Atmosphere Mars

the tenuous atmosphere of mars visible on horizon

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

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

potential sources , sinks of methane (ch

4) on mars

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

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

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

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

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

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

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

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

aurora

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

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

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

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