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Swedish Institute of Space Physics, Uppsala

Rosetta Mars flyby: geometry and modeling

Niklas Edberg, Ronan Modolo, Anders Eriksson

This page contains plots showing the geometry of the Rosetta Mars flyby in 25 February 2007, and some modeling results. The work is done as an undergraduate project work by Niklas Edberg. Trajectory files provided by ESOC are transformed into suitable coordinates. The data are combined with hybrid simulations computed by Ronan Modolo and Gérard Chanteur, and the crustal magnetic field model of Jafar Arkani-Hamed, to produce predictions of plasma parameters and the magnetic field as seen on Rosetta, to facilitate operations planning.

Trajectory
Hybrid simulations
Crustal magnetic field model

Trajectory

Trajectory plots in MSO coordinates (X to sun, Z along Mars orbital angular momentum vector), with Phobos and Deimos orbits:

Hybrid simulations

Plasma and external magnetic field modeling, using the hybrid multi-species hybrid model developped by Ronan Modolo and Gérard Chanteur (CETP/IPSL, France), describe the solar wind interaction with Mars:

Model in a nutshell (see Modolo et al., Ann. Geophysicae, 23, 433-444, 2005 for simulation details):

Fixed cartesian-grid hybrid simulation (space resolution : 300 km)
Several ion species and ions dynamics well represented; electrons passive fluid (ensure the conservation of the charge neutrality of the plasma), so no conclusions on Te possible
Includes neutral exosphere model (Oxygen(thermal/supra-thermal) and Hydrogen neutral corona)
Ionization processes : solar photons, electronic impacts and charge exchange reactions
Crustal magnetic field is not included; only IMF
IMF has no sunward component, but the clock angle is arbitrary as there is no other asymmetry in the model (the angle between the IMF and the solar wind velocity direction is taken to 90°)
Solar minimum conditions are assumed for the solar UV flux and the oxygen and hydorgen corona
Solar wind/IMF: proton density 2.3 cm-3, speed 400 km/s, B = 3 nT, He++ at 5% of total ion number density.
Coordinates are MSO (Mars Solar Orbital, with X to sun and Z perpendicular to Mars' orbital plane; i.e. the GSE equivalent for Mars)

Maps with sample Rosetta trajectory superimposed, assuming IMF is in the orbital plane of Mars -- trajectory can be rotated around the X axis to represent any desired IMF clock angle

Magnetic field, XY/XZ and YZ projections. (The magnetic field environment obtained from the hybrid model is presented in a new paper to be submitted soon. The solid and dashed curves represent fits from Mars Global Surveyor spacecraft for respectively the bow shock and the magnetic pile-up boundary (Vignes et al, 2000)).
Plasma density, XY/XZ and YZ projections
Bulk plasma flow speed, XY/XZ and YZ projections

Time series of plasma parameters during the Rosetta flyby, for five different IMF clock angles:

Electron and ion densities (H⁺_sw,He⁺⁺_sw,H⁺_pl,O⁺,O₂⁺)
Magnetic field (components and total)
Ion average energies (bulk + thermal, in Rosetta's moving frame)
Bulk plasma velocity (components and total)

Crustal field model

Crustal magnetic field modeling, using Jafar Arkani-Hamed's crustal field model:

Please send comments, bug reports etc to Anders.Eriksson@irfu.se.

http://www.space.irfu.se/rosetta/sci/mars/index2.html
last modified onMonday, 28-Nov-2005 11:40:53 CET