venus - university of oregonhomework.uoregon.edu/pub/class/121/venus.pdfvenus • similar to earth...
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![Page 1: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/1.jpg)
Venus
![Page 2: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/2.jpg)
Venus
• SimilartoEarthin– size(95%diameterofEarth)
– density(95%ofEarth)– mass(82%ofEarth’smass)– Hasanatmosphere!
Thickcloudlayerobscuressurface.Beforeeraofsatellites,itwasbelievedthatVenuswasaswampy,warmplanetthatharboredlife.
![Page 3: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/3.jpg)
• Mariner2(1962)wasfirstsuccessfulmissiontoVenus(therewere4beforethisthatfailedforvariousreasons)
• Orbitedtheplanet.Foundthat:• VenusisHot(~500degCor900degF)• VenushasliUleornomagneVcfield• Nowaterinatmosphere(97%CO2)• Mariner5detectedatmosphericpressure90xthatofEarth’s.
MarinerMissions
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• Venera7wasthefirstsatellitetolandonVenusand“lived”for23minutesbeforepressure,heatandsulfuricaciddropletskilledit.
• Venera8measuredlightlevels.Lightenoughforpictures.• Venera9tooktheveryfirstopVcalimagesofthesurface.
Bunchofrocks,onalavabed.Didn’tlastlongeither.• Venera10‐14tookmoreimages,lifeVmearound~2hours
VeneraMissions
![Page 5: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/5.jpg)
Venera9Images
![Page 6: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/6.jpg)
• Venusrotatesveryslowly(243Earthdays).AVenusiandayislongerthanaVenusianyear(225Earthdays).
• RotaVonisretrograde,sunrisesinwestandsetsineast.• SlowrotaVon–causedbyfricVonaldragofatmosphere.• SmallinducedmagneVcfieldfrominteracVonofsolarwind
andIonosphere.
OtherVenusFacts
![Page 7: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/7.jpg)
• SincedensityandsizeofVenusaresimilartoEarth,thencoreshouldbesimilartoEarth’score.Magnetosphereshouldbesimilaraswell.
• ButsmallVenus’intrinsicmagneVcfieldisafracVonofEarth’s(~1/100000).Weird.Possiblyduetosolidcore,nomoltenoutercoretocreatedynamoandinducemagneVcfield.
MoreVenusFacts
![Page 8: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/8.jpg)
• FromtheperspecVveoftheEarth,Venushasphaseslikeourmoon.ThisisbecauseVenusislocatedinsidetheorbitoftheEarth.AndunlikeMars,JupiterandotherplanetsoutsideEarth’sorbit,wedon’talwaysseethesunlitside
• Cloudsarecomposedofsulfuricacid(H2SO4,reallynastycorrosivestuff)whichstartat50kmabovethesurface.BelowthisalVtude,theatmosphereappearsclear.
EvenMoreVenusFacts
![Page 9: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/9.jpg)
• CO2andH2Oaregreenhousegases–transparenttoopVcallightbutabsorbalotofinfraredlight(heat).
• Sunemitslightprimarilyinvisiblepartofspectrum.Thisgetsabsorbedorreflectedbyplanet.
• Theplanetemitslightitself–ininfrared.Carbondioxideandwatervaporabsorbinfraredandare“transparent”tovisiblelight.
• DumpingmoreCO2andH2Ovaporintoatmosphereincreasestheamountofgreenhousegasestherebyincreasingthetemperature.
GreenhouseEffect
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• Temperatureofsurfacereachesboilingpoint(100Cor212F)ofwater.Waterevaporatesfromoceans,dumpingH2Ointoatmosphere‐>increasingtemp‐>acceleraVngtheevaporaVon‐>dumpsmorewaterintosky‐>increasestempandsoon….
• NotethatVenustemperatureiswaybeyondtheboilingpointofwater,soyeah,Venusatmosphereistheproductofrunawaygreenhouseeffect.
• Watermoleculesrisetotopofatmospherearebrokenapart,andblastedawaybysolarwind.
RunawayGreenhouseEffect
![Page 11: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/11.jpg)
• Problem–howdoyouexplorethesurfaceofVenuswhen– a.eachlandingprobethrownatittransmitsfor~1hour…NotenoughVme!
– b.orbiterscan’tseethroughheavyclouds• SoluVon!Radarmapping• PioneerVenusProbes(1978)werethefirsttodothis.
• MagellanMission(1990‐1994)highlysuccessfulathighresoluVonimaging…..buthowdoesradarwork?
Neededmoredata…
![Page 12: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/12.jpg)
• RadarstandsforRAdioDetecVonAndRanging.
• Asourceemitsapulseofradiowaves.Thesewavesbounceoffa“target”(planetsurface).
• ThewavesbounceinalldirecVons,however,somecomebackinthedirecVonofthesource.
• Conveniently,aUachedtothissourceisadetectorandreceiverthatmeasurestheVmeittakesforthewavetotravelthedistance.
• Inmathterms:Distance=3mexspeedofpulse/2.
– Thespeedofthepulseisspeedoflight(300,000km/s)
– thefactor2isneededtoaccountforthewavetravelingtoandawayfromtarget.
Radarsimplified
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• AmazingHiresradarmaps:
MagellanResults
![Page 14: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/14.jpg)
• Found:– NoindicaVonofoceans(atleastinlast500millionyears).Noerosion.
– TectonicacVvityisnonexistent• randomlydistributedvolcanoes(notonplateboundaries)
• faultlinesexist,butnotsimilartoridges/rinsonEarth• NosubducVonzones
– Millionsofvolcanoes,butnoapparentongoinglavaflow.VolcanoesmaybeacVvebutpresentlythereisnosolidevidence.
– SurfaceisrelaVvelyyoung300‐500Myrs
MagellanResults
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• ChainsofVolcanoes–likeHawaiianIsland“hotspot”formaVon.– ButthisispartofseveralrandomlyspreadvolcanicformaVons.
MagellanResults
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• NewweirdfeatureswithnoanalogonEarth– Coronae(100km‐1000km)probablycausedbymagmaliningthesurface,coolsthensinksformingcircularrings.
– Arachnoids(precursortoCoronae?)Smallerversionsofcoronaewithradiallines.
MagellanResults
![Page 17: Venus - University of Oregonhomework.uoregon.edu/pub/class/121/venus.pdfVenus • Similar to Earth in – size (95% diameter of Earth) – density (95% of Earth) – mass (82% of Earth’s](https://reader033.vdocuments.us/reader033/viewer/2022041800/5e50b33bba14f26129505daa/html5/thumbnails/17.jpg)
• SimilarfeaturestoEarth:– Shieldvolcanoes(flatvolcanoescausedbylavaflowaccumulaVon)
– Caldera‐>Howcanonetellthedifferencebetweenimpactcratersandvolcanoes?
MagellanResults
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ImpactcratersvsVolcanicCraters
• Impactcraters:– centralpeak– sharpedges
• Volcanoes– BullseyeridgepaUern– smoothcraterfloor
– rounded/flaUenedrim– lavaflow
Isthiscausedbyameteororvolcano?
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Impactcraters
• Nosmallcraters,meteoritesareprobablydestroyedinatmosphere.
• Craterclustersexist–largermeteoritesbreakupbeforeimpact
• Alsoalackoflargecratersindicatesresurfacedarea.