Transcript Slide 1
Solar Wind Induced Escape on Mars and Venus. Mutual Lessons from Different Space Missions E. Dubinin Max-Planck Institute for Solar System Research, Katlenburg-Lindau, Germany SOLAR WIND INDUCED ESCAPE E B Plume of PI lobes BL Plasma sheet Ionospheric (polar) wind MEX /ASPERA-3 SOLAR WIND INDUCED ESCAPE COLD IONOSPHERIC IONS FAR IN TAIL POLAR WIND Cold ionospheric ions Cold ionospheric ions SOLAR WIND INDUCED ESCAPE ESCAPE OVER REGIONS WITH STRONG CRUSTAL FIELDS UV background PLASMA SHEET P (ASPERA-3) dyn PM (MARSIS) dayside 2 nsw mswV 2 Bd / 2o nightside Bn / o nO mO VO2 2 some part of momentum thermal pressure ESCAPE THROUGH PLASMA SHEET IS CONTROLLED BY SW VARIATIONS fO f sw k 1/ 2 ( ) 2 (1 r ) fO f sw r k 1/ 2 ( ) 2 2 (1 r ) 2 nO nsw r nO 2 nO K is momentum transfer factor (~0.1) CMEs IMPACT VENUS AND MARS MERCURY CME CME PP PM~29 nPa 4-5 June hours VENUS CME CME hours PM~5.3 nPa MARS (MARSIS DATA) Sequential plot for local |B|: 9475, 9481, 9482, 9487 MARS (MARSIS DATA) Sequential plot for ionospheric peak ne: 9475, 9481, 9482, 9487 VENUS MARS Different modes of ELS - OTHER OPEN QUESTIONS? - ION FORESHOCK ? (There are no reflected protons upstream of the nose of the Martian BS. Ion foreshock lies entirely downstrem of the subsolar point) - HOT OXYGEN CORONA? (There are no ASPERA observations of oxygen ions which could be reliably identified as originated from hot oxygen corona) ’FILAMENTATION’ OF PLASMA FLOW AROUND MARS 2050 2100 2110 2120 2130 PLASMA FILAMENTATION IN MULTI-FLUID AND HYBRID SIMULATIONS YZ-PLANE XZ-PLANE PROTON NUMBER DENSITY PROTON NUMBER DENSITY MULTIPLE SW Z, Rm X, Rm Y, Rm MAGNETIC FIELD IN IONOSPHERE IONOPAUSE OR… ? density altitude WHAT IS AN OBSTACLE FOR SW ? PHOTOELECTRON BOUNDARY PILEUP BOUNDARY ALFVEN SPEED INVERTED V STRUCTURES ON MARS AND AURORA? M A R S E A R T H DO WE UNDERSTAND CLEARLY WHAT IS INDUCED MAGNETOSPHERE? SOLAR WIND WITH ALIGNED IMF VENUS EXPRESS OBSERVATIONS FIELD CONFIGURATION (POLOIDAL FIELDS) Without flow With flow With flow and leakage of dipole field outwards REVERSED DRAPING OR WRAPPING EFFECT REVERSED DRAPING OR WRAPPING EFFECT CURRENT PATTERN E+ - hemisphere E- - hemisphere CONCLUSIONS WHILE THE IDEA OF AN INDUCED MAGNETOSPHERE AT FIRST SEEM STRAIGHTFORWARD, IT IS NOT A PARTICULARLY WELL-CONSTRAINED CONCEPT WHEN APPLIED TO VENUS AND MARS WE NEED A MISSION WITH ADEQUATE PAYLOAD TO ADDRESS THESE QUESTIONS (MAVEN ?) BACKUP Launch, 18 November 2013 3-axis-stabilized, sun-pointing spacecraft 75o inclination, 4.5-hour period orbit Five 5-day “deep dip” campaigns with periapsis altitudes down to the homopause (~125 km). Nominal periapsis: ~150 km Eight science instruments, grouped into three packages The MAVEN Science Instruments Mass Spectrometry Instrument Remote-Sensing Package Particles and Fields Package BACKUP ESCAPE FLUXES AS A FUNCTION OF SW FLUX IONOSPHERIC EROSION EROSION IS TRIGGERED BY SOME OVER CRUSTAL FIELD REGIONS UNKNOWN FACTORS 5th Alfven Conference, October 5, 2010, Sapporo, Japan ELECTRON ACCESS VERSUS TOTAL CRUSTAL FIELD By (IMF) > 0 By(IMF) < 0 ALT, km SW Electron Flux By < 0 E= - VxB B (400km),nT B (400km),nT - By_IMF < 0 supports electron access to lower altitudes 5th Alfven Conference, October 5, 2010, Sapporo, Japan Dubinin et al., AG, 2008 MAGNETIC FIELD AT LOW ALTITUDES By (IMF) is negative j B nmi inV MAGNETIC FIELD AT LOW ALTITUDES By (IMF) is positive FLUX ROPE (Zhang et al. 2012) OR ELECTROJET j B nmi inV -Thermal escape of hydrogen is the dominant process 26 8 -2 Mean flux ~ 1.6 x 10 cm s -1 -1 ~ 2x 10 s ? 26 -1 ~ 10 s