PoLArInves,ga,onoftheSun
POLARIS
T.Appourchaux
Ins,tutd’AstrophysiqueSpa,ale,Orsay
Asetofpolarmissions
Exis,ngmissions
•  Ulysses:ESAmissionoperatedfrom1990to2009
•  SolarOrbiter:ESAmissiontobelaunchedin2018
Projects
•  PolarisproposedtoCosmicVisionin2007
•  Solar-CPlanAstudiedatJAXAin2008-2010
Notruepolarmissionyet!
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POLARIS
A Solar Polar Imager reaching a 75º
inclination can answer a class of
heliophysics science questions not
possible using any other existing or
planned mission.
Major breakthroughs in both solar &
heliospheric physics will results from
observations made possible by its unique
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polar orbit.
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Whyandhow?
•  Solarsailpropulsionuseofphotonpressure(not
solarwind...)
•  Solarsailpropulsionispropellantfreeand
con,nuous(chemicalpropulsionisshortanduse
propellant)
•  Accelera,onissmall,solarsailneedstobelight
andlarge(180mx180m)
•  Payloadneedsalsotobelight
Deployment
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IKAROS
Anexampleoforbit
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ScienceforaPolarMission
Remotesensing
Scien,ficObjec,ves
DSI
Howistheglobalcyclic,solarmagne,cfield
generated?
x
Whatisthenatureofflowsinthepolarregionsofthe
Sun,andhowdotheyvarywithmagne,cfields?
x
Howdoestheradia,veenergyoutputoftheSun
dependsonla,tude?
Howdoesmagne,cac,vityshapethestructureand
evolu,onofthepolarsolarcoronaandhowdoesit
affecttheEarth?
DSI=DopplerandStokesImager
TSI=TotalSolarIrradiance
HI=HeliosphericImager
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TSI
HI
EUI
EUS
x
x
x
x
EUI=ExtremeUltravioletImager
EUS=ExtremeUmtravioletSpectrometer
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Whatarethepriori,es?
Each priority corresponds to a well iden,fied
payloadormission
1.  La,tudevaria,onsofirradiance
2.  Solarinternalstructureanddynamo
3.  Corona,CoronalMassEjec,onanddynamo
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1.La,tudevaria,onsofirradiance
•  Requireslongobserva,onathighla,tudeina
thermallystableenvironment
•  Nolongobserva,onofthepolesareavailablefor
irradiance
•  Circularorbitpreferred
•  Highla,tude>75o(goal60o)
•  Minimalpayloadis:
–  TSI(TotalSolarIrradiance)
–  Mass<5kg
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2.Solarinternalstructureand
dynamo
•  Requireslongobserva,onathighla,tudeina
thermallystableenvironment
•  Nolongobserva,onofthepolesareavailablefor
helioseismologyandmagne,cfieldstudies
•  Circularorbitpreferred
•  Highla,tude>75o(goal60o)
•  Minimalpayloadis:
–  DSI(Dopplervelocityandmagne,cfield)
–  TSI(TotalSolarIrradiance)
–  Mass<15kg
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3.Coronaanddynamo
•  ClosetotheSun(about0.5to1AU)
•  Highinclina,on>60o
•  Maximumpayload(<40kg):
–  DopplerandStokesImager
–  Heliosphericimager(coronagraph)
–  ExtremeUltravioletImagerandSpectrometer
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Conclusion
•  Priority1:Focusonirradiancewithaminimalpayload
andatrulynewmission(payload<5kg)
•  Priority2:Focusonhelioseismologywithaminimal
payloadandatrulynewmission(payload<15kg)
•  Priority3:addcoronalobjec,vesmeanaddi,onalRS
instruments(payload<40kg)
•  Needtoworkongenuinescienceobjec,vesfor
Priority3(differentfromSolarOrbiter/Ulysses)
Europeanlegacyforpolarmissions:useit!
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The"Polaris"speech
"WechoosetogototheMoon.WechoosetogototheMoon
in this decade and do the other things, not because they are
easy, but because they are hard, because that goal will serve
to organize and measure the best of our energies and skills,
because that challenge is one that we are willing to accept,
oneweareunwillingtopostpone,andonewhichweintendto
win,andtheothers,too."
J.F.Kennedy(1962)
J.F.Kennedy"MoonSpeech"
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Adisplacedorbit
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