the rosetta mission to comet 67p/ churyumov-gerasimenko : needs for swmf modeling
DESCRIPTION
The Rosetta Mission to Comet 67P/ Churyumov-Gerasimenko : Needs for SWMF Modeling. K.C. Hansen Zhenguang Huang. University of Michigan. SWMF User Meeting, October 13-14, 2014. Comet Modeling at UM. ICES Tools Andre Bieler Jeff Kopmanis K.C. Hansen Tamas Gombosi - PowerPoint PPT PresentationTRANSCRIPT
THE ROSETTA MISSION TO COMET 67P/CHURYUMOV-GERASIMENKO:
NEEDS FOR SWMF MODELING
K.C. HANSENZHENGUANG HUANG
University of Michigan
SWMF User Meeting, October 13-14, 2014
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
COMET MODELING AT UM
ICES TOOLS Andre Bieler Jeff Kopmanis K.C. Hansen Tamas Gombosi
PLASMA/NEUTRALS – SWMF Zhenguang Huang Yinsi Shou Gabor Toth Martin Rubin (Univ. Bern) Xianzhe Jia K.C. Hansen Tamas Gombosi
GAS & DUST – AMPS/DSMC Nicolas Fougere Andre Bieler Valeriy Tenishev Mike Combi
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
COMET-SOLAR WIND INTERACTION
MASS LOADING Extends millions of km
upstream Major contributor to structure
and dynamics Leads to major comet challenge
of resolving multiple length scales
SOLAR WIND Greatly slowed due to mass
loading upstream of the comet Low Mach number shock due to
mass loading
MULTIPLE SEPARATING SURFACES Bow shock Diamagnetic cavity Inner shock
LOW MASS LOADING REGIME Shock -> Mach cone Mach cone may touch body No-diamagnetic cavity
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
ROSETTA MISSION
ESA LED MISSION WITH SUBSTANTIAL US PARTICIPATIONCOMET 67P/CHURYUMOV-GERASIMENKOORBITER (ROSETTTA) Follows the comet from 3.5AU until just after perihelion
(nominal mission) 20-200 km “orbits” Aug 2014 – Dec 2015
LANDER (PHILAE) Planned to land on November 12, 2014
UM CO-I ROLE Rosina – Rosetta Orbiter Spectrometer for Ion and
Neutral Analysis spectrometer VIRTIS - Visible and Infrared Mapping Spectrometer RPC - Rosetta Plasma Consortium
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
OBSERVED MODELING NEEDS
MODELING DURING THE EARLY MISSION PHASES Landing of Philea is a critical mission element Neutrals and plasma are very low density
ABILITY TO MODEL THE REGION VERY NEAR THE COMET (<200KM) Early mission will spend significant time < 50
km Later mission will remain within 200-300 km
FIRST IMAGES REVEALED A SHAPE THAT IS VERY NON-SPHERICAL Shape just became a much more important
factor to model
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
RESULTING NUMERICAL NEEDS
FLUID MODEL OF THE NEUTRALS Low density Fast numerical turn around due to non-steady nature of the comet
COUPLED NEUTRALS AND PLASMA Nature of comet shape dictates that the neutrals near the comet
will be very non-uniform Plasma is a result of mass loading the neutrals Clear that the two cannot be modeled independently for this case
MULTI-FLUID HALL MHD Low plasma densities mean that standard MHD may not
technically be reliable
ABILITY TO MODEL IRREGULAR BODY SHAPE IN BATSRUS/SWMF Shape is likely to greatly influence the near body neutral and
plasma distribution Sources on the body should be able to be calculated using
illumination and other properties
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
MULTI-FLUID HALL RESULTS FOR GIOTTO @ HALLEY
One of the major advantages of this model is the self consistent calculation of the electron temperatures. The electron temperature at comets can play a major role in the location of ion-boundaries and other cometary features.
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
MULTI-FLUID HALL RESULTS FOR GIOTTO @ HALLEY
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
MULTI-FLUID HALL RESULTS FOR GIOTTO @ HALLEY
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
MULTI-FLUID MHD VS. HYBRID
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
COMETARY NEUTRAL AND PLASMA ENVIRONMENT SIMULATIONS WITH RMOC
SHAPE MODEL
Setting the comet shape in the simulation: Cell center within the shape: body cell Cell center outside the shape: true cell Illumination is considered Inner boundary conditions are specified at the face
boundary
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
COMETARY NEUTRAL AND PLASMA ENVIRONMENT SIMULATIONS WITH RMOC
SHAPE MODEL
Hydrodynamic equations for cometary neutrals
Inner boundary: neutral density, velocity and temperature match the mass and energy flux of a half-maxwellian particle distribution. the number density flux and the temperature varies as a function of the solar zenith angle relative to the shape model’s triangular faces. the outflow velocity is in the direction of the normal of the triangulated surface.
Outer boundary: open boundary condition
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
COMETARY NEUTRAL AND PLASMA ENVIRONMENT SIMULATIONS WITH RMOC
SHAPE MODEL
Comparison of neutral density from AMPS & BATS-R-US
AMPS BATSRUS/SWMF
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
COMETARY NEUTRAL AND PLASMA ENVIRONMENT SIMULATIONS WITH RMOC
SHAPE MODEL
Comparison of bulk velocity from AMPS & BATS-R-US
AMPS BATSRUS/SWMF
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
COMETARY NEUTRAL AND PLASMA ENVIRONMENT SIMULATIONS WITH RMOC
SHAPE MODEL
Comparison of neutral density from the simulation and COPS
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
COMETARY NEUTRAL AND PLASMA ENVIRONMENT SIMULATIONS WITH RMOC
SHAPE MODEL
MHD equations for cometary heavy ions, solar wind protons, and electrons
The neutral and plasma fluids are coupled.
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
COMETARY NEUTRAL AND PLASMA ENVIRONMENT SIMULATIONS WITH RMOC
SHAPE MODEL
SWMF User Meeting K.C. Hansen, Zhenguang Huang October 13-14, 2014
CONCLUSIONS AND FUTURE WORK
Multi-fluid Hall MHD simulations agree well with Hybrid simulations.
The first coupled hydrodynamic and MHD simulation of a comet.
The first realistic simulation with a shape model.
Neutral results agree well with COPS data.
Compare plasma results with RPC data.
Simulate the neutral and plasma environment at different heliocentric locations.