FANDOM


Template:About Template:Pp-move-indef Template:Pp-semi-indef Template:Use mdy dates

Name of the object
Unknown


Diameter 0 km
0 miles
Distance from primary 0 km
0 miles
Volume 1.6318×1011{{#switch:km3 arcsec|'|′|arcminute|arcmin|"|″|deg|°|percent|per cent|%|permil|per mil|permill|per mill|permille|per mille|‰= #default= Script error[1]

0.151 Earths km3

Mass 6.4185×1023{{#switch:kg arcsec|'|′|arcminute|arcmin|"|″|deg|°|percent|per cent|%|permil|per mil|permill|per mill|permille|per mille|‰= #default= Script error[1]

0.107 Earths kg

Density 3.9335±0.0004[1] g/cm³ g/cm3

Mars is the fourth planet from the Sun and the 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 reddish appearance.[2] 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 and seasonal 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 Solar System (the tallest on a planet), and of Valles Marineris, one of the largest canyons. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature.[3][4] Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids,[5][6] similar to 5261 Eureka, a Mars trojan.

Until the first successful Mars flyby in 1965 by Mariner 4, many speculated about the presence of liquid water on the planet's surface. This was based on observed periodic variations in light and dark patches, particularly in the polar latitudes, which appeared to be seas and continents; long, dark striations were interpreted by some as irrigation channels for liquid water. These straight line features were later explained as optical illusions, though geological evidence gathered by unmanned missions suggests that Mars once had large-scale water coverage on its surface at some earlier stage of its life.[7] In 2005, radar data revealed the presence of large quantities of water ice at the poles[8] and at mid-latitudes.[9][10] The Mars rover Spirit sampled chemical compounds containing water molecules in March 2007. The Phoenix lander directly sampled water ice in shallow Martian soil on July 31, 2008.[11]

Mars is host to seven functioning spacecraft: five in orbit – 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. Defunct spacecraft on the surface include MER-A Spirit and several other inert landers and rovers such as the Phoenix lander, which completed its mission in 2008. Observations by the Mars Reconnaissance Orbiter have revealed possible flowing water during the warmest months on Mars.[12] In 2013, NASA's Curiosity rover discovered that Mars' soil contains between 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 compounds and thus not freely accessible).[13]

Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −3.0,[14] which is surpassed only by Jupiter, Venus, the Moon, and the Sun. Optical ground-based telescopes are typically limited to resolving features about 300 km (186 miles) across when Earth and Mars are closest because of Earth's atmosphere.[15]

Physical characteristics Edit

Template:Multiple image

Mars has approximately half the diameter of Earth. It is less dense than Earth, having about 15% of Earth's volume and 11% of the mass. Its surface area is only slightly less than the total area of Earth's dry land.[16] Although 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 the surface—that of Mars is stronger by less than 1%. The red-orange appearance of the Martian surface is caused by iron(III) oxide, more commonly known as hematite, or rust.[17] It can also look butterscotch,[18] and other common surface colors include golden, brown, tan, and greenish, depending on minerals.[18]

Internal structure Edit

Like Earth, this planet has undergone differentiation, resulting in a dense, metallic core region overlaid by less dense materials.[19] Current models of the planet's interior imply a core region about Script error in radius, consisting primarily of iron and nickel with about 16–17% sulfur.[20] This iron sulfide core is partially fluid, and it has twice the concentration of the lighter elements that exist at Earth's core. The core is surrounded by a silicate mantle that formed many of the tectonic and volcanic features on the planet, but it now appears to be dormant. Besides silicon and oxygen, the most abundant elements in the Martian crust are iron, magnesium, aluminum, calcium, and potassium. The average thickness of the planet's crust is about Script error, with a maximum thickness of Script error.[21] Earth's crust, averaging Script error, is only one third as thick as Mars's crust, relative to the sizes of the two planets. The InSight lander planned for 2016 will use a seismometer to better constrain the models of the interior.

Surface geology Edit

Mars is a terrestrial planet that consists of minerals containing silicon and oxygen, metals, and other elements that typically make up rock. The surface of Mars is primarily composed of tholeiitic basalt,[22] 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 regions displaying higher than normal concentrations of sheet silicates and high-silicon glass. Parts of the southern highlands include detectable amounts of high-calcium pyroxenes. Localized concentrations of hematite and olivine have also been found.[23] Much of the surface is deeply covered by finely grained iron(III) oxide dust.[24][25]

File:USGS-MarsMap-sim3292-20140714-crop.png

Although Mars has no evidence of a current structured global magnetic field,[29] observations show that parts of the planet's crust have been magnetized, and that alternating polarity reversals of its dipole field have occurred in the past. This paleomagnetism of magnetically 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-examined in October 2005 (with the help of the Mars Global Surveyor), is that these bands demonstrate plate tectonics on Mars four billion years ago, before the planetary dynamo ceased to function and the planet's magnetic field faded away.[30]

During the Solar System's formation, Mars was created as the result of a stochastic process of run-away accretion out of the protoplanetary disk that orbited the Sun. Mars has many distinctive chemical features caused by its position in the Solar System. Elements with comparatively low boiling points, such as chlorine, phosphorus, and sulphur, are much more common on Mars than Earth; these elements were probably removed from areas closer to the Sun by the young star's energetic solar wind.[31]

After the formation of the planets, all were subjected to the so-called "Late Heavy Bombardment". About 60% of the surface of Mars shows a record of impacts from that era,[32][33][34] whereas much of the remaining surface is probably underlain by immense impact basins caused by those events. There is evidence 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 the Moon's South Pole – Aitken basin, the largest impact basin yet discovered.[3][4] This theory suggests that Mars was struck 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.[35][36]

The geological history of Mars can be split into many periods, but the following are the three primary periods:[37][38]

File:734781main pia16804-full full.jpg
  • 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 2.9–3.3 billion years ago. The Hesperian period is marked by the formation of extensive lava plains.
  • Amazonian period (named after Amazonis Planitia): 2.9–3.3 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 Athabasca Valles is home to sheet-like lava flows up to about 200 Mya. Water flows in the grabens called the Cerberus Fossae occurred less than 20 Mya, indicating equally recent volcanic intrusions.[40] On February 19, 2008, images from the Mars Reconnaissance Orbiter showed evidence of an avalanche from a 700 m high cliff.[41] Template:Clear left

Soil Edit

File:Spirit Mars Silica April 20 2007.jpg

The Phoenix lander returned data showing Martian soil to be slightly alkaline and containing elements such as magnesium, sodium, potassium and chlorine. These nutrients are found in gardens on Earth, and they are necessary for growth of plants.[42] Experiments performed by the Lander showed that the Martian soil has a basic pH of 8.3, and may contain traces of the salt perchlorate.[43][44]

Streaks are common across Mars and new ones appear frequently on steep slopes of craters, troughs, and valleys. The streaks are dark at first and get lighter with age. Sometimes, the streaks start in a tiny area which then spread out for hundreds of metres. They have also been seen to follow the edges of boulders and other obstacles in their path. The commonly accepted theories include that they are dark underlying layers of soil revealed after avalanches of bright dust or dust devils.[45] Several explanations have been put forward, some of which involve water or even the growth of organisms.[46][47]

Hydrology Edit

File:Nasa mars opportunity rock water 150 eng 02mar04.jpg

Liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is about 100 times thinner than Earth's,[48] except at the lowest elevations for short periods.[49][50] The two polar ice caps appear to be made largely of water.[51][52] The volume of water ice in the south polar ice cap, if melted, would be sufficient to cover the entire planetary surface to a depth of 11 meters.[53] A permafrost mantle stretches from the pole to latitudes of about 60°.[51]

Large quantities of water ice are thought to be trapped within 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)[8][54] and at mid-latitudes (November 2008).[9] The Phoenix lander directly sampled water ice in shallow Martian soil on July 31, 2008.[11]

Landforms visible on Mars strongly suggest that liquid water has at least at times existed on the planet's surface. Huge linear 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 the catastrophic release of water from subsurface aquifers, though some of these structures have also been hypothesized to result from the action of glaciers or lava.[55][56] One of the larger examples, Ma'adim Vallis is 700 km long and much bigger than the Grand Canyon with a width of 20 km and a depth of 2 km in some places. It is thought to have been carved by flowing water early in Mars' history.[57] The youngest of these channels are thought to have formed as recently as only a few million years ago.[58] Elsewhere, particularly on the oldest areas of the Martian surface, finer-scale, dendritic networks of valleys are spread across significant proportions of the landscape. Features of these valleys and their distribution strongly imply that they were carved by runoff resulting from rain or snow fall in early Mars history. Subsurface water flow and groundwater sapping may play important subsidiary roles in some networks, but precipitation was probably the root cause of the incision in almost all cases.[59]

Along crater and canyon walls, there are also thousands of features that appear similar to terrestrial gullies. The gullies tend to be in the highlands of the southern hemisphere and to face the Equator; all are poleward of 30° latitude. A number of authors have suggested that their formation process demands the involvement of liquid water, probably from melting ice,[60][61] although others have argued for formation mechanisms involving carbon dioxide frost or the movement of dry dust.[62][63] No partially degraded gullies have formed by weathering and no superimposed impact craters have been observed, indicating that these are young features, possibly even active today.[61]

Other geological features, such as deltas and alluvial fans preserved in craters, also argue strongly for warmer, wetter conditions at some interval or intervals in earlier Mars history.[64] Such conditions necessarily require the widespread presence of crater lakes across a large proportion of the surface, for which there is also independent mineralogical, sedimentological and geomorphological evidence.[65] Some authors have even gone so far as to argue that at times in the Martian past, much of the low northern plains of the planet were covered with a true ocean hundreds of meters deep, though this remains controversial.[66]

File:PIA16791-MarsCuriosityRover-Composition-YellowknifeBayRocks.png

Further evidence that liquid water once existed on the surface of Mars comes from the detection of specific minerals such as hematite and goethite, both of which sometimes form in the presence of water.[67] Some of the evidence believed to indicate ancient water basins and flows has been negated by higher resolution studies by the Mars Reconnaissance Orbiter.[68] In 2004, Opportunity detected the mineral jarosite. This forms only in the presence of acidic water, which demonstrates that water once existed on Mars.[69] More recent evidence for liquid water comes from the finding of the mineral gypsum on the surface by NASA's Mars rover Opportunity in December 2011.[70][71] Additionally, the study leader Francis McCubbin, a planetary scientist at the University of New Mexico in Albuquerque looking at hydroxals in crystalline 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 50–300 parts per million of water, which is enough to cover the entire planet to a depth of Script error.[72]

On March 18, 2013, NASA reported evidence from instruments on 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 well as in veins and nodules in other rocks like "Knorr" rock and "Wernicke" rock.[73][74][75] Analysis using the rover's DAN instrument provided evidence 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 Bradbury Landing site to the Yellowknife Bay area in the Glenelg terrain.[73]

Polar caps Edit

Template:Multiple image Mars has two permanent polar ice caps. During a pole's winter, it lies in continuous darkness, chilling the surface and causing the deposition of 25–30% of the atmosphere into slabs of CO2 ice (dry ice).[76] When the poles are again exposed to sunlight, the frozen CO2 sublimes, creating enormous winds that sweep off the poles as fast as 400 km/h. These seasonal actions transport large amounts of dust and water vapor, giving rise to Earth-like frost and large cirrus clouds. Clouds of water-ice were photographed by the Opportunity rover in 2004.[77]

The polar caps at both poles consist primarily of water ice. Frozen carbon dioxide accumulates as a comparatively thin layer about one metre thick on the north cap in the northern winter only, whereas the south cap has a permanent dry ice cover about eight metres thick.[78] This permanent dry ice cover at the south pole is peppered by flat floored, shallow, roughly circular pits, which repeat imaging shows are expanding by meters per year; this suggests that the permanent CO2 cover over the south pole water ice is degrading over time.[79] The northern polar cap has a diameter of about 1,000 kilometres during the northern Mars summer,[80] and contains about 1.6 million cubic km of ice, which, if spread evenly on the cap, would be 2 km thick.[81] (This compares to a volume of 2.85 million cubic km (km3) for the Greenland ice sheet.) The southern polar cap has a diameter of 350 km and a thickness of 3 km.[82] The total volume of ice in the south polar cap plus the adjacent layered deposits has also been estimated at 1.6 million cubic km.[83] Both polar caps show spiral troughs, which recent analysis of SHARAD ice penetrating radar has shown are a result of katabatic winds that spiral due to the Coriolis Effect.[84][85]

The seasonal frosting of some areas near the southern ice cap results in the formation of transparent 1-metre-thick slabs of dry ice above the ground. With the arrival of spring, sunlight warms the subsurface and pressure from subliming CO2 builds up under a slab, elevating and ultimately rupturing it. This leads to geyser-like eruptions of CO2 gas mixed with dark basaltic sand or dust. This process is rapid, observed happening in the space of a few days, weeks or months, a rate of change rather unusual in geology – especially for Mars. The gas rushing underneath a slab to the site of a geyser 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.[86][87][88][89]

Geography and naming of surface features Edit

Template:See also

File:Mars topography (MOLA dataset) with poles HiRes.jpg

Although better remembered for mapping the Moon, Johann Heinrich Mädler and Wilhelm Beer were the first "areographers". They began by establishing that most of Mars's surface features were permanent and by more precisely determining the planet's rotation period. In 1840, Mädler combined ten years of observations and drew the first map of Mars. Rather than giving names to the various markings, Beer and Mädler simply designated them with letters; Meridian Bay (Sinus Meridiani) was thus feature "a".[90]

Today, features on Mars are named from a variety of sources. Albedo features are named for classical mythology. Craters larger than 60 km are named for deceased scientists and writers and others who have contributed to the study of Mars. Craters smaller than 60 km are named for towns and villages of the world with populations of less than 100,000. Large valleys are named for the word "Mars" or "star" in various languages; small valleys are named for rivers.[91]

Large albedo features retain many of the older names, but are often updated to reflect new knowledge of the nature of the features. For example, Nix Olympica (the snows of Olympus) has become Olympus Mons (Mount Olympus).[92] The surface of Mars as seen from Earth is divided into two kinds of areas, with differing albedo. The paler plains covered with dust and sand 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, hence their names Mare Erythraeum, Mare Sirenum and Aurorae Sinus. The largest dark feature seen from Earth is Syrtis Major Planum.[93] The permanent northern polar ice cap is named Planum Boreum, whereas the southern cap is called Planum Australe.

Mars's equator is defined by its rotation, but the location of its Prime Meridian was specified, as was Earth's (at Greenwich), by choice of an arbitrary point; Mädler and Beer selected a line in 1830 for their first maps of Mars. After the spacecraft Mariner 9 provided extensive imagery of Mars 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 to coincide with the original selection.[94]

Because Mars has no oceans and hence no "sea level", a zero-elevation surface also had to be selected as a reference level; this is also called the areoid[95] of Mars, analogous to the terrestrial geoid. Zero altitude was defined by the height at which there is Script error of atmospheric pressure.[96] 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).[97] In practice, today this surface is defined directly from satellite gravity measurements.

Map of quadrangles Edit

The following imagemap of the planet Mars is divided into the 30 quadrangles defined by the United States Geological Survey[98][99] The quadrangles are numbered with the prefix "MC" for "Mars Chart."[100] Click on the quadrangle and you will be taken to the corresponding article pages. North is at the top; Template:Coord is at the far left on the equator. The map images were taken by the Mars Global Surveyor. Template:Clear Template:Mars Quads - By Name Template:Clear

Impact topography Edit

File:PIA15038 - Spirit lander and Bonneville Crater on Mars.jpg

The dichotomy of Martian topography is striking: northern plains flattened by lava flows contrast with the southern highlands, pitted and cratered by ancient impacts. Research in 2008 has presented evidence regarding a theory proposed in 1980 postulating that, four billion years ago, the northern hemisphere of Mars was struck by an object one-tenth to two-thirds the size of Earth's Moon. If validated, this would make the northern hemisphere of Mars the site of an impact crater 10,600 km long by 8,500 km wide, or roughly the area of Europe, Asia, and Australia combined, surpassing the South Pole–Aitken basin as the largest impact crater in the Solar System.[3][4]

File:PIA18381-Mars-FreshAsteroidImpact2012-Before27March-After28March.jpg

Mars is scarred by a number of impact craters: a total of 43,000 craters with a diameter of 5 km or greater have been found.[102] The largest confirmed of these is the Hellas impact basin, a light albedo feature clearly visible from Earth.[103] Due to the smaller mass of Mars, the probability of an object colliding with the planet is about half that of Earth. Mars is located closer to the asteroid belt, so it has an increased chance of being struck by materials from that source. Mars is also more likely to be struck by short-period comets, i.e., those that lie within the orbit of Jupiter.[104] In spite of this, there are far fewer craters on Mars compared with the Moon, because the atmosphere of Mars provides protection against small meteors. Some craters have a morphology that suggests the ground became wet after the meteor impacted.[105]

Volcanoes Edit

File:Olympus Mons alt.jpg
File:Tharsis - Valles Marineris MOLA shaded colorized zoom 32.jpg

The shield volcano Olympus Mons (Mount Olympus) is an extinct volcano in the vast upland region Tharsis, which contains several other large volcanoes. Olympus Mons is roughly three times the height of Mount Everest, which in comparison stands at just over 8.8 km.[106] It is either the tallest or second tallest mountain in the solar system, depending on how it is measured, with various sources giving figures ranging from about 21 to 27 km high.[107][108]

Tectonic sites Edit

The large canyon, Valles Marineris (Latin for Mariner Valleys, also known as Agathadaemon in the 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 and extends across one-fifth the circumference of Mars. By comparison, the Grand Canyon on Earth is only Script error long and nearly Script error deep. Valles Marineris was formed due to the swelling of the Tharsis area which caused the crust in the area of Valles Marineris to collapse. In 2012, it was proposed that Valles Marineris is not just a graben, but also a plate boundary where 150 km of transverse motion has occurred, making Mars a planet with possibly a two-plate tectonic arrangement.[109][110]

Holes Edit

Images from the Thermal Emission Imaging System (THEMIS) aboard NASA's Mars Odyssey orbiter have revealed seven possible cave entrances on the flanks of the volcano Arsia Mons.[111] The caves, named after loved ones of their discoverers, are collectively known as the "seven sisters."[112] Cave entrances measure from 100 m to 252 m wide and they are believed to be at least 73 m to 96 m deep. Because light does not reach the floor of most of the caves, perhaps they extend much deeper than these lower estimates and widen below the surface. "Dena" is the only exception; its floor is visible and was measured to be 130 m deep. The interiors of these caverns may be protected from micrometeoroids, UV radiation, solar flares and high energy particles that bombard the planet's surface.[113]

Atmosphere Edit

Template:Wide image

Mars lost its magnetosphere 4 billion years ago,[114] possibly because of numerous asteroid strikes,[115] so the solar wind interacts directly with the Martian ionosphere, lowering the atmospheric density by stripping away atoms from the outer layer. Both Mars Global Surveyor and Mars Express have detected ionised atmospheric particles trailing off into space behind Mars,[114][116] and this atmospheric loss will be studied by the upcoming MAVEN orbiter. Compared to Earth, the atmosphere of Mars is quite rarefied. Atmospheric pressure on the surface today ranges from a low of Script error on Olympus Mons to over Script error in Hellas Planitia, with a mean pressure at the surface level of Script error.[117] The highest atmospheric density on Mars is equal to that found Script error[118] above Earth's surface. The resulting mean surface pressure is only 0.6% of that of Earth (101.3 kPa). The scale height of the atmosphere is about Script error,[119] which is higher than Earth's (Script error) because the surface gravity of Mars is only about 38% of Earth's, an effect offset by both the lower temperature and 50% higher average molecular weight of the atmosphere of Mars.

File:Mars atmosphere.jpg

The atmosphere of Mars consists of about 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water.[16][120] The atmosphere is quite dusty, containing particulates about 1.5 µm in diameter which give the Martian sky a tawny color when seen from the surface.[121]

Methane has been detected in the Martian atmosphere with a mole fraction of about 30 ppb;[122][123] it occurs in extended plumes, and the profiles imply that the methane was released from discrete regions. In northern midsummer, the principal plume contained 19,000 metric tons of methane, with an estimated source strength of 0.6 kilogram per second.[124][125] The profiles suggest that there may be two local source regions, the first centered near Template:Coord and the second near Template:Coord.[124] It is estimated that Mars must produce 270 tonnes per year of methane.[124][126]

The implied methane destruction lifetime may be as long as about 4 Earth years and as short as about 0.6 Earth years.[124][127] This rapid turnover would indicate an active source of the gas on the planet. Volcanic activity, cometary impacts, and the presence of methanogenic microbial life forms are among possible sources. Methane could also be produced by a non-biological process called serpentinizationTemplate:Efn involving water, carbon dioxide, and the mineral olivine, which is known to be common on Mars.[128]

File:PIA16461-MarsMethane-20121102.jpg

The Curiosity rover, which landed on Mars in August 2012, is able to make measurements that distinguish between different isotopologues of methane,[129] but even if the 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.[130] The first measurements with the Tunable Laser Spectrometer (TLS) indicated that there is less than 5 ppb of methane at the landing site at the point of the measurement.[131][132][133][134] On September 19, 2013, NASA scientists, from further measurements by Curiosity, reported no detection of atmospheric methane with a measured value of 0.18±0.67 ppbv corresponding 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.[135][136][137] The Mars Trace Gas Mission orbiter planned to launch in 2016 would further study the methane,[138][139] as well as its decomposition products such as formaldehyde and methanol.

Ammonia was also tentatively detected on Mars by the Mars Express satellite, but with its relatively short lifetime, it is not clear what produced it.[140] Ammonia is not stable in the Martian atmosphere and breaks down after a few hours. One possible source is volcanic activity.[140]

Climate Edit

Template:Multiple image Of all the planets in the Solar System, the seasons of Mars are the most Earth-like, due to the similar tilts of the two planets' rotational axes. The lengths of the Martian seasons are about twice those of Earth's because Mars's greater distance from the Sun leads to the Martian year being about two Earth years long. Martian surface temperatures vary from lows of about −143 °C (at the winter polar caps)[141] to highs of up to 35 °C (in equatorial summer).[142] The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure, and the low thermal inertia of Martian soil.[143] The planet is also 1.52 times as far from the Sun as Earth, resulting in just 43% of the amount of sunlight.[144]

If Mars had an Earth-like orbit, its seasons would be similar to Earth's because its axial tilt is similar to Earth's. The comparatively large eccentricity of the Martian 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 the southern hemisphere and summer in the north. As a result, the seasons in the southern hemisphere are more extreme and the seasons in the northern are milder than would otherwise be the case. The summer temperatures in the south can reach up to 30 kelvins warmer than the equivalent summer temperatures in the north.[145]

Mars also has the largest dust storms in the Solar System. These can vary from a storm over a small area, to gigantic storms that cover the entire planet. They tend to occur when Mars is closest to the Sun, and have been shown to increase the global temperature.[146]

Orbit and rotation Edit

File:Marsorbitsolarsystem.gif

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 slightly longer than an Earth day: 24 hours, 39 minutes, and 35.244 seconds. A Martian year is equal to 1.8809 Earth years, or 1 year, 320 days, and 18.2 hours.[16]

The axial tilt of Mars is 25.19 degrees, which is similar to the axial tilt of Earth.[16] As a result, Mars has seasons like Earth, though on Mars, they are nearly twice as long given its longer year. Currently, the orientation of the north pole of Mars is close to the star Deneb.[147] Mars passed an aphelion in March 2010[148] and its perihelion in March 2011.[149] The next aphelion came in February 2012[149] and the next perihelion came in January 2013.[149]

Mars has a relatively pronounced orbital eccentricity of about 0.09; of the seven other planets in the Solar System, only Mercury shows greater eccentricity. It is known that in the past, Mars has had a much more circular orbit than it does currently. At one point, 1.35 million Earth years ago, Mars had an eccentricity of roughly 0.002, much less than that of Earth today.[150] Mars's cycle of eccentricity is 96,000 Earth years compared to Earth's cycle of 100,000 years.[151] Mars also has a much longer cycle of eccentricity with a period of 2.2 million Earth years, and this overshadows the 96,000-year cycle in the eccentricity graphs. For the last 35,000 years, the orbit of Mars has been getting slightly more eccentric because of the gravitational effects of the other planets. The closest distance between Earth and Mars will continue to mildly decrease for the next 25,000 years.[152]

Search for life Edit

File:Mars Viking 11d128.png

The current understanding of planetary habitability—the ability of a world to develop and sustain life—favors planets that have liquid water on their surface. This most often requires that the orbit of a planet lie within the habitable zone, which for the Sun extends from just beyond Venus to about the semi-major axis of Mars.[153] During perihelion, Mars dips inside this region, but the planet's thin (low-pressure) atmosphere prevents liquid water from existing over large regions for extended periods. The past flow of liquid water demonstrates the planet's potential for habitability. Some recent evidence has suggested that any water on the Martian surface may have been too salty and acidic to support regular terrestrial life.[154]

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 solar wind and insufficient atmospheric pressure to retain water in a liquid form (water instead sublimates to a gaseous state). Mars is also nearly, or perhaps totally, geologically dead; the end of volcanic activity has apparently stopped the recycling of chemicals and minerals between the surface and interior of the planet.[155]

File:PIA16239 High-Resolution Self-Portrait by Curiosity Rover Arm Camera.jpg

Evidence suggests that the planet was once significantly more habitable than it is today, but whether living organisms ever existed there remains unknown. The Viking probes of the mid-1970s carried experiments designed to detect microorganisms in Martian soil at their respective landing sites and had positive results, including a temporary increase of CO2 production on exposure to water and nutrients. This sign of life was later disputed by some scientists, resulting in a continuing debate, with NASA scientist Gilbert Levin asserting that Viking may have found life. A re-analysis of the Viking data, in light of modern knowledge of extremophile forms of life, has suggested that the Viking tests were not sophisticated enough to detect these forms of life. The tests could even have killed a (hypothetical) life form.[156] Tests conducted by the Phoenix Mars lander have shown that the soil has a alkaline pH and it contains magnesium, sodium, potassium and chloride.[157] The soil nutrients may be able to support life, but life would still have to be shielded from the intense ultraviolet light.[158]

At the Johnson Space Center lab, some fascinating shapes have been found in the meteorite ALH84001, which is thought to have originated from Mars. Some scientists propose that these geometric shapes could be fossilized microbes extant on Mars before the meteorite was blasted into space by a meteor strike and sent on a 15 million-year voyage to Earth. An exclusively inorganic origin for the shapes has also been proposed.[159]

Small quantities of methane and formaldehyde recently detected by Mars orbiters are both claimed to be possible evidence for life, as these chemical compounds would quickly break down in the Martian atmosphere.[160][161] Alternatively, these compounds may instead be replenished by volcanic or other geological means, such as serpentinization.[128]

Habitability Edit

The German Aerospace Center discovered that Earth lichens can survive in simulated Mars conditions, making the presence of life more plausible according to researcher Tilman Spohn.[162] The simulation based temperatures, atmospheric pressure, minerals, and light on data from Mars probes.[162] An instrument called REMS is designed to provide new clues about the signature of the Martian general circulation, microscale weather systems, local hydrological cycle, destructive potential of UV radiation, and subsurface habitability based on ground-atmosphere interaction.[163][164] It landed on Mars as part of Curiosity (MSL) in August 2012.

Exploration missions Edit

File:Sol454 Marte spirit.jpg

In addition to observation from Earth, some of the latest Mars information comes from five active probes on or in orbit around Mars, including three orbiters and two rovers. This includes 2001 Mars Odyssey,[165] Mars Express, Mars Reconnaissance Orbiter, Opportunity rover, and Curiosity rover.

Dozens of unmanned spacecraft, including orbiters, landers, and rovers, have been sent to Mars by the Soviet Union, the United States, Europe, and Japan to study the planet's surface, climate, and geology. The public can request images of Mars via the 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 Mars Exploration Rovers, with a movement rate up to 90 m per hour.[166] Experiments include a laser chemical sampler that can deduce the make-up of rocks at a distance of 7 m.[167] On February 10 the Curiosity Mars rover obtained the first deep rock samples ever taken from another planetary body, using its onboard drill.[168]

On September 24, 2014, Mars Orbiter Mission nicknamed Mangalyaan launched by The Indian Space Research Organization has successfully reached the Mars orbit. ISRO launched the Mars Orbiter Mission, Mangalyaan, on November 5, 2013, with the aim of analyzing the Martian atmosphere and topography. The Mars Orbiter Mission used a Hohmann transfer orbit to escape Earth's gravitational influence and catapult into a nine-month-long voyage to Mars. The mission is the first successful Asian interplanetary mission.[169]

Astronomy on Mars Edit

File:15-ml-06-phobos2-A067R1.jpg
File:NASA-14090-Comet-C2013A1-SidingSpring-Hubble-20140311.jpg

With the existence of various orbiters, landers, and rovers, it is now possible to study astronomy from the Martian skies. Although 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 brighter than Venus does from Earth.[170]

There are various phenomena, well-known on Earth, that have been observed on Mars, such as meteors and auroras.[171] A transit of Earth as seen from Mars will occur on November 10, 2084.[172] There are also transits of Mercury and transits of Venus, and the moons Phobos and Deimos are of sufficiently small angular diameter that their partial "eclipses" of the Sun are best considered transits (see Transit of Deimos from Mars).[173][174]

On October 19, 2014, Comet Siding Spring passed extremely close to Mars, so close that the coma may have enveloped Mars.[175][176][177][178][179][180] Template:Auto images Template:Wide image

Viewing Edit

File:Apparent retrograde motion of Mars in 2003.gif

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 planet is in conjunction with the Sun.[14] Mars usually appears distinctly yellow, orange, or red; the actual color of Mars is closer to butterscotch, and the redness seen 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 red sand.[181] When farthest away from Earth, it is more than seven times as far from the latter as when it is closest. When least favorably positioned, it can be lost in the Sun's glare for months at a time. At its most favorable times – at 15- or 17-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.[182]

As Mars approaches opposition, it begins a period of retrograde motion, which means it will appear to move backwards in a looping motion with respect to the background stars. The duration of this retrograde motion lasts for about 72 days, and Mars reaches its peak luminosity in the middle of this motion.[183]

Closest approaches Edit

Relative Edit

The point at which Mars's geocentric longitude is 180° different from the Sun's is known as opposition, which is near the time of closest approach to Earth. The time of opposition can occur as much as 8½ days away from the closest approach. The distance at close approach varies between about 54[184] and about 103 million km due to the planets' elliptical orbits, which causes comparable variation in angular size.[185] The last Mars opposition occurred on April 8, 2014 at a distance of about 180 million km.[186] The average time between the successive oppositions of Mars, its synodic period, is 780 days but the number of days between the dates of successive oppositions can range from 764 to 812.[187]

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

Absolute, around the present time Edit

File:Mars oppositions 2003-2018.png

Mars made its closest approach to Earth and maximum apparent brightness in nearly 60,000 years, 55,758,006 km (Template:Val/delimitnum/commas00 Script error; 34,646,400 mi), magnitude −2.88, on August 27, 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 to see from Earth. The last time it came so close is estimated to have been on September 12, 57 617 BC, the next time being in 2287.[188] This record approach was only slightly closer than other recent close approaches. For instance, the minimum distance on August 22, 1924 was Template:Val/delimitnum/commas00 Script error, and the minimum distance on August 24, 2208 will be Template:Val/delimitnum/commas00 Script error.[151]

Historical observations Edit

The history of observations of Mars is marked by the oppositions of Mars, when the planet is closest to Earth and hence is most easily visible, which occur every couple of years. Even more notable are the perihelic oppositions of Mars, which occur every 15 or 17 years and are distinguished because Mars is close to perihelion, making it even closer to Earth.

Ancient and medieval observations Edit

The existence of Mars as a wandering object in the night sky was recorded by the ancient Egyptian astronomers and by 1534 BCE they were familiar with the retrograde motion of the planet.[189] By the period of the Neo-Babylonian Empire, the Babylonian astronomers were making regular records of the positions 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 to the predicted positions of the planets.[190][191]

In the fourth century BCE, Aristotle noted that Mars disappeared behind the Moon during an occultation, indicating the planet was farther away.[192] Ptolemy, a Greek living in Alexandria,[193] attempted to address the problem of the orbital motion of Mars. Ptolemy's model and his collective work on astronomy was presented in the multi-volume collection Almagest, which became the authoritative treatise on Western astronomy for the next fourteen centuries.[194] Literature from ancient China confirms that Mars was known by Chinese astronomers by no later than the fourth century BCE.[195] In the fifth century CE, the Indian astronomical text Surya Siddhanta estimated the diameter of Mars.[196] In the East Asian cultures, Mars is traditionally referred to as the "fire star" (Template:Lang), based on the Five elements.[197]

During the seventeenth century, Tycho Brahe measured the diurnal parallax of Mars that Johannes Kepler used to make a preliminary calculation of the relative distance to the planet.[198] When the telescope became available, the diurnal parallax of Mars was again measured in an effort to determine the Sun-Earth distance. This was first performed by Giovanni Domenico Cassini in 1672. The early parallax measurements were hampered by the quality of the instruments.[199] The only occultation of Mars by Venus observed was that of October 13, 1590, seen by Michael Maestlin at Heidelberg.[200] In 1610, Mars was viewed by Galileo Galilei, who was first to see it via telescope.[201] The first person to draw a map of Mars that displayed any terrain features was the Dutch astronomer Christiaan Huygens.[202]

Martian "canals" Edit

Template:Multiple image

By the 19th century, the resolution of telescopes reached a level sufficient for surface features to be identified. A perihelic opposition of 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 first detailed 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, straight lines on the surface of Mars, to which he gave names of famous rivers on Earth. His term, which means "channels" or "grooves", was popularly mistranslated in English as "canals".[203][204]

Influenced by the observations, the orientalist Percival Lowell founded an observatory which had a 30 cm and 45 cm telescope (11.8 and 17.7 in). The observatory was used for the exploration of Mars during the last good opportunity in 1894 and the following less favorable oppositions. He published several books on Mars and life on the planet, which had a great influence on the public.[205] The canali were also found by other astronomers, like Henri Joseph Perrotin and Louis Thollon in Nice, using one of the largest telescopes of that time.[206][207]

The seasonal changes (consisting of the diminishing of the polar caps and the dark areas formed during Martian summer) in combination with the canals lead to speculation about life on Mars, and it was a long-held belief that Mars contained vast seas and vegetation. The telescope never reached the resolution required to give proof to any speculations. As bigger telescopes were used, fewer long, straight canali were observed. During an observation in 1909 by Flammarion with an 84 cm (33 in) telescope, irregular patterns were observed, but no canali were seen.[208]

Even in the 1960s articles were published on Martian biology, putting aside 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.[209]

Spacecraft visitation Edit

File:PIA16068 - Mars Curiosity Rover - Aeolis Mons - 20120817.jpg

Once spacecraft visited the planet during NASA's Mariner missions in the 1960s and 70s these concepts were radically broken. In addition, the results of the Viking life-detection experiments aided an intermission in which the hypothesis of a hostile, dead planet was generally accepted.[210]

Mariner 9 and Viking allowed better maps of Mars to be made using the data from these missions, and another major leap forward was the Mars Global Surveyor mission, launched in 1996 and operated until late 2006, that allowed complete, extremely detailed maps of the Martian topography, magnetic field and surface minerals to be obtained.[211] These maps are now available online, for example, at Google Mars. Mars Reconnaissance Orbiter and Mars Express continued exploring with new instruments, and supporting lander missions. Template:Clear

In culture Edit

Mars is named after the Roman god of war. In different cultures, Mars represents masculinity and youth. Its symbol, a circle with an arrow pointing out to the upper right, is also used as a symbol for the male gender.

The many failures in Mars exploration probes resulted in a satirical counter-culture blaming the failures on an Earth-Mars "Bermuda Triangle", a "Mars Curse", or a "Great Galactic Ghoul" that feeds on Martian spacecraft.[212]

Intelligent "Martians" Edit

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 put forward the standard notion of a planet that was a drying, cooling, dying world with ancient civilizations constructing irrigation works.[213]

Many other observations and proclamations by notable personalities added to what has been termed "Mars Fever".[214] In 1899 while investigating atmospheric radio noise using his receivers in his Colorado Springs lab, inventor Nikola Tesla observed repetitive signals that he later surmised might have been radio communications coming from another planet, possibly Mars. In a 1901 interview 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 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.[215]

File:Kirks Soap Yerkes Mars.jpg

Tesla's theories gained support from Lord Kelvin who, while visiting the United States in 1902, was reported to have said that he thought Tesla had picked up Martian signals being sent to the United States.[216] Kelvin "emphatically" denied this report shortly before departing America: "What I really said was that the inhabitants of Mars, if there are any, were doubtless able to see New York, particularly the glare of the electricity."[217]

In a New York Times article in 1901, Edward Charles Pickering, director of the Harvard College Observatory, said that they had received a telegram from Lowell Observatory in Arizona that seemed to confirm that Mars was trying to communicate with Earth.[218]

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.[218]

Pickering later proposed creating a set of mirrors in Texas, intended to signal Martians.[219]

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, but pseudoscientific speculation about intelligent life on Mars continues from commentators such as Richard C. Hoagland. Reminiscent of the canali controversy, some speculations are based on small scale features perceived in the spacecraft 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.[204]

File:War-of-the-worlds-tripod.jpg

The depiction of Mars in fiction has been stimulated by its dramatic red color and by nineteenth century scientific speculations that its surface conditions might support not just life but intelligent life.[220] Thus originated a large number of science fiction scenarios, among which is H. G. Wells's The War of the Worlds, published in 1898, in which Martians seek to escape their dying planet by invading Earth. A subsequent US radio adaptation of The War of the Worlds on October 30, 1938, by Orson Welles was presented as a live news broadcast and became notorious for causing a public panic when many listeners mistook it for the truth.[221]

Influential works included Ray Bradbury's The Martian Chronicles, in which human explorers accidentally destroy a Martian civilization, Edgar Rice Burroughs' Barsoom series, C. S. Lewis' novel Out of the Silent Planet (1938),[222] and a number of Robert A. Heinlein stories before the mid-sixties.[223]

Author Jonathan Swift made reference to the moons of Mars, about 150 years before their actual discovery by Asaph Hall, detailing reasonably accurate descriptions of their orbits, in the 19th chapter of his novel Gulliver's Travels.[224]

A comic figure of an intelligent Martian, Marvin the Martian, appeared on television in 1948 as a character in the Looney Tunes animated cartoons of Warner Brothers, and has continued as part of popular culture to the present.[225]

After the Mariner and Viking spacecraft had returned pictures of Mars as it really is, an apparently lifeless and canal-less world, these ideas about Mars had to be abandoned, and a vogue for accurate, realist depictions of human colonies on Mars developed, the best known of which may be Kim Stanley Robinson's Mars trilogy. Pseudo-scientific speculations about the Face on Mars and other enigmatic landmarks spotted by space probes have meant that ancient civilizations continue to be a popular theme in science fiction, especially in film.[226]

The theme of a Martian colony that fights for independence from Earth is a major plot element in the novels of Greg Bear as well as the movie Total Recall (based on a short story by Philip K. Dick) and the television series Babylon 5. Some video games also use 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 Martian Gothic.

Moons Edit

Template:Multiple image

Mars has two relatively small natural moons, Phobos (about 14 miles in diameter) and Deimos (about 8 miles in diameter), which orbit close to the planet. Asteroid capture is a long-favored theory, but their origin remains uncertain.[227] Both satellites were discovered in 1877 by Asaph Hall; they are named after the characters Phobos (panic/fear) and Deimos (terror/dread), who, in Greek mythology, accompanied their father Ares, god of war, into battle. Mars was the Roman counterpart of Ares.[228][229] In modern Greek, though, the planet retains its ancient name Ares (Aris: Άρης).[230]

From the surface of Mars, the motions of Phobos and Deimos appear different from that of our own moon. Phobos rises in the west, sets in the east, and rises again in just 11 hours. Deimos, being only just outside synchronous orbit – where the orbital period would match the planet's period of rotation – rises as expected in the east but slowly. Despite the 30 hour orbit of Deimos, 2.7 days elapse between its rise and set for an equatorial observer, as it slowly falls behind the rotation of Mars.[231]

File:Orbits of Phobos and Deimos.gif

Because the orbit of Phobos is below synchronous altitude, the tidal forces from the planet Mars are gradually lowering its orbit. In about 50 million years, it could either crash into Mars' surface or break up into a ring structure around the planet.[231]

The origin of the two moons is not well understood. Their low albedo and carbonaceous chondrite composition have been regarded as similar to asteroids, supporting the capture theory. The unstable orbit of Phobos would seem to point towards a relatively recent capture. But both have circular orbits, near the equator, which is unusual for captured objects and the required capture dynamics are complex. Accretion early in the history of Mars is also plausible, but would not account for a composition resembling asteroids rather than Mars itself, if that is confirmed.

A third possibility is the involvement of a third body or some kind of impact disruption.[232] More recent lines of evidence for Phobos having a highly porous interior,[233] and suggesting a composition containing mainly phyllosilicates and other minerals known from Mars,[234] point toward an origin of Phobos from material ejected by an impact on Mars that reaccreted in Martian orbit,[235] similar to the prevailing theory for the origin of Earth's moon. Although the VNIR spectra of the moons of Mars resemble those of outer-belt asteroids, the thermal infrared spectra of Phobos are reported to be inconsistent with chondrites of any class.[234]

Mars may have additional moons smaller than 50–100 meters, and a dust ring is predicted between Phobos and Deimos.[236]

Gallery Edit

See also Edit

Template:Wikipedia books Template:Div col

Template:Div col end Template:Portal bar

Notes Edit

  1. Cite error: Invalid <ref> tag; no text was provided for refs named lodders1998
  2. Cite error: Invalid <ref> tag; no text was provided for refs named nasa_hematite
  3. Cite error: Invalid <ref> tag; no text was provided for refs named northcratersn
  4. Cite error: Invalid <ref> tag; no text was provided for refs named northcraterguard
  5. John P. Millis. Mars Moon Mystery.
  6. Adler, M.; Owen, W. and Riedel, J. (2012). "Use of MRO Optical Navigation Camera to Prepare for Mars Sample Return" 1679.
  7. Cite error: Invalid <ref> tag; no text was provided for refs named marswater
  8. Cite error: Invalid <ref> tag; no text was provided for refs named specials1
  9. Cite error: Invalid <ref> tag; no text was provided for refs named jsg.utexas.edu
  10. Cite error: Invalid <ref> tag; no text was provided for refs named esa050221
  11. Cite error: Invalid <ref> tag; no text was provided for refs named spacecraft1
  12. Cite error: Invalid <ref> tag; no text was provided for refs named NASA.C2.A0.E2.80.93_NASA_Spacecraft_Data_Suggest_Water_Flowing_on_Mars
  13. Cite error: Invalid <ref> tag; no text was provided for refs named Guardian
  14. Cite error: Invalid <ref> tag; no text was provided for refs named MallamaSky
  15. Cite error: Invalid <ref> tag; no text was provided for refs named usra
  16. Cite error: Invalid <ref> tag; no text was provided for refs named nssdc
  17. Cite error: Invalid <ref> tag; no text was provided for refs named rust
  18. 18.0 18.1 NASA – Mars in a Minute: Is Mars Really Red? (Transcript)
  19. Cite error: Invalid <ref> tag; no text was provided for refs named Nimmo_2005
  20. Cite error: Invalid <ref> tag; no text was provided for refs named icarus213_2_451
  21. Cite error: Invalid <ref> tag; no text was provided for refs named jacque03
  22. Cite error: Invalid <ref> tag; no text was provided for refs named science324_5928_736
  23. Cite error: Invalid <ref> tag; no text was provided for refs named jgr107_E6
  24. Cite error: Invalid <ref> tag; no text was provided for refs named sci300a
  25. Cite error: Invalid <ref> tag; no text was provided for refs named sci300b
  26. Tanaka, Kenneth L.;Skinner, James A., Jr.; Dohm, James M.; Irwin, Rossman P., III; Kolb, Eric J.; Fortezzo, Corey M.; Platz, Thomas; Michael, Gregory G.; Hare, Trent M. (July 14, 2014). Geologic Map of Mars - 2014. USGS. Retrieved on July 22, 2014.
  27. Krisch, Joshua A., "Brand New Look at the Face of Mars", New York Times, July 22, 2014. Retrieved on July 22, 2014.
  28. Staff (July 14, 2014). Mars - Geologic map - Video (00:56). USGS. Retrieved on July 22, 2014.
  29. Cite error: Invalid <ref> tag; no text was provided for refs named magnetosphere
  30. Cite error: Invalid <ref> tag; no text was provided for refs named plates
  31. Cite error: Invalid <ref> tag; no text was provided for refs named ssr96_1_4_197
  32. Cite error: Invalid <ref> tag; no text was provided for refs named zharkov93
  33. Cite error: Invalid <ref> tag; no text was provided for refs named icarus165_1
  34. Cite error: Invalid <ref> tag; no text was provided for refs named barlow88
  35. Cite error: Invalid <ref> tag; no text was provided for refs named sciam080627
  36. Cite error: Invalid <ref> tag; no text was provided for refs named nyt080626
  37. Cite error: Invalid <ref> tag; no text was provided for refs named jog91
  38. Cite error: Invalid <ref> tag; no text was provided for refs named ssr_96_1_4
  39. Bluish Color in Broken Rock in 'Yellowknife Bay'. Nasa.gov. Retrieved on April 22, 2013.
  40. Cite error: Invalid <ref> tag; no text was provided for refs named ag44_4
  41. Cite error: Invalid <ref> tag; no text was provided for refs named dc080304
  42. Cite error: Invalid <ref> tag; no text was provided for refs named bbc080627
  43. Cite error: Invalid <ref> tag; no text was provided for refs named marssalt
  44. Cite error: Invalid <ref> tag; no text was provided for refs named jpl_soil
  45. Cite error: Invalid <ref> tag; no text was provided for refs named jpl_dust_devil
  46. Cite error: Invalid <ref> tag; no text was provided for refs named gpl29_23_41
  47. Cite error: Invalid <ref> tag; no text was provided for refs named oleb33_4_515
  48. NASA Rover Finds Clues to Changes in Mars' Atmosphere
  49. Cite error: Invalid <ref> tag; no text was provided for refs named h
  50. Cite error: Invalid <ref> tag; no text was provided for refs named jgr110
  51. Cite error: Invalid <ref> tag; no text was provided for refs named kostama
  52. Cite error: Invalid <ref> tag; no text was provided for refs named sci299
  53. Cite error: Invalid <ref> tag; no text was provided for refs named nasa070315
  54. Cite error: Invalid <ref> tag; no text was provided for refs named bbc040124
  55. Cite error: Invalid <ref> tag; no text was provided for refs named Kerr2005
  56. Cite error: Invalid <ref> tag; no text was provided for refs named Jaeger2007
  57. Cite error: Invalid <ref> tag; no text was provided for refs named lucchita_rosanova
  58. Cite error: Invalid <ref> tag; no text was provided for refs named nature434
  59. Cite error: Invalid <ref> tag; no text was provided for refs named CraddockHoward2002
  60. Cite error: Invalid <ref> tag; no text was provided for refs named sci288
  61. Cite error: Invalid <ref> tag; no text was provided for refs named nasa061206
  62. Cite error: Invalid <ref> tag; no text was provided for refs named bbc061206
  63. Cite error: Invalid <ref> tag; no text was provided for refs named nasa061206b
  64. Cite error: Invalid <ref> tag; no text was provided for refs named Lewis2006
  65. Cite error: Invalid <ref> tag; no text was provided for refs named Matsubara2011
  66. Cite error: Invalid <ref> tag; no text was provided for refs named Head1999
  67. Cite error: Invalid <ref> tag; no text was provided for refs named nasa040303
  68. Cite error: Invalid <ref> tag; no text was provided for refs named sci317
  69. Cite error: Invalid <ref> tag; no text was provided for refs named nasa101001
  70. Cite error: Invalid <ref> tag; no text was provided for refs named nasa
  71. Cite error: Invalid <ref> tag; no text was provided for refs named nationalgeographic
  72. Cite error: Invalid <ref> tag; no text was provided for refs named nationalgeographic1
  73. 73.0 73.1 Curiosity Mars Rover Sees Trend In Water Presence. NASA (March 18, 2013). Retrieved on March 20, 2013.
  74. Rincon, Paul (March 19, 2013). Curiosity breaks rock to reveal dazzling white interior. BBC. Retrieved on March 19, 2013.
  75. Staff (March 20, 2013). Red planet coughs up a white rock, and scientists freak out. MSN. Archived from the original on March 23, 2013. Retrieved on March 20, 2013.
  76. Cite error: Invalid <ref> tag; no text was provided for refs named icarus169
  77. Cite error: Invalid <ref> tag; no text was provided for refs named clouds
  78. Cite error: Invalid <ref> tag; no text was provided for refs named darling_marspoles
  79. Malin, M.C.; Caplinger, M.A.; Davis, S.D. (2001). "Observational evidence for an active surface reservoir of solid carbon dioxide on Mars". Science 294 (5549): 2146–8. DOI:10.1126/science.1066416.
  80. Cite error: Invalid <ref> tag; no text was provided for refs named mira
  81. Cite error: Invalid <ref> tag; no text was provided for refs named brown
  82. Cite error: Invalid <ref> tag; no text was provided for refs named phillips
  83. Cite error: Invalid <ref> tag; no text was provided for refs named sci315
  84. Cite error: Invalid <ref> tag; no text was provided for refs named Onset_and_migration_of_spiral_troughs_on_Mars_revealed_by_orbital_radar
  85. Cite error: Invalid <ref> tag; no text was provided for refs named Mystery_Spirals_on_Mars_Finally_Explained
  86. Cite error: Invalid <ref> tag; no text was provided for refs named 2006-100
  87. Cite error: Invalid <ref> tag; no text was provided for refs named Kieffer2000
  88. Cite error: Invalid <ref> tag; no text was provided for refs named Portyankina
  89. Cite error: Invalid <ref> tag; no text was provided for refs named Hugh2006
  90. Cite error: Invalid <ref> tag; no text was provided for refs named sheehan_ch04
  91. Cite error: Invalid <ref> tag; no text was provided for refs named usgs
  92. Cite error: Invalid <ref> tag; no text was provided for refs named viking_1950_2000
  93. Cite error: Invalid <ref> tag; no text was provided for refs named seds_huygens
  94. Cite error: Invalid <ref> tag; no text was provided for refs named archinal_caplinger
  95. Cite error: Invalid <ref> tag; no text was provided for refs named NASAMola2007
  96. Cite error: Invalid <ref> tag; no text was provided for refs named pers66
  97. Cite error: Invalid <ref> tag; no text was provided for refs named lunine99
  98. Morton, Oliver (2002). Mapping Mars: Science, Imagination, and the Birth of a World. New York: Picador USA.
  99. Online Atlas of Mars. Ralphaeschliman.com. Retrieved on December 16, 2012.
  100. Catalog Page for PIA03467. Photojournal.jpl.nasa.gov (February 16, 2002). Retrieved on December 16, 2012.
  101. Webster, Guy (May 22, 2014). NASA Mars Weathercam Helps Find Big New Crater. NASA. Retrieved on May 22, 2014.
  102. Cite error: Invalid <ref> tag; no text was provided for refs named wright03
  103. Cite error: Invalid <ref> tag; no text was provided for refs named ucar_geography
  104. Cite error: Invalid <ref> tag; no text was provided for refs named emp9
  105. Cite error: Invalid <ref> tag; no text was provided for refs named emp45
  106. Cite error: Invalid <ref> tag; no text was provided for refs named scsdes49
  107. Olympus Mons. mountainprofessor.com.
  108. Cite error: Invalid <ref> tag; no text was provided for refs named glenday09
  109. Wolpert, Stuart (August 9, 2012). UCLA scientist discovers plate tectonics on Mars. UCLA. Retrieved on August 13, 2012.
  110. Lin, An (June 4, 2012). "Structural analysis of the Valles Marineris fault zone: Possible evidence for large-scale strike-slip faulting on Mars". Lithosphere 4 (4): 286–330. DOI:10.1130/L192.1. Retrieved on October 2, 2012.
  111. Cite error: Invalid <ref> tag; no text was provided for refs named cushing_titus_wynn07
  112. Cite error: Invalid <ref> tag; no text was provided for refs named nau070328
  113. Cite error: Invalid <ref> tag; no text was provided for refs named bbc070317
  114. Cite error: Invalid <ref> tag; no text was provided for refs named swind
  115. Multiple Asteroid Strikes May Have Killed Mars’s Magnetic Field
  116. Cite error: Invalid <ref> tag; no text was provided for refs named swind2
  117. Cite error: Invalid <ref> tag; no text was provided for refs named bolonkin09
  118. Cite error: Invalid <ref> tag; no text was provided for refs named atkinson07
  119. Cite error: Invalid <ref> tag; no text was provided for refs named carr06
  120. Abundance and Isotopic Composition of Gases in the Martian Atmosphere from the Curiosity Rover. Sciencemag.org (July 19, 2013). Retrieved on August 19, 2013.
  121. Cite error: Invalid <ref> tag; no text was provided for refs named dusty
  122. Cite error: Invalid <ref> tag; no text was provided for refs named methane-me
  123. Cite error: Invalid <ref> tag; no text was provided for refs named methane
  124. Cite error: Invalid <ref> tag; no text was provided for refs named plumes
  125. Cite error: Invalid <ref> tag; no text was provided for refs named hand08
  126. Cite error: Invalid <ref> tag; no text was provided for refs named results
  127. Cite error: Invalid <ref> tag; no text was provided for refs named nature460
  128. Cite error: Invalid <ref> tag; no text was provided for refs named olivine
  129. Tenenbaum, David (June 9, 2008). Making Sense of Mars Methane. Astrobiology Magazine. Archived from the original on September 23, 2008. Retrieved on October 8, 2008.
  130. Steigerwald, Bill, "Martian Methane Reveals the Red Planet is not a Dead Planet", NASA's Goddard Space Flight Center, NASA, January 15, 2009. Retrieved on January 24, 2009.
  131. Mars Curiosity Rover News Telecon -November 2, 2012.
  132. Kerr, Richard A. (November 2, 2012). Curiosity Finds Methane on Mars, or Not. Science (journal). Retrieved on November 3, 2012.
  133. Wall, Mike (November 2, 2012). Curiosity Rover Finds No Methane on Mars —Yet. Space.com. Retrieved on November 3, 2012.
  134. Chang, Kenneth, "Hope of Methane on Mars Fades", New York Times, November 2, 2012. Retrieved on November 3, 2012.
  135. (September 19, 2013)"Low Upper Limit to Methane Abundance on Mars". Science. DOI:10.1126/science.1242902. Retrieved on September 19, 2013.
  136. Cho, Adrian (September 19, 2013). "Mars Rover Finds No Evidence of Burps and Farts". Retrieved on September 19, 2013.
  137. Chang, Kenneth, "Mars Rover Comes Up Empty in Search for Methane", New York Times, September 19, 2013. Retrieved on September 19, 2013.
  138. Rincon, Paul, "Agencies outline Mars initiative", BBC News, July 9, 2009. Retrieved on July 26, 2009.
  139. "NASA orbiter to hunt for source of Martian methane in 2016", Thaindian News, March 6, 2009. Retrieved on July 26, 2009.
  140. Cite error: Invalid <ref> tag; no text was provided for refs named davidw
  141. What is the typical temperature on Mars?. Astronomycafe.net. Retrieved on August 14, 2012.
  142. Mars Exploration Rover Mission: Spotlight. Marsrover.nasa.gov (June 12, 2007). Retrieved on August 14, 2012.
  143. Cite error: Invalid <ref> tag; no text was provided for refs named nasa_surface
  144. Cite error: Invalid <ref> tag; no text was provided for refs named disc920901
  145. Cite error: Invalid <ref> tag; no text was provided for refs named goodman97
  146. Cite error: Invalid <ref> tag; no text was provided for refs named philips01
  147. Cite error: Invalid <ref> tag; no text was provided for refs named barlow08
  148. Cite error: Invalid <ref> tag; no text was provided for refs named mars2010
  149. Cite error: Invalid <ref> tag; no text was provided for refs named Mars2011
  150. Cite error: Invalid <ref> tag; no text was provided for refs named mars_eccentricity
  151. Cite error: Invalid <ref> tag; no text was provided for refs named Meeus2003
  152. Cite error: Invalid <ref> tag; no text was provided for refs named Baalke2003
  153. Cite error: Invalid <ref> tag; no text was provided for refs named Nowack
  154. Cite error: Invalid <ref> tag; no text was provided for refs named saltlife
  155. Cite error: Invalid <ref> tag; no text was provided for refs named hannsson97
  156. Cite error: Invalid <ref> tag; no text was provided for refs named physorg070107
  157. Cite error: Invalid <ref> tag; no text was provided for refs named nutrient
  158. Cite error: Invalid <ref> tag; no text was provided for refs named UV
  159. Cite error: Invalid <ref> tag; no text was provided for refs named am89
  160. Cite error: Invalid <ref> tag; no text was provided for refs named icarus172
  161. Cite error: Invalid <ref> tag; no text was provided for refs named form
  162. 162.0 162.1 DLR – Surviving the conditions on Mars (26 April 2012). Dlr.de (April 26, 2012). Retrieved on December 16, 2012.
  163. MSL Science Corner: Rover Environmental Monitoring Station (REMS). NASA/JPL. Retrieved on September 9, 2009.
  164. Mars Science Laboratory Fact Sheet. NASA/JPL. Retrieved on June 20, 2011.
  165. NASA's Mars Odyssey Shifting Orbit for Extended Mission. NASA (October 9, 2008). Retrieved on November 15, 2008.
  166. Mars Science Laboratory — Homepage. NASA. Archived from the original on July 30, 2009.
  167. Chemistry and Cam (ChemCam). NASA.
  168. Curiosity Mars rover takes historic drill sample. BBC (February 10, 2013). Retrieved on February 10, 2013.
  169. ISRO: Mars Orbiter Mission. isro.gov.in.
  170. Cite error: Invalid <ref> tag; no text was provided for refs named pl_org_deimos
  171. Bertaux, Jean-Loup (June 9, 2005). "Discovery of an aurora on Mars". Nature 435 (7043): 790–4. DOI:10.1038/nature03603.
  172. Cite error: Invalid <ref> tag; no text was provided for refs named jbaa93
  173. Cite error: Invalid <ref> tag; no text was provided for refs named nature436
  174. Cite error: Invalid <ref> tag; no text was provided for refs named sd040317
  175. Webster, Guy (October 19, 2014). All Three NASA Mars Orbiters Healthy After Comet Flyby. NASA. Retrieved on October 20, 2014.
  176. Agence France-Presse. "A Comet's Brush With Mars", New York Times, October 19, 2014. Retrieved on October 20, 2014.
  177. Denis, Michel (October 20, 2014). Spacecraft in great shape – our mission continues. European Space Agency. Retrieved on October 21, 2014.
  178. Staff. "I'm safe and sound, tweets MOM after comet sighting", The Hindu, October 21, 2014. Retrieved on October 21, 2014.
  179. (December 1, 2013)"The meteoroid fluence at Mars due to comet C/2013 A1 (Siding Spring)". Icarus. DOI:10.1016/j.icarus.2013.11.028. Retrieved on December 7, 2013.
  180. Grossman, Lisa (December 6, 2013). Fiercest meteor shower on record to hit Mars via comet. New Scientist. Retrieved on December 7, 2013.
  181. Cite error: Invalid <ref> tag; no text was provided for refs named lloyd06
  182. Cite error: Invalid <ref> tag; no text was provided for refs named shallowsky
  183. Cite error: Invalid <ref> tag; no text was provided for refs named zeilik02
  184. Cite error: Invalid <ref> tag; no text was provided for refs named Laskar2003
  185. Cite error: Invalid <ref> tag; no text was provided for refs named nasa051103
  186. Cite error: Invalid <ref> tag; no text was provided for refs named sheehan970202
  187. Cite error: Invalid <ref> tag; no text was provided for refs named astropro
  188. Cite error: Invalid <ref> tag; no text was provided for refs named rao030822
  189. Cite error: Invalid <ref> tag; no text was provided for refs named paob85
  190. Cite error: Invalid <ref> tag; no text was provided for refs named north08
  191. Cite error: Invalid <ref> tag; no text was provided for refs named swerdlow98
  192. Cite error: Invalid <ref> tag; no text was provided for refs named poor08
  193. Cite error: Invalid <ref> tag; no text was provided for refs named google
  194. Cite error: Invalid <ref> tag; no text was provided for refs named google7
  195. Cite error: Invalid <ref> tag; no text was provided for refs named needham_ronan85
  196. Cite error: Invalid <ref> tag; no text was provided for refs named jse97
  197. Template:Chinaplanetnames
  198. Cite error: Invalid <ref> tag; no text was provided for refs named taton03
  199. Cite error: Invalid <ref> tag; no text was provided for refs named hirschfeld01
  200. Cite error: Invalid <ref> tag; no text was provided for refs named sat57
  201. Cite error: Invalid <ref> tag; no text was provided for refs named jha15
  202. Cite error: Invalid <ref> tag; no text was provided for refs named arizona
  203. Cite error: Invalid <ref> tag; no text was provided for refs named snyder01
  204. Cite error: Invalid <ref> tag; no text was provided for refs named sagan80
  205. Cite error: Invalid <ref> tag; no text was provided for refs named basalla06
  206. Cite error: Invalid <ref> tag; no text was provided for refs named maria_lane05
  207. Cite error: Invalid <ref> tag; no text was provided for refs named ba3
  208. Cite error: Invalid <ref> tag; no text was provided for refs named zahnle01
  209. Cite error: Invalid <ref> tag; no text was provided for refs named science136_3510
  210. Cite error: Invalid <ref> tag; no text was provided for refs named ward_brownlee00
  211. Cite error: Invalid <ref> tag; no text was provided for refs named Distant_worlds:_milestones_in_planetary_exploration
  212. Cite error: Invalid <ref> tag; no text was provided for refs named dinerman04
  213. Cite error: Invalid <ref> tag; no text was provided for refs named prion
  214. Cite error: Invalid <ref> tag; no text was provided for refs named fergus04
  215. Cite error: Invalid <ref> tag; no text was provided for refs named tesla01
  216. Cite error: Invalid <ref> tag; no text was provided for refs named cheney81
  217. Cite error: Invalid <ref> tag; no text was provided for refs named nyt020511
  218. Cite error: Invalid <ref> tag; no text was provided for refs named nyt2
  219. Cite error: Invalid <ref> tag; no text was provided for refs named fradin99
  220. Cite error: Invalid <ref> tag; no text was provided for refs named lightman97
  221. Cite error: Invalid <ref> tag; no text was provided for refs named lubertozzi_holmsten03
  222. Cite error: Invalid <ref> tag; no text was provided for refs named sanford09
  223. Cite error: Invalid <ref> tag; no text was provided for refs named buker02
  224. Cite error: Invalid <ref> tag; no text was provided for refs named jonathan_swift
  225. Cite error: Invalid <ref> tag; no text was provided for refs named rabkin05
  226. Cite error: Invalid <ref> tag; no text was provided for refs named miles_peters
  227. Cite error: Invalid <ref> tag; no text was provided for refs named esa31031
  228. Cite error: Invalid <ref> tag; no text was provided for refs named theoi
  229. Cite error: Invalid <ref> tag; no text was provided for refs named qjras19
  230. Cite error: Invalid <ref> tag; no text was provided for refs named Greek_Names_of_the_Planets
  231. Cite error: Invalid <ref> tag; no text was provided for refs named phobos.html
  232. Cite error: Invalid <ref> tag; no text was provided for refs named ellis07
  233. Cite error: Invalid <ref> tag; no text was provided for refs named Andert
  234. Cite error: Invalid <ref> tag; no text was provided for refs named Giuranna
  235. Cite error: Invalid <ref> tag; no text was provided for refs named Blast
  236. M. Adler, et al. – Use of MRO Optical Navigation Camera .. (2012) (PDF). lpi.usra.edu. Retrieved on December 16, 2012.

Template:Notes

References Edit

Template:Cmn

External links Edit

Template:Sister project links

Media
Cartographic resources

Template:Mars Template:Manned mission to Mars Template:Mars spacecraft Template:Solar System

Template:Featured article

Ad blocker interference detected!


Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.