Slide 1Mars – Recent HistorySlide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36PYTS/ASTR 206 – Mars: Recent History1AnnouncementsUse Priyanka Sharma as TA[email protected]Office hours: Tuesday 10.30am-12.30pmRoom 316, Kuiper BuildingThursday office hours?Can only stick around for ~1 hour today…but these office hours are under-utilized in generalDo away with these hours?Calculate your expected grade…Add HW1 and HW2 percentages together, multiply by 0.15Add the two in-class activity marks (out of 5) together, multiply by 2Take your mid-term score (out of 45), multiply by 1.111Add these three things together…. And compare to grade tableThis is a REALLY rough guess, you can easily move up/down a gradePYTS/ASTR 206 – Mars: Recent History2PTYS/ASTR 206 – The Golden Age of Planetary ExplorationShane Byrne – [email protected] – Recent HistoryPYTS/ASTR 206 – Mars: Recent History3In this lecture…In this lecture…Martian weather todaySeasonal frostIce cloudsDust stormsRecapAncient MarsTransition to cold dry conditionsGiant FloodsOutflow channelsClimate change on MarsPolar ice capsOrbital variationsRunning water today?GulliesFlowing iceVolcanism and life?Methane in the atmospheremsss.comPYTS/ASTR 206 – Mars: Recent History4Mars has seasonal ice capsMars has dust-stormsDry dusty southern summerWarmerMars has water ice cloudsWetter northern summercoolerCurrent ClimateCurrent ClimatePYTS/ASTR 206 – Mars: Recent History5Earth-like seasons – but with a twistMartian orbit is eccentric (eccentricity ~ 0.1)Mars is farther from the Sun in the northern summer (1.37 AU)Closer in the southern summer (1.67 AU)Northern SummerCoolerLongerMore water vaporMore cloudsSouthern SummerHotterShorterLess water vaporMore dust stormsPYTS/ASTR 206 – Mars: Recent History6Mars has a similar obliquity (25°) to the Earth.Ensures seasons with periods of permanent polar darkness and daylight.Mars has a low pressure CO2 atmosphere.Permits seasonal icecaps of CO2 ice to form -Leighton and Murray (1966)PYTS/ASTR 206 – Mars: Recent History7Not every part of the ice cap is frostyLow albedo region inside the CO2 capSpectral indicators of large grain sizeLarge areas anneal into a transparent slab in 100’s of daysPYTS/ASTR 206 – Mars: Recent History8Behavior of a transparent slab of CO2 icePSP_002533_0935PSP_002675_0945Multiple fan (wind) directionsScouring of channels to produce ‘spiders’PYTS/ASTR 206 – Mars: Recent History9Clouds are commonIn the northern summer…Especially over volcanoesLifting of air over obstacles cause water to condensePYTS/ASTR 206 – Mars: Recent History10Dust StormsRegional dust storms common in southern summerGlobal dust storms occur every few years Reasons for interannual variability not well understoodPYTS/ASTR 206 – Mars: Recent History11The Tharsis volcanic bulge formedThick (>8 kilometers thick) sequence of volcanic rocksOutgassing of a lot of volcanic gas changed the climateWarmer conditions allowed more liquid waterHow Mars became cold and dryHow Mars became cold and dryPYTS/ASTR 206 – Mars: Recent History12Earth, Venus, MarsAll start with CO2 and water in their atmosphereMars, EarthCO2 and water goes into rocksVenusWater not stable as liquidVenusCO2 stays in atmosphereEarthRocks recycled by plate tectonicsMarsNo plate tectonics–CO2 stuck in rocksRunaway icehouseRock cycleRunaway greenhousePYTS/ASTR 206 – Mars: Recent History13There’s just one problemWe can’t find these CO2 bearing rocks (carbonates)Some recent progress on this…Spectral evidence of carbonates discovered and announced 2 months agoPYTS/ASTR 206 – Mars: Recent History14Mars at the end of the warm periodMaybe an ocean?Some evidence of former shorelines – but this is still controversialPYTS/ASTR 206 – Mars: Recent History15Former shorelines should be all the same elevation“sea-level” on MarsOne shoreline matches this…Shorelines have been alteredBy subsequent volcanoesBy polar wanderHead et al., 1999PYTS/ASTR 206 – Mars: Recent History16Early greenhouse atmosphere quickly removedWarm-wet transition to cold-dryHaberle, 1998A Changing PlanetLots of fluvial erosionNot much fluvial erosionPYTS/ASTR 206 – Mars: Recent History17Mars starts to freezeFrom the surface downwardsOcean starts to freezeCryosphere formsGround is frozen to some depthCryosphere gets thicker as planet gets colderGroundwater exists between cryosphere and basementGiant floods…Giant floods…Clifford and Parker, 2001PYTS/ASTR 206 – Mars: Recent History18What happens next?No ice covered ocean in the northern lowlands todayIce is transferred to the polar regionsOcean goes awayGroundwater system fills upClifford and Parker, 2001PYTS/ASTR 206 – Mars: Recent History19Accidents can happenCryosphere could break Ground water can flood outClifford and Parker, 2001PYTS/ASTR 206 – Mars: Recent History20Outflow channels on MarsGround water outbreaks - Carves huge flood channelsFloods 100’s of meters deep at ~25 m/sDischarge rates of ~ 107 m3s-1Enormous by terrestrial standards!!Mississippi river ~ 3x104 m3s-1PYTS/ASTR 206 – Mars: Recent History21Terrestrial analogueEnd of the last ice-ageGlacial lake Missoula- Ice-dam breaksChanneled scablands, WashingtonOutflow channel, MarsPYTS/ASTR 206 – Mars: Recent History22About 20% of the size of the Greenland ice-sheet1.2 million km31.1 million km3Climate change and ice capsClimate change and ice capsPYTS/ASTR 206 – Mars: Recent History23Orbital changes create layersLaskar et al., 2003Putzig et al. 2008Earth’s obliquity variationPYTS/ASTR 206 – Mars: Recent History24Big ice sheets of the inner solar system – Earth 30 million km36 million km3PYTS/ASTR 206 – Mars: Recent History25These layers could tell us a lot about martian climate over the past few million yearsSimilar to terrestrial ice coresMars: north poleEarth: GreenlandEarth: AntarticaPYTS/ASTR 206 – Mars: Recent History26Running water
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