Институт космических исследований Российской Академии наук Необычная магнитосфера Марса – сопоставление результатов предшествующих и последних исследований М. Веригин Пятая конференция ОФН 15 «Физика плазмы в солнечной системе» 8  12 февраля 2010 г., ИКИ РАН

Содержание  Mariner 4, Марс 2, 3, 5 – ранние измерения  Марс 3 – первые наблюдения намагниченности марсианской коры 21 января, 1972  о магнитном моменте Марса  особенности околомарсианских плазменных границ: -стабильность ударной волны у терминатора; -отсутствие  V 2 инвариантности магнитопаузы; -очень большой отход ударной волны от Марса при малых M a в солнечном ветре; -олияние неоднородной намагниченности марсианской коры на положение магнитопаузы;  конкуренция двух механизмов ускорения ионов в магнитном хвосте Марса  об источниках ночной ионосферы планеты

Mariner 4, Mars 2,3,5 observations Mariner 4, July 15, 1965 Марс 2-3, 5, , 1974  Martian bow shock discovery discovery  Martian magnetosphere magnetosphere discovery discovery  multiple bow shock bow shock crossings crossings Mars Мars Мars

Strong (~27 nT) and regular magnetic field in the vicinity of Mars 3 closest (~ 1500 km) approach to the day side of the planet Mars 3 magnetospheric observations Dolginov et al., Doklady AN SSSR, 207, No.6, , 1972 Dolginov et al., JGR, 81, No.19, , 1976 Originally interpreted as an evidence of planetary dipole magnetic field M m = 2.4x10 22 G cm 3 Later Russell et al. (GRL, 5, No.1, 81-84, 1978) inferred that “…observed magnetic field was draped over the Martian obstacle as expected if the field were simply shocked and compressed solar wind magnetic field.”

Magnetic field direction has discon- tinuity around the Mars 3 closest approach region (orange arrows) Inconsistency with simple IMF draping Magnetic field direction is inconsis- tent to those one expected for simple draping in the closest approach region Mars 3, Jan. 21, 1972 Hence :  “…Mars most probably possesses a small intrinsic field magnetosphere.” Slavin & Holzer, JGR, 87, No.B12, , 1982 but:

What was below Mars 3 on Jan.21, 1972 ?  Mars 3 observed strong and regular magnetic field exactly above the region of the strongest magnetization of the Martian crust Mars 3 orbit Jan. 21, 1972 projection to surface Horizontal magnetic field Connerney et al., GRL., 28, No.21, 4015–4018, 2001 Total magnetic field

Do MGS crustal field direction corresponds to those one observed by Mars 3 ? YES !  Comparison of Mars 3 magnetic field with those one of MGS provides evidence that Mars 3 really detected the magnetic field of Martian crust in the early Verigin & Slavin, EPSC 2006-A  This observations was not properly interpreted before MGS crustal magnetization discovery.

Mars Global Surveyor : M m  2 · гс · см 3 (Acuna et al., 2001) ??? with B equat  0.5 nT but B equat ~ 10 nT (Arkani-Hamed, 2001)  M m ~ 4 · гс · см 3 Phobos 2: M m  8 · гс · см 3 magnetopause model by Verigin et al. (1997) Prior to Phobos 2: Luhmann et al., 1992 On planetary magnetic moment of Mars

  There is an essential dipole component exists in the multipole moment of planet Mars  Further methodology development is necessary for its accurate determination, including consideration of current systems produced by solar wind – Mars interaction Nothern hemisphere: “TO THE PLANET” Southern hemisphere: “FROM THE PLANET” Mars Global Surveyor Mars Global Surveyor : Connerney et al., 2001

Phobos 2 – detailed BS and MP position dependencies on  V 2 Martian magnetotail diameter D ~ 550 (  V 2 ) -1/5.9 км similar to geomagnetic tail compressibility Distance to terminator bow shock R ~ 6000 (  V 2 ) км practically independent on the  V 2 !!! Phobos 2 statistics of the bow shock and magnetopause crossings

Martian magnetopause shape and variations Phobos 2  V 2 dependent Martian magnetopause model MGS  V 2 dependent Martian magnetopause model Verigin et al., Adv. Space Res., 33, 12, 2222, 2004  Martian magnetopause is not of  V 2 invariant  Stagnation of the magnetopause nose position and increase of its curvature radius with increasing of  V 2 are explaining  V 2 independence of the bow shock terminator position, found by Phobos 2 data

Distant BS excursions at small solar wind M a values Upstream solar wind on March 24, 1989  Unusually distant Martian bow shock excursions were initiated by extremely small upstream  V 2 and M a values Verigin et al., Sp.Sci.Rev.,111, 233, Modeled typical (BS 3, MP 3 ) and distant (BS 1, MP 1 ) positions of the Martian bow shock and magnetopause

Influence of the Martian crustal magnetization on the magnetopause position  Localized Martian crust magnetization increases downstream magnetopause height by km additionally. Equatorial magnetotail diameter dependence on the longitude of the upstream terminator (Phobos 2) Increase of the magnetopause height over magnetized regions (MGS data) Verigin et al., Adv. Space Res., 28 (6), 885, 2001; 33(12), 2222, 2004.

Martian magnetotail magnetic field and plasma arrangement by IMF Schwingenschuh et al., Adv. Space Res., 12(9), 213, 1992 Yeroshenko et al., GRL, 17, No.9, 885, 1990 Mars Express ASPERA 3 experiment Barabash et al., Science 315, 502, 2007 plasma sheet

Loss of planetary ions through plasmasheet Phobos 2, Feb. – Mar. 1989, High SA Ф ~ ions/s Verigin et al., Planet. Space Sci. 39, 131, 1991 MEX, May 2004 – May 2006, Low SA Ф ~ / s / s C0 2 + / s ~ ions/s Barabash et al., Science 315, 502, 2007 Direct Simulation Monte Carlo (DSMC) + 3D Mars Thermosphere General Circulation (MTGCM) modeling Valeille, Combi, Tenishev, Bougher, Nagy, Icarus, doi: /j.icarus , 2008  Both experimental estimates are in qualitative agreement with variation of the planetary ion escape rates within solar cycle, although  the escape of Martian ions integrated over near-planetary region is only the minor part of planetary ion escape rate (Ф highSA ~ /s, Valeille, et al., 2008 ).  Direct measurement of total ion escape rate are highly welcomed.

Hot oxygen corona is the main channel of Martian ions loss – how to measure it? Solar wind pre bow shock deceleration Phobos 2, High SA Comparison with DSMC+MTGCM modeling L i ~ 4x10 6 km ! total pick-up ion flux F < 2·10 5 (10 4 km / r ) cm -2 s -1 pick-up ion number density cm -3  Measurements of pick-up ion radial profile, starting from ~ 10 6 km to Mars, can provide reliable evaluation of the total Martian ions loss rate Kotova et al., JGR, 102, A2, 2165, 1997

Competing processes of Martian plasmasheet ion acceleration 1) Magnetic field line stress acceleration  withand  2) Across magnetotail electric field E acceleration Ion energy increase  E i after its cyclotron diameter 2R c displacement across the magnetotail  

Competing processes of Martian plasmasheet ion acceleration   V 2 > 6  дин/см 2  V 2 < 6  дин/см 2 Across magnetotail electric field acceleration prevails – ”magnetospheric obstacle” Magnetic field line stress acceleration prevails – “induced obstacle”  Change of the plasmasheet ion acceleration process take place at that  V 2 value when magnetopause nose position starts to increase after its stagnation at high ram pressures Kotova et al., Phys. Chem. Earth (C), 25(1-2), 157, 2000

Martian nightside ionosphere source Martian nightside ionosphere source  Phobos 2 electron spectra measurements (HARP experiment) revealed permanent presence electron fluxes of J 0 ~ 10 8 cm -2 s -1 in the areomagnetic tail with energies sufficient for ionization of Martian neutral atmosphere constituents

Estimated peak n e max of the night- side ionization layer corresponds to that one observed by radio occultations of Mars 4,5 and Viking 1,2 spacecraft. “Why was the peak of nightside ionization observed in 100% of th s/c radio occultations at but in only 40% of radio occultations at Mars? The reason may be connected with the partial screening of the Martian nightside atmosphere by a weak intrinsic magnetic field of the planet which is completely absent in the case of Venus” Verigin et al., JGR, 96(A11), 1991 Haider et al., JGR, 97, 10637, 1992 Martian nightside ionosphere source Martian nightside ionosphere source

Leblanc et al., JGR, 111(A09313), doi: /2006JA011763, 2006 Martian nightside ionosphere source: comparison with subsequent observations Martian nightside ionosphere source: comparison with subsequent observations Magnetization of Martial crust that partially screens planetary atmosphere was really found… Acuna et al., JGR, 106(E10), 23400, 2001 Comparison of nightside low altitude electron spectra measured by MEX/ASPERA 3 and MGS/ER (thick line) with Phobos 2/HARP (color) ones used for nightside ionization calculations Brain et al., GRL, 33, L01201, 2006 Dubinin et al., Pl.Sp.Sci., 56, 846, 2008 Comparison with SPICAM UV spectroscopy measurements aboard Mars Express Detailed multi-ion nightside Martian ionosphere model is available now, considering e-impacts and galactic cosmic ray ionization until planetary surface Haider et al., JGR, 112(A12309), doi: /2007JA012530, 2007

Спасибо за внимание ! Пятая конференция ОФН 15 «Физика плазмы в солнечной системе» 8  12 февраля 2010 г., ИКИ РАН