Atmosphere of Mars 4548379 217750484 2008-06-07T14:15:05Z 78.86.94.247 {| class="wikitable" align="right" | colspan="2" | [[Image:2005-1103mars-full.jpg|200px|center|[[Mars]] from [[Hubble Space Telescope]] [[October 28]], [[2005]] with sandstorm visible.]] |- | [[Carbon dioxide]] | 95.32% |- | [[Nitrogen]] | 2.7% |- | [[Argon]] | 1.6% |- | [[Oxygen]] | 0.13% |- | [[Carbon monoxide]] | 0.07% |- | [[Water vapor]] | 0.03% |- | [[Nitric oxide]] | 0.013% |- | [[Neon]] | 2.5 [[Parts per million|ppm]] |- | [[Krypton]] | 300 [[Parts per billion|ppb]] |- | [[Formaldehyde]] | 130 ppb [http://www.pfs-results.it/] |- | [[Xenon]] | 80 ppb |- | [[Ozone]] | 30 ppb |- | [[Methane]] | 10.5 ppb |} [[Mars]], the fourth [[planet]] from the [[Sun]], has a very different [[celestial body atmosphere|atmosphere]] from that of [[Earth's atmosphere|Earth]]. There has been much interest<ref name="baucom">[http://www.americanscientist.org/template/AssetDetail/assetid/49613 Life on Mars?] - Geological and biological processes observed on Earth provide hunky-dory explanations for methane on Mars, Martin Baucom, ''American Scientist'', March-April 2006.</ref><ref name="whodunit">[http://www.astrobio.net/news/article1651.html Interplanetary Whodunit - Methane on Mars], David Tenenbaum, ''Astrobiology Magazine'', [[NASA]], 20 Jul 2005. (Note: part one of a four-part series.)</ref> in studying its composition since the recent detection of a small amount of [[methane]],<ref name="methane3">Mumma, M. J.; Novak, R. E.; DiSanti, M. A.; Bonev, B. P., [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003DPS....35.1418M&amp;db_key=AST&amp;data_type=HTML&amp;format= "A Sensitive Search for Methane on Mars"] (abstract only). American Astronomical Society, DPS meeting #35, #14.18.</ref> which may signal [[life on Mars]]. The '''atmosphere of Mars''' is relatively thin, and the [[atmospheric pressure]] on the surface varies from around 30 [[pascal (unit)|Pa]] (0.03 kPa) on [[Olympus Mons]]'s peak to over 1155 Pa (1.155 kPa) in the depths of [[Hellas Planitia]], with a mean surface level pressure of 600 Pa (0.6 kPa), compared to Earth's 101.3 kPa. However, the [[scale height]] of the atmosphere is about 11&nbsp;km, somewhat higher than Earth's 6&nbsp;km. The atmosphere on Mars consists of 95% [[carbon dioxide]], 3% [[nitrogen]], 1.6% [[argon]], and contains traces of [[oxygen]], [[water]], and [[methane]]. The atmosphere is quite dusty, giving the Martian sky a [[:wiktionary:tawny|tawny]] color when seen from the surface; data from the [[Mars Exploration Rovers]] indicates the suspended dust particles are roughly 1.5 [[micrometre]]s across.<ref name=dusty>[http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004Sci...306.1753L&amp;db_key=AST&amp;data_type=HTML&amp;format=&amp;high=439c7b95b425777 Lemmon et al., "Atmospheric Imaging Results from the Mars Exploration Rovers: Spirit and Opportunity"]</ref> ==Structure== Mars' atmosphere is composed of the following major divisions: *Lower Atmosphere: This is a warm region affected by heat from airborne [[dust]] and from the ground. *Middle Atmosphere: Mars has a [[jetstream]] which flows in this region. *Upper Atmosphere, or Thermosphere: This region has very high temperatures caused by heating from the Sun. Here, atmospheric gases start to separate from each other rather than forming the even mix found in the lower atmospheric layers. *Exosphere: 200 kilometers and higher. This region is where the last wisps of atmosphere merge into space. There is no hard boundary so it is very difficult to tell where the atmosphere ends. ==Composition== [[Image:Mars atmosphere.jpg|thumb|left|210px|Mars' thin atmosphere, visible on the horizon in this low orbit image.]] ===Carbon dioxide=== The main component of the atmosphere of Mars is carbon dioxide (CO<sub>2</sub>). During the Martian winter the poles are in continual darkness and the surface gets so cold that as much as 25% of the atmospheric CO<sub>2</sub> condenses at the polar caps into solid [[Carbon dioxide|CO<sub>2</sub>]] ice ([[dry ice]]). When the poles are again exposed to sunlight during the Martian summer, the CO<sub>2</sub> ice [[Sublimation (physics)|sublimes]] back into the atmosphere. This process leads to a significant annual variation in the atmospheric pressure and atmospheric composition around the Martian poles. ===Argon=== The atmosphere of Mars is considerably enriched with the [[noble gas]] [[argon]] in comparison to that atmosphere of the other planets within the [[solar system]]. Unlike carbon dioxide, the argon content of the atmosphere does not condense, and hence the total amount of argon in the Mars atmosphere is constant. However, the relative concentration at any given location can change as carbon dioxide moves in and out of the atmosphere. Recent satellite data shows an increase in atmospheric argon over the southern pole in autumn, which dissipates the following spring.<ref name="weather"> {{cite web | title = Alien Weather at the Poles of Mars | author = Francois Forgot | publisher = Science | url = http://www-mars.lmd.jussieu.fr/mars/publi/forget_science2004.pdf | accessdate = 2007-02-25}}</ref> ===Water=== Other aspects of the Martian atmosphere vary significantly. As carbon dioxide sublimes back into the atmosphere during the martian summer, enormous winds sweep off the poles at speeds approaching 250&nbsp;mph (400 km/h). These seasonal actions transport large amounts of dust and water vapor giving rise to Earth-like [[frost]] and large [[cirrus cloud]]s. These clouds of water-ice were photographed by the ''[[Opportunity rover|Opportunity]]'' rover in 2004.<ref name=clouds>[http://marsrovers.jpl.nasa.gov/gallery/press/opportunity/20041213a.html Clouds] - Dec. 13, 2004 [[NASA]] Press release. URL accessed March 17, 2006.</ref> ===Methane=== Trace amounts of methane, at the level of several parts per billion, were first reported in Mars' atmosphere by a team at the NASA Goddard Space Flight Center in 2003.<ref name="methane3" /><ref name="repeat1">{{cite web | title = Mars Methane Boosts Chances for Life | author = Michael J. Mumma | publisher = Skytonight.com | url = http://www-mgcm.arc.nasa.gov/MGCM.html | accessdate = 2007-02-23}}</ref> In [[March 2004]] the [[Mars Express Orbiter]]<ref name="Formisano"> {{cite journal | title = Detection of Methane in the Atmosphere of Mars | author = V. Formisano, S. Atreya T. Encrenaz, N. Ignatiev, M. Giuranna | journal = Science | volume = 306 | issue = 5702 | pages = 1758–1761 | year = 2004 | url = | doi = 10.1126/science.1101732}}</ref> and ground based observations from [[Canada-France-Hawaii Telescope]]<ref name="Krasnopolskya">{{cite journal | title = Detection of methane in the martian atmosphere: evidence for life? | author = V. A. Krasnopolskya, J. P. Maillard, T. C. Owen | journal = Icarus | volume = 172 | issue = 2 | pages = 537–547 | year = 2004 | url = | doi = 10.1016/j.icarus.2004.07.004}} </ref> also suggested the presence of [[methane]] in the Martian atmosphere, with a concentration of about 10 [[Parts per billion|ppb]] by volume.<ref name="methane">{{cite web | title = Mars Express confirms methane in the Martian atmosphere | author = [[ESA]] Press release | publisher = [[ESA]] | url = http://www.esa.int/SPECIALS/Mars_Express/SEMZ0B57ESD_0.html | accessdate = 2006-03-17}}</ref> 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. It is estimated that Mars must produce 150 ton/year of methane.<ref name="results">[http://www.pfs-results.it/ Planetary Fourier Spectrometer website] (ESA, Mars Express)</ref> [[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 to occur in patches, which suggests that it is being rapidly broken down before it has time to become uniformly distributed in the atmosphere, and so it is presumably also continually being released to 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]]. It was also recently shown that methane could be produced by a non-biological process involving water, [[carbon dioxide]], and the [[mineral]] [[olivine]], which is known to be common on Mars.<ref name="olivine">{{cite journal | title = Have olivine, will gas: Serpentinization and the abiogenic production of methane on Mars | author = Oze, C., M. Sharma | journal = Geophys. Res. Lett. | volume = 32 | issue = | pages = L10203 | year = 2005 | url = http://www.agu.org/journals/gl/gl0510/2005GL022691/ | doi = 10.1029/2005GL022691}} </ref> The required conditions for this reaction (i.e. temperature and pressure) do not exist on the surface, but likely exist within the crust. To prove this process is occurring, [[serpentine]], a mineral by-product of the process would be detected. The ESA found that the concentrations of methane in the martian atmosphere was not even, but rather that it coincided with the presence of water vapor. In the upper atmosphere these two gasses are uniformly distributed, but near the surface they concentrate in three equatorial regions, namely [[Arabia Terra]], [[Elysium Planitia]], and [[Memnonia (Mars)|Arcadia Memnonia]]. Planetary scientist David H. Grinspoon (Southwest Research Institute) feels that the coincidence of water vapor and methane increases the chance of a biological source, but cautions that it is uncertain how life could have survived so long on a planet as inhospitable as Mars.<ref name = "repeat1" /> Ultimately, to prove an organic nature for the methane, a future probe or lander hosting a mass spectrometer will be needed, since the isotopic proportions of C12 to C14 can clearly distinguish between an [[inorganic]] and an [[Organic matter|organic]] (biologic, e.g. bacterial decay) origin of the methane.<ref name="nasa">[http://rst.gsfc.nasa.gov/Sect19/Sect19_13a.html Remote Sensing Tutorial, Section 19-13a] - Missions to Mars during the Third Millennium, Nicholas M. Short, Sr., et al., NASA</ref> ==Potential for utilization by humans== {{main article |In-Situ Resource Utilization}} The atmosphere of Mars is a resource of known composition which is available at any landing site on Mars. For this reason, it has been proposed that [[Manned mission to Mars|human exploration of Mars]] could use carbon dioxide from Martian atmosphere as feedstock to manufacture [[rocket fuel]] to use for the return mission. Mission studies which propose using the atmosphere in this way include the [[Mars Direct]] proposal of [[Robert Zubrin]] and the NASA [[Design reference mission 3.0|Design reference mission]] study. Two major chemical pathways for utilization of the carbon dioxide are the [[Sabatier reaction]], converting atmospheric carbon dioxide along with additional hydrogen to produce methane and oxygen, and [[electrolysis]], using a [[zirconia]] solid oxide electrolyte to split the carbon dioxide into oxygen and carbon monoxide. However, if humans are to colonize Mars in the future, they would likely need as many [[greenhouse gas]]es as they can get in order to maintain a warm climate. So using the Martian atmosphere as a consumable resource with no intentions of replenishing it may be considered dubious. (see [[terraforming mars]]) ==References== {{reflist}} ==See also== *[[Climate of Mars]] *[[Life on Mars]] *[[In Situ Resource Utilization]] *[[Terraforming of Mars]] *[[Earth's atmosphere]] *''[[Total Recall (film)|Total Recall]]'', a science-fiction film where the irrespirability of [[Mars in fiction|Mars' atmosphere]] is part of the plot. {{Mars}} {{Atmospheres}} ==External links== * [http://www.space.com/scienceastronomy/060828_mars_clouds.html Mars Clouds Higher Than Any On Earth] - Mars is home to the highest clouds ever discovered above the surface of a planet, Space.com * {{cite web|url=http://hypertextbook.com/facts/2000/LaurenMikulski.shtml|title=Pressure on the Surface of Mars|work=The Physics Factbook|first=Lauren|last=Mikulski|year=2000}} * [http://www-k12.atmos.washington.edu/k12/resources/mars_data-information/pressure_overview.html Atmospheric pressure - summary of the Viking lander results] [[Category:Mars]] [[Category:Planetary atmospheres|Mars]] {{Link FA|vi}} [[bg:Атмосфера на Марс]] [[cs:Atmosféra Marsu]] [[ko:화성의 대기]] [[id:Atmosfer Mars]] [[it:Atmosfera di Marte]] [[pl:Atmosfera Marsa]] [[pt:Atmosfera de Marte]] [[ru:Атмосфера Марса]] [[fi:Marsin kaasukehä]] [[vi:Khí quyển Sao Hỏa]]