Transcript ASPERA-3 - IRF publications

Solar wind interaction with
the inner, Earth-like, planets
(Venus and Mars)
Stas Barabash
Swedish Inst. of Space Physics
Kiruna, Sweden
1
Solar wind interaction with a nonmagnetized planet (1)
•
A sufficiently large planet with a
sufficiently cool upper atmosphere will
retain its heaviest atmospheric
constituents against thermal or Jean’s
escape for the age of the solar system
•
Solar radiation extends into the EUV
range where these atoms and
molecules can be ionized and
dissociated
•
If the solar wind were unmagnetized the
solar wind would be absorbed
•
The presence of the solar wind
magnetic field enables the solar wind to
be deflected and enables atmospheric
loss
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Solar wind interaction with a nonmagnetized planet (2)
•
•
•
•
•
Basic physics of the interaction is
similar for Venus and Mars
The convective electric field of
the solar wind E=-VxB results in
ionospheric currents.
The currents create magnetic
field to deviate the solar wind
plasma flow.
A solar wind plasma void, an
induced magnetosphere, is
formed.
The induced currents decay with
time depending on the electrical
conductivity that varies with
height and solar cycle.
3
Solar wind interaction with a nonmagnetized planet (3)
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The thermal pressure in the
ionosphere, nkT, is generally sufficient
to balance the dynamic pressure in
the solar wind,rv2
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The induced magnetosphere acts as
a cap on the ionosphere and an
obstacle to the solar wind flow
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The magnetic pressure in the induced
magnetosphere above the ionosphere
reaches a value strong enough to
hold the ionosphere down and deflect
the solar wind
•
The induced magnetosphere is
immersed into the planet’s exosphere.
4
Bow shock formation
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The solar wind magnetic field is
draped over the highly electrically
conducting ionosphere forming a
magnetic barrier
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This barrier deflects the flow around
the ionosphere
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The necessary pressure gradient to
cause the deflection cannot be
created in the supersonic flow
•
The shock forms to deflect and heat
the solar wind so that the pressure
gradient can steer the solar wind
around the induced magnetosphere
5
Pressure balance at Mars. Mars Express observations
IMB
Ne, cm-3
Ne (cold, MARSIS)
P, dyn/cm2
Ne (hot, ASPERA)
R, Rm
UT
Dubinin et al., 2008
Ptot=B2/8p+ kNeTe
Pe(Te =0.3 eV)
Pe(Te =1.0 eV)
Pi=kNeTp
Pd=NempV2cos2(f)
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Tail formation
•
•
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Magnetic flux tubes that become “hung-up” deep in the night and day
ionosphere are heavily mass-loaded and contribute to the central region
of the tail
Magnetic flux tubes at higher altitudes that may only be lightly mass
loaded also become tail-like
Magnetic pressure and curvature force act to accelerate the ionospheric
plasma in the tail and straighten the magnetic field lines.
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Magnetic anomalies on Mars
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•
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The Martian crust was magnetized by the ancient intrinsic magnetic field
The Martian dynamo ceased to operated ca. 3.5 billion years ago due to too
small size of the planet. The crust magnetization remained.
The magnetization forms east - west stripes of 100-200 km wide and 8001500 km long with alternative magnetic field polarity
The anomaly’s field affects locally the solar wind interaction region
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Unique phenomena for nonmagnetized planets
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•
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Bow shocks in mass loaded plasmas with neutral background
Waves and instabilities in plasma (solar wind) with neutral background
Physics of minimagnetospheres: magnetic anomalies (Mars)
Kinetic effects (Mars): the interaction region and bow shock size are
comparable with the Larmour radius for protons
Impact of the interaction on the atmospheres
• Energy transfer to the upper atmosphere: higher temperatures on
Mars than predicted
• Mass transfer: helium in the Martian and Venusian atmospheres are
from captured solar wind a-particles
• Atmospheric loss: 0.01 - 1.0 kg/s
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Processes leading to escape
Process
Charge Energy s ource
Jeans escape
N
Thermodynamic free energy
Chemical reactions
N
Thermodynamic free energy / inner energy
Photochemical r eactions
N
Solar photon energy
Solar wind induced escape
I
Solar wind kinetic and magnetic energy
Polar wind
I
Electron thermodynamic free energy
Magnetic field energy
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Escape and planetary atmosphere evolution
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The escape due to the solar wind interaction is the dominant channel for
the atmospheric loss at Venus but it is small relative to the mass of the
atmosphere.
It is also significant for Mars both relative to the other channel and relative
to the atmosphere mass.
Venus
Earth
Mars
Titan
Atm. Mass, kg
4.8E+20
5.3E+18
2.5E+16
9.2E+18
Min escape, kg/Gy
1.5E+16
8.4E+15
3.8E+15
2.6E+17
Max escape, kg/Gy
2.5E+16
1.7E+17
1.5E+17
2.8E+17
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Escape and the evolution of Martian atmosphere
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Past Mars (~3.5 Gy) “warm and wet”
• Wet, warm place, 1-3 bars CO2 atmosphere, strong green house effect
• Water and CO2 escaped or stored in unknown undersurface / surface storage
• Effective escape to space, if no reservoirs are found
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Past Mars (~3.5 Gy) “cold and dry”
• Cold place, CO2 gone early in the history, no green house effect
• Water frozen and released sporadically during volcanoes eruptions and/or meteor
impacts
• No effective escape to space
•
Present Mars: dry desert, with 0.01 bar CO2 atmosphere
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Four main scientific questions on the escape
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Induced magnetosphere response to the solar and solar wind conditions
• Variation of the atmospheric loss
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Detailed composition of the escaping plasma
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Mechanisms of ion extraction from the ionosphere
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Plasma physics of the magnetic anomalies at Mars and their role in the
escape
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Evolution of the solar wind
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Solar conditions for the solar wind interaction missions
200
Mars-5
Phobos-2
MEX
180
Sunspot Numbers
160
140
120
100
80
60
40
20
0
1973
1978
1983
1988
1993
1998
2003
2008
Years
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Solar cycle variations. Escape rates
1.E+26
Total planetary ion escape, 1/s
Phobos-2
Venus Express
1.E+25
PVO
1.E+24
Mars-5
Mars Express
1.E+23
1970
1975
1980
1985
1990
1995
2000
2005
2010
Year of observation
Mars
Venus
Mars-5: Vaisber, 1986; Phobos-2: Lundin, 1990; Verigin, 1990; MEX: Barabash, 2007; Fedorov, 2008
PVO: McComass, 1986; Brace, 1987; VEX: Fedorov, 2008
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Dependence of the escape on the upstream conditions
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The planetary ion fluxes increases with the SW dynamic pressure (Lundin et al.,
2007) but the obstacle size decreases (Dubinin et al, 1996, 2007; Crider et al.,
2003). The net effect on the total escape is not yet clear.
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To determine the dependence of the escape rate requires sufficient coverage of
the escape region at a fixed upstream and XUV conditions.
Dubinin et al, 1996
Lundin et al, 2007
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Plasma composition in the induced magnetosphere. Mars
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O+, CO2+, O2++ : CO2+/O+ = 20%, O2+/O+ ~1 (Carlsson et al., 2005)
He+ : escape rate 1.2·1024 s-1 (Barabash, 1995)
H+ and H2+: cold (Norberg, Barabash, 1992; Lundin et al., this meeting).
Double charged O++ (Norberg, Barabash, 1992)
O++
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Solar cycle variations. Ionospheric supply (Fox, 1997)
Qhigh
3
Qlow

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Plasma composition in the induced magnetosphere. Venus
Energy depends on mass: ion-pick up
Energy does not depend
on mass: polarization
electric field
Barabash, Fedorov et al., 200720
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If the ionosphere is separated from the
solar wind by the magnetic barrier region,
how ions can be extracted from the
ionosphere?
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Penetration of the solar wind and
convective electric field through IMB near
terminator results in acceleration of ion in
the form of narrow (energy/angle) beams.
The energy increases with altitude (Dubinin
et al., 2005).
•
Cold plasma scavenging is observed on
Phobos-2 and MEX. Mechanism is not
clear. Plasma clouds up 700 cm-3 observed
at 1000 km at SZA=60° (Pedersen et al.,
1991). Bulk velocity is unknown.
Energy, eV/e
Ion extraction from the ionosphere. E-field and scavenging
Dubinin et al., 2005
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Ion acceleration in the tail
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Classical pick-up operates in the magnetospheath. The ion energy
proportional to the ion mass
•
JxB force acting on magnetized electrons, due to magnetic field stress in
the kink of the draping field, accelerates ions due to the ambipolar electric
field. It operates mainly in the plasma sheet. The ion energy does not
depend on mass, E(O+)~E(O2+)~0.5 E(O++).
Lundin and Dubinin et al., 1992
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Magnetic anomalies. Morphology
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Anomalies are minimagnetospheres
(Mitchel et al., 2001).
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Close field lines of the magnetic
anomalies screen-off the solar wind and
prohibit vertical transport of the
ionospheric plasma. Open field lines
connect the ionosphere with the solar
wind.
Soobiah et al., 2005
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Magnetic anomalies. Aurora
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Reconnection signatures observed in the MGS magnetometer data (Brain
et al., 2003). Reconnection regions occupy 7% of the Martian surface.
Cusp-like structures results in aurora-like emissions (Bertaux et al., 2005)
Martian aurora is a highly localized (~10 km along LOS), sporadic, low
intensity (20..50-700 R) emissions of CO, CO2+, and O (180-240nm,
289nm, 297.2nm) observed above the strong magnetic anomalies.
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Magnetic anomalies. Particle acceleration (1)
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Aurora-like electron spectra were observed
above the anomalies (Lundin et al., 2006;
Brain et al., 2006).
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The acceleration mechanism is not clear
because the field-aligned field cannot be
maintained due to high Pedersen
conductivity in the ionosphere (Dubinin et
al., 2007).
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No statistically significant correlation
between the occurrence of the ion beams
and beam intensity and magnetic anomaly
(Nilsson et al., 2005).
•
Role of the anomalies for the ion
acceleration and escape is still not clear
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History of the Mars and Venus exploration
at IRF
Collaboration with Japan
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Plasma measurements at Mars
Mission (Launch)
B-field
Electrons*
Ions*
X
X
Waves and Efield
-
Mariner 4 (1964)
Mars 2,3,5 (1971-1973)
Th ermal
plasma
-
ENAs
Comment / Results
X
X
Ion mass
composition*
-
X
-
X
X
X
X
X
X
X
-
-
X
X
-
X
X
X
X
X
X
-
X
X
-
?
X
-
X
-
-
X
X
X
-
X
Plasma probe failed
Basic ideas on the type of interaction
Main domains of the near – Mars space
Indirect detection of heavy ions
Ionospheric profile during entry and descend
Mars not reached
Limited (3 months) operations
First mass composition instruments
Mars not reached
Mars not reached
Mars not reached
400 km circular orbit
Magnetic anomalies
Limited operations in the eclipse
First combin ed ion, electron, and E NA
measurements
Viking 1/2 (1975)
Phobos – 1 (1988)
Phobos – 2 (1988)
X
X
X
Only E-field
Mars Observer (1992)
Mars – 96 (1996)
Nozomi (1998)
MGS (1998)
X
X
X
X
Mars Exp ress (2003)
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* hot plasma, sola r wind, partic le ene rgy > few eV
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IRF missions to Mars and Venus
Phobos, 1988
VEX, 2005
Mars-96, 1996
1990
2000
2010
Nozomi,
1998
MEX, 2003
2009
Phobos-Grunt
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The beginning (ca. 1983 - 1989). Phobos / ASPERA
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Following successful ion mass
spectrometers PROMICS-1 and 2 on
the Soviet Prognoz 7 and 8 missions
(1979 and 1980) our USSR
colleagues at IKI (Space Research
Institute, Moscow) invited IRF to
participate in Venera-15/16 missions
(1983). But we were not ready yet!
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In 1983 Academician Roald Sagdeev
(IKI director) invited Prof. Rickard
Lundin to participate in the PHOBOS
project.
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ASPERA the first instrument at Mars
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ASPERA is the first IRF experiment
at Mars
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Two ion mass analyzers and an
electron spectrometer
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Mechanical scanner: first IRF
mechanics in space
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Own solar arrays (30% power)
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Two microprocessors
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Sven Olsen (1934 - 2005)
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The difficult 90-s. Mars - 96 / Nozomi
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Beginning of 90-s the group in
Kiruna was already known for its
light weight plasma mass analyzers
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In 1992 the invitation came to
participate in the Japanese Nozomi
mission (Planet-B) with the IMI
instrument (Ion Mass Imager). At
that time we were already working
on ASPERA-C for the Russian
Mars-96.
Nozomi / IMI, 1998
Mars-96 / ASPERA-C, 1996
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Nozomi missed Mars in Dec. 2003,
5 years after launch.
Mars-96 with ASPERA-C sunk in the Pacific (Nov.
1996) after malfunction of the kick-off (4th) stage
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Nozomi heroic story (1)
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Nozomi (Planet-B) was launched in July, 1998. Performing powered
swing-by at the Earth on December 20, 1998 (after two Moon swing-by’s)
a main engine malfunction occurred and too much fuel was consumed.
The remaining fuel was not sufficient for the planned Mars orbit insertion
in October 1999.
New trajectory was devised but it would require 4 more years in space.
The insertion would occur in December 2003 at the time of the ESA Mars
Express insertion.
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Nozomi heroic story (2)
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Spring 2002 radiation caused by a solar flare hit Nozomi affecting its
power distribution system. Since April 26, 2002 no TM could be sent and
the spacecraft thermal control system could not function.
Our ISAS colleague devised a beacon mode (ON/OFF) to receive at least
some knowledge on the Nozomi state. The mode was extremely time and
man-power consuming but the Nozomi team did not give up
In August 2002 the team regain control over attitude and orbit maneuver
capabilities. 4 orbit corrections and 2 earth swing-by’s were performed
(the last in June 2003). Nozomi was on its way to Mars with the hope the
power distribution system recovers.
The Nozomi team was fighting until October 2003, when a new orbit
correction maneuver was performed to avoid any potential collisions with
Mars (Originally planned as an orbiter, the spacecraft did not go through
sterilization).
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Nozomi heroic story (3)
While not fully successful, Nozomi
provided extremely important
experience and paved the way for the
other planetary missions in Japan,
new instruments, and international
collaboration.
Farewell image,
Earth as seen by
a Nozomi camera
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The new times (1998 - 2007)
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ESA Mars Express was initiated
as a recovery for European
instruments from the Mars-96
failure.
•
Venus Express was a follow-on of
the successful Mars Express
•
Following the participation in
Soviet Phobos, Japanes Nozomi,
and Russian Mars-96 IRF led
team including colleagues from
ISAS (Japan) was selected to
provide ASPERA-3 and ASPERA4 experiments for Mars and Venus
Express missions.
2003
ASPERA-3 /
Mars Express
2005
ASPERA-4 /
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Venus Express
Mars Express
Venus Express
Nya tiderna (1998 - 2007). Venus Express / ASPERA - 4
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MEX, 2003
VEX, 2005
Nya tiderna (1998 - 2007). Venus Express / ASPERA - 4
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The future. Swedish satellites at the other planets
•
IRF together with the Swedish Space
Corporation, other Swedish groups and
international partners, Japan being the
major one, is developing ideas on
microsatellites to study Mars, Venus, the
Moon, and asteroids.
•
Such missions are indeed feasible!
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
40
Future cooperation with Japan. Joint instruments
•
•
•
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Ultra light mass analyzers (< 500g) with the functionality and performance
of the Nozomi and Mars Express type of instruments
Neutral gas mass spectrometers (M/DM > 1000, up to 100 amu) (in
cooperation with University of Bern)
Energetic Neutral Atom (ENA) imagers for the energy range 10 eV - few
keV
Solutions of joint plasma packages
41
Future cooperation with Japan. Joint simulation projects
•
Uses software built on the public FLASH software from University of
Chicago. Parallel, adaptive grid. Handles fluid (MHD) and particle (hybrid
and DSMC) simulations. Uses the Akka cluster with 5376 cores at the
High Performance Computing Center North (HPC2N) in Umeå
•
Hybrid model of the Mars-solar wind interaction under development.
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Moon hybrid modeling. Will be used to interpret the observations of an
IRF instrument on the Indian Chandrayaan-1. We are also open on
collaboration in the frame of the Japanese Moon mission Kaguya.
42
Future cooperation with Japan. Data analysis
•
Data analysis: all our Mars and Venus
Express data sets are open. We are
ready to provide Japanese users all
necessary support.
•
Collaboration with the X-ray telescope
Suzaki team to observe charge exchange X-rays from Mars
• Solar wind multi-charged ions (O7+,
O6+, .., C5+, C6+, ,…) charge
exchanging on the Martian
exosphere produces X-rays (0.3 - 1
keV)
• The satellite borne X-ray telescope
Suzaki performs X-ray imaging
from an Earth orbit
• Mars Express/ASPERA-3 monitors
local plasma conditions
43
A lot of joint research can be made in the area
of the solar wind - Mars/Venus interaction.
We are open for collaboration!
44