Bone Trajectories and Model Simulations

Kathleen Mandt, Ray Goldstein, Christoph KoendersMay 29, 2013IES Team Meeting – San Antonio

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Objectives and Projected Benefits

• Determine for each planning stage which science objectives can and cannot be achieved– Help frame arguments for pointing, trajectory selection and

future bones– Determine what data we will obtain, such as our ability to

measure the solar wind parameters• Evaluate overall which objectives will not be achieved due

to trajectories (e.g. observing the bow shock)• Science

– Model-data comparisons have important scientific value– How can the models be refined to improve the science return of

the data?

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Plasma model simulations

• Three models available– MHD – 2D simulations

with H2O, CO and CO2

– “Hybrid” – 2D hybrid simulations with H2O, CO and CO2

– “Hybrid-AIKEF” – 3D hybrid simulations with single constituent

Distance(AU)

Model Outgassingrate (s-1)

1.3MHD 5 x 1027

Hybrid 5 x 1027

2.0MHD 8 x 1026

Hybrid 8 x 1026

2.5Hybrid 8 x 1025

AIKEF 1.5 x 1027

2.5 x 1026

2.8 AIKEF 1.12 x 1027

1.63 x 1026

2.9 AIKEF 7.36 x 1026

7.93 x 1025

3.0MHD 6 x 1025

2.2 x 1027

AIKEF 3.6 x 1026

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Trajectory planning (so far…)• Three types of

trajectories– Icosahedral– Orbit– Flyby

• Available trajectories– Prelanding: all of 2014

including comet approach– High Activity Case (HAC)

• 8 month plan

– Low Activity Case (LAC – in progress)

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Sample of predicted observations for the comet approach

• Distance to sun ~3.5 AU• 6/25/14-8/25/14• Hybrid model– 3.3 AU– Limit 400 km

• Approach from behind the comet heading toward the Sun

• Approach close to the comet and maneuver – may require too much fuel

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The results for the comet approach and characterization

Total ion densityCometary ion densitySolar wind ion density

Solar wind ion density is predicted by the model to be nearly constant over the entire range

Cometary ion density increases by two orders of magnitude between 350 km and closest approach

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Sample of predicted observations with a 10 km orbit (now ruled out by FD)

• Distance to sun ~2.9 AU• Orbit the comet at ~10

km• Any orbit distance (10-30

km) is too close to see any of the boundaries or to identify the ion tail

• We can watch for temporal and spatial variability in the coma

Hybrid-AIKEF simulation

Total ion velocityCometary ion velocitySolar wind ion velocity

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More work to be done• Keep up with changes

in the planning process– e.g. Icosahedral now

ruled out by FD

• Evaluate what distance is needed to see boundaries of interest

• Determine what new science can be gained within trajectory limitations

Total magnetic fieldBx By Bz

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Backup slides

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Rosetta distance to the Earth and to the Sun over the time of the mission

11IES Team Meeting