IMI - Nozomi Ion Mass Imager
R. Lundin, M. Yamauchi, and H. Borg, Swedish Institute of Space Physics
H. Hayakawa, M. Hirahara, T. Mukai, Institute of Space and Astronautics Science
10
Bow Shock
8
Bow Shock
Ionization Layer
Solar Wind
6
MLB
4
Magneto
pause
2
Flank Cold Ion
Outflow (1 - 100 eV)
-4
-6
-20
-15
-10
-5
XSE (R )
0
5
M
24 January, 2001
1st NOZOMI_MEX Science Workshop, 24-26 Jan, 2001
-8 -10
Ion Pickup
(2 - 60 keV)
M
-2
Nozomi orbit
YSE (R )
0
Tail Beams
(0,1 - 3 keV)
Ion Mass Imager, IMI, on Nozomi
• Measures E/q of ions (0.01 - 35 KeV/e)
• H+, He++, He+, O+, and O2+,CO2+ (mol ions)
• 3D observation every half spin
24 January, 2001
1st NOZOMI_MEX Science Workshop, 24-26 Jan, 2001
IMI Cross Section
(& meas. Principles)
View from S/C antenna
(towards the Earth)
24 January, 2001
1st NOZOMI_MEX Science Workshop, 24-26 Jan, 2001
IMI characteristics
24 January, 2001
1st NOZOMI_MEX Science Workshop, 24-26 Jan, 2001
IMI data of the
Solar Wind
(1999 & 2000)
He++
24 January, 2001
H+
1st NOZOMI_MEX Science Workshop, 24-26 Jan, 2001
Nozomi Cruise Phase Science
• 3-D plasma structure of the solar wind. The unsusual Nozomi orbit, 0.1 AU above
the Earth (spring 2003), is an opportunity for STP studies (e.g. SOHO, Cluster etc)
• Cruise solar wind studies with Mars-Express => Analysis of the heliospheric
current sheet, and other interplanetary phenomena (e.g., interplanetary field-aligned
current, k-vector measurement)
Martian Science
• Escape of ions and neutrals, faciliated by a relatively low gravity and weak magnetic
field and an atmosphere and ionosphere directly exposed to the solar wind. The escape
velocity 5 km/s => escape energies 2.1 eV for O+ and 4.2 eV for O2 +.
• Dawn-dusk asymmetries of the Martian bow-shock
• Expanded neutral atmosphere /corona (low gravity and weak magnetic field). Neutral
gas expand beyond the bow shock, enhancing the interaction with the solar wind (mass
loading etc.).
• Venus-like (and comet-like) interaction with the solar wind due to the weak intrinsic
magnetic field.
24 January, 2001
1st NOZOMI_MEX Science Workshop, 24-26 Jan, 2001
Mars Ion Acceleration (ASPERA, Phobos-2)
10
Bow Shock
8
Bow Shock
Ionization Layer
Solar Wind
6
MLB
4
Magneto
pause
2
Flank Cold Ion
Outflow (1 - 100 eV)
-2
-4
-6
-8
-20
24 January, 2001
-15
-10
-5
0
1st NOZOMI_MEX Science Workshop, 24-26 Jan, 2001
5
-10
Ion Pickup
(2 - 60 keV)
YSE (RM)
0
Tail Beams
(0,1 - 3 keV)
Martian Science (cont)
• Outgassing from the surfaces of the two Martian satellites, Phobos and Deimos.
• Asymmetry of the neutral corona - decisive factors may be a thin atmosphere, a
relatively slow rotation, and magnetospheric forcing. The asymmetry does not
disappear in the tail because of the relatively large gyroradii compared to the size
of the Martian magnetosphere.
• Interesting boundary layer physics in an environment of weak magnetic fields,
large ion gyroradii, and an expanded corona.
Sensor:D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D1
100
9400
3750
10
1500
Energy (eV)
• Studies of the bow shock
(asymmetric comet-like
transition, backstreaming and
acceleration), mass-loading
boundary (planetopause?),
magnetopause (or proton
dropout boundary), and
ionopause.
ASPERA P-Scan: Feb 1 1989, 18.17 UT
591
Solar Wind
Reflected
Ions
98
16
4.6
1.1
0°
90°
180°
270°
Elevation Angle
24 January, 2001
1st NOZOMI_MEX Science Workshop, 24-26 Jan, 2001
360°
1
Critical Martian science issues :
(1) The Martian bow shock
• How far does back-streaming of ions and electrons travel from the quasi-parallel shock?
• Rate of ion pickup phenomena in the flanks?
• CIV phenomenon?
10
9
 Magnetopause  MLB
8


7
M
(Y2 + Z2)-1/2 (R )
(2) Boundary layers
• Consensus lacking on classification, locations, and physical
role of various boundaries
• Dynamics, dawn-dusk
asymmetry, and solar wind
dependence?
Mars Plasma Boundaries
(ASPERA, Phobos-2)
6
 Bow Shock


5



4


3



2
















1
0
-18
-16
-14
-12
-10
-8
-6
XSE (R )
M
24 January, 2001
1st NOZOMI_MEX Science Workshop, 24-26 Jan, 2001
-4
-2
0






2
Critical Martian science issues (cont):
(3) Phobos ring and Deimos torus
• Plasma tail from the dust ring
• Dusty plasma and a dense plasma in the
dust ring?
• Outgassing?
(4) Ion energization process
• To the SW velocity, to the SW energy, or
to twice the SW energy?
• SW condition during energization event.
• O+ energization
• Acceleration in the central plasma sheet
• Acceleration mechanism (Electrostatic,
waves, or MHD)
24 January, 2001
1st NOZOMI_MEX Science Workshop, 24-26 Jan, 2001
Critical Martian science issues (cont):
5) Helium and molecular ions
• Helium rich sources?
• Non-thermal escape from the
atmosphere
• Molecular ions in the plasma sheet
• Additional sources of ions other
than the atmosphere (Phobos and
Deimos?)
6) The effect of localized magnetic
induction regions on the solar wind
interaction with Mars
• Perturbed magnetosphere shape ?
• Localized ”cusp” regions?
• Enhanced atmospheric escape?
• Impact on weather?
24 January, 2001
1st NOZOMI_MEX Science Workshop, 24-26 Jan, 2001