The Interaction ofThe Interaction ofthe Solar Windthe Solar Wind

with Mars with Mars

D.A. BrainD.A. Brain

Fall AGUDecember 8, 2005

UC BerkeleySpace Sciences Lab

Mars in Context

Comets

SW

Earth Moon

SW SW

SW SW /Earth plasma

Saturn plasma/ SW

Mars

Titan

Venus

40 Years of Investigation

19851975 19951965 2005

Mariner 4,6,7,91965-1972

Mars 2,3,51971-1974

Viking 1,21976-1983

Phobos 21989

MGS1997-?

MEX2003-?

1st non-terrestrial bow-shock crossing

bow shocks galore!sheath sampled

ionosphere profiles

wake/tail studiedescape products measured

crustal fields discoveredno significant dynamo

aurora discoveredlow-altitude heavy ions

ModelsGasdynamic, MHD, hybrid, empirical, multi-fluid, …

Spacecraft

Milestones

The Interaction Region

shock

foreshock

Ionopause / PEB

sheath

MPR / mantle / …

tail

wake

MPB / IMB / ICB / PDB /

planetopause / protonopause /

magnetopause / mantle boundary /

“the boundary” / …

Plasma sheet

Compare: fields particles waves

Upstream / Shock

||

Mazelle et al., 2005

Trotignon et al., 1993

Solar Wind at 1.5 AU|B| ~ 3 nT ~ 1 cm-3

T ~ 4 eV

MA ~ 10MMS ~ 6

Small, active shock

RMars < RVenus

Sheath

MPB

Pile-up region

Dayside Interaction

PEB

exobase

B - turbulentPlasma - hot SWWaves - Mirror mode

B - drapes, increasesPlasma - heavies effect flow

B - calmPlasma - cooler, w/ heaviesWaves - fast magnetosonic

SW e- not allowed!Same as ionopause?

Collisional atmosphere

Øieroset et al., 2004

Iono-sphere

Usually magnetized

10 eV100 eV

Mitchell et al., 2001

Nightside Interactionprotons

Hot oxygen

Cold oxygen

Little/no ionosphere

Plasma sheet

Kallio, 2001

Brain et al., 2005

Crustal FieldsPerturb Boundaries Change Topology

Crider et al., 2004

MPB Altitude Closed Flux Tubes

Brain et al., 2005

Variability

Crider et al., 2003

MPB Altitude

Brain et al., 2005

MPB Altitude

Brain et al., 2005

Open Flux Tubes

Lat

Lon Lon

Westward IMF Eastward IMF

Mitchell, 2003

PEB Altitude

Pressure

IMF Direction

EUV

Season

Simulations• Approaches

Gasdynamic, MHD, Non-ideal MHD, Hybrid, …

• GoalsEscape, Boundaries, Topology, Ionosphere, Detailed physics, Prediction, …

Brecht et al., 2004

Harnett and Winglee, 2003; 2005

Ma et al., 2004

Terada et al., 2005Modolo et al., 2005

Escape to Space

• Want to Know:— Processes— Variability— Products— Quantity

• Measurements— Phobos— MEX

• Simulations

neutralion

≈ 1 ton/hr

Kallio et al., 1995

Upper Atmosphere Effects

• Energy deposition• Structure• Dynamics• Chemistry• AuroraLeblanc et al., 2002

Brain et al., 2005

Law and Cloutier, 1997

Withers et al., 2005

Krymskii et al., 2002

ENAs

SEPs

EUV

Vertical Field

Horizontalfield

Fundamental Plasma Processes

reconnection

potential

current

acceleration

instabilities

Espley et al., 2005

Frontiers

• Escape

• MPB Physics

• Auroral Physics

• Space Weather

• Asymmetries

• Fluid vs. Kinetic

• Crustal Influence

ER background

SW PressureMEX Event

Brain et al., 2005

Ferguson et al., 2005

Bertucci et al., 2005

Summary

1. The Martian interaction is unique and highly variable.

Key factors: Planetary size, SW at 1.5 AU, crustal fields

2. Understanding the interaction helps with many “Big Picture” questions. Climate evolution; Upper atmospheric structure and dynamics; Plasma physics in the solar system and universe

3. Many outstanding questions remain. Need further analyses, measurements, and models

Here’s to 40 more years!