): 17491752. Bibcode :1997Sci...278.1749F . doi :10.1126/science.278.5344.1749 . ISSN 0036-8075 .

6. *Jump up ^ * Mallama, A. (2007). "T

e magnitude and albedo of Ma s". /Ica us/ *192* (2): 404416. Bibcode :2007Ica ..192..404M . doi :10.1016/j.ica us.2007.07.011 .7. ^ Jump up to: ^/*a*/ ^/*b*/ ^/*c*/ ^/*d*/ ^/*e*/ ^/*f*/ ^/*g*/ ^/* */ Williams, David R. (Septembe 1, 2004). "Ma s Fact S eet" .

/National Space Science Data Cente /. NASA. Ret ieved 2006-06-24.8. ^ Jump up to: ^/*a*/ ^/*b*/ ^/*c*/


36/83

Mallama, A. (2011). "Planeta y magnitudes". /Sky and Telescope/. 121(1): 5156.9. ^ Jump up to: ^/*a*/ ^/*b*/ "W at is t e typical tempe atu e on Ma s?" . /Ast onomycafe.net/. Ret ieved 2012-08-14.10. ^ Jump up to: ^/*a*/ ^/*b*/

"Ma s Explo ation Rove Mission: Spotlig t" . /Ma

s

ove

.nasa.gov/. 2007-06-12. Ret

ieved 2012-08-14.11. *Jump up ^ * K asnopolsky, Vladimi A.; Feldman, Paul D. (2001). "Detection of Molecula Hyd ogen in t e Atmosp e e of Ma s". /Science/ *294* (5548): 19141917. Bibcode :2001Sci...294.1914K . doi :10.1126/science.1065569 . PMID 11729314 .

12. *Jump up ^ * Clancy, R. T.; Sando

, B. J.; Mo ia ty-Sc ieven, G. H. (2004). "A measu ement of t e 362 GHz abso ption line of Ma s atmosp e ic H2O2". /Ica us/ *168* (1): 116121. Bibcode :2004Ica ..168..116C . doi :10.1016/j.ica us.2003.12.003 .13. ^ Jump up to: ^/*a*/ ^/*b*/ Fo misano, V.; At eya, S.; Enc enaz, T.; Ignatiev, N.; Giu anna, M. (2004). "Detection of Met ane in t e Atmosp e e of Ma s". /Science / *306* (5702): 17581761. Bibcode :2004Sci...306.1758F . doi

:10.1126/science.1101732 . PMID 15514118 .14. ^ Jump up to: ^/*a*/ ^/*b*/ Ba low, Nadine G. (2008). /Ma s: an int oduction to its inte io , su face and atmosp e e/. Camb idge planeta y science *8*. Camb idge Unive sity P ess. p. 21. ISBN 0-521-85226-9 .15. *Jump up ^ * "T e Lu e of Hematite" .

/Science@NASA/. NASA. Ma

c

28, 2001. Ret

ieved 2009-12-24.16. ^ Jump up to: ^/*a*/ ^/*b*/ ^/*c*/ Yeage , As ley (July 19, 2008). "Impact May Have T ansfo med Ma s" . ScienceNews.o g. Ret ieved 2008-08-12.17. ^ Jump up to: ^/*a*/ ^/*b*/ ^/*c*/ Sample, Ian (June 26, 2008). "Cataclysmic impact c eated no t -sout divide on Ma s" .

London: Science @ gua dian.co.uk. Ret ieved 2008-08-12.18. *Jump up ^ * Jo n P. Millis. "Ma s Moon Myste y" .


37/83

19. *Jump up ^ * Adle , M.; Owen, W. and Riedel, J. (2012). "Use of MRO Optical Navigation Came a to P epa e fo Ma s Sample Retu n" . /Concepts and App oac es fo Ma s Explo ation, eld June 1214, 2012 in Houston, Texas. LPI Cont ibution No. 1679, id.4337/ *1679*: 4337. Bibcode :2012LPICo1679.4337A

.20. *Jump up ^ * "NASA Images Suggest Wate Still Flows in B

ief Spu

ts on Ma

s" . NASA/JPL. Decembe 6, 2006. Ret ieved 2007-01-04.21. ^ Jump up to: ^/*a*/ ^/*b*/ "Wate

ice in c

ate

at Ma

tian no

t

pole" . ESA. July 28, 2005. Ret ieved 2010-03-19.22. ^ Jump up to: ^/*a*/ ^/*b*/ "Scientists Discove

Concealed Glacie s on Ma s at Mid-Latitudes"

. Unive sity of Texas at Austin. Novembe 20, 2008. A c ived f om t e o iginal on 2011-07-25. Ret ieved 2010-03-19.23. *Jump up ^ * Staff (Feb ua y 21, 2005). "Ma s pictu es eveal f ozen sea" . ESA. Ret ieved 2010-03-19.24. ^ Jump up to: ^/*a*/ ^/*b*/ "NASA Spacec aft Confi ms Ma tian Wate , Mission Extended" .

Science @ NASA. July 31, 2008. Ret ieved 2008-08-01.25. *Jump up ^ * "NASA NASA Spacec aft Data Suggest Wate Flowing on Ma s" . Nasa.gov. 2011-08-04. Ret ieved 2011-09-19.26. *Jump up ^ * J a, Alok. "Nasa's Cu iosity ove finds wate in Ma tian soil" . t egua dian.com. Ret ieved 2013-11-06.

27. *Jump up ^ * THE RED PLANET: A SURVEY OF MARS (Slide 2 Ea t Telescope View of Ma s index 28. *Jump up ^ * Peplow, Ma k. "How Ma s got its ust" . /BioEd Online/. MacMillan Publis e s Ltd. Ret ieved 2007-03-10.29. ^ Jump up to: ^/*a*/ ^/*b*/ NASA /Ma s in a Minute: Is Ma s Really Red?/ (T ansc ipt

)30. *Jump up ^ * Nimmo, F ancis; Tanaka, Ken


38/83

(2005). "Ea ly C ustal Evolution Of Ma s". /Annual Review of Ea t and Planeta y Sciences/ *33* (1): 133. Bibcode :2005AREPS..33..133N . doi :10.1146/annu ev.ea t .33.092203.122637 .31. *Jump up ^ * Rivoldini, A. et al.

(June 2011). "Geodesy const aints on t e inte io st uctu e and composition of Ma s". /Ica us/ *213* (2): 451472. Bibcode :2011Ica

..213..451R . doi :10.1016/j.ica us.2011.03.024 32. *Jump up ^ * Jacqu, Dave (Septembe

26, 2003). "APS X- ays eveal sec ets of Ma s' co e" . A

gonne National Labo

ato

y. Ret

ieved 2006-07-01.33. *Jump up ^ * McSween, Ha y Y.;

Taylo

, G. Jeff

ey; Wyatt, Mic

ael B. (May 2009). "Elemental Composition of t e Ma tian C ust". /Science/ *324* (5928): 736. Bibcode :2009Sci...324..736M . doi :10.1126/science.1165871 34. *Jump up ^ * Bandfield, Jos ua L. (June 2002). "Global mine al dist ibutions on Ma s". /Jou nal of Geop ysical Resea c (Planets)/ *107* (E6): 91. Bibcode :2002JGRE..107.5042B . doi :10.1029/2001JE001510

35. *Jump up ^ * C istensen, P ilip R.; et al. (June 27, 2003). "Mo p ology and Composition of t e Su face of Ma s: Ma s Odyssey THEMIS Results". /Science/ *300* (5628): 20562061. Bibcode :2003Sci...300.2056C . doi :10.1126/science.1080885 . PMID 12791998 .36. *Jump up ^ * Golombek, Matt ew P. (June 27, 2003). "T e Su face of Ma s: Not Just Dust and Rocks". /Science/ *300* (5628): 20432044. doi

:10.1126/science.1082927 . PMID 12829771 .37. *Jump up ^ * Tanaka, Kennet L.;Skinne , James A., J .; Do m, James M.; I win, Rossman P., III; Kolb, E ic J.; Fo tezzo, Co ey M.; Platz, T omas; Mic ael, G ego y G.; Ha e, T ent M. (14 July 2014). "Geologic Map of Ma s - 2014" . /USGS /. Ret ieved 22 July 2014.38. *Jump up ^ * K isc , Jos ua A. (22 July 2014). "B and New Look at t e Face of Ma s" . /New Yo k Times /. Ret ieved 22 July 2014.39. *Jump up ^ * Staff (July 14, 2014).


39/83

"Ma s - Geologic map - Video (00:56)" . /USGS /. Ret ieved July 22, 2014.40. *Jump up ^ * Valentine, T e esa; Amde, Lis an (2006-11-09). "Magnetic Fields and Ma s" . Ma s Global Su veyo @ NASA. Ret ieved 2009-07-17.

41. *Jump up ^ * Neal-Jones, Nancy; O'Ca oll, Cynt ia. "New Map P ovides Mo e Evidence Ma s Once Like Ea t " . NASA/Godda d Space Flig t Cente . Ret ieved 2011-12-04.42. *Jump up ^ * Halliday, A. N.; Wnke, H.; Bi ck, J.-L.; Clayton, R. N. (2001). "T e Acc etion, Composition and Ea

ly Diffe

entiation of Ma

s". /Space Science Reviews/ *96* (1/4): 197230. Bibcode :2001SSRv...96..197H . doi :10.1023/A:1011997206080 .43. *Jump up ^ * Z a kov, V. N. (1993). "T e

ole of Jupite

in t

e fo

mation of planets". /Evolution of t

e Ea t and planets/. pp. 717. Bibcode :1993GMS....74....7Z .44. *Jump up ^ * Lunine, Jonat an I.; C ambe s, Jo n; Mo bidelli, Alessand o; Les in, Lau ie A. (2003). "T e o igin of wate on Ma s". /Ica us/ *165* (1): 18. Bibcode :2003Ica ..165....1L . doi :10.1016/S0019-1035(03)00172-6 .45. *Jump up ^ * Ba low, N. G. (Octobe 57, 1988). "Conditions on Ea ly Ma s: Const aints f om t e C ate ing

Reco d". In H. F ey. "MEVTV Wo ks op on Ea ly Tectonic and Volcanic Evolution of Ma s. LPI Tec nical Repo t 89-04". Easton, Ma yland: Luna and Planeta y Institute. p. 15. Bibcode :1989eamd.wo k...15B .46. *Jump up ^ * "Giant Aste oid Flattened Half of Ma s, Studies Suggest" . Scientific Ame ican. Ret ieved 2008-06-27.47. *Jump up ^ * C ang, Kennet (June 26, 2008). "Huge Meteo St ike Explains Ma s's Shape, Reports Say" . New York Times. Retrieved 2008-06-27.48. *Jump up ^ * Tanaka, K. L. (1986). "The Stratigraphy of Mars". /Journal of Geophysical Research / *91* (B13): E139E158. Bibcode :1986JGR....91..139T . doi :10.1029/JB091iB13p0E139 .49. *Jump up ^ * Ha tmann, William K.; Neukum, Ge a d (2001). "C ate ing C onology and t e Evolution of Ma s". /Space Science Reviews/ *96* (1/4): 165194. Bibcode :2001SSRv...96..165H

. doi :10.1023/A:1011945222010 .


40/83

50. *Jump up ^ * "Bluis Colo in B oken Rock in 'Yellowknife Bay'" . /Nasa.gov/. Ret ieved 2013-04-22.51. *Jump up ^ * Mitc ell, Ka l L.; Wilson, Lionel (2003). "Ma s: ecent geological activity : Ma s: a geologically active planet". /Ast onomy & Geop ysics

/ *44* (4): 4.164.20. Bibcode :2003A&G....44d..16M . doi :10.1046/j.1468-4004.2003.44416.x .52. *Jump up ^ * "Ma s avalanc e caug t on came

a" . /Discove y C annel/. Discove y Communications. 2008-03-04. Ret ieved 2009-03-04.53. *Jump up ^ * "Ma

tian soil 'could suppo

t life'" < ttp://news.bbc.co.uk/2/ i/science/natu e/7477310.stm>. BBC

News. June 27, 2008. Ret

ieved 2008-08-07.54. *Jump up ^ * C ang, Alicia (August 5, 2008). "Scientists: Salt in Ma s soil not bad fo life" . /USA Today/. Associated P ess. Ret ieved 2008-08-07.55. *Jump up ^ * "NASA Spacec aft Analyzing Ma tian Soil Data" . JPL. Ret ieved 2008-08-05.56. *Jump up ^ * "Dust Devil Etc -A-Sketc (ESP_013751_1115)" . NASA/JPL/Unive sity of A izona. 2009-07-02. Ret ieved 2010-01-01.

57. *Jump up ^ * Sc o g ofe , No be t; A a onson, Oded; K atiwala, Sama (2002). "Slope st eaks on Ma s: Co elations wit su face p ope ties and t e potential ole of wate ". /Geop ysical Resea c Lette s/ *29* (23): 411. Bibcode :2002GeoRL..29w..41S . doi :10.1029/2002GL015889 .58. *Jump up ^ * Gnti, Tibo et al. (2003). "Da k Dune Spots: Possible Bioma ke s on Ma s?". /O igins of Life and Evolution of t e Biosp e e/ *33* (4): 515557. Bibcode :2003OLEB...33..515G

. doi :10.1023/A:1025705828948 .59. *Jump up ^ * "NASA, Ma s: Facts & Figu es" . Ret ieved 2010-01-28.60. *Jump up ^ * Heldmann, Jennife L.; et al. (May 7, 2005). "Fo mation of Ma tian gullies by t e action of liquid wate flowing unde cu ent Ma tian envi onmental conditions" (PDF). /Jou nal of Geop ysical Resea c

/ *110* (E5): Eo5004. Bibcode :2005JGRE..11005004H . doi


41/83

:10.1029/2004JE002261 . Ret ieved 2008-09-17.

'conditions suc as now occu on Ma s, outside of t e tempe atu e-p essu e stability egime of liquid wate '... 'Liquid wate is typically stable at t e lowest elevations and at low latitudes on t e planet because t e atmosp e ic p essu e is g eate t an t e vapo p essu e of wate and su face

tempe atu es in equato ial egions can eac 273 K fo pa ts of t e day [Habe le /et al/., 2001]'61. ^ Jump up to: ^/*a*/ ^/*b*/ Kostama, V.-P.; K eslavsky, M. A.; Head, J. W. (June 3, 2006). "Recent ig -latitude icy mantle in t e no t e n plains of Ma s: C a acte istics and ages of emplacement" . /Geop ysical Resea c Lette s/ *33* (11): L11201. Bibcode :2006GeoRL..3311201K . doi :10.1029/2006GL025946 . Ret ieved 2007-08-12.

'Ma

tian

ig

-latitude zones a

e cove

ed wit

a smoot

, laye

ed ice- ic mantle'.62. *Jump up ^ * By ne, S ane; Inge soll, And ew P. (2003). "A Sublimation Model fo Ma tian Sout Pola Ice Featu es". /Science/ *299* (5609): 10511053. Bibcode :2003Sci...299.1051B . doi :10.1126/science.1080148 . PMID 12586939 .63. *Jump up ^ * "Ma s' Sout Pole Ice Deep and Wide"

. NASA. Ma c 15, 2007. A c ived f om t e o iginal on 2009-04-20. Ret ieved 2007-03-16.64. *Jump up ^ * W ite ouse, David (Janua y 24, 2004). "Long isto y of wate and Ma s" . /BBC News/. Ret ieved 2010-03-20.65. *Jump up ^ * Ke , Ric a d A. (Ma c 4, 2005). "Ice o Lava Sea on Ma s? A T ansatlantic Debate E upts". /Science/ *307* (5714): 13901391. doi

:10.1126/science.307.5714.1390a . PMID 15746395 .66. *Jump up ^ * Jaege , W. L.; et al. (Septembe 21, 2007). "At abasca Valles, Ma s: A Lava-D aped C annel System". /Science/ *317* (5845): 17091711. Bibcode :2007Sci...317.1709J . doi :10.1126/science.1143315 . PMID 17885126 .

67. *Jump up ^ * Lucc itta, B. K.; Rosanova, C. E. (August 26, 2003). "Valles Ma ine is; T e G and Canyon of Ma s"


42/83

. USGS. A c ived f om t e o iginal on 2011-06-11. Ret ieved 2007-03-11.68. *Jump up ^ * Mu ay, Jo n B.; et al. (Ma c 17, 2005). "Evidence f om t e Ma s Exp ess Hig Resolution

Ste eo Came a fo a f ozen sea close to Ma s' equato ". /Natu e/ *434* (703): 352356. Bibcode :2005Natu .434..352M . doi :10.1038/natu e03379 . PMID 15772653 .69. *Jump up ^ * C addock, R.A.; Howa d, A.D. (2002). "T e case fo ainfall on a wa m, wet ea ly Ma s". /Jou nal of Geop ysical Resea c / *107* (E11). Bibcode :2002JGRE..107.5111C . doi

:10.1029/2001JE001505 .70. *Jump up ^ * Malin, Mic ael C.; Edgett, KS (June 30, 2000). "Evidence fo Recent G oundwate Seepage and Su face Runoff on Ma s". /Science/ *288* (5475): 23302335. Bibcode :2000Sci...288.2330M . doi :10.1126/science.288.5475.2330 . PMID 10875910 .71. ^ Jump up to: ^/*a*/ ^/*b*/ "NASA Images Suggest Wate Still Flows

in B ief Spu ts on Ma s" . NASA. Decembe 6, 2006. Ret ieved 2006-12-06.72. *Jump up ^ * "Wate flowed ecently on Ma s" . BBC. Decembe 6, 2006. Ret ieved 2006-12-06.73. *Jump up ^ * "Wate May Still Flow on Ma s, NASA P oto Suggests" . NASA. Decembe 6, 2006. Ret ieved 2006-04-30.74. *Jump up ^ * Lewis, K.W.; A a onson, O. (2006). "St atig ap ic analysis of t e dist ibuta y fan in

Ebe

swalde c

ate

using ste

eo image

y". /Jou

nal of Geop

ysical Resea c / *111* (E06001). Bibcode :2006JGRE..11106001L . doi :10.1029/2005JE002558 .75. *Jump up ^ * Matsuba a, Y.; Howa d, A.D.; D ummond, S.A. (2011). "Hyd ology of ea ly Ma s: Lake basins". /Jou nal of Geop ysical Resea c / *116* (E04001). Bibcode :2011JGRE..11604001M . doi :10.1029/2010JE003739 .

76. *Jump up ^ * Head, J.W., et al. (1999). "Possible Ancient Oceans on Ma s: Evidence f om Ma s O bite Lase Altimete Data". /Science/ *286* (5447): 21347. Bibcode


43/83

:1999Sci...286.2134H . doi :10.1126/science.286.5447.2134 . PMID 10591640 .77. *Jump up ^ * "Mine al in Ma s 'Be ies'

Adds to Wate Sto y" (P ess elease). NASA. Ma c 3, 2004. A c ived f om t e o iginal on 2007-11-09. Ret ieved 2006-06-13.78. *Jump up ^ * McEwen, A. S.; et al. (Septembe

21, 2007). "A Close Look at Wate -Related Geologic Activity on Ma s". /Science/ *317* (5845): 17061709. Bibcode :2007Sci...317.1706M . doi :10.1126/science.1143987

. PMID 17885125 .79. *Jump up ^ * "Ma s Explo ation Rove Mission: Science" . NASA. 2007-07-12. Ret ieved 2010-01-10.80. *Jump up ^ * "NASA NASA Ma s Rove Finds Mine al Vein Deposited by Wate " . /Nasa.gov/. 2011-12-07. Ret ieved 2012-08-14.81. *Jump up ^ * "Rove Finds "Bulletp oof" Evidence of Wate on Ea ly Ma s"

. /News.nationalgeog ap ic.com/. 2011-12-08. Ret ieved 2012-08-14.82. *Jump up ^ * "Ma s Has "Oceans" of Wate Inside?" . /News.nationalgeog ap ic.com/. 2012-06-26. Ret ieved 2012-08-14.83. ^ Jump up to: ^/*a*/ ^/*b*/ Webste , Guy; B own, Dwayne (Ma c 18, 2013). "Cu iosity Ma s Rove Sees T end In Wate P esence" . /NASA /. Ret ieved Ma c 20, 2013.84. *Jump up ^ * Rincon, Paul (Ma c 19, 2013). "Cu iosity b eaks ock to eveal dazzling w ite inte io " . BBC. Ret ieved Ma c 19, 2013.85. *Jump up ^ * Staff (Ma c 20, 2013). "Red planet coug s up a w ite ock, and scientists f eak out" . /MSN /. A c ived f om t e o iginal on 2013-03-23. Ret ieved Ma c 20, 2013.

86. *Jump up ^ * Mellon, J. T.; Feldman, W. C.; P ettyman, T. H. (2003). "T e p esence and stability of g ound ice in t e sout e n emisp e e of Ma s". /Ica us/ *169* (2):


44/83

324340. Bibcode :2004Ica ..169..324M . doi :10.1016/j.ica us.2003.10.022 .87. *Jump up ^ * "Ma s Rove s Spot Wate -Clue Mine al, F ost, Clouds" .

NASA. Decembe 13, 2004. Ret ieved 2006-03-17.88. *Jump up ^ * Da ling, David. "Ma

s, pola

caps" . /Encyclopedia of Ast obiology, Ast onomy, and Spaceflig t/. Ret ieved 2007-02-26.89. *Jump up ^ * Malin, M.C.; Caplinge

, M.A.; Davis, S.D. (2001). "Obse vational evidence fo an active su face ese voi of solid ca bon dioxide on Ma s" . /Science/ *294* (5549): 21468. Bibcode

:2001Sci...294.2146M . doi :10.1126/science.1066416 . PMID 11768358 .90. *Jump up ^ * "MIRA's Field T ips to t e Sta s Inte net Education P og am" . Mi a.o . Ret ieved 2007-02-26.91. *Jump up ^ * Ca , Mic ael H. (2003). "Oceans on Ma s: An assessment of t e obse vational evidence and possible fate". /Jou nal of Geop ysical Resea c / *108* (5042): 24. Bibcode

:2003JGRE..108.5042C . doi :10.1029/2002JE001963 .92. *Jump up ^ * P illips, Tony. "Ma s is Melting, Science at NASA" . Ret ieved 2007

Date post:	07-Aug-2018
Category:	Documents
Upload:	eshobha
View:	218 times
Download:	0 times

Mars Explored

Documents