火星和月球静电环境

TheElectrostaticEnvironmentsofMarsandtheMoon火星和月球的静电环境Abstract.TheelectricalactivitypresentintheenvironmentnearthesurfacesofMarsandthemoonhasverydifferentoriginsandpresentsachallengetomannedandroboticplanetaryexplorationmissions.Marsiscoveredwithalayerofdustthathasbeenredistributedthroughouttheentireplanetbyglobalduststorms.Dust,levitatedbythesestormsaswellasbythefrequentdustdevils,isexpectedtobeelectrostaticallychargedduetothemultiplegraincollisionsinthedust-ladenatmosphere.Dustcoveringthesurfaceofthemoonisexpectedtobeelectrostaticallychargedduetothesolarwind,cosmicrays,andthesolarradiationitselfthroughthephotoelectriceffect.Electrostaticallychargeddusthasalargetendencytoadheretosurfaces.NASA'sMarsexplorationrovershaveshownthatatmosphericdustfallingonsolarpanelscandecreasetheirefficiencytothepointofrenderingtheroverunusable.AndastheApollomissionstothemoonshowed,lunardustadhesioncanhindermannedandunmannedlunarexplorationactivities.Takingadvantageoftheelectricalactivityonbothplanetarysystembodies,dustremovaltechnologiesarenowbeingdevelopedthatuseelectrostaticanddielectrophoreticforcestoproducecontrolleddustmotion.ThispaperpresentsashortreviewofthetheoreticalandsemiempiricalmodelsthathavebeendevelopedforthelunarandMartianelectricalenvironments.纲要：火星和月球表面邻近环境的电行为有着极为不一样的发源，对载人和机器人行星探究任务是个挑战。火星表面覆盖一层灰尘，因全世界尘暴从头散布。灰尘，被这些风暴也常常被尘卷风带入高空，一般以为由于在充满灰尘的大气中发生多颗粒碰撞而带电。覆盖月球表面的灰尘一般以为由于太阳风、宇宙射线和太阳辐射自己经过光电效应而带电。带电灰尘有很强的附着表面偏向。美国国家航空航天局火星探测器证明大气灰尘落在太阳能电池板上轻则降低其效率，重则令其完全报废。阿波罗登月任务表示，月尘附着可能阻碍载人和无人月球探测活动。利用两个行星的电行为，此刻正在开发利用静电和介电泳力产生可控的灰尘运动的灰尘消除技术。本文简述了针对月球和火星电环境开发的理论和半经验模型。I.IntroductionMarsandtheEarth'smoonhaveverydifferentsurfaceandatmosphericenvironments,ascanbeseeninTables1and2.They,however,haveonethingincommon:theirsurfacesarecoveredwitharelativelyhomogeneouslayerofdust.ThissurfacedustdominatestheelectrostaticenvironmentofMarsandplaysanimportantroleinthatofthemoon.Ⅰ，简介火星和地球的月亮有着完整不一样的表面和大气环境，见表1和表2.但是，它们有一个共同点：它们的表面覆盖着一层相对均匀的灰尘。这类表面灰尘决定了火星的静电环境而且在月球表面起侧重要作用。表1.火星和月球的物理性质火星月球轨道倾斜度23°19’6°41’轨道周期24小时37分27.3天直径6796km3476km质量0.64*1024kg7.35*1020kg密度3.94g/cm33.36g/cm3表面重力0.379g0.167g表面温度-1400to20°C-1700to1300C表2.火星和月球的大气性质火星月球表面压力5到101×10-12（mbar）气体%气体%CO295Ar79.2N22.7He19.8组分Ar1.6O1O20.15Na微量H2O0.03H微量Theseelectrostaticenvironmentsarefarfrombeingfullyunderstood.Thedesirefortheirstudygoesbeyondscientificinquiry.Humanandroboticexplorationmissionstobothbodiesrequireagoodunderstandingofthisenvironmenttoavoidfailuresandmishaps.我们对这些静电环境还知之甚少。对它们的研究欲念不只是是科学好奇。对这两个星体的人类和机器人探测任务要求我们深入认识这个环境以防止失败和不幸。2.LunarandMartianElectrostaticEnvironments月球和火星的静电环境2.1.TheMoon2.1.月球At10-12mbar,thelunaratmosphereisextremelyrarefiedanditsinfluenceintheelectrostaticenvironmentnearthesurfaceofthemoonisnegligible.Thisenvironmentisinsteadcontrolledbythefluxofphotonsandionsfromthesolarwind,cosmicrays,andgalacticcosmicrays.Thelunarsurfaceiscomposedofrocksandgranularmaterialwithgrainsanddustparticlesranginginsizefromafewcentimetersdowntoafewnanometers.ThisgranularmaterialisexpectedtobeelectrostaticallychargedduetotheincidentplasmaandtotheUVfromthesun,whichreleasesphotoelectronsfromthesurfaceofthematerial.在10-12mbar压力下，月球大气及其稀疏，对月球表面邻近的静电环境影响能够忽视。月球的静电环境是由光子和太阳风、宇宙射线和星云宇宙射线带来的离子流主导的。月球的表面是由岩石和颗粒物质组成的，这些颗粒和灰尘微粒的尺寸从几个厘米到几个纳米。我们以为这些颗粒物质因入射等离子和太阳紫外线而带电，颗粒物质的表面失掉光电子。Theplasmaandphotonfluxesbathingthemoonproduceacomplexelectrostaticenvironment.Onthesunlitside,photoelectricchargingbysolarUVphotonsdominates.Theemissionofphotoelectronsleavesthesurfacepositivelychargedtoapotentialofabout5to10V[1].Onthedarkside,plasmaelectronsdominateandthesurfacebecomesnegativelychargedtoanegativepotentialortheorderoftheelectrontemperature,about-50to-100V[2].Themoonisessentiallyachargedbodyinaplasma,creatingascreeningeffectintheplasmawithacharacteristicdistanceorDebyelengthoftheorderofmetersonthelunardaysideandoftheorderofkilometersonthedarkside.ADebyesheathisthenfonnedaroundthemoonwhichreachesameterorsoonthedaysideandseveralkilometersonthenightside[3,4].ThenightsideDebyesheath,dominatedbyphotoelectrons,isusuallycalledthephotoelectronsheath.等离子和光子流照耀月球表面造成了复杂的静电环境。在日照一面，太阳紫外线光电效应造成带电占主导。光电子离开表面造成物质带5到10V正电【1】。在阴面，等离子电子占有主导，物质表面达到-50到-100V负电势或电子温胸怀级【2】。月球其实是个带电等离子，在月球的阳面米级和阳面公里级的特点距离或德拜距离内产生等离子障蔽效应。德拜障蔽在月球阳面达一米或几米，在阴面可达几公里【3,4】。阴面德拜障蔽由光电子主导，往常称为光电子障蔽。Lunarsurfacepotentialsdependgreatlyonchangesinthesolarwindandcosmicrays,whichaffecttheplasmaenvironment.WhenthemooncrossestheEarth'splasma,negativesurfacepotentialscanreachseveralkV.Surfacepotentialsreaching-5kVwereobservedbyLunarProspectorduringperiodsofintensesolaractivity[5].月球表面电势很大程度上取决于太阳风和宇宙射线带来的电荷，它们影响等离子环境。当月球经过地球的等离子层时，表面负电势可达几KV。LunarProspector探测器在密集的探月活动时期以前察看到-5KV的表面负电势【5】。Inourairlessmoon,itwouldseemlikelythatthedustonitssurfaceberelativelystatic.However,thecomplexelectrostaticenvironmentjustdescribedaffectsdustbehaviorinunexpectedways.Thereappearstobeevidenceofdustlevitationanddusttransportonthemoon.ThisissuehasbeencontroversialsinceitwasfirstraisedduringtheApollomissions[6].AhorizonglowwasreportedbyApolloastronauts[7](Fig.1).Thisglowhasbeeninterpretedasevidenceoftransientdustcloudsabovethelunarsurfacethatcouldreachseveralkmabovethesurface.ObservationswiththelunarSurveyorspacecraft[8]andtheLunarEjectaandMeteoritesExperiment(LEAM)onApollo17indicatedthepresenceofdustclouds[9].Althoughnotheoreticalmodelsatisfactorilyexplainsthephenomenon,ithasbeensuggestedthatelectrostaticchargingofthelunarsurfaceduetoexposuretochargedparticlesfromthesolarwindaswellasUVradiationcouldresultinthelevitationandtransportofdustparticles[10].在我们的没有空气的月球上，灰尘看上去极有可能是相对静止的。但是，刚才谈到的复杂的静电环境对灰尘的影响高出了我们的想象。仿佛有凭证表示灰尘飘荡和挪动在月球上存在。这个问题自它在阿波罗行动中初次提出向来饱受争议【6】。阿波罗宇航员报告了地平线处有霞光【7】（见图1.）。这个霞光被以为是月球表面透明的高达几公里的灰尘云的凭证。Surveyor月球探测飞船【8】和阿波罗17号的月球抛射物和流星试验的察看证了然灰尘云的存在【9】。只管没有令人满意的理论模型解说这类现象，它向来提示我们来自太阳风以及紫外线的带电粒子造成的月球表面带电致使灰尘颗粒飘荡和挪动【10】。（图片缺失）Figure1.SketchesdonefromorbitbyApolloastronautsshowingstreamersreachingupto100kmfromthesurface.[CourtesyNASA]图1.轨道上的阿波罗宇航员画的草图表示飘荡带可达自月面100公里的高度【NASA惠允】2.2.Mars火星ParticleSizeDistributionintheMartianAtmosphere火星大气的颗粒尺寸散布ThesurfaceofMarsiscoveredwithalayerofdustthathasbeensomewhathomogenizedbyplanet-wideduststorms.Theseduststorms,whichhavewindvelocitiesupto32m/s,havebeenobservedtolastforseveralmonths(Fig.2)[11].Dustdevilsupto10kmhighweredetectedduringthe1997MarsPathfindermissionwithdailyfrequency.NASA'sMarsroverSpirithasphotographeddozensofdustdevilsfromitslocationinsidetheredplanet'sGusevCrater(Fig.3).Opportunity,themission'ssecondrover,hadnotbeenabletocaptureanimageofadustdeviluntilthispastJuly,sixyearsafteritsarrivalonMars.Itslocation,onMeridianiPlanum,isnotasdusty.NASA'sPhoenixMarsLanderalsophotographeddustdevilsintheMartianarcticduringits2008mission.火星表面覆盖着一层由遍布星球的尘暴某种程度上均匀散布的灰尘。已察看到的这些尘暴的风速可达32m/s，连续几个月之久（图2.【11】。1997年的MarsPathfinder行动每日发现了高达10公里的尘卷风。NASA的勇气号火星探测器在这个红色星球的Gusev火山口处拍摄到了大批尘卷风的照片（图3.）机会号，这个行动的第二个探测器，直到它达到火星6年后与昨年的7月份才拍摄到尘卷风的照片。它的地点在Meridiani大高原，并不是多尘地域。NASA的凤凰号火星登岸器也在它的2008年行动中在火星极地拍摄到了尘卷风的照片。（图片缺失）Figure2.AMartianglobalduststorm[CourtesyNASA].图2.一个火星全世界尘暴【NASA惠允】Thesestorms,alongwiththefrequentdustdevils,carrydustparticlesthatareupliftedintothethinatmosphereoftheplanet.Theactualmechanismthatupliftsdustintotheatmosphereisstillnorclearlyunderstood.Fromtheknowledgeoftheterrestrialmechanism,ithasbeenproposedthatsaltationaidedbydustdevilsandthepresenceofelectricfieldsmayupliftdust[12,13].Fromopticaldatausinginstrumentsonorbitingspacecraftandonlanders,estimatesofthesizedistributionofdustparticlesintheatmospherehavebeenmade.Thesemeasurementsyieldavalueforparticlediameterof1.5±0.2μm.However,thesizedistributionofatmosphericdustchangeswiththepresenceofdustdevilsandduststorms,asonewouldexpect.Atthepeakofthe2001globalduststormdepictedinFigure2,particlediametersderivedfromdatafromtheThermalEmissionSpectrometeronboardtheMarsGlobalSurveyororbitingspacecraftrangedfrom2to5μm[14].这些尘暴，以及屡次出现的尘卷风，把灰尘颗粒提高到这个星球的稀疏大气中。提高灰尘到大气中的机理还没有搞清楚。依据地形机理知识，人们广泛以为尘卷风造成的颗粒跃升和电场的存在可能提高了灰尘【12,13】。依据轨道器和登岸器上的设施的光学察看数据，我们给出了火星大气中灰尘颗粒尺寸散布的预计。这些丈量给出了1.5±0.2μm的颗粒直径值。但是，认可预期，大气灰尘的尺寸散布跟着尘卷风和尘暴的存在而改变。在图2描绘的2001年全世界尘暴顶峰，火星全世界探测器的轨道器的热辐射分光仪给出的颗粒直径从2到5μm不等【14】。（图片缺失）Figure

3.Adust

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the

488dayof

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行动的地

488天勇气号火星探测器拍摄到的尘卷风【

NASA惠允】UsingmeasurementsbytheMicroscopicImager(MI)ontheMarsExplorationRovers,Landisetalseemtofindevidenceforathree-componentparticledistributionforatmosphericdust:Atmosphericdustsuspendedforlongperiodsoftime,withdiametersinthe2to4μm;settleddustraisedintotheatmospherebywindanddustdevils,withdiametersinthe10μmandunderrange;andsaltatingparticles,withdiametersgreaterthan80μm,thatmoveduetosaltation[15].依据火星探测器上的MicroscopicImager微观图形仪(MI)的数据，Landis等人发现了大气灰尘散布的三个组分的凭证：长久悬浮在大气中的灰尘直径在2到4μm;被风和尘卷风提高的静止灰尘的直径在10μm以下；跃升颗粒，直径大于80μm,由于跃升作用被提高到大气中【14】。ParticlesizedistributiondatafortheMartiansoilhasbeenobtainedbytheMarsExplorationRoversSpiritandOpportunityatthelocationsthatthetwocrafthavevisited.Thesevaluesarehoweversomewhatskewedbecausetheinstrumentusedtomeasurethem,theMicroscopicImager,hasaresolutionof31μmperpixel,whichlimitsthedetectionofverysmallparticlesizes.TheMIonSpirithasrecentlycompletedmeasurementsofthesoilonScamanderCrater,obtainingaverageparticlesizesof220μm[16].勇气号和机会号火星探测器在它们探测过的地方获取了相应的火星土壤颗粒尺寸散布数据。但是这些数值某种程度上由于丈量它们的设施而有些偏差，微观图形仪的清楚度为每个像素31μm，这限制了它探测很小的颗粒尺寸。勇气号上的微观图形仪近来达成了Scamander火山口处的土壤的丈量，获取颗粒的均匀尺寸为220μm【16】。Atmosphericelectricfields2.2.2.大气电场StationarysurfacesandanddustonMarsmaybeelectrostaticallychargedduetoincidentUVradiationreachingthesurface.AlthoughthetotalintegratedUVfluxover200-400nmiscomparabletoEarth's,shorterwavelengthscontributealargerproportionofthisflux[17].Contactchargingmayalsooccurduetocollisionsbetweenwind-blowndustparticlesandstationarysurfaceparticulatematter.火星表面的静止沙粒和灰尘可能由于抵达表面的紫外线入射带电。只管从200-400nm波长的整个紫外线流与地球上的相当，短波长的紫外线占有了大多数【17】。由于风吹灰尘和表面的静止颗粒物质互相碰撞产生的接触带电也可能出现。Thereisexperimentalevidencethatcollisionsduetodustmotioncanresultinelectrostaticchargingofdustparticles.Intheearly1970s,EdenandVonnegutobservedaglowaswellasfilamentarydischargesasacontainerwithsandwasshakenunderMartianatmosphericconditions[18].Shortlyafter,MillssuggestedthattriboelectricallyproducedglowdischargesintheMartianatmospheremightexplaintheapparentabsenceofcarbonaceousmatterontheplanet[19].Morerecently,wewereabletoobserveglowdischargescausedbycollisionsofMarssimulantdustparticlesunderatmosphericconditionsmimickingthoseofMarsandshowedthatthesedischargesalteredknownorganicsonMarssimulantdust[20].FabianetalandKraussetaldesignedexperimentstodemonstratethattheverticalmotionofdustissufficientforthischargingmechanismtoproducestrongelectricfieldscapableofcreatingelectricaldischargesinalow-pressureCO2atmosphere[21,22].Theywereabletodetectdischargesbothvisuallyandelectronicallyandmeasuredthedischargefrequenciesandintensities.Therangeofpressuresrequiredtoefficientlyproducethesedischargeswasalsoexamined,demonstratingthatelectricaldischargescanoccurunderconditionsexpectedontheMartiansurface.Additionally,asimpletheoreticalmodelhasbeencreatedtoconstraintheparametersinvolvedinthedustchargingexperiment.Theirmodelsupportstheideasdevelopedintheirexperiment.SimilartheoreticalcalculationshadbeenperformedearlierbyMelnikandParrot[23].试验表示灰尘挪动造成碰撞能够致使灰尘颗粒带电。在1970年月初期，Eden和Vonnegut在晃动一个盛有沙子的切合火星大气环境的容器时察看到了霞光和丝状放电【18】。今后不久，Mills指出火星大气中的摩擦产生的放电霞光可能用来解说这个星球显然缺乏含碳物质的原由【19】。就在近来，我们察看到了模拟火星大气条件下的模拟火星灰尘颗粒碰撞产生的放电霞光而且展现了这些放电改变了模拟火星灰尘中的已知有机物【20】。Fabian等人和Krauss等人设计的试考证明垂直挪动的灰尘足以以这类带电机理产生强盛的电场造成低压CO2大气放电【21，22】。它们能够目击和用电测方法察看到放电而且丈量它们的频次和强度。足以产生这些放电的压力范围也获取了丈量，表示放电可能在料想的火星表面的条件下产生。此外，他们还创建了一个理论模型来拘束有关的灰尘带电试验参数。他们的模型支持他们的试验中产生的想法。byMelnik和Parrot早些时候做了近似的理论计算【23】。AccuratedeterminationsofthechargeandparticlesizedistributionparticlesintheMartianatmospherecouldbeobtainedwhendedicatedinstrumentationisflownonafuturemission.Withthatinmind,ourlaboratory,incollaborationwiththeUniversityofArkansas,developedaDustParticleAnalyzerinstrumentthatiscapableofdeterminingtheelectrostaticchargeandtheaerodynamicdiameterofdustparticlesintheMartianatmosphere[24].AerodynamicdiametersandelectrostaticchargevaluesofMartiansimulantdustparticlesinavacuumchamberatsimulatedMartianatmosphericconditionsareshowninFig.4.

for对火星大气中颗粒的尺寸散布和电荷的精准测定能够由未来火星探测发射的专用仪器获取。考虑到这一点，我们的实验室与阿肯色大学合作开发了一款能够测定火星大气中灰尘颗粒的空气动力直径和静电荷的灰尘颗粒剖析仪【24】。模拟火星大气条件的真空室里的火星模拟灰尘颗粒的空气动力直径和静电荷值见图。（图片缺失）Figure4.AerodynamicdiameterandchargeofMartiansimulantdustparticlesmeasuredwithNASA'sDustParticleAnalyzerundersimulatedMartianatmosphericconditions.图4.模拟火星大气条件下NASA的灰尘颗粒剖析仪测定的火星模拟灰尘颗粒的空气动力直径和电荷3.ChallengesandPossibilitiesforExplorationMissions探测任务的挑战和可能ThecomplexelectrostaticenvironmentsofMarsandthemoonpresentchallengesforhumanandroboticexploration.Onbothsurfaces,dustcandepositonthesurfacesofsolarcells,equipment,thermalradiators,andotherhardwarelikelytobeusedinexplorationmissions.LunardustisexpectedtobeelectrostaticallychargedbytheincidentplasmaandbythesolarUV.DustintheMartianatmosphereisalsoexpectedtobechargedbydustcollisionsindustdevilsandduststorms.火星和月球的复杂的静电环境给人类和机器人探测带来极大挑战。在两个星球的表面，灰尘可能堆积在太阳能电池板、设施、热辐射仪、和其余探测任务可能使用的硬件的表面。月球灰尘可能因等离子入射和太阳紫外线带静电。火星大气中的灰尘还可能因尘卷风和尘暴中的灰尘碰撞带静电。ThepresenceofelectrostaticallychargeddustonMarsandthemoonalsopresentsopportunitiestoenableexplorationmissions.Ourlaboratoryhasbeendevelopingadustmitigationtechnologythattakesadvantageoftheseelectrostaticenvironments[25-27].TheElectrodynamicDustShield,asystembasedonthegenerationofchangingnon-uniformelectricfieldsabletoacceleratechargeddustparticleswiththedielctrophericforce,hasproventobeextremelyefficientatclearingdustatlunarandMartianenvironmentalconditions.Inclusionofthistechnologyalongwithotherinstrumentationfortheaccuratemeasurementsneededwillenhanceandenablefuturemissions.火星和月球上带静电灰尘的存在也给探测任务供给了时机。我们的实验室向来在开发利用这些静电环境的灰尘消除技术【25—27】。静电灰尘障蔽，一个鉴于生成非均匀电场用电泳力来加快带电灰尘颗粒的系统，已经获取证明在消除月球和火星环境条件下的灰尘方面特别有效。这项技术与其余需要的精准丈量联合将增强和使未来的探测任务成为可能。References参照文件[1]Manka,R.H.,"Plasmaandpotentialatthelunarsurface,"Photonandparticleinteractionswithsurfacesinspace,RJ.LGrard,Ed.,Springer,NY,347-361(1973)].Halekas,J.S.,Mitchell,R.P.Lin,L.L.Hood,M.H.Acuf'la,andA.Binder,"Evidencefornegativechargingofthelunarsurfaceinshadow,"Geophys.Res.Lett,29,1436(2002)Singer,S.F.andE.H.Waker,"Photoelecticscreenignofbodiesininterplanetaryspace,:Icarus,1,7-12(1962)[4]Freeman,J.W.andM.Ibrahim,"Lunarelectricfields,surfacepotentialandassociatedplasmasheaths,"Moon,14,103-114(1975)[5]Halekas,J.S.,S.D.Bale,D.L.Mitchell,andR.P.Lin,"Electronsandmagneticfieldsinthelunarplasmawake,"J.Geophys.Res.,110(2005)Gold,T.andGJ.Williams,"ElectrostaticTransportationofDustontheMoon,"PhotonandParticleInteractionswithSurfacesinSpace,RJ.L.Grard,Ed.,Reidel,Dordrecht(1973)Zook,H.A.andJ.E.McCoy,"LargeScaleLunarHorizonGlowandaHighAltitudeLunarDustExosphere,"Goephys.Res.Lett.,18,2117(1991)Rennison,JJ.,AndD.R.Criswell,"SurveyorObservationsofLunarMoon,10,121(1973).[9]Berg,O.E.,H.Wolf,andJ.Rhee,"LunarSoilMovementRegisteredbytheApollo17CosmicDustExperiment,"inInterplanetaryandZodiacalLight,p.233,Springer-Verlag,Heidelberg(1975)[10]Horanyi,M.,"ElectrostaticChargingofLunarDust,"LPSXXIX,1527(1998)[II]Gaier,J.R.,Perez-Davis,M.E.,Marabito,M.,"AeolianRemovalofDustFromPhotovoltaicSurfacesonMars"NASATechnicalMemorandum102507(1990)Reno,N.O.andJ.F.Kok,"ElectricalactivityanddustliftingonEarth,Marsandbeyond,"SpaceSci.Rev.137,4'19-134(2008)Greely,R.etal,J.Geophys,Res.108,5041(2003)WolfandClancy,"ConstrainsonthesizeofMartianaerosolsfromThennalEmissionSpectrometerobservations,J.Geophys.Res.(Planets)t08(2003)].[IS]Landis,G.A.,K.Herkenhoff,R.Greeley,S.Thompon,P.Whelley,andtheMERAthenaScienceTeam,DustandsanddepositionontheMERsolararraysasviewedbytheMicroscopicImager,"LPS37(2006)Siebach,Ardidson,Cabrol,andtheAthenaScienceTeam,"RecentSpiritresults:MicroscopicImageranalysisofparticlepropertiesinScamanderCrater,westofhome,"LPS41(2010)CockellCS,Catling0,DavisWL,KepnerRN,LeePC,SnookK,McKayCPo2000.TheultravioletenvironmentofMars:biologicalimplicationspast,presentandfuture.Icarus146,343-359.[18]Eden,H.F.andB.Vonnegut,"Electricalbreakdowncausedbydustmotioninlow-pressureatmospheres:ConsiderationsforMars,"Nature,280,pp.962(1973)[19]Mills,A.,DustcloudsandfrictionalgenerationofglowdischargesonMars,Nature268,(1977)[20]Hintze,P.E.,C.R.Buhler,A.C.Schuerger,LM.Calle,andC.1.Calle,"Alterationoffiveorganiccompoundsbyglowdischargeplasma