Len Culhane,6 th - 10 th September, 2009 Space-based ObservationsSTFC Leeds Summer School Space –...

Len Culhane, 6th - 10th September, 2009 Space-based Observations STFC Leeds Summer School

Space – based ObservationsTechniques, Instruments and Missions

for the Sun-Earth System

Len Culhane

Mullard Space Science Laboratory

University College London


Introduction• Following a brief discussion of photons and their interaction with Earth’s

atmosphere, short wavelength optics and the role of CCDs are reviewed

• The difficulties posed by operating in the Space environment are outlined

• Several current space solar missions are described and results sumarised

• The Sun-Earth connection is discussed including- solar eruptions- nature of magnetic clouds- instruments for in-situ plasma observations- solar wind and CME influence on the Earth’s Magnetosphere

2


Wavelength (m) Frequency (Hz) Energy (J)

Radio > 1 x 10-1 <3 x 109 <2 x 10-24

Micro-wave

1 x 10-3 – 1 x 10-1 3 x 109 – 3 x 1011 2 x 10-24 – 2 x 10-22

Infrared 7 x 10-7 – 1 x 10-3 3 x 1011 – 4 x 1014 2 x 10-22 – 3 x 10-19

Optical 4 x 10-7 – 7 x 10-7 4 x 1014 – 7.5 x 1014 3 x 10-19 – 5 x 10-19

UV 1 x 10-8 – 4 x 10-7 7.5 x 1014 – 3 x 1016 5 x 10-19 – 2 x 10-17

X-ray 1 x 10-11 – 1 x 10-8 3 x 1016 – 3 x 1019 2 x 10-17 – 2 x 10-14

-ray < 1 x 10-11 > 3 x 1019 > 2 x 10-14

Electromagnetic Spectrum

Regions of the Spectrum

Quantum nature of radiation: E = h = hc/ Radio/Microwave (Frequency/Wavelength) → THz, GHz, MHz, cm, m

Infra-red/Sub-mm (Wavelength) → m, mm

Visible/UV/EUV (Wavelength) → Å, nm

X-ray, -ray (Photon Energy) → eV

3

Len Culhane, 6th - 10th September, 2009 Space-based Observations STFC Leeds Summer School 4

Radiation and Particle Interaction in the Earth’s Atmosphere Photon absorption by Earth’s atmosphere

• X-rays - E > 50keV, penetrate to ~30 km above Earth’s surface - can measure from balloons

• In practical terms need to go to space for these wavelengths

• Better observations even for the optical band (400-1000 nm) - avoid atmospheric turbulence


Telescope and Spectrometer Optical Design

• For angles of glancing incidence, ≤ c, rays are reflected

• Reflectivity of materials at soft X-ray/EUV wavelengths can be enhanced by the use of multilayer coatings

- these operate in a similar manner to Bragg crystal diffraction

• Normal incidence optical systems used at IR, visible and near-UV wavelengths

• EUV and X-ray photons are absorbed by trivial material thicknesses - for normal incidence, reflectivity R ~ 10- 4 at ~ 100 Å

- refractive index n ~ 0.995 for typical metals thus allowing Total External Reflection- for n = 1 – d, the critical angle for external reflection is given by Cos c = 1 – d ~ √2d

- at EUV and X-ray wavelengths, c is typically 1o to 3o → grazing incidence optics

5


6

Optical Configurations for X-ray Reflection

• ≤Cis a highly restrictive condition for optical designs - small value implies figuring and polishing large areas of substrate to achieve only small Aeff

• For imaging, the Abbe sine condition must be obeyed - needs at least two reflections to avoid severe coma for off-axis rays

• Wolter Type I design uses successive reflections from confocal paraboloids and hyperboloids

• Fields of view of ~ 1o with resolution ≥ 0.5 arc sec represent the present state of the art

• Wolter II configuration involves external reflection from the paraboloid and is used to feed spectrometers e.g. SOHO CDS, because of its lower beam divergence at the focus


• To increase the small effective aperture at grazing incidence Wolter Type I telescopes are nested

• Movie shows schematic operation of the Chandra X-ray Astronomy telescope

• Radiation is absorbed at normal incidence but reflected at grazing incidence for ≤ c

Grazing Incidence X-ray Optical System

7


Multilayer Coated Optics at Normal and Grazing Incidence• Multilayer coatings allow normal incidence reflectivities ≥ 30% for the range 10 nm < < 50 nm

• Multilayer operation is similar to that of a Bragg crystal spectrometer - crystal atoms, plane spacing d, diffract X-rays (at glancing incidence following Bragg’s law: n = 2d sin

• Alternate layers of high and low Z material, with well controlled thickness, are deposited on an optical substrate – mirror or grating, where d is the thickness of one layer pair

• Photons are reflected from thin high Z layers while low Z – low absorption, layers separate the high-Z layers by appropriate distances with much higher reflectivities possible than for a Bragg crystal

• For layer boundaries, RMS roughness of 0.6 nm limits wavelengths at normal incidence to ≥ 8 nm

• At normal incidence, the bandwidth of the reflectance curve is ~ /NLP where NLP is number of layer pairs

• Increasing NLP reduces and enhances Rpeak

- absorption in the layers sets an eventual limit

High Z

Low Z

d


EUV Multilayer Instruments for Solar PhysicsSOHO EIT, TRACE, SDO AIASOHO EIT, TRACE, SDO AIA

Simplified Schematicof the EIS Instrument

SunFilter

GratingPrimary

CCD Long

CCD Short

Slit

Simplified Schematic of the

EIS Instrument

Hinode/EIS…Hinode/EIS…

EUV Imaging Spectrometer

9

Len Culhane, 6th - 10th September, 2009 Space-based Observations STFC Leeds Summer School10

Photon Response in Semiconductors - Charge Coupled Devices• Photon absorption with E > EBandGap will lift an electron into the conduction band and create an electron-hole pair – intrinsic photoconduction

• CCDs are photon detecting pixel arrays that use intrinsic photoconduction in Si

• Response has been extended to E > 10 keV and they have revolutionised Astronomy

• CCD operation uses a Metal Oxide Semiconductor (MOS) structure which acts like a capacitor

• With +ve voltage on the p-type Si, majority carrier holes are repelled and a depletion region, depth d, is swept free of charge

• Incoming photons produce electron-hole pairs and the electrons are attracted to the insulator under the electrode

• For backside illumination, physical device depth is etched or thinned to be as close as possible to d = (2V)1/2

• For Si resistivity, ~ 10 – 20 cm gives d ~ 3 – 10 m - complex electrode structure defines pixels and enables charge transfer

+

Ground

Oxide Insulator

Electrode

Depletion Region

hP-type Si

e-

Ground

d


Charge Coupled Devices (CCDs) as Photon Detectors• Quantum efficiency: - percentage of photons actually detected is the Quantum Efficiency (QE) of the CCD

• Wavelength range: - CCDs have a wide wavelength response from ~ 1 Å (X-ray) to ~ 10,000 Å (Infra- red) with a peak sensitivity at around 7000 Å - use of back-thinning is necessary to extend the CCD wavelength response to shorter wavelengths e.g. EUV and X-ray or ≤ 500 Å - note that 1 Å = 10 nm and E (keV) = 12.38/ (Å)

• Dynamic range: - CCD dynamic range describes the minimum and maximum number of electrons that can be imaged - with more photons incident on the CCD, more electrons are collected in the MOS potential well - when no more electrons can be accommodated in the well, the pixel is saturated.

11


Environmental Challenges in Orbit• Vacuum of Space

- contaminants can move from one part of an instrument to another - will preferentially deposit on cold surfaces - can cause serious degradation of optical surfaces particularly at EUV wavelengths - high voltage discharge can occur if instrument is not fully evacuated

• Thermal Environment - spacecraft illuminated by Sun on one side (T~6000K) and Earth (T~300K) or space (T~4K) on the other - temperature must be controlled to ~ 10 ± 5 deg C to maintain e.g. optical alignments

• Ionizing radiation - electronic components susceptible to radiation damage

- radiation-hard devices must be used particularly in high dose orbits

- photon and particle detectors can suffer high backgrounds

12


Spacecraft - Solar Array Radiation Damage


Rocket Launching• Chemical rocket motors (liquid or solid fuel) generally employed - electrical (ion) propulsion being developed for interplanetary missions

• Primary cost driver for a launch is the payload e.g. spacecraft, mass

• Cost or vehicle performance envelopes will restrict spacecraft size

• Instruments will suffer severe vibration and acoustic energy inputs from the rocket motors - pre-flight vibration testing is mandatory

• Mechanical shocks will also be present - caused by e.g. first stage separation, rocket motor restarts

14


Telemetry – Spacecraft Data Transmission to Earth• Downlink data rate can be a crucial constraint for solar space observations, - limits the cadence of imaging instruments - reduces the quantity of spectral information

• Initial SOHO/EIT telemetry allocation was 1 kilobits/s (1 kbps) - allowed only 6 full-disk images/day but can now operate with ~ 12 minute cadence - SOHO has a standard science telemetry rate of 40 kbs

• TRACE employs several different multilayer passbands - has an on-board mass memory of 700 Gbits capacity

- manage memory use to achieve partial Sun image cadence of ~30 seconds

• SDO has eight multilayer image channels - uses a dedicated ground station at White Sands and transmits at 150 Mbits/s - acquires and transmits eight full-sun images every 10 seconds

15


Choice of Orbit• Low Earth Orbit (LEO) - 200-1200km above Earth with orbital period of 90-100 m

- orbit between atmosphere and Van-Allen radiation belts - minimizes the damaging effect of high energy particles

• Sun Synchronous Orbit (SSO) - special LEO case at ~ 800km with Sun always in view e.g. TRACE, Hinode

• High Earth Orbit (HEO) - above the radiation belts e.g. XMM-Newton, with apogee > 30,000km - more energy and cost to launch

• Geosynchronous Orbit (SSO) - same orbital period as the sidereal period of the Earth at an altitude of 42,164 km - full time contact e.g. IUE

16

Len Culhane, 6th - 10th September, 2009 Space-based Observations STFC Leeds Summer School17

Sun-Earth Lagrange Points• Quasi-stable orbits can be maintained around the Lagrange points with minimum energy use

• L2, on the anti-sun side of earth and at a distance of 1.5 x 106 km, allows a spacecraft to run cold (T ~ 50 K) and to have a relatively unconstrained view of the Universe

• L1, L4 and L5 are suitable for sun-viewing spacecraft while L2 is useful for Astronomy L3 is difficult due to communication problems


Space Missions

for

Solar Observations

18


Solar Remote Sensing• The Sun in X-rays and white light - X-ray emission from the corona is associated with photospheric activity

• Access to space is essential for remote sensing observations - atmosphere absorbs X-ray and EUV emission - seeing limits visible spatial resolution to ≥ 1 arc sec for long duration observations

19

• Space is also essential for long term observations of coronal variability • Movie shows SOHO/EIT 195Å images of the corona for the interval 10 – 23 December, 1999 - coronal structures vary on timescales of minutes through hours to months


Sun-Earth Observations

20

• Solar phenomena influencing the near-Earth environment - Solar Flares - Coronal Mass Ejections (CMEs) - Solar Wind

• In a flare an unstable magnetic field relaxes to a lower energy state with released energy - accelerating particles - heating plasma - often causing a filament eruption and a CME

• Accelerated high energy particles from the flare can reach the Earth

• CMEs are large outbursts of material detected by coronagraphs with ~ 1015 g lost from the Sun

• In-situ instruments sample the particles and ejected plasma near the Earth


Solar Wind Results from Ulysses

21

Near Minimum →Average wind speed at: - high latitude ~ 700 km/s (Polar Coronal Holes)- equator ~ 350 km/s (Equatorial Streamers)Abrupt transition from low to high speed

Spacecraft orbit, established by gravity assist fromJupiter, allowed the first sampling of the Heliosphereout of the ecliptic plane

Solar Minimum pass – 1992/97

Comparison with Solar maximumpass – 1998/2003

← Through MaximumHighly variable flows are observed at all heliolatitudes. Flows arise from a mixture of sources including extended polar holes, streamers, CMEs, small low latitude coronal holes


22

Advanced Composition Explorer (ACE)NASA mission to study Solar Wind and CMEs

• This spacecraft is located at the Lagrange L1 point between Earth and Sun

• Includes a set of nine instruments to sample the arriving Solar Wind and CME plasma close to Earth. It measures in-situ: - element composition and ion state - plasma velocity - particle energies - magnetic field • Launched in August, 1997, the spacecraft is still operating and has fuel to continue at L1 until ~ 2024


23

SOHO – cooperative project between ESA and NASA

• Spacecraft is also located at the Lagrange L1 point between Earth and Sun- 1.5 x 106 km from Earth

• Includes set of 12 instruments to study: - Solar Interior - Solar Atmosphere - Extended Corona and particles ( in-situ)

• Launched in December, 1995, the spacecraft is still operating


SOHO EUV Imaging Telescope – Use of Multilayer Passbands• EIT has 4 different Mo/Si coatings with layer thicknesses tuned for 175 Å, 195 Å, 284 Å, 304 Å to observe lines of Fe IX/X, Fe XII, Fe XV and He II

• Rotatable quadrant shutter can select each of the four mirror sectors in turn

• CHIANTI theoretical spectrum shown with a) 175 Å passband and b) resulting line intensities

24

a)

b)


25

TRACE Solar Telescope – Example of Multilayer Application• Schematic of the TRACE EUV telescope is shown below – a 0.3 m Cassegrain system

• Primary and secondary mirrors are sectored in four quadrants, three with Mo2C/Si layers• Quadrant shutter allows one sector at a time to view the Corona and register images on the CCD in the appropriate passband• Reflectivity curves are shown for two of the three quadrants – peaks at 173 Å and 195 Å• Mo2C/Si layers have enhanced performance compared to Mo/Si


Fe IX 171 1 MK

TRACE: AR Loops on 06 NOV 1999

Fe IX 171 1 MK

H I Ly-10,000 K

TRACECooling Loops

EUV Corona - TRACE Images

Fe IX 171 1 MK

TRACE: AR Loops on 19 APR 2001

25

• The four TRACE passbands obtain images of the photosphere, chromosphere and corona for 5000 K ≤ Te ≤ 4 MK

- image cadence:30s - pixel size: 0.5 arcsec - FoV: 8.5 arcmin x 8.5arcmin


Japanese Hinode Spacecraft in Cooperation with US and UK

SOT

FPP

EIS

XRT

• Instrument responsibilities: - SOT/FPP: NAOJ, ISAS/Lockheed, HAO - EIS: MSSL, Birmingham, RAL with US NRL - XRT: Harvard CfA, NAOJ, ISAS

• Spacecraft is in 800 km Sun-synchronous orbit

26

• Includes set of three instruments: - 0.5m Solar Optical Telescope (SOT) for 150 km images and vector magnetograms - EUV Imaging Spectrometer (EIS) for plasma velocity, temperature and density - X-ray Telescope (XRT) to image X-ray emitting coronal structures

• Hinode was launched in September, 2006 - making major advances in high resolution structure and magnetic field studies


Solar Optical Telescope (SOT) on Hinode(size of Earth)50000km

Emerging MagneticFlux

Convection

27


28

• Dark channels rise vertically at ~ 10km/s to ~ 15 Mm above the limb

• Associated bright channels show related downflows

• Suggests hot rising thermal plumes and density enhanced turbulent downflows

•Current models have low- prominence plasma constrained to follow B field

•Observation suggests turbulent B field motion or the presence of convection in high- plasma

Hinode SOT Observation of Prominence Dynamics• Ca II H-line observations of a hedgerow prominence on the W-limb, 30-NOV-06 (Berger, 2007)


Polar Coronal Activity – XRT and EIS Jet Observations• Hinode XRT sees constant activity in polar Coronal Holes - coronal jets• First observed with Yohkoh SXT by Shibata et al. (1995)

• Flux emerging in open magnetic field structure can produce jets

• Blueshift of 30 km/s above the bright point in the polar coronal hole is interpreted as a jet caused by reconnection (Kamio et al. 2007)

29


CoronalDynamics Hinode/EIS SpectralImaging Observations

• EIS scanned a 40 arcsec wide strip with a height of 7 arcmin

• Slot images, 40 arc sec wide, are displayed for lines of He II and Fe XV

• Resolved spectrum taken with a 1 arcsec slit from a pixel near the bottom of the slit is shown

• “First Light” spectrum in early November, 2006

XRT 　 FeXV 284

Hinode XRT Image

EIS spectrum (1arcsec slit width)

HeII 256

Wavelength (nm)

30


5 – 10 Minute Break

31


STEREO Mission• Solar-Terrestrial Relations Observatory

• Two identical spacecraft leading and following the Earth

• Launch - October, 2006

• Four instrument packages– SECCHI– PLASTIC– SWAVES– IMPACT

• Goal:– Understand the origin and consequences of CMEs

32


34

Deployed SWAVES Radio Burst Antennae

U. Paris Meudon

DeployedIMPACT Boom

IMPACTSolar Wind Electron Analyzer (SWEA)

IMPACTSuprathermal Electron Detector

(STE)

IMPACTMagnetometer

(MAG)

SECCHI - UK RALHeliospheric Imager(HI: 12 – 300 R)

SECCHI - US NRL Sun-Centered Imaging

Package (COR-1, COR-2, EUVI)

EUV Corona and 1.4 – 15 R White Light

PLASTIC InstrumentU. New HampshireHigh Charge Ions

IMPACT Solar Energetic Particles (SEP)

U. Cal Berkeley

STEREO-B (Behind) Spacecraft and Instruments• Stereo-A (Ahead) has identical instrument suite

• A and B spacecraft are now 150 deg apart


SECCHI – EUVI• EUV multilayer solar telescope - Images at Fe IX 171Å, Fe XII 195Å, Fe XIV 211Å, He II 304Å• Larger detector than EIT (2048x2048 pixels) leads to

- Higher spatial resolution (1.6 arcsec vs. 2.5 arcsec) - Larger field-of-view (1.7 Rʘ vs. 1.4 Rʘ)

• Higher data rate ensures higher image cadence (2.5 min vs 30 min)

SECCHI – COR1 & COR2 • Two coronagraphs do a similar job to the three coronagraphs on LASCO• COR1 - 1.1 - 3.0 Rʘ and 7.5 arcsec pixels

- Measures polarization• COR2

- 2 - 15 Rʘ and 14 arcsec pixels

- Higher spatial resolution and time cadence than LASCO C3

34


STEREO Mission OrbitsTwo identical spacecraft “lead” and “lag” Earth

35

Sun SunEarth

Ahead @ +22/year

Behind @ -22/year

Heliocentric Inertial Coordinates(Ecliptic Plane Projection)

Geocentric Solar Ecliptic CoordinatesFixed Earth-Sun Line

(Ecliptic Plane Projection)

Ahead

Behind

Earth

1 yr.

2 yr.

3 yr.4 yr.

1yr.

2yr.

3 yr.4 yr.


STEREO Post-launch Positioning – Day 1 to Day 110

37


38

STEREO Orbit Evolution: Day 60 to Day 790


STEREO Spacecraft Positions

- to see the positions at any time go to: http://stereo-ssc.nascom.nasa.gov/where/• On 5th August 2010, positions were with 150 degree separation

38

710 790


NASA Solar Dynamics Observatory (SDO)

• SDO is the first mission to provide full-sun imaging both above and below the Sun’s surface

• Includes set of three instruments: - High Resolution Imager (HRI) for precision velocity measurements and vector magnetograms - Atmospheric Imaging Array (AIA) uses 4 telescopes for high-speed EUV images of the Corona - Extreme Ultraviolet Variablity Experiment (EVE) gives well calibrated EUV irradiance measurements

• SDO, launched in February, 2010, is designed to operate for 10 years - All instruments are fully operational

- Generates ~ 2 Tbyte/day of data from its main instruments! 40


Fe IX 171 1 MK

SDO: AR andFilament

41

SDO: Pre-flare AR Structures

SDO: AR Loops (AIA) B-field (HMI)Blue: -veOrange: +ve

Fe IX 171 1 MK

Recent Images from the SDO AIA Instrument• Four dual-channel telescopes of similar design to TRACE obtain images of photosphere, chromosphere and corona for 5000 K ≤ Te ≤ 20 MK

- 8 images/10s; pixel size: 0.6 arcsec; FoV: 41arcmin x 41arcmin (full Sun)

• Fe XX, Fe XXIII and Fe XXIV bands available for the high Te flare plasma


Solar Orbiter – Mission to the Inner Heliosphere

• ESA/NASA mission - launch ~2017

• Approach to 0.29 AU of the Sun- up to 35o above ecliptic plane

• Carries remote sensing and in-situ instruments

• Remote sensing:- Visible Imager and Magnetograph- EUV Imager- EUV Spectrometer- Coronagraph- Heliospheric Imager- X-ray Imager

• In-situ: - Energetic Particle Detector - Magnetometer - Radio and Plasma Wave detector - Solar Wind Analyser

41


43

• In-situ instruments include - Fast Ion and electron analyzers - Ion Composition Analyzer - Energetic Particle Instrument - Magnetometer - Plasma Wave Instrument - Neutron/Gamma-ray Spectrometer - Coronal Dust Detector

Solar Probe Plus – NASA Solar Encounter Mission • Launch 2015 or 2017 - remains in ecliptic plane - approach to within 0.05 AU of Sun

• No forward viewing solar instruments - emphasizes in-situ observations - sample plasmas and dust in outer corona

• Also carries side-viewing Heliospheric Imager

• Observations complimentary to those of Solar Orbiter


Japan’s SOLAR-C - two mission concepts under study• Plan A - out-of-ecliptic magnetic field, X-ray, optical and helioseismic observations - emphasise studies at high solar latitude - investigate meridional flow and magnetic structure inside Sun to convection zone base

• Plan B - high spatial resolution, throughput and cadence spectroscopic/polarimetric observations at optical, EUV and X-ray wavelengths - emphasise photosphere to corona connection - investigate solar magnetism and its role in the heating and dynamics of solar atmosphere • Launch Date: Japanese fiscal year 2016 (provisional)

- anticipate productive joint observations with complimentary solar missions - NASA SDO (whole sun field of view) - ESA/NASA Solar Orbiter - NASA Solar Probe Plus


45

Sun-Earth Connection


46

Radiationbelt

Ionosphere Atmosphere

Flares, Coronal Mass Ejections,Energetic Particles Coronal Mass Ejection, Solar Wind Shock

Sun – Earth ConnectionSun Interplanetary Medium Near-Earth Environment


47

Filament Eruption and Flare – 19-May-2007

Hmovie from Kanzelhöhe Observatory

TRACE 171 Å movie – flare ribbons and eruption

STEREO – A and – B reconstruction of erupting materialin He II 304 Å and Fe VIII 171 Å emission


Halo CME on 28-OCT-2003• Halo CMEs are likely to be Earth-directed - disturbances near Earth when ejected magnetic field is opposite to Earth’s field


B - Azimuthal

B - Axial

CME-related Magnetic Clouds Near-Earth• At the Sun CMEs always involve twisted magnetic field structures or “fluxropes”

• CMEs are observed in situ as transients in IP space with changes to physical parameters- stronger magnetic field (low value) with smooth rotation indicating a twisted flux rope structure- higher density and lower temperature than the surrounding solar wind with boundary discontinuities

• Spacecraft intercepting a cloud near Earth can measure its magnetic and plasma properties - components of B give cloud magnetic Flux - cloud model and B values yield magnetic Helicity

• Magnetic Flux is associated with a solar region or area e.g. Active Region, Filament channel - Φ = ∫ ∫ B. dS weber (maxwells)

• Magnetic Helicity H = ∫V A.B dV where A is the vector potential with B = xA

• Magnetic Helicity a globally conserved quantity - Convection zone → Corona → IPM

• In-situ measurements with magnetometers and ion analysers


ACE In-situ Observation of a Magnetic Cloud – 15th May, 1997

Sheath

Magnetic Cloud

Shock Solar Wind proton velocity step shows shock arrival

Magnetic field shows strength increase after shock

Magnetic field direction angle shows uniform rotation inside cloud

Density decreases through sheath to low value in cloud

Electron pitch angle distribution suggests bi-directional flow


Top Hat Electrostatic Analyzer - Solar Wind & CME Ion Detection

• Incoming ions selected by electrostatic deflection according to ion energy to charge ratio - uniform narrow 360o disc shaped field of view - ions registered with microchannel plate multiplier and position-sensitive anode - used in this form on spinning spacecraft e.g. Cluster

• Ions enter below the top hat into the space between two concentric hemispheres - fast sweep voltage difference between spheres selects ion energy - sweep range covers 5 eV/charge to 32 keV/charge in 62.5 ms - exit position on readout measures incident polar angle (A → a; B → b and C → c)

• Sector resolution ~ 6o allows flow velocity of incoming Solar Wind and CME ions to be measured

Top HatIons Ions

HemispheresPosition Readout

± 4o


Cluster Hot Ion Analyser (Rème et al., 1997)

• Detail of Cluster ion analyser - ions deflected through 90o in passage between hemispheres - grids provide 2300 V for post-acceleration to enhance ion detection - geometric factor and sensitivity vary with polar angle

• Cluster analyser readout section with 32 sectors - low sensitivity section has 16 sectors to measure solar wind direction - high sensitivity section measures ambient ions in the magnetosphere


53

Solar Wind and the Earth’s Magnetosphere


54

Solar Wind and CME Interactions with the Earth

MOVIE


Conclusions• In this talk we first dealt with:

- absorption of radiation by the earth’s atmosphere and the need to observe from Space- reflection, imaging and detection of short wavelength radiation

- operating in the space environment and the choice of spacecraft orbit

• Features of the Sun-Earth system and several significant space missions for solar and for in-situ observations were briefly described

• CMEs, magnetic clouds, in-situ plasma instruments and the response of the Earth’s magnetosphere to solar disturbances were discussed

• Increasing emphasis on: - Sun-Earth connection - Space Weather as an applied discipline

indicates the growing importance of space observations in these fields

55

Date post:	15-Dec-2015
Category:	Documents
Upload:	kayleigh-mapp
View:	215 times
Download:	1 times

Len Culhane,6 th - 10 th September, 2009 Space-based ObservationsSTFC Leeds Summer School Space –...

Documents