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

Plume of PI Plasma sheet lobes BL Ionospheric (polar) wind SOLAR WIND INDUCED ESCAPE E B MEX / ASPERA-3

SOLAR WIND INDUCED ESCAPE

COLD IONOSPHERIC IONS FAR IN TAIL Cold ionospheric ions POLAR WIND

SOLAR WIND INDUCED ESCAPE

ESCAPE OVER REGIONS WITH STRONG CRUSTAL FIELDS UV background

PLASMA SHEET P (ASPERA-3) P (MARSIS) dyn M dayside nightside some part of momentum thermal pressure

ESCAPE THROUGH PLASMA SHEET IS CONTROLLED BY SW VARIATIONS K is momentum transfer factor (~0.1)

CMEs IMPACT VENUS AND MARS

MERCURY VENUS 4-5 June hours hours CME PP P M ~29 nPa P M ~5.3 nPa

MARS (MARSIS DATA) Sequential plot for local |B|: 9475, 9481, 9482, 9487

MARS (MARSIS DATA) Sequential plot for ionospheric peak n e : 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

PLASMA FILAMENTATION IN MULTI-FLUID AND HYBRID SIMULATIONS Z, Rm Y, Rm x=0 SW MULTIPLE SHOCKLETS PROTON NUMBER DENSITY X, Rm PROTON NUMBER DENSITY XZ-PLANE YZ-PLANE

MAGNETIC FIELD IN IONOSPHERE

IONOPAUSE OR… ? density altitude

WHAT IS AN OBSTACLE FOR SW ? ALFVEN SPEED PILEUP BOUNDARY PHOTOELECTRON BOUNDARY

MARSMARS EARTHEARTH INVERTED V STRUCTURES ON MARS AND AURORA?

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

CURRENT PATTERN

E + - hemisphereE - - 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 axis-stabilized, sun-pointing spacecraft 75 o 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

OVER CRUSTAL FIELD REGIONS IONOSPHERIC EROSION EROSION IS TRIGGERED BY SOME UNKNOWN FACTORS 5th Alfven Conference, October 5, 2010, Sapporo, Japan

ELECTRON ACCESS VERSUS TOTAL CRUSTAL FIELD E= - V x B SW By < 0 ALT, km By (IMF) > 0 By(IMF) < 0 B (400km),nT Electron Flux - B y_IMF < 0 supports electron access to lower altitudes Dubinin et al., AG, th Alfven Conference, October 5, 2010, Sapporo, Japan

B y (IMF) is negative MAGNETIC FIELD AT LOW ALTITUDES

B y (IMF) is positive MAGNETIC FIELD AT LOW ALTITUDES FLUX ROPE (Zhang et al. 2012) OR ELECTROJET

- Thermal escape of hydrogen is the dominant process Mean flux ~ 1.6 x 10 cm s 8 -2 ~ 2x s ~ s ?