The Europa Plasma Environment
Tristan Weber – LASP
Fran Bagenal, Robert Wilson, Vincent Dols
Friday, August 9, 2013
Europa Overview
 Our interest in Europa
 Our current understanding
 Success/Limitations of our data
 Refinement/Compilation of the
data
 Future improvements for the
study of Europa
http://photojournal.jpl.nasa.gov/catalog/PIA00502
Friday, August 9, 2013
Interest in Europa
 Europa is “the first step in understanding the
potential of the outer solar system as an abode for
life” (Space Studies Board 2011, p.1)
 Enough energy and
water to sustain life
Friday, August 9, 2013
Our Current Set of Data
Variety of sources
Ground Based
Voyager
Galileo
1. http://solarsystem.nasa.gov/galileo
2. http://www.cfa.harvard.edu/sma/
3. http://voyager.jpl.nasa.gov/
Friday, August 9, 2013
Galileo
-Failed Antenna Deployment
-Lack of data resolution
-Large range of trajectories
-Wide spread of data if we could
analyze it
Friday, August 9, 2013
What We Know So Far
Water Oceans
Ice on surface shown from ground-based observations
-Changing Magnetic Field
Induces Currents
-Seen by Galileo
Hard to separate
from Ionosphere
Friday, August 9, 2013
What We Know So Far
Water Oceans
Ice on surface shown from ground-based observations
-Changing Magnetic Field
Induces Currents
-Seen by Galileo
Hard to separate
from Ionosphere
Friday, August 9, 2013
What We Know So Far
Water Oceans
Ice on surface shown from ground-based observations
-Changing Magnetic Field
Induces Currents
-Seen by Galileo
Hard to separate
from Ionosphere
Friday, August 9, 2013
What We Know So Far
Water Oceans
Ice on surface shown from ground-based observations
-Changing Magnetic Field
Induces Currents
-Seen by Galileo
Hard to separate
from Ionosphere
Friday, August 9, 2013
What We Know So Far
Alfvén Wings
Europa’s
Footprint
Friday, August 9, 2013
What We Know So Far
Sputtered Atmosphere
-Radiolysis embeds
incoming particles and
ejects others
-Oxygen Atmosphere
-Sulfur Deposits
Friday, August 9, 2013
What We Know So Far
Sputtered Atmosphere
-Radiolysis embeds
incoming particles and
ejects others
-Oxygen Atmosphere
-Sulfur Deposits
-Mostly Observed through
Spectroscopy
-Direct data has issues…
Friday, August 9, 2013
Modeling
 Working on a
simulation with
Vincent Dols
 Magnetic Field
Modeling
 Data from NASA
PDS
Friday, August 9, 2013
Modeling
 Working on a
simulation with
Vincent Dols
 Magnetic Field
Modeling
 Data from NASA
PDS
E04 Flyby - 1996
Friday, August 9, 2013
Modeling
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E04 Flyby - 1996
Friday, August 9, 2013
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E11 Flyby - 1997
Friday, August 9, 2013
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E11 Flyby - 1997
Friday, August 9, 2013
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Modeling
 Magnetic Field
Modeling has been
fairly successful
 See Effects of
Induced Currents and
Alfvén Wings

Kivelson et al. (1997)
E04 Flyby - 1996
Friday, August 9, 2013
Modeling the Plasma Properties
 Want to compare model to direct plasma data.
 Obtained plasma parameters with Rob Wilson’s fitting routine
Friday, August 9, 2013
Modeling the Plasma Properties
 Want to compare model to direct plasma data.
 Obtained plasma parameters with Rob Wilson’s fitting routine
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Friday, August 9, 2013
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Modeling the Plasma Properties
 Want to compare model to direct plasma data.
 Obtained plasma parameters with Rob Wilson’s fitting routine
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Friday, August 9, 2013
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Problems with the PLS data
 Fitting routine originally designed
for full magnetosphere.
Friday, August 9, 2013
Problems with the PLS data
 Fitting routine originally designed
for full magnetosphere.
At moon encounters, the plasma might be
changing too quickly to find a fit
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Friday, August 9, 2013
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A Possible Remedy
 If the issue is over-averaging, edit the fitting to only run each
spin individually
 Danger of not having enough appreciable detections.
Friday, August 9, 2013
A Possible Remedy
Obs. Data
Background
Sim. Data
+23.96:1.71 m:q
3
3
2
2
10
10
1
1
10
10
0
0
10
10
3
3
10
2
2
10
10
1
1
10
10
0
0
10
10
3
3
Anode 5
Counts/Accum.
10
10
2
2
10
10
1
1
10
10
0
0
10
52
3
10
Anode 7
Counts/Accum.
Anode 4
Counts/Accum.
Anode 3
Counts/Accum.
10
2
10
1
10
0
10
Anode 2
Counts/Accum.
10
0
52
104
156
208
Record #
260
312
364
416
DE run 1, Iter. = 1, Cost = 4.00001e+06
Friday, August 9, 2013
104
156
208
Record #
260
312
364
10
416
Anode 6
Counts/Accum.
Anode 1
Counts/Accum.
10
A Possible Remedy
Obs. Data
Background
Sim. Data
+23.96:1.71 m:q
3
3
2
2
10
10
1
1
10
10
0
0
10
10
3
3
10
2
2
10
10
1
1
10
10
0
0
10
10
3
3
Anode 5
Counts/Accum.
10
10
2
2
10
10
1
1
10
10
0
0
10
52
3
10
Anode 7
Counts/Accum.
Anode 4
Counts/Accum.
Anode 3
Counts/Accum.
10
2
10
1
10
0
10
Anode 2
Counts/Accum.
10
0
52
Friday, August 9, 2013
104
156
208
Record #
260
312
364
416
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Record #
260
312
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Anode 6
Counts/Accum.
Anode 1
Counts/Accum.
10
A Possible Remedy
Obs. Data
Background
Sim. Data
+23.96:1.71 m:q
3
3
2
2
10
10
1
1
10
10
0
0
10
10
3
3
10
2
2
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10
1
1
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10
3
3
Anode 5
Counts/Accum.
10
10
2
2
10
10
1
1
10
10
0
0
10
49
Record #
3
10
Anode 7
Counts/Accum.
Anode 4
Counts/Accum.
Anode 3
Counts/Accum.
10
2
10
1
10
0
10
Anode 2
Counts/Accum.
10
0
Friday, August 9, 2013
49
Record #
98
DE run 1, Iter. = 150, Cost = 1.76856
98
10
Anode 6
Counts/Accum.
Anode 1
Counts/Accum.
10
New PLS Results
 Very Mixed – Several unreasonable features removed
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Friday, August 9, 2013
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New PLS Results
 But lack of enough data points sometimes makes for
enormous errors.
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Friday, August 9, 2013
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New PLS Results
 But lack of enough data points sometimes makes for
enormous errors.
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Friday, August 9, 2013
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A Final Issue/Interest
3
10
Anode 7
Counts/Accum.
2
10
1
10
0
10
0
52
104
156
208
Record #
260
312
364
416
DE run 1 Iter = 10 Cost = 4 00
Double peaks show two plasma species – in this case we have pickup ions
Friday, August 9, 2013
A Final Issue/Interest
3
10
Anode 7
Counts/Accum.
2
10
Spacing shows they’re in the same plane
1
10
0
10
0
52
104
156
208
Record #
260
312
364
416
DE run 1 Iter = 10 Cost = 4 00
Double peaks show two plasma species – in this case we have pickup ions
Friday, August 9, 2013
A Final Issue/Interest
Energy differs by a factor of ~8 (4 for pickup ions)
3
10
Anode 7
Counts/Accum.
2
10
Spacing shows they’re in the same plane
1
10
0
10
0
52
104
156
208
Record #
260
312
364
416
DE run 1 Iter = 10 Cost = 4 00
Double peaks show two plasma species – in this case we have pickup ions
Friday, August 9, 2013
A Final Issue/Interest
How can we figure out what ion is being picked up?
3
10
Anode 7
Counts/Accum.
2
10
Spacing shows they’re in the same plane
1
10
0
10
0
52
104
156
208
Record #
260
312
364
416
DE run 1 Iter = 10 Cost = 4 00
Double peaks show two plasma species – in this case we have pickup ions
Friday, August 9, 2013
Ion Cyclotron Waves
 Resonance between gyrofrequency and magnetic waves.
http://www.efda.org/fusion
Friday, August 9, 2013
Ion Cyclotron Waves
 Resonance between gyrofrequency and magnetic waves
1
0.9
0.8
Frequency (Hz)
0.7
0.6
0.5
0.4
18
0.3
23
0.2
32
0.1
64
0
06:40
Friday, August 9, 2013
06:45
06:50
06:55
Time
07:00
07:05
07:10
Ion Cyclotron Waves
 Remove the background magnetic field
1
0.9
0.8
Frequency (Hz)
0.7
0.6
0.5
0.4
18
0.3
23
0.2
32
0.1
64
0
06:40
Friday, August 9, 2013
06:45
06:50
06:55
Time
07:00
07:05
07:10
Ion Cyclotron Waves
 Remove the background magnetic field
1
0.9
0.8
Frequency (Hz)
0.7
0.6
0.5
0.4
18
0.3
23
0.2
32
0.1
64
0
06:40
06:45
06:50
06:55
Time
07:00
07:05
07:10
Is this actually a result?
Friday, August 9, 2013
Ion Cyclotron Waves
 Remove the background magnetic field
1
0.9
0.8
Frequency (Hz)
0.7
0.6
0.5
0.4
18
0.3
23
0.2
32
0.1
64
0
06:40
06:45
06:50
06:55
Time
Probably Not
Friday, August 9, 2013
07:00
07:05
07:10
Is this actually a result?
Final Compilations – Where We Are
Orbit04
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Friday, August 9, 2013
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Final Compilations – Where We Are
Some things we can explain
Pickup ions in wake
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Final Compilations – Where We Are
Some things we can explain
Orbit12
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Friday, August 9, 2013
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Fluid flow around the moon
Final Compilations – Where We Are
Some things we can’t…
Orbit12
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Friday, August 9, 2013
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The Future For Europa Data
 Hope in the Europa Clipper
-Higher resolution MAG data?
-Better plasma data?
Hope to better understand the
induced fields and the surface
composition.
http://www.jpl.nasa.gov
Friday, August 9, 2013