Transcript SCOPEの目指すサイエンス

The science targets of the SCOPE
mission
Masaki Fujimoto
ISAS, JAXA
The solar system, the natural
laboratory for space plasma
• Formation of planetary magnetospheres
via interaction between the solar wind and
the planet’s intrinsic magnetic field
• Dynamics behavior of plasma in the
magnetospheres
The same is true for
the earth’s magnetosphere
• Aurora. Its attractive
behavior reflects
the dynamism of
the plasma in
the earth’s
magnetosphere
Earth and planetary
magnetospheres:
The point of view
• Interest in itself.
Earth and planetary
magnetospheres:
The point of view
• Interest in itself.
• The laboratory of space plasma dynamics
• The only field where in-situ measurements
of particles and fields can be made.
Magnetospheric physics:
The new stage
• “The Plasma Universe”
• “The Magnetic Universe”
The question
What makes the cosmic gas
to behave so dynamically?
#Looking
through the earth’s magnetosphere
at the Plasma Universe
Plasmas throughout the Universe
What SCOPE can do to establish
the Plasma Universe concept
• Perform unprecedented in-situ observations
targeted at
shocks, reconnection, and turbulence.
• The target physical processes are of
fundamental importance in the universal context,
and are operative in the earth’s magnetosphere.
• Construct hands-on-data basis towards the
fundamental understanding of the processes.
• Critical knowledge that can come only through
in-situ observations.
The MHD way of looking at
space plasmas
• MHD Approximation
- Gas motion under the influence of
magnetic field and electric currents
- The gas motion twists the field lines.
- A new spatial distribution of electric
currents are set up.
- Gas motion is altered.
- (refrain)
Electric currents in space
• J = rot B in MHD
• J is determined by the spatial structure of B. No
problem in producing whatever current density
required.
??!
Electric currents in space
• J = rot B in MHD
• J is determined by the spatial structure of B. No
problem in producing whatever current density
required.
• In reality, J reflects differential motion between
ions and electrons, namely, J=en(Vi-Ve).
• A mechanism (non-MHD physics) is needed
when extremely large current density (thin
current sheet) is required.
• Onset of non-MHD effects in a thin current sheet
embedded in the MHD-scale dynamics that
pinches the current sheet: This is where most
of the wonders in space plasmas originate!
Beyond MHD
• MHD is useful but misses the most
attractive part of space plasma physics
• We are determined to step forward and
to construct a new framework that truly
captures the attraction
• SCOPE will generate hands-on-data basis
for the new framework.
The only field
where detailed in-situ measurements
of the complicated physical system is possible
The target physical processes
Shocks,
reconnection,
and turbulence:
Shocks
• Shocks themselves
are fluid-dynamical
entities
• In space physics,
shocks are said to be
particle accelerators
• Fluid versus particle?!
The energy spectrum
of cosmic ray
Particle acceleration at shocks
ＳＮR１００６
Shocks: ordinary fluid-dynamics
versus space plasma physics
Downstream
Slow and hot, Maxwell distribution
Upstream
Fast and cold, Maxwell distribution
Very thin transition layer,
where viscosity is effecttive
Explosive magnetic reconnection
In the night-side magnetosphere,
Large scale current sheet
pinching motion
Production of
energetic particles
Thin current sheet foramtion,
onset of electron scale dynamics
Within it.
Maturing of the reconnection engine
(diffusion region)
Creation of reconnection jet
Jet interacting with the surrounding
plasma
Set-up of auroral current system
Theory “predicts” very curious behavior of
collisionless plasma. Is it truly happening
in the real space plasma?
We won’t identify ourselves understanding it
until we “see” it in the data.
Turbulence
• Turbulence is something you cannot get
away from if you are interedted in nonlinear fluid/gas dynamics
• The addition of the magnetic effects adds
even more complication in space plasmas
• One of the fundamental problem in space
plasma physics, particle acceleration, is
closely related with turbulence.
Magnetic field, collisionless system,
dynamical coupling among different scales
• Cascade  power at short wavelength 
viscous dissipation: Ordinary picture
• Cascade  power at short wavelength 
New terms start to dominate giving rise to
new effects: Space plasmas
Space plasma turbulence
Power
Energy cascase
MHD-scale
Ion-scale
Non-MHD effects arise
as cascade proceeds
Electron-scale
k
Magnetic field, collisionless system,
dynamical coupling among different scales
• Cascade  power at short wavelength 
viscous dissipation: Ordinary picture
• Cascade  power at short wavelength 
New terms start to dominate giving rise to
new effects: Space plasmas
• Background (zero-th order) inhomogeneity
supported by magnetic field is ubiquitous
Dipole-tail current sheet
transition region
Shocks, reconnection, and turbulence
MHD phenomenon as a whole.
MHD does not let you truly understand
what you are attracted to in space plasma physics
It is the coupling between MHD-scale dynamics
and non-MHD (ion and electron scale physics)
that is crucial for the fundamental understanding
of space plasma dynamics
What SCOPE can do to establish
the Plasma Universe concept
• Perform unprecedented in-situ observations
targeted at
shocks, reconnection, and turbulence.
What exactly is this?
Simultaneous
multi-scale observations
Cross Scale Coupling
MHD-scale dynamics
Addition
of
curious
Large-scale Dynamic
effects
Non-MHD processes
add interesting
Non-linear
phenomenon
develops
effects unreachable
MHD
dynamics
onlyby
when
the
systemeffects
works
as a whole
Key process in
key region
Boundary
condition
In most cases, ion/electron scale physics
Simultaneous multi-scale
measurements
• Zoom-in to the electron-scale and
monitoring ion/MHD-scale dynamics
at the same time
# Large FOV and high-resolution pixels at
the same time, in the case of imaging.
SCOPE
Shock wave
Turbulence at
dipole-current sheet transition region
Magnetic Reconnection
Boundary Layer Turbulence
Processes of fundamental importance in the Plasma Universe
The science questions of SCOPE
• Shocks
• Reconnection
• Turbulence
Shocks
• How does a shock dissipate and distribute
the upstream kinetic energy?
• What is the role of the extended turbulent
region upstream of a shock front due to
the collision-less nature of the plasma?
• How does a shock accelerate particles to
high energies?
Reconnection
• How is reconnection triggered?
• How does the energy conversion in
reconnection progress?
• How does reconnection produce nonthermal particles?
Turbulence
• How does turbulence transport energy
over multiple scales?
• How does turbulence lead to anomalous
transport of plasma?
• How does turbulence interact with the
background non-uniformity to produce
anomalous transport?
The worst question
you can ever think of:
“Will SCOPE just confirm
what theorists predict?”
• The key issue: How does the system act
locally in response to the requirement
J = rot B given by MHD-scale dynamics
• Collisionless plasma: Almost infinite
degrees of freedom in the distr. fn. shape
that satisfies
J=en(Vi – Ve)
• How Nature makes the choice is
the question.
• You just cannot convince yourself until
you “see the data in your hand”.
Simulation studies and SCOPE
• Due to computational resource limitations,
one should think that simulation results are
suggesting possibilities but nothing more.
• At the same time, one should be excited to see
in the simulation results how curious space
plasmas can possibly behave.
• Then one should be motivated to dig into the
data to discover that is very exciting, or plan a
mission that will produce very exciting data.
• Likewise simulation studies are occasionally
directed by data analysis studies.
• In any case, most simulationists (at least
in JP) will invest their efforts in multi-scale
simulations for the next ~10 years.
SCOPE: The mission
Daughter(far)：5km 〜 5000km
MHD Scale
Daughter(far)
Daughter(near)：5km 〜 100ｋｍ
Electron Scale
Daughter(far)
Mother
Ultra high-speed
electron measurements
SCOPE-Original
Daughter(far)
Mother-NearDaughter pair
• As good as/bettter than the MMS s/c
• FESA: 10 msec ele detection in the magnetotail
(100 times higher sensitivity than MMS)
• MEP: Covers 10~100 keV energy range
continuously
• Wave-particle correlator
• Sun-pointing spin axis of ND: Precise
measurements of north-south DC E-field
component
• Inter-s/c distance <100km: Electron-scale pair
FarDaughters
• More or less a standard spacecraft (~150kg)
• 3-component E&B wave measurements on all
s/c enabling quantitative analysis of the wave
energy flow
• Inter-s/c distance <100km ~ 5000km
Electron~ion~MHD scales
M-ND pair@electron scale + FD@ion/MHD
 simultaneous multi-scale obs.
Obs. supporting systems
• Inter-s/c comm. for localization, timesynchronization, commanding, and data
link for intelligent coordination
• Large volume data storage
• Spin axis antenna
Right size budget?
• M-ND by JAXA
• FD by CSA
• SIs onboard SCOPE by JAXA-CSA led
consortium
• Launcher = H2A: More capability than
ISAS science program can afford to fill
 NASA as the dual-launch partner
The toughest question
• Is the number of the s/c outside the
mother-daughter pair, three, good
enough?
• Two-scales at the same time, at most.
• More straightly, more is not only better but is
different.
International collaboration helps.
The whole picture of
SCOPE/Cross-Scale:
Full-scale coverage via international collaboration
with clear interfaces
ESA’s component Cross-Scale
To be launched by JAXA’s H2-A
SCOPE mother and near/far-daughter
Far-daughters
(JAXA)
(CSA)
Dual launch partner THEMIS-like s/c
(NASA)
China’s component
Russia’s component
The status of SCOPE
• Passed MDR in Jan 09
• Ready to move on to Phase A (another
review expected in May 09)
• Intense collaboration with CSA started
• Need to accelerate the study on the NASA
component
• SCOPE/Cross-Scale MUST happen with
the full-scale international collaboration
scheme.
The whole picture of
SCOPE/Cross-Scale:
Full-scale coverage via international collaboration
with clear interfaces
ESA’s component Cross-Scale
To be launched by JAXA’s H2-A
SCOPE mother and near/far-daughter
Far-daughters
(JAXA)
(CSA)
Dual launch partner THEMIS-like s/c
(NASA)
China’s component
Russia’s component
Hey, how about Taiwan?!