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Advanced Lithium Ion Venus Explorer (ALIVE)
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Abstract
The COncurrent Multidisciplinary Preliminary Assessment of Space Systems (COMPASS) Team partnered with the Applied Research Laboratory to perform a NASA Innovative Advanced Concepts (NIAC) Program study to evaluate chemical based power systems for keeping a Venus lander alive (power and cooling) and functional for a period of days. The mission class targeted was either a Discovery (500M)orNewFrontiers(750M to 780M)classmission.HistoricSovietVenuslandershaveonlylastedontheorderof2hoursintheextremeVenusenvironment:temperaturesof460degreesCentigradeandpressuresof93bar.Longerdurationmissionshavebeenstudiedusingplutoniumpoweredsystemstooperateandcoollandersforuptoayear.However,theplutoniumloadisverylarge.ThisNIACstudysoughttostillprovidepowerandcoolingbutwithouttheplutonium.Batteriesarefartooheavybutasystemwhichusestheatmosphere(primarilycarbondioxide)andonon−boardfueltopowerapowergenerationandcoolingsystemwassought.TheresulingdesignwastheAdvancedLong−LifeLanderInvestigatingtheVenusEnvironment(ALIVE)Spacecraft(S/C)whichburnslithium(Li)withtheCO2atmospheretoheataDuplexStirlingtopowerandcoolthelanderfora5−dayduration(untiltheLiisexhausted).WhileitdoesnotlastyearsachemicalpoweredsystemsurvivingdayseliminatesthecostassociatedwithutilizingaflybyrelayS/Candallowsacontinuouslowdataratedirecttoearth(DTE)linkinthisinstancefromtheOvdaRegioofVenus.Thefive−daycollectiontimeprovidedbythechemicalpowersystemsalsoenablessciencepersonnelonearthtointeractandretargetscience−somethingnotpossiblewithanapproximately2−hourspacecraftlifetime.Italsoallowsforcontingencyoperationsdirectedbytheground(reducedrisk).ThesciencepackagewasbasedonthatenvisionedbytheVenusIntrepidTesseraLander(VITaL)DecadalSurveyStudy.TheLiBurnerwithinthelongdurationpowersystemcreatesapproximately14000Wofheat.This1300degreeCentigradeheatusingLiinthebottom"ballast"tankismeltedtoliquidbytheVenustemperature,drawnintoafurnacebyawickandburnedwithatmosphericCO2.TheLicarbonateexhaustisliquidat1300degreesCentigradeandbeingdenserthanLidrainsintothetheLitankandsolidifies.Sincetheexhaustproductisadenseliquidno"chimney"isrequiredwhichconservestheheatforthestirlingpowerconvertor.TheDuplexStirlingprovidesabout300Wofpowerandremovesabout300Wofheatfromtheavionicsandheatthatleaksintothe1−bar−insulatedpayloadpressurevesselkeptat25degreesCentigrade.TheNaKradiatorisruntothetopofthedragflap.TheALIVEvehicleiscarriedtoVenusviaanAtlas411launchvehicle(LV)withaC3of7km2/s2.AnAeroshell,derivedfromtheGenesismission,enablesadirectentryintotheatmosphereofVenus(−10degreesCentigrade,40gmax)and6m/sforlanding(44g)usingadragring.Forsurfacescienceandcommunication,a100WRF(WebExRecordingFormat),X−Band0.6−meterpointableDTE(Direct−to−Earth)antennaprovides2kbps(kilobitspersecond)toDSN(Deep−SpaceNetwork)34−meterantennaclusters.Table1.1summarizesthetop−leveldetailsofeachsubsystemthatwasincorporatedintothedesign.CostestimatesoftheALIVEmissionshowitatapproximately760M which puts it into the New Frontiers class.The ALIVE landed duration is only limited by the amount of Li which can be carried by the lander. Further studies are needed to investigate how additional mass can be carried, perhaps by a larger launcher and larger aeroshell