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MAVEN observations of substorm-like processes in the Martian magnetosphere Gina A DiBraccio NASA Goddard Space Flight Center 13 th International Conference on Substorms Portsmouth, NH 29 September 2017 Mars Magnetic Environment No

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Gina A DiBraccio

NASA Goddard Space Flight Center

13th International Conference on Substorms Portsmouth, NH 29 September 2017

MAVEN observations of substorm-like processes in the Martian magnetosphere

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2 Gina.A.DiBraccio@nasa.gov

Mars’ Magnetic Environment

Connerney et al., PNAS, 2005

  • No global intrinsic field
  • Localized crustal magnetic fields
  • Strongest sources at 180°E Longitude in southern hemisphere
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3 Gina.A.DiBraccio@nasa.gov

Martian Magnetosphere

Brain et al. [2015]

  • Induced

magnetosphere with localized planetary fields

  • IMF direction

influences the field structure

  • Similar regions to

intrinsic magnetospheres with similar processes on different scales

  • No ‘Dungey Cycle’
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4 Gina.A.DiBraccio@nasa.gov

MAVEN’s Orbit Orbit precesses to provide complete coverage

Side View View from tail

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5 Gina.A.DiBraccio@nasa.gov

Magnetic Reconnection at Mars

Halekas et al. [2009]

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6 Gina.A.DiBraccio@nasa.gov

DiBraccio et al. [2015]

  • Particle acceleration in the tail

current sheet

  • Downtail speeds of 100 km/s
  • r greater

Tail Reconnection: Fast Flows

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7 Gina.A.DiBraccio@nasa.gov

DiBraccio et al. [2015]

Tail Reconnection: Flux Ropes

Current sheet crossing with embedded flux rope supports magnetic reconnection

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8 Gina.A.DiBraccio@nasa.gov

MGS - Eastwood et al. [2012] MAVEN - Hara et al. [2017]

Tail Reconnection: Flux Rope Chains

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9 Gina.A.DiBraccio@nasa.gov

  • 20
  • 10

10 20 BMSO [nT] Bx By Bz |B| 0.0 0.5 1.0 |B-Bc| /|B|

  • 1

1 b1 . b2 cs

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10 20 BLMN [nT] BL BM BN 10 100 1000 e- Energy [eV] 10 100 1000 104 105 106 107 108 Eflux 90 180 e- P.A. [deg.] 90 180 104 105 106 Eflux 10-1 100 101 102 103 104 Ion Energy [eV/q] 10-1 100 101 102 103 104 104 105 106 107 108 Eflux

  • 10
  • 5

5 10 15 20 VL [km/s] 2449.6 156.8 1914 2291.8 159.8 1916 2132.3 162.8 1918 1971.6 165.9 1920 1810.3 169.1 1922

  • 4
  • 2

2 4 VN [km/s]

  • Alt. [km]

SZA [deg.] hhmm 2014 Nov 30 H+ O+ O2

+

H+ O+ O2

+

S/C

λL / λM = 18.73 λM / λN = 6.79 L = [ 0.99, 0.15, 0.08] M = [-0.17, 0.76, 0.63] N = [ 0.04,-0.63, 0.77]

(a) (b) (c) (d) (e) (f) (g) (h) (i) (j)

Hall B polarity => Crossing sunward

  • f the X line

#3 S/C #3 VL BL BN BM

Sunward flow enhancement trapped e-

L M N

Tail Reconnection: Hall Fields

Harada et al. [2017]

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10 Gina.A.DiBraccio@nasa.gov

Energy-time Dispersed Electrons

Impulsive injections of electrons onto closed crustal fields

  • Falling tones from ~200 eV to ~50 eV
  • Electrons PADs show two-sided loss

cones

Harada et al. [2016]

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11 Gina.A.DiBraccio@nasa.gov

DiBraccio et al. [2015]

Tail Loading and Unloading

Loading

  • Occurs over

intervals of 3-5 min

  • IMF drapes over

planet and flux builds Unloading

  • Occurs over

intervals of 2-4 min

  • Sudden |B| decrease

by factor of 6

  • Flux ropes support

reconnection

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12 Gina.A.DiBraccio@nasa.gov

Image credit: M. Holstrom/ESA

Aurora

Schneider et al. [2015]

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13 Gina.A.DiBraccio@nasa.gov

Discrete Aurora

MEX/SPICAM aurora detection:

  • Confined increase in UV

brightness

  • Emission from vertical crustal

field or ‘cusp’ region

  • ~130 km altitude

Bertaux et al. [2005] Brain et al. [2006]

MGS observations:

  • Peaked electron distributions
  • 400 km altitude on nightside
  • Correlated with strong crustal

fields

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14 Gina.A.DiBraccio@nasa.gov

Diffuse Aurora

MAVEN observations:

  • Rise in auroral brightness

correlated with SEP arrival

  • 60-100 km altitude
  • Coverage obtained over

subsequent orbits

  • 5 day period

Schneider et al. [2015]

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15 Gina.A.DiBraccio@nasa.gov

Effects of Solar Storms

EUV irradiance SEP energy SWIA Energy Btot

  • Three solar events occurred on March 1st, 6th, and 8th 2015
  • Global magnetosphere disruption

Earlier flare and SEPs Second flare and SEPs

Jakosky et al., Science, 2015

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16 Gina.A.DiBraccio@nasa.gov

Summary

  • Mars experiences substorm-like signatures:

– Magnetic reconnection (hall fields, fast flows, etc.) – Flux rope formation – Tail Loading/Unloading – Aurora – Energy-time dispersed electrons – Global response to solar events – FACs – Inverted-Vs

  • A global process has yet to be quantified

– Does one exist? – It is possible to find a single definition of a Mars storm?