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{{tl|Planet Infobox/Mars}}
[[File:Mars_Hubble.jpg|thumb|right|Mars, with polar ice caps visible.]]
[[File:Mars NPArea-PIA00161.jpg|thumb|right|North Polar region with icecap. (Courtesy NASA/JPL-Caltech.)]]

:''This article is about the planet. For the Roman mythological figure, see [[Mars (god)]]; for other meanings, see [[Mars (disambiguation)]].''
'''Mars''' is the fourth [[planet]] from the [[Sun]] in the [[solar system]]. It is named after [[Mars (god)|Mars]], the god of war in [[Roman mythology]] (the counterpart to [[Ares]], the god of war in [[Greek mythology]]) because of its [[red]] colour as viewed in the night sky. This feature also earned it the name of "the Red Planet." Mars has two [[Natural satellite|moon]]s ([[Phobos (moon)|Phobos]] and [[Deimos (moon)|Deimos]]) which are both small and oddly-shaped, possibly being captured [[asteroid]]s. The prefix '''areo-''' refers to Mars.

Its symbol, ♂ (a circle with a small arrow pointing out from behind it), is a stylized representation of the god [[Mars (mythology)|Mars]]' shield and spear. This symbol is also used to represent the [[male]] sex.

Mars happens to be intertwined with Ancient Egypt in curious ways:

The planet was known as "Horus the Red" (Hor Dshr), and for a long time the Sphinx was painted red. They also called it "Horus of the Horizon" (Horakhti), which was the same name given to the Great Sphinx. Because of Mars' apparent retrograde motion, Egyptians said that it "traveled backwards." The Egyptian capital Cairo, situated adjacent to Giza, derives its name from Al Qahira (Arabic name for Cairo) denoting Mars. (More literally it means ‘the victorious’.)

Chinese, Korean, and Japanese culture designates the planet Mars with the characters 火星, which translate as "Star of Fire". This is based on Five Elements which was traditionally used to classify natural elements.

Mars is also very important in Indian culture. In Jyotish, Mars is known in Sanskrit as Mangal (auspicious), Angaraka (burning coal), and Kuja (the fair one). It represents energetic action, confidence and ego. Also, in Ancient Hindu myths Mars is Nr-Simha, the "Man-Lion".

Mars is also important to astrology. According to [[Marcus Manilius]] ([[1st century AD]]) in his epic (8000 verses) poem ''Astronomica'', Mars is ardent, and presides over the genitals. Called "The Bringer Of War" in Alan Leo's ''What is a Horoscope?'', since the planet is associated with the Roman god of war, Mars in Western [[astrology]] is associated with confident, aggressive personalities. Mars is the [[ruling planet]] of [[Aries (astrology)|Aries]]. Before the discovery of [[Pluto (planet)|Pluto]], Mars was also the ruling planet of [[Scorpio]] (and still is for the more traditional astrologers).

In [[Chinese astrology]], Mars is ruled by the element Fire.

Mars would appear to fall under the auspices of the [[Outer Space Treaty]], placing it under the same jursidiction as international waters and disallowing weapons of mass destruction or military installations of any kind.  When and if the colonization of Mars becomes feasible, the issue will probably be reconsidered, especially considering the value of the planet's natural resources.

==Physical characteristics==
Mars has always fascinated people. Its red, fiery appearance is caused by Iron Oxide (rust) on its surface. Mars has only a quarter the surface area of the [[Earth]] and only one-tenth the [[mass]] (though its surface area is approximately equal to that of the Earth's dry land because Mars lacks [[ocean]]s). The [[solar day]] on Mars is almost the same length as it is on earth: 24 hours, 39 minutes, and 35.244 seconds.

===Atmosphere===
Mars' [[celestial body atmosphere|atmosphere]] is thin: the [[air pressure]] on the surface is only 750 [[Pascal (unit)|pascals]], about 0.75 percent of the average on Earth. However, the [[scale height]] of the atmosphere is about 11 km, somewhat higher than Earth's 6 km. The atmosphere on Mars is 95 percent [[carbon dioxide]], 3 percent [[nitrogen]], 1.6 percent [[argon]], and traces of [[oxygen]] and [[water]]. In [[2003]], [[methane]] was also discovered in the atmosphere by Earth-based [[telescope]]s, and possibly confirmed in [[March 2004]] by the [[Mars Express Orbiter]], present measurements state an average methane concentration of about 11±4 [[Parts per billion|ppb]] by volume (see [[#references|reference]]). The thin atmosphere cannot hold heat and is the cause of the lower temperatures on Mars (68 farenheight is about as hot as it gets).

The presence of methane on Mars is very intriguing, since as an unstable gas it indicates that there must be (or have been within the last few hundred years) a source of the gas on the planet.  [[volcanism|Volcanic]] activity, [[comet]] impacts and the existence of life in the form of [[microorganism]]s such as [[methanogen]]s are among possible but as yet unproven sources.  The methane appears in patches, which suggests that it is being rapidly broken down (and so is presumably also continually being released to the atmosphere) before it has time to become uniformly distributed in the atmosphere. Plans are now being made to look for other 'companion' gases that may suggest which sources are most likely; in the Earth's oceans biological methane production tends to be accompanied by [[ethane]], while volcanic methane is accompanied by [[sulfur dioxide]].

Apart from methane release and breakdown, other aspects of the atmosphere are also dynamic, with water vapor moving from one pole to the other with the change between summer and winter, giving rise to Earth-like [[frost]] and large [[cirrus cloud]]s [http://marsrovers.jpl.nasa.gov/gallery/press/opportunity/20041213a/merb_sol290_clouds-B313R1_br.jpg] of water-ice that were photographed by the Opportunity rover in 2004.

===Geology===
Observations of the [[magnetic field]]s on Mars by the [[Mars Global Surveyor]] spacecraft have revealed that parts of the planet's [[Crust (geology)|crust]] has been magnetized in alternating bands, typically measuring 100 miles wide by 600 miles long, in a similar pattern to those found on the ocean floors of Earth. One interesting theory, published in [[1999]] is that these bands could be evidence of the past operation of [[plate tectonics]] on Mars, although this has yet to be proven [http://photojournal.jpl.nasa.gov/catalog/PIA02008]. If true, the processes involved may have helped to sustain an Earth-like atmosphere by transporting carbon rich rocks to the surface, while the presence of a magnetic field would have helped to protect the planet from [[cosmic radiation]]. Other explanations have also been proposed.

[[File:nasa_mars_opportunity_rock_water_150_eng_02mar04.jpg|thumb|left|Microscopic rock forms indicating past signs of water taken by ''[[Opportunity rover|Opportunity]]'']]

Amongst the findings from the Opportunity rover is the presence of [[hematite]] on Mars in the form of small spheres on the [[Meridiani Planum]]. The spheres are only a few millimeters in diameter and are believed to have formed as rock deposits under watery conditions billions of years ago. Other minerals have also been found containing forms of sulfur, iron or bromine such as [[jarosite]]. This and other evidence led a group of 50 scientists to conclude in the December 9, 2004 edition of the journal ''[[Science (journal)|Science]]'' that "Liquid water was once intermittently present at the Martian surface at Meridiani, and at times it saturated the subsurface. Because liquid water is a key prerequisite for life, we infer conditions at Meridiani may have been habitable for some period of time in Martian history".  On the opposite side of the planet the mineral [[goethite]], which (unlike hematite) forms ''only'' in the presence of water, along with other evidence of water, has also been found by the Spirit rover in the "Columbia Hills".

In [[1996]], researchers studying a meteorite ([[ALH84001]]) believed to have originated from Mars reported features which they attributed to microfossils left by life on Mars.  [[As of 2005]], this interpretation remains controversial with no consensus having emerged.

===Topography===
The dichotomy of Martian topography is striking: northern plains flattened by lava flows contrast with the southern highlands, pitted and cratered by ancient impacts. The surface of Mars as seen from Earth is consequently 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]].

Mars has polar ice caps that contain frozen water and [[carbon dioxide]] that change with the Martian seasons-the carbon dioxide ice sublimates in summer, uncovering a surface of layered rocks, and forms again in winter. An extinct [[shield volcano|shield]] [[volcano]], [[Olympus Mons]] (''[[Mount Olympus]]''), is at 27 km the highest mountain in the solar system. It is in a vast upland region called [[Tharsis]], containing several large volcanos. See [[list of mountains on Mars]].  Mars also has the solar system's largest canyon system, [[Valles Marineris]] or the ''[[Mariner program|Mariner]] Valley'', which is 4000 km long and 7 km deep.  Mars is also scarred by a number of [[impact crater]]s.  The largest of these is the [[Hellas Planitia|Hellas impact basin]], covered with light red sand.  See [[list of craters on Mars]].

The difference between Mars' highest and lowest points is nearly 31 km (from the top of Olympus Mons at an altitude of 27 km to the bottom of the Hellas impact basin at an altitude of 4 km below the datum). In comparison, the difference between Earth's highest and lowest points ([[Mount Everest]] and the [[Mariana Trench]]) is only 19.7 km. Combined with the planets' different radii, this means Mars is nearly three times "rougher" than Earth.

The [[International Astronomical Union]]'s [[Working Group for Planetary System Nomenclature]] is responsible for naming Martian surface features.

[[File:MarsTopoMap-PIA02031 modest.jpg|thumb|left|250px|Topographic map of Mars, courtesy NASA/JPL-Caltech. Notable features include the Tharsis volcanoes in the west (including [[Olympus Mons]]), Valles Marineris to the east of Tharsis, and Hellas Basin in the southern hemisphere.]]

Other notes:

'''Zero elevation''': Since Mars has no oceans and hence no 'sea level', a zero-elevation surface or [[mean gravity surface]] must be selected. The [[datum]] for Mars is defined by the fourth-degree and fourth-order spherical harmonic gravity field, with the zero altitude defined by the 610.5 Pa (6.105 mbar) atmospheric pressure surface (approximately 0.6% of Earth's) at a temperature of 273.01 K. This pressure and temperature correspond to the [[triple point]] of water.

'''Zero meridian''': Mars' equator is defined by its rotation, but the location of its [[Prime Meridian]] was specified, as was Earth's, by choice of an arbitrary point which was accepted by later observers. The German astronomers [[Wilhelm Beer]] and [[Johann Heinrich Mädler]] selected a small circular feature as a reference point when they produced the first systematic chart of Mars features in 1830-32. In [[1877]], their choice was adopted as the prime meridian by the Italian astronomer [[Giovanni Schiaparelli]] when he began work on his notable 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') along the line of Beer and Mädler, was chosen by [[Merton Davies]] of the [[RAND Corporation]] to provide a more precise definition of 0.0° longitude when he established a planetographic control point network.

===Canals===
Mars has an important place in human imagination due to the belief by some that life existed on Mars, due mainly to observations by [[Percival Lowell]] of [[Martian canal]]s, apparently artificial linear features on the surface that he asserted were canals, and due to seasonal changes in the brightness of some areas that were thought to be caused by vegetation growth.  This gave rise to [[Mars in fiction|many stories]] concerning Martians.  The linear features are now known to be mostly non-existent or, in some cases, dry ancient watercourses. The color changes have been ascribed to dust storms.

==Mars' moons==
[[File:Phobos Deimos orbit Mars.jpg|thumb|left|250px|Orbits of Phobos and Deimos (to scale)]]

Both [[Phobos (moon)|Phobos]] and [[Deimos (moon)|Deimos]] are [[tidal locking|tidally locked]] with Mars, always pointing the same face towards it. Since Phobos orbits around Mars faster than the planet itself rotates, tidal forces are slowly but steadily decreasing its orbital radius. At some point in the future Phobos will be broken up by gravitational forces (see [[Roche limit]]). Deimos, on the other hand, is far enough away that its orbit is being slowly boosted instead.

Both satellites were discovered in [[1877]] by [[Asaph Hall]], and are named after the characters [[Phobos (mythology)|Phobos]] and [[Deimos (mythology)|Deimos]] in [[Greek mythology]], sons of the [[Ancient Greece|Greek]] god [[Ares]].

{| border="1" cellspacing="0" cellpadding="2"
|+ Mars' [[natural satellite]]s
|- style="background:#efefef;"
! Name
! Diameter (km)
! Mass (kg)
! Mean orbital<br>radius (km)
! Orbital period
|-
| Phobos
| 22.2 (27 &times; 21.6 &times; 18.8)
| 1.08&times;10<sup>16</sup>
| 9378
| 7.66 hours
|-
| Deimos
| 12.6 (10 &times; 12 &times; 16)
| 2&times;10<sup>15</sup>
| 23,400
| 30.35 hours
|}
As seen from Mars, Phobos has an [[angular diameter]] of about 12', while Deimos has an angular diameter of about 2'.  The Sun's angular diameter, by contrast, is about 21'.
{|
| [[File:15-ml-06-phobos2-A067R1.jpg|thumb|Phobos [[astronomical transit|transits]] the [[Sun]], as seen by Mars Rover ''[[MER-B|Opportunity]]'' on [[March 10]] [[2004]].  See [[Transit of Phobos from Mars]]]]
| width="10%"|&nbsp;
| [[File:Transit of Deimos from Mars.jpg|thumb|Deimos [[astronomical transit|transits]] the [[Sun]], as seen by Mars Rover ''[[MER-B|Opportunity]]'' on [[March 4]] [[2004]].  See [[Transit of Deimos from Mars]]]]
|}

==The exploration of Mars==
''Main article: [[Exploration of Mars]]''

[[File:Mars_Viking_11h016.png|thumb|right|Viking Lander 1 site (click for detailed description).]]
Dozens of [[spacecraft]], including [[orbiter]]s, [[Lander (spacecraft)|lander]]s, and [[rover]]s, have been sent to Mars by the [[Soviet Union]], the [[United States]], [[Europe]], and [[Japan]] to study the planet's surface, climate, and geography. Roughly two-thirds of all spacecraft destined for Mars have failed in one manner or another before completing or even beginning their missions. Part of this high failure rate can be ascribed to technical problems, but enough have either failed or lost communications for no apparent reason that some researchers half-jokingly speak of an Earth-Mars "[[Bermuda Triangle]]" or of a Great [[Galactic Ghoul]] which subsists on a diet of Mars probes.

Among the most successful missions are the [[Mars probe program]], the [[Mariner program|Mariner]] and [[Viking program]]s, [[Mars Global Surveyor]], [[Mars Pathfinder]], and [[Mars Odyssey]]. Global Surveyor has taken pictures of gullies and debris flow features that suggest there may be current sources of liquid water, similar to an [[aquifer]], at or near the surface of the planet. Mars Odyssey determined that there are vast deposits of water ice in the upper three meters of Mars' soil within 60° latitude of the south pole.

In [[2003]], the [[European Space Agency|ESA]] launched the [[Mars Express]] craft consisting of the [[Mars Express Orbiter]] and the lander [[Beagle 2]]. Mars Express Orbiter confirmed the presence of water ice and carbon dioxide ice at the planet's south pole. NASA had previously confirmed their presence at the north pole of Mars. Attempts to contact the Beagle 2 failed and it was declared lost in early February 2004.

[[File:Marsorizon232.JPG|thumb|center|800px|Cahokia Paronama.]]

Also in 2003, NASA launched the twin [[Mars Exploration Rover Mission|Mars Exploration Rover]]s named ''Spirit'' ([[MER-A]]) and ''Opportunity'' ([[MER-B]]). Both missions landed successfully in January 2004 and have met or exceeded all their targets; while a 90-day nominal mission was planned, as of February 2005, their missions have been extended twice and they continue to return science, although some mechanical faults have occurred. Among the most significant science return has been evidence of liquid water some time in the past at both landing sites.  In addition, for the first time, [[dust devils]] imaged from ground-level have been detected moving across the surface of Mars by ''Spirit'' ([[MER-A]]). (See picture below).
[[File:Marsdustdevil2.gif|thumb|center|580px|Dust devil on Mars, photographed by the Mars rover ''Spirit'']]

==Observation of Mars==

[[File:PIA02405.jpg|thumb|The "Ares Vallis" area as photographed by Mars Pathfinder (click for detailed description).]]
Earth passes Mars every 780 days (or two years plus seven weeks) at a distance of about 80,000,000 km. However, this varies because the orbits are [[ellipse|elliptical]]. To a naked-eye observer, Mars usually shows a distinct yellow, orange or reddish colour, and varies in brightness more than any other planet as seen from Earth over the course of its orbit, due to the fact that when furthest away from the Earth it is more than seven times as far from the latter as when it is closest (and can be lost in the Sun's glare for months at a time when least favourably positioned). At its most favourable times &mdash; which occur twice every 32 years, alternately at 15 and 17-year intervals, and always between late [[July]] and late [[September]] &mdash; Mars shows a wealth of surface detail to a [[telescope]]. Especially noticeable, even at low magnification, are the [[polar ice cap]]s.

On [[August 27]], [[2003]], at 9:51:13 UT, Mars made its closest approach to Earth in nearly 60,000 years: 55,758,006 km (approximately 35 million miles) without [[Light-time correction]]. This close approach came about because Mars was one day from [[Astronomical opposition|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]], [[Middle Paleolithic|57,617 BC]]. Detailed analysis of the solar system's gravitational landscape forecasts an even closer approach in [[2287]].  However, to keep this in perspective, this record approach was only an imperceptibly tiny fraction less than other recent close approaches that occur four times every 284 years.  For instance, the minimum distance on [[August 22]] [[1924]] was 0.37284 [[astronomical unit|AU]], compared to 0.37271 AU on [[August 27]] [[2003]], and the minimum distance on [[August 24]] [[2208]] will be 0.37278 AU.

A [[transit of Earth from Mars|transit of the Earth as seen from Mars]] will occur on [[November 10]], [[2084]]. At that time the Sun, the Earth and Mars will be exactly in a line.  There are also [[transit of Mercury from Mars|transits of Mercury]] and [[transit of Venus from Mars|transits of Venus]], and the moon [[Deimos (moon)|Deimos]] is of sufficiently small [[angular diameter]] that its partial "eclipses" of the Sun are best considered transits (see [[Transit of Deimos from Mars]]).

===Appearance===
{| border="1" cellpadding="4" cellspacing="0"
 ! Stationary, retrograde || Opposition || Stationary, prograde || Conjunction to Sun
 |-
 | [[July 30]], [[2003]] || [[August 28]], [[2003]] || [[September 29]], [[2003]] || [[September 15]], [[2004]]
 |-
 | [[October 1]], [[2005]] || [[November 7]], [[2005]] || [[December 10]], [[2005]] || [[October 23]], [[2006]]
 |-
 | [[November 15]], [[2007]] || [[December 24]], [[2007]] || [[January 30]], [[2008]] || [[December 5]], [[2008]]
 |-
 | [[December 21]], [[2009]] || [[January 29]], [[2010]] || [[March 11]], [[2010]] || [[February 4]], [[2011]]
 |-
 | [[January 25]], [[2012]] || [[March 3]], [[2012]] || [[April 15]], [[2012]] || [[April 18]], [[2013]]
 |-
 | [[March 1]], [[2014]] || [[April 8]], [[2014]] || [[May 21]], [[2014]] || [[June 14]], [[2015]]
 |-
 | [[April 17]], [[2016]] || [[May 22]], [[2016]] || [[June 30]], [[2016]] || [[July 27]], [[2017]]
 |-
 | [[June 28]], [[2018]] || [[July 27]], [[2018]] || [[August 28]], [[2018]] || [[September 2]], [[2019]]
 |-
 | [[September 9]], [[2020]] || [[October 13]], [[2020]] || [[November 15]], [[2020]] || [[October 8]], [[2021]]
 |}

==Martian meteorites==
''Main article: [[Martian meteorite]]s''

A handful of objects are known that are surely [[meteorite]]s and may be [[Martian meteorite|of Martian origin]]. Two of them may show signs of ancient bacterial activity.  On [[August 6]], [[1996]] NASA announced that analysis of the [[ALH84001|ALH 84001]] [[meteorite]] thought to have come from Mars, shows some features that may be [[fossil]]s of single-celled organisms, although this idea is controversial.

In ''[[Solar System Research]]'' (March 2004, vol 38, page 97) it was suggested that the unique [[Kaidun meteorite]], recovered from [[Yemen]], may have originated on the Martian moon of Phobos.

On [[April 14]], [[2004]], NASA revealed that a rock known as "Bounce", studied by the Mars Exploration Rover ''Opportunity'', was similar in composition to the meteorite EETA79001-B, discovered in [[Antarctica]] in 1979. The rock may have been ejected from the same crater as the meteorite, or from another crater in the same area of the Martian surface.

==Life on Mars==
''Main article: [[Life on Mars]]''

Evidence exists that the planet once was significantly more habitable than today, but the question whether living [[organism]]s ever actually existed there is an open one. Some researchers think that a certain [[rock (geology)|rock]] which is believed to have originated on Mars - specifically, meteorite [[ALH84001]] - does contain evidence of past biologic activity, but no consensus about these claims has been achieved so far.

The [[Viking program|Viking probes]] carried experiments designed to detect microorganisms in Martian soil at their respective landing sites, but are thought to have come back empty in this respect. Also, present biologic activity is one of the explanations that have been suggested for the presence of traces of [[methane]] within the Martian [[atmosphere]], but other explanations not involving life are generally considered more likely.

If [[colonization]] is going to happen, Mars seems a likely choice due to its rather hospitable conditions (compared with other planets, it is most like Earth).

==Mars in fiction==
{{Main|Mars in fiction}}

Because of early scientific speculations that its surface conditions might be capable of supporting life, Mars has become one of the most often mentioned real planets in [[science fiction]].

In [[H.G. Wells]]' novel "[[The War of the Worlds]]", Martians have [[tentacle]]s and a [[squid]]-like head. They reproduce by budding off a parent.

In [[The Martian Chronicles]] by Ray Bradbury, Martians have copper skin. They have humanlike emotions and the ability to read minds(telepathy). They are a dying race whose culture is quite advanced.

The [[Mars Trilogy]] (Red Mars, Green Mars, Blue Mars) by Kim Stanley Robinson details a human colonization of Mars based on more current scientific knowledge of the Red Planet.

In ''The Heritage Trilogy'' and ''The Legacy Trilogy'', by Ian Douglas, the [[Cydonia]] region of Mars is home to ancient alien ruins where mummified early humans are found in 2040.

In the television show, [[Futurama]], Leo and Inez Wong (parents of [[Amy Wong]]) own the whole Western hemisphere of Mars and the solar system's most prestigious college, Mars University, is located there.

Mars was the home planet of the [[Biker Mice from Mars]]:  Throttle, Modo & Vinnie.  Other Martian Mice include Carbine, Patty, Sakura, Stoker, and Rimfire.

==See also==
*[[Astronomy on Mars]]
*[[Colonization of Mars]]
*[[Darian calendar]]
*[[Ephemeris of Mars]]
*[[Timekeeping on Mars]]
*[[Exploration of Mars]]
*[[List of artificial objects on Mars]]
*[[List of craters on Mars]]
*[[List of mountains on Mars]]
*[[Martian meteorite]]
*[[Mars photos]]
*[[Extraterrestrial life]]
*[[Terraforming]]
*[[Mars Direct]]
*[[Planets in astrology#Mars|Mars in astrology]]
*[[Ares]]
*[[Mars_(god)|Mars]], the Roman god
*[[Nergal]]
*[[Tyr]]

==External links==
{{Commons|Mars}}
* [http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html NASA's Mars fact sheet]
* [http://www.nineplanets.org/mars.html Nine Planets Mars page]
* [http://www.marsnews.com MarsNews.com - News and info site]
* [http://www.student.oulu.fi/~jkorteni/space/mars/surface/ Introduction to Martian topography, with Hubble Space Telescope photos]
* [http://www.geoinf.fu-berlin.de/mex/ FU Berlin: HRSC (camera) experiment at Mars Express] (eng. & ger.; press releases and high resolution images)
* [http://www.giss.nasa.gov/tools/mars24/help/notes.html Technical Notes about Time on Mars]
* [http://history.nasa.gov/SP-4212/on-mars.html On Mars: Exploration of the Red Planet 1958-1978] from the NASA History Office.
* [http://flagspot.net/flags/mars.html The Mars Society flag]
* [http://www.vias.org/spacetrip/mars_globalview.html A Trip Into Space] Photos and descriptions of Mars
* [http://www.cato.org/pubs/wtpapers/980815paper.html Martian Law - a CATO white paper]
* [http://www.marsunearthed.com/ Mars Unearthed] - Comparisons of terrains between Earth and Mars
[[File:nasa_mars_opportunity_rock_water_150_eng_02mar04.jpg|frame|right|Microscopic rock forms indicating past signs of water taken by [[MER-B]]]]

===Water on Mars===

* Dr. [[Tony Phillips]]: [http://science.nasa.gov/headlines/y2000/ast29jun_1m.htm "Making a Splash on Mars"], ''Science@[[NASA]]'' article, [[June 29]], [[2000]]. Phillips describes the Martian "gullies" and explains the conditions under which liquid water can exist on the surface of Mars.
* [http://news.bbc.co.uk/hi/english/sci/tech/newsid_2009000/2009318.stm BBC News story on subsurface ice deposits on Mars]
* [http://news.bbc.co.uk/1/hi/sci/tech/3426539.stm BBC News update on Mars Express' findings of polar water ice and water-eroded features on the surface]
* [http://www.nasa.gov/vision/universe/solarsystem/opportunity_water.html Mars Rover Scientists Wring Water Story from Rocks] This image taken by Mars Rover ''Opportunity'' shows microscopic rock forms indicating past signs of water.  Courtesy: NASA
* [http://news.bbc.co.uk/1/hi/sci/tech/4285119.stm BBC News Mars pictures reveal frozen sea]

===Mars exploration===

* [http://www.transhumanist.com/volume4/space.htm The Political Economy of Very Large Space Projects (Journal Of Evolution and Technology)]
* [http://www.exploremarsnow.org/ exploreMarsnow] Interactive Mars base simulation. Winner of 2003 Webby Award for Science.
* [http://marsrovers.jpl.nasa.gov/home/index.html NASA Mars Exploration Rover Home Page]
* [http://dualmoments.com/marsrovers/index.html Be on Mars] Anaglyphs from the Mars Rovers (3D)

==References==
* [[Vladimir A. Krasnopolsky]], [[Jean-Pierre Maillard]], [[Tobias C. Owen]], ''[http://www.cosis.net/abstracts/EGU04/06169/EGU04-A-06169.pdf Detection of methane in the Martian atmosphere: evidence for life?]'', [[Icarus]], 172 (2), 537-547.

{{Mars}}
{{Solar System}}

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