Presentation - Centre for Aerospace Science and Technologies by dffhrtcv3

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									Plasma in the solar system:
   science and missions
             Stas Barabash
 Swedish Institute of Space Physics (IRF)
            Kiruna, Sweden
                                    Swedish Institute of Space Physics

• Established 1957
• A governmental research institute under the auspice
  of Ministry of Education. Annual budget ~ 9 M€
• Basic research in the area of space physics, space
  technology/instrumentation, atmospheric physics,
  and long-term observations (geophysical
  observatory)
• Division of Space engineering of Luleå Technical
  University and EU Erasmus Mundus SpaceMaster
  program
                                                        PI missions since 1978
Experiment       Mission         Launch, Org/Country   Targe t
PROMICS-1        Prognoz-7       1978, USSR            Earth's magnetosphere
PROMICS-2        Prognoz-8       1980, USSR            Earth's magnetosphere
V3               Viking          1986, Sweden          Earth's magnetosphere
ASPERA           Phobos-1/2      1988, USSR            Mars / Phobos
TICS/MATE        Freja           1992, Sweden          Earth's magnetosphere
PROMICS-3        Interball-1/2   1995/96, Russia       Earth's magnetosphere
PIPPI/EMIL/MIO   Astrid-1        1995, Sweden          Earth's magnetosphere
ASPERA-C         Mars-96         1996, Russia          Mars
IMI              Nozomi          1998, Japan           Mars
MEDUSA, PIA      Astrid-2        1999, Sweden          Earth's magnetosphere
MEDUSA, DINA     Munin           2000, Sweden          Earth's magnetosphere
ASPERA-3         Mars Express    2003, ESA             Mars
NUADU (Co-PI)    Double Star     2004, China           Earth's magnetosphere
ICA              Rosetta         2004, ESA             Comet Churyumov-Gerasimenko
ASPERA-4         Venus Express   2005, ESA             Venus
SARA             Chandrayaan-1   2007, ISRO            Moon
PRIMA            PRISMA          2010, Sweden          Technol.
YPP              Yinghuo         2011, China           Mars
DIM              Phobos-Grunt    2011, Russia          Mars
MINA             Mars 2013       2013, China           Mars
LINA             Luna-Globe      2014, Russia          Moon (lander)
MIPA             BC M PO         2014, ESA             Mercury
ENA              BC M MO         2014, ESA             Mercury
                                                            Swedish missions
                                                                Odin 2001
 Magnetospheric physics: Viking, Freja, Astrid-1/2, Munin
 Technology demonstrator: PRISMA
 Atmospheric physics / Astronomy: Odin

                                                 PRISMA, 2008


                                                                 Astrid-2, 1999



Viking, 1986                               Astrid-1, 1995

Munin, 2000



                    Freja, 1992
                                                                       Solar wind

• Solar wind is a plasma flow blowing
  away from the Sun.
• The complicated wave - particle
  interaction near the photoshere (“Sun
  surface”), which is not well -
  understood, results in the heating of
  the solar corona plasma from 6·103 K
  to 106 K.                                      QuickTime™ an d a
                                           Sorenson Video deco mpressor
• The thermal expansion of the solar       are need ed to see this p icture .
  corona in the presence of the
  gravitation field converts the thermal
  energy to the direction flow
  (“gravitational nozzle”).
• Solar wind is a supersound flow of
  plasma (95% p+, 5% a-particles) with
  a velocity of 450 km/s and density
  about 70 cm-3 (Mercury) to 3 cm-3 at
  Mars
                   What defines the type of the solar wind interaction

• Charge particles of the solar wind can be only affected by a magnetic
  field at an obstacle
• The magnetic field may originates from:
    • Intrinsic field of an obstacle
    • Currents induced in a conductive obstacle as a result of the
       interaction
• The obstacle’s magnetic field:
    • Intrinsic dipoles (Earth, Mercury, Jupiter, Uranus, Neptune)
    • Local crust magnetizations (Moon, Mars)

• Conductivity of the obstacle (Mars, Venus)
   • Conductivity of rocks low
   • The presence of the conductive material (ionosphere, an ionized
     part of the atmosphere) increases conductivity ( s ~ne , for
     magnetized plasmas we >> nc)
Types of the solar wind interactions
    Corotating Jovian magnetosphere                                  Induced magnetospheres of
                                                                               Mars and Venus

Earth magnetosphere

                   QuickTime™ and a
               TIFF (LZW) decompressor
            are neede d to see this picture.




     Terrestrial magnetosphere                 Interaction with the Moon
                  Field of the solar wind interactions. Why is it important?
• The fundamental scientific questions to address:
   • Space plasma physics: What is the structure and characteristics of the near-
     planet environment? What physics governs the interaction?
   • Planetology: What is the impact of the interaction (environment) on the
     central body?
       • Non-thermal atmospheric escape (non-magnetized planets)
       • Auroral phenomena and influence on thermospheres
       • Surface space weathering (airless bodies)
                     Magnetic field measurements. Why are they important?
•   Magnetic field measurements are essential to organize and understand energetic charged
    particle and plasma measurements.

•   Magnetic field measurements also represent one of the very few remote sensing tools that
    provide information about the deep interior.
     • Magnetic field of Earth, Jupiter, Saturn are generated by currents circulating in their
        liquid metallic cores.
     • Uranus’ and Neptune’s magnetic fields are generated closer to the surface by
        electrical currents flowing in high-conductivity crustal ‘‘oceans.’’
     • Mercury is currently magnetized by the remains of an ancient dynamo
     • Subsurface oceans on Europa, Ganymede, Callisto were first sensed by a
        magnetometer
                   Instrumentation to study near-planet space. Particles

• Particle distribution functions: amount of particles of a
  certain kind from a certain direction at a certain energy in
  each measurement point
   f  f (M, , , E, x, y, z)
• Types of instruments
   • Ion and electron spectrometers
   • Ion mass analyzers                              Mars-96 / ASPERA
   • Energetic neutrals imagers
   • Energetic particle telescopes
   • Radiation monitors
• Energy ranges
   • meV - 10s eV: thermal plasma
   • 10s eV - 10s keV: hot plasma
   • 10s keV - Mev: energetic particles
   • MeV - 100s MeV: radiation flux
      Instrumentation to study near-planet space. Field and waves

• Thermal plasma density and temperature
   • Langmuir probes
   • Density 0.1 - 100 cm-3
                                            Ørsted satellite (1999)
   • T ~ 0.1 - 10 eV

• Magnetic and electric field vectors and
  magnitude. Frequency spectra
• Typical instruments
   • Magnetometers
   • Electric field experiments
   • Correlators with particle fluxes
• Typical magnitudes
   • B-field: 0.01 nT - few 10 000 nT
   • E-field: 0.01 - 10 mV / m
                                            Basic platform requirements

• Particle measurements (energetic particles)
   • Unobscured omnidirectional (4p) field of view
   • Avoidance of thruster plumes and firing
   • Spacecraft potential control

• Thermal plasma measurements (plasma density/temperature)
   • Minimizing effect of the spacecraft on thermal plasma: booms/sticks

• Fields and plasma wave measurements
   • Minimizing effect of the spacecraft
        • Magnetic cleanliness
        • Booms
   • Electro-Magnetic Compatibility (EMC) programs. Some what more
      stringent than usual (not discussed here)
                                Unobscured omnidirectional field of view
                                                             Lewis et al., 2009
• The main and the most challenging
  requirement
• Can be fully (4p) fulfilled only on
  spinning platforms
• Possible solutions for 3-axis
  stabilized platforms
   • 2 hemispheric identical sensors:
      mass increase!
   • Fan-type field of view (180° over
      polar angle) on mechanical
      scanners and attenuators:
      attitude disturbances
   • Spun sections on 3-axis
      stabilized platforms: enormously
      expensive
Galileo despun platform
                                                 Mechanical scanners (1)

• Typical moving mass 4 kg, L ~ 0.1 m, w ~ 1 rpm
• Typical spacecraft mass 0.5 - 1 tons, L ~ 1 m, w ~ 10-4 rpm



                                                                Spin axis
        Mechanical scanners (2)




0.02°
                                      Spin-stabilized platforms (spinners)
                                                         MMO
• Mission examples
   • JAXA Mercury Magnetospheric Orbiter
   • ESA Cluster (Earth magnetosphere)
   • Swedish Freja (Earth magnetosphere)
• Typical spin rates 10 - 20 rpm
• Only limited imaging experiments can be
  carried out
   • High intensity emissions / large fields   Cluster
      of view
   • Auroral / EUV imaging
   • Scanning photometers
                         Freja
                                       Thruster plumes and firing
                                            Rosetta / Schläppi et al., 2010
• Operating even attitude thrusters
  (1 - 10 N) increase gas pressure
  around spacecraft.                            Attitude maneuver
• It may result in discharge in
  instruments ion optics using high
  voltage of few kV
• Hydrazine / Nitrogen thetroxide
  may contaminate open particle
  detectors

• Usually weak requirement
• Can be fulfilled by proper
  accommodation and thruster
  shields (conflict with blocking of
  field-of-view)
                                                       Spacecraft potential

• Due to release of photoelectrons (discharging) and accommodation of
  electrons and ions from the ambient plasmas (charging), spacecraft
  surfaces get charged and are under a potential relative to the ambient
  plasma
• Typical values between -10..-20 to +30…+50 V
• In energetic plasma on night side the potential may reach -500…-1000 V
• The spacecraft potential affects the particle measurement at the
  respective energies: energy cut-off at ~q Vsc
• Differential charging over the spacecraft affects particle trajectories

• The surfaces (MLI) surrounding instruments must be conductive.
• Spacecraft potential control systems (electron emitters) may be required.
• If not possible, the spacecraft potential should be measured.
                                          Thermal plasma measurements (1)

• Langmuir probes: small spheres (5-10 cm diam.) biased at different
  voltages. The measurable is the current to the sphere (volt-amp
  characteristics)
• From voltage - current curve one deduces:
   • Plasma density and temperature
   • Spacecraft potential (voltage when the current = 0)
• Spacecraft potential affects the surrounding plasma and the influence
  should be minimized
        Rosetta simulations / Sjögren, 2009




                                         32 m
                                    Thermal plasma measurements (2)

• Rigid (quasi-rigid) booms / sticks are required
• The length depends on the spacecraft size and plasma parameters (the
  denser plasma, the shorter boom)
• The longer, the better. Minimum 1 m



           Cassini Langmuir probe
                                                     Magnetic field measurements

                                                                        Voyager-1 (1977)
• It is practically impossible to reduce the stray
  spacecraft magnetic field from a platform to
  the smallest required levels.
    • Solar arrays, motors, actuators, power
       systems, magnetic materials, etc
• The magnetic cleanliness programs on the
  early planetary missions were enormously
                                                                 14 m
  expensive (will never repeat again).
• Pioneer 10 / 11 (launched 1973) achieved
  0.01 nT at the 3 m distance (practical limit)

• Long booms are required: B ~ 1/r3
• Double magnetometer techniques: shorter
  booms with two magnetometers to obtain the
  spacecraft stray field (extra mass)
                                                      Electric field measurements

    • A space voltmeter: the potential difference between two terminals (probes)
      is measured.
    • The electrostatic spacecraft potential (1 - 10 V) and V ~ Vsc Dsc/r
    • To measure fields of Emin ~ 0.01 mV/m

                    DscVsc
             L~            ~ 30 m
                    E m in

    • Booms of 30m are required!




                         V = V1 - V2 (measured), E = V / L
                                                General boom designs (1)

• Rigid tubular booms max. 3 segments
  mostly for magnetometers                                          6m
• Scissor booms on MAGSAT (1979)
   • Optical mirrors are mounted on the
     magnetometer sensor platform to
     ‘‘transfer’’ its orientation to the main
     body of the spacecraft using infrared
     beams.
• Truss-like “astromast” designs (Polar /                      MAGSAT
  WIND)

                                                               6m
                                                    General boom designs (2)

       • Wire booms deployed by centrifugal force for E-field experiments and
         Langmuir probes



                          Magnetometer
                          and star camera




Langmuir probe           E-field wire booms




                                                                     Swedish Astrid-2
      A typical plasma science spacecraft
ESA-JAXA BepiColombo / Mercury Magnetospheric Orbiter
                                           Plasma instruments vs. remote sensing

Requirement                    Space plasma measurements                    Remote sensing
                                                                            instruments
Unobscured hemispheric FoV     Critical. Challenging to fulfill             Not required
Spin-stabili zed platforms /   Critical. Challenging to fulfill             Not compatible
scanners
Thruster avoidance             Moderate. Easy to fulfill                    Critical. Easy to fulfill
Spacecraft potential           Minor                                        Not required
Minimizing spacecraft          Critical. Challenging to fulfill             May not be compatible
influence (booms)
Magnetic cleanliness           Critical. Challenging/expensive to fulfill   Not required
EMC program                    Critical. Relatively easy to fulfill         Moderate. Easy to fulfill


    • Main conclusion: Requirements (and thus platform design drivers) are
      different and in general not compatible.
    • Trade-off may not be always possible
           Very few dedicated space plasma missions (planetary)

• Mars: Nozomi (ISAS, Japan, 1998)      Nozomi

• Mars: MAVEN (NASA, 2013)
   • Not a spinner!
• Mercury: BepiColombo MMO Mercury
  Magnetospheic orbiter (JAXA, 2014)
   • Piggy-backing on ESA BepiColombo
     Mercury Planetary Orbiter

       MAVEN
                                           Possible “main stream” solutions
• Piggy-backing on “planetary-proper” missions
• Small scale national / bilateral dedicated missions

• Proposals from the Swedish Institute of Space Physics
   • 3 missions to Mars
      • MOPS, a microsat on Phobos-Grunt (discussions with NPO Lavochkin)
      • Mjolnir, a microsat on the ESA Cosmic vision MEMOS (proposal)
      • Solaris, a microsat on a NASA discovery mission (proposal)
   • 2 missions to the Moon
      • Lunar Explorer, a Swedish microsat (proposal)
      • A mission within the Chinese space program (under discussion)
   • A microsat on Venus Express (mission idea)
                                         Moon space plasma mission (1)

• A small space plasma mission to the Moon: Swedish Space Corporation
  feasibility study of 1996
• Payload: Particle instruments, magnetic and electric field measurements
  including waves
• Study conclusion: a small space plasma mission at the Moon is doable
  and can be conducted on the moderate (national) level.
• Estimated cast: ca. 23 M€ (229 MSEK) in 1996
                                             Moon space plasma mission (2)


Basic mission characteristics from the feasibility study
   • Launch: Kosmos-3M/Tsiklon
   • TTI (Translunar Trajectory Injection)
       • From an eccentric LEO
       • DV = 1300 - 2200 m/s (depending on
         launcher)
   • Lunar Orbit Insertion (LOI)
       • Direct insertion from TTI
       • DV = 1200-1600 m/s depending on the
         final orbit
   • Propulsion system for TTI/LOI (2 alternatives)
       • Solid (STAR 24A) /Mono-propellant
       • Bi-propellant/ Bi-propellant
                                            Moon space plasma mission (3)


Basic mission characteristics from the feasibility
  study
   • A spinning platform with spin axis pointing
      to the Sun
   • 166 kg total mass at the Moon inc. 36 kg
      of payload with booms
   • Equatorial orbit 400 x 5000 km to sample
      the lunar wake
   • Communications
        • Omnidirec. LGA S-band to 9-m G/S
          antenna (ESRANGE): 5-6 kbps
        • 40 cm HGA S-band to 9-m G/S
          antenna (ESRANGE): 133 kps
                         Mars Orbiting Plasma Surveyor (MOPS). Overview

•   Dedicated space plasma mission to Mars
•   Earth - pointing spin stabilized platform
•   Direct communication with the Earth
•   Wet mass: 76.1 kg
•   Dry mass: 60.0 kg (inc. 5% margin)
•   Payload mass: 10 kg

•   Piggy-back on a mission to Mars
•   Separation right after MOI
•   Hohmann transfer onto a working orbit (500 km
    x 10000 km, equatorial)
•   Life time: 1 Martian year (687 days)
•   Operations in the eclipse

•   Pre-phase A technical study completed by
    Swedish Space Corporation, Solna, Sweden.
    Example mother ship - Russian Phobos-Grunt
•   The project is technically feasible
                                        “Art house” ideas. Impact probes

   • A small (nano) satellite to conduct measurements until not- surviving
     impact
   • Greatly reduced platform masses
   • Only for airless bodies (Moon, Callisto, Ganymede, Pluto)
   • Feasible for fly-by missions or scientific objectives requiring
     measurements at the surface
                                             Pluto probe (proposal). 2.8 kg / ø22 x 7 cm
Chandrayaan-1 / MIP
              Feasible AND interesting new targets (beside the Earth)
• Mercury, Mars, comets, Saturn covered
• Venus: A dedicated space plasma mission on a spin-stabilized platform
• Jupiter. Jupiter Magentospheric Orbiter (JAXA)
   • Solar sail
   • Combined with a mission to Trojans
• Uranus orbiter: Identified in the recent the 2011 Planetary and Astronomy
  Decadal Survey
   • Mission to a new type of object “Icy Giants”
   • Not a dedicated space plasma mission but the Uranus’ magnetosphere is
     unique: magnetic moment rotates around solar wind direction

								
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