Current and Future
Solar Observing Missions
Tom Woods
LASP / University of Colorado
<tom.woods@lasp.colorado.edu>
Presented by Frank Eparvier
(with some edits)
Outline

Brief History of Solar Observations
– Ground-based observations prior to space era (1600-1950)
– Early solar observations from space (1950-1995)

Current Solar Observing Missions (1995-2008)
– Solar physics (imaging) missions
– Solar irradiance measurements

Future Solar Observing Missions (2009 and beyond)
– Solar physics (imaging) missions
– Solar irradiance measurements
Solar Observing Missions
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Brief History of Solar Observations
Ground-based Observations (1600-1950)
The sunspot record is the longest (~ 400 years) direct solar observation.
Modern
Maximum
Maunder
Minimum
3
19
Dalton
Minimum
22
21
2
23
20
1
[From D. Hathaway]
Galileo
Picard
Telescope invention, French continued
Sunspot measurements despite few spots
Herschel
Spots are cooler
and deeper,
IR discovery
Solar Observing Missions
REF: http://www.hao.ucar.edu/Public/education/spTimeline.html
Schwab
Solar cycle,
Wolf: cycle #1
is 1755-1766
Carrington
& Sporer:
Diff. solar
rotation &
Sporer Law
Hale
22-year
magnetic
cycle
4
Spörer's Law of Sunspot Migration
Spörer’s relationship of
sunspot latitude with solar
cycle activity
Modern view is known as
the “Butterfly” diagram
Solar Observing Missions
5
Early Detections of Solar Flares

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Routine scientific observations of the Sun began soon after the discovery of the
telescope in the early 1600s
Stephen Gary observed flash in sunspot on Dec. 27, 1705
Richard C. Carrington noted visible light flare on Sept. 1, 1859 while making
routine sunspot observation
–
–
–
–
–
Brightening started at points A & B
Brightening flowed along sunspot
Disappeared at points C & D
Lasted for a few minutes
Drawing from Carrington (M.N.R.A.S, 20, 13, 1860).
Solar Observing Missions
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Early Space Observations (1950-1995)

Orbiting Solar Observatory (OSO) series: 1962-1978
–
–
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–
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OSO-1: 1962
OSO-2: 1965
OSO-3 & -4: 1967
OSO-5 & 6: 1969
OSO-7: 1971
OSO-8: 1975
1950
OSO: solar / coronal imaging in X-ray, EUV, UV
1960
1970
Sounding Rockets
1947-now
1980
Skylab
Orbiting Solar Observatory
8 missions
1990
2000
Yohkoh
(Japan)
Solar Maximum Mission
Solar Observing Missions
7
Skylab - 8 Solar Instruments - 1973
Film Canister
corona, coronal holes, bright points,
chromospheric (active) network,
loops, spicules, polar plumes, prominences
REF: http://history.nasa.gov/SP-402/ A NewSolar
Sun: The
Observing
Solar Results
Missions
From Skylab
8
Solar Maximum Mission (SMM) - 1980

4 solar imaging instruments
corona, coronal holes, bright points, flares,
coronal mass ejections (CME),
chromospheric evaporation
Solar Observing Missions
9
Yohkoh (Japanese) Solar Observatory - 1991

4 solar imaging instruments
Solar X-ray Images
Solar Max to Min
corona, coronal holes, bright points,
arcades, flares, magnetic reconnection
Solar Observing Missions
10
Solar Physics Critical Questions - 1995

Coronal Heating Process
– What heats up the corona to 2 MK?


Nanoflares
Nature of Solar Flares
– What causes solar flares and coronal mass ejections?


Magnetic reconnection in the corona
Origin of the Sunspot Cycle
– What is the basic physical principles that drive the 11-year solar cycle
(22-year magnetic cycle)?


Dynamo (magnetic field dynamics) at base of convection zone
Missing Neutrinos
– Why is the number of neutrinos observed about a factor of 2 less than
predicted?

Discovery of muon neutrino oscillations, and thereby neutrino mass
REF: http://solarscience.msfc.nasa.gov/
Solar Observing Missions
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Previous Solar Irradiance Measurements

Total Solar Irradiance
–
–
–
–
ERB/ERBE
SMM ACRIM
UARS ACRIM
SOHO VIRGO

Solar Spectral Irradiance
–
–
–
–
Visible: GOME
MUV: Nimbus, SBUV, SME, UARS, GOME
FUV: OSO, AE-E, SME, UARS
XUV/EUV: SOLRAD, AE-E, GOES, SNOE
Solar Irradiance Questions
Solar Observing Missions

What is the solar cycle
variability in the
XUV/EUV, visible, and
infrared ranges?

What are the long-term
(decade-century) changes
in the TSI and SSI?

What are the spectral
variations during flares?
12
Composite Time Series Important for Climate Change


Issues in combining data sets
– Calibration differences
– Instrument degradation issues
– Gaps between measurements
Factor of 2 difference is found at times in the UV range
Example is composite Lyman- (121.6 nm) time series
REF: Woods et al., JGR, 2000
Solar Observing Missions
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Are Solar Minima All the Same?

Understanding long-term
solar forcing on climate
change depends on
understanding how the
solar cycle minima are
changing
– Some assume NONE
– Paleo-climate requires SOME

VIRGO composite shows
small change, if any,
between SC 22 min.

But ACRIM composite
shows large increase
Solar Observing Missions
SC-22
14
Current NASA Missions
NASA Heliophysical Great Observatory


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LASP has contributed instruments to 4 of these missions
Operating the AIM mission at LASP
Involved at some level with almost all of these missions
AIM
THEMIS
New Missions for the Heliophysical Great Observatory


LASP contributing instruments for 3 of these missions
Involved at some level with most of these missions
NASA Earth Science Missions
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
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LASP built 4 instruments for SORCE mission
Operating the SORCE, ICESat, and QuikSCAT missions at LASP
Involved at some level with many of these missions
Earth Science
Missions
Current Solar Observing Missions
(1995-2009)
Current Solar Physics Missions
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Solar and Heliospheric Observatory (SOHO)
Transition Region & Coronal Explorer (TRACE)
Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
Solar-B (Japan) - renamed Hinode
Solar-Terrestrial RElations Observatory (STEREO)
GOES Solar X-ray Imager (SXI)
CORONAS-F (Russia)
1990
SOHO
1995
2000
2005
TRACE
2010
Hinode (Solar-B)
RHESSI
Solar Observing Missions
2015
STEREO
2 S/C
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SOHO: Helioseismology, Corona, Solar Wind


In orbit about Sun-Earth Lagrangian point (L1)
9 solar instruments, 3 particle instruments
Helioseismology (surface oscillations used for “imaging” the interior of the Sun)
Back-side solar imaging
Corona Dynamics
Global Waves (after large flares)
Solar Wind and CMEs (particle outflow from the Sun)
Solar Observing Missions
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TRACE: High Spatial Resolution Imaging

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SMEX with single instrument: telescope with EUV and FUV filters
High spatial resolution: 0.5 arc-sec per pixel
High time cadence: 5 sec usually (< 1 sec sometimes)
Not full-disk imager: 8 x 8 arc-min region
Solar Observing Missions
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RHESSI: Hard X-ray Solar Imaging
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SMEX with single instrument: hard X-ray “telescope”
Study high-energy processes of flares
Solar Observing Missions
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Hinode (Solar-B): Dynamic Magnetic Fields

Japanese solar mission with 3 instruments
– Advanced instruments for vector magnetic fields, coronal X-ray full-disk
imaging, and coronal EUV long-slit (spectral) imaging
– Very high spatial resolution (0.2 arc-sec) for magnetic field imaging
Solar Observing Missions
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STEREO: Stereographic Imaging of CMEs

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4 instrument suites on two identical spacecraft
2 different locations provides first ever stereographic imaging of CMEs
Solar Observing Missions
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Current Solar Irradiance Measurements
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NOAA SBUV (200-400 nm) and XRS (2 X-ray bands: 0.05-0.8 nm)
SOHO SEM (2 EUV bands: 0.1-50 nm)
SOHO VIRGO (TSI)
TIMED SEE (0.1-194 nm)
SORCE (TSI, 0.1-27 nm and 115-2400 nm)
Solar Observing Missions
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SOHO Irradiance Measurements

SOHO SEM: 2 EUV bands
– Transmission grating with Si photodiodes, 15-sec cadence
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1st order: 26-34 nm and 0th order: 0.1-50 nm
SOHO VIRGO: TSI
– 2 instruments: PMO6V and DIARAD
Solar Observing Missions
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NOAA Irradiance Measurements

POES SBUV
– Ozone spectrometer
– Daily (calibration) solar
measurements from 200 nm
to 400 nm
– Mg II core-to-wing ratio important chromospheric
proxy

GOES XRS
– 2 soft x-ray photometers,
0.05-0.4 nm and 0.1-0.8 nm
– Reference for X-ray flare
classification


eXtreme, Medium class
small = C, B, A
– 3-sec cadence, but only 1min and 5-min data available
Solar Observing Missions
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TIMED SEE Measures Solar VUV Irradiance
EGS = EUV Grating Spectrograph
Rowland-circle grating spectrograph with
64x1024 CODACON (MCP-based) detector
XPS = XUV Photometer System
Set of 12 Si photodiodes - 8 for XUV, 1 for
Ly-, and 3 for window calibrations
XUV
EUV
FUV
EGS 27-194 nm with Dl=0.4 nm
XPS 0.1-34 nm with Dl=7-10 nm
and Ly- (121.6 nm) with Dl=2 nm
http://lasp.colorado.edu/see/
Solar Observing Missions
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Example TIMED SEE Time Series

New measurements of the solar EUV irradiance time series are
providing new results on the solar variations, especially
important for shortward of 115 nm where daily measurements
have not been made since 1981 (the EUV Hole).
Chromosphere
Corona
REF: Woods et al., JGR, 2005.
Solar Observing Missions
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SORCE Measures TSI and SSI
Solar Radiation and Climate
Experiment (SORCE)
Instrument
l Range (nm)
Dl(nm)
TIM: Total Irradiance Monitor
TSI (all)
-
SIM: Spectral Irradiance Monitor
200-2700
1-30
SOLSTICE: Solar Stellar Irradiance
Comparison Experiment
115-320
0.1
XPS: XUV Photometer System
0.1-27, 121.6
7-10
http://lasp.colorado.edu/sorce/
REF: SORCE, Solar Phys., 2005.
Solar Observing Missions
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TSI Record Relies on Continuity
Satellite measurements of TSI
have been made since 1978.
Current TSI measurements are
from SOHO VIRGO,
ACRIMSAT, and SORCE TIM.
Solar Observing Missions
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Is Modern Maximum Ending?

SOHO VIRGO and ACRIM results for this current solar cycle
minimum (2008) suggests a small drop from last minimum in
1996
– Both indicate 0.02% decreasing trend
– Note that solar cycle variaiblity is ~0.1%
VIRGO Composite
-0.02%
Solar Observing Missions
ACRIM Composite
-0.02%
33
Future Solar Observing Missions
(2009 and beyond)
Outstanding Questions in Solar Research

New Research Initiatives from “The Sun to the Earth - and Beyond” (2005)
1) What physical processes are responsible for coronal heating and solar wind
acceleration, and what controls the development and evolution of the solar
wind in the innermost heliosphere?
2) What determines the magnetic structure of the Sun and its evolution in time,
and what physical processes determine how and where magnetic flux
emerges from beneath the photosphere?
3) What is the physics of explosive energy release (e.g., flares, CMEs) in the
solar atmosphere, and how do the resulting heliospheric disturbances evolve
in space and time?
4) What is the physical nature of the outer heliosphere, and how does the
heliosphere interact with the galaxy?
5) How do the changes in solar irradiance relate to the evolving solar magnetic
field, and how do these irradiance changes affect the short-term space
weather operations and the long-term climate changes?
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Areas of Research
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Solar Interior
Quiet Sun
Active Sun
Solar Wind / Heliospheric Processes
Solar Irradiance
Solar Observing Missions
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Future Solar Physics Missions

NASA
– SDO: 2009 - HMI, AIA, EVE for helioseismology , EUV images, EUV
irradiance
– Glory TIM: 2010 - TSI
– Solar Probe: mission to the Sun !

NOAA
– GOES: SXI and SUVI are solar imagers
– GOES: XRS and EUVS are X-ray and EUV solar irradiance instruments
– NPOESS: TSIS for TSI and SSI

ESA
– Space Station solar irradiance instruments (SOVIM, SOLSPEC, SOLACES)

ESA SOLAR package installed in Feb. 2008
– French PICARD: 2009 - first solar diameter measurements from satellite
– Solar Orbiter

Other Missions
–
–
–
–
Russian CORONAS-PHOTON: 2007
French-Chinese SMESE: 2010
Chinese KuaFu: 2012
Japan, South Korea, India, Canada, Taiwan, Brasil, and potentially others are
also considering future solar missions
Solar Observing Missions
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NOAA Taking Over Solar Irradiance Monitoring
Solar Radiation and Climate
Experiment (SORCE)
2003 to 2010 or longer
Solar Irradiance: TSI,
0.1-27 nm, 115-2700 nm
Glory
Launch 2010
TIM: TSI
2005
2010
NOAA NPOESS
Launch 2012 or later
TSIS TIM: TSI
TSIS SIM: 200-2000 nm
2015
Solar Dynamics
Observatory (SDO)
Launch 2009
EVE: 0.1-121 nm
TIMED
2001 to 2010 or longer
Solar EUV Irradiance:
0.1-190 nm
2020
NOAA GOES-R,S
Launch 2014, 2016
EXIS XRS: 0.05-0.8 nm
EXIS EUVS: 17-130 nm, Mg II
SDO is Ultimate Flare Mission

SOHO, TIMED, and SORCE (and previous missions)
have observed hundreds of flares but the information is
incomplete:
– Observations of single, small region on Sun (SOHO)
– Observations of single wavelength at time (SOHO, SORCE)
– Observations with limited time coverage



Duty cycle low (TIMED - 3%, but simultaneous spectral coverage)
Time cadence slow (SORCE 5-min to 100-min)
NASA SDO mission addresses these issues with fulldisk solar images, complete EUV spectral coverage,
10-sec cadence, and 100% duty cycle


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HMI: vector magnetogram images
AIA: full-disk EUV images
EVE: EUV irradiance at 0.1 nm spectral resolution
– Launch planned for November 2009
– Web site: http://sdo.gsfc.nasa.gov/
Solar Observing Missions
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