International SOLAR-C
science definition meeting
November 18-21 2008 JAXA/ISAS-JSPECJAXA SOLAR-C Working Group
Saku Tsuneta (WG chair)

Tansei(Path finder mission)

Solar physics fromspaceinJapan
With NASA, UK
With NASA, UK

Hinotori (ASTRO-A)
188 kg, 1981

Yohkoh (SOLAR-A)
390 kg, 1991

Hinode (SOLAR-B)
Non-thermal acceleration
・Hard-Xray imaging with Non-thermal acceleration ~ 900kg, 2006
and plasma heating
Magnetic fields with corona
rotation modulation
・HXR Fourier telescope (J) ・SOT (Japan, US)collimator 10 arcsec
7 arcsec
0.2 arcsec
・Bragg crystal spectrometer
・Soft X-ray telescope (J/US) ・XRT (US, Japan)
・SXS, HXS
5arcsec2arcsec・Bragg spectrometer
・EIS (UK, US, Japan)(J, US, UK)
2arcsec
・WBS
2

Hinode (SOLAR-B) mission objective: systems approach tounderstand generation, transport and ultimate dissipation of solar
magnetic fields with 3 well-coordinated advanced telescopes.
Solar Optical Telescope（SOT） EUV Imaging
0.2 arcsec vector-magnetic
and photometric images

Spectrometer（EIS）
LOS velocity and turbulence maps
at log T = 4.7, 5.4, 6.0 - 7.3 K,
Sensitivity ~1% of Alfven velocity

X-ray Telescope（XRT）
Sensitive to 1-10MK
1arcsec resolution withhigh cadence

Launched on Sep 23, 2006 by JAXA
Japan-US-UK-ESA project
Mission Lifetime: > 3 years
Orbit: Polar, Sun Synchronous3

Results from Hinode should be thebasis for SOLAR-C
Hinode discoveries
Waves in prominence
Chromospherictransition region
jets due toreconnection

Slow solar wind

Polar kG fields
Supersonic downflow
Convective collapse

Waves alongspicules
Penumbral
micro-jets
Magnetic velocity
Fluctuation
Local dynamoprocessUbiquitous
Horizontal fields

High coronalturbulence

44

Rutten, R., ASP-CS, 184, 181, 1999

Solar-B chronology• 1994-1995 Ad-hoc working group at NAOJ
• 1995
Mission proposal (MUSES-C)• 1996
Mission proposal2 (IR-mission)• 1997
Mission proposal3 (finally won)==parallel activity in US and UK==
• 1998New start with basic research ¥• 1999-2001 Proto-model design/fab./test• 2001-2004 Flight-model design/fab./test• 2005-2006 Final test/launch• 2006
PV Observations start5

SOLAR-B science mission design（1995-１９９7）
What are the lessons learned from SOLAR-B?
• SOT：Modest 50cm diffraction-limited telescope,considering science requirement, technical and cost
reality.
• Stokes polarimeter is a must instrument (can not fly
only with filter instrument)• Needs velocity maps with EUV imaging spectrometer• Simultaneous observations with high co-alignment
accuracy• XRT: Choice of grazing incidence optics to havetemperature sensitivity in 1-20 MK, while maintaining
high spatial resolution• Once the concept was established, there has been nocompromise during the development.
6SOLAR-B Heritage
50cm diffraction-limited telescopewith image-stabilization system

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Strong international collaborationfor SOLAR-B over 8 years
3 space agencies, 11 organizations in 4 countries
UK
MSSL(EIS)RAL(EIS)ESA

NorwayUniv. Oslo(EIS)LMSAL (FPP)HAO(FPP)SAO(XRT)

JAXAJapan

USNASA

NRL (EIS)

NAOJ
NASA GSFC(EIS)(OTA, FPP, XRT, EIS)
NASA MSFC(FPP, XRT, EIS)JAXA(Rocket, Spacecraft,OTA, FPP, XRT, EIS)

8

What is next?
Yohkoh (1991- 2001)
With NASA/PPARC

Open issues in solar physics
Global and local dynamo
Chromospheric and coronal activity andHinotori(1981-1982)
heatingHinode (2006-) with NASA/STFC/ESASOLAR-CJ-FY2016(provisional)

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Two SOLAR-C mission concepts
under study• Plan A: Out-of-ecliptic magnetic/X-ray and helioseismic
observations of the polar and the equatorial regions toinvestigate properties of the polar region, meridional flow
and magnetic structure inside the Sun to the base of theconvection zone.
• Plan B：High spatial resolution, high throughput, highcadence spectroscopic (polarimetric) and X-ray
observations seamlessly from photosphere to corona toinvestigate magnetism of the Sun and its role in heatingand dynamism of solar atmosphere.
• Launch Date: Japanese fiscal year 2016 (provisional)– Expects joint observations with highly complementary missions– NASA SDO (whole sun field of view)– ESA&NASA Solar Orbiter (Insitu and stereo obs with SOLAR-C)– NASA Solar probe (In-situ)
10What is going on in polar region ?
Source of fast solar wind
Location of global poloidal fields
sink of meridional flow
High speed solar wind
Polar fields
Ulysses

Kitt Peak(McComasetal 2000)(Wang et al)Hinode XRTHigh coronal
Activity in polarregion
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Cirtain etal 2007Plan-A: Exploration of polar region,internal structure and solar dynamo
The Sun as a star
• Scientific objective– Measure meridional flow at high latitudes, and see where it turns
downwards– Detect magneto-sound speed anomaly located in the tachocline
region (flux tube/sheet imaging in tachocline)– Detect toroidal flows driven by Coriolis force– Observe the vector magnetic fields of photosphere andchromosphere and coronal imaging in X-ray/EUV– Obtain acoustic speed and angular rotation speed distribution in
the polar region– Understand acceleration mechanism of fast solar wind
– Monitor total irradiance (optional)– Study influence of the Sun to heliosphere• Model payload– Photospheric and chromospheric dopplergram– Stokes-polarimeter for photosphere and chromosphere– X-ray/EUV imager– Optional: total irradiance monitor
12Polar landscape kG field
Tsuneta et al., 2008, ApJ, 688, 1374.

707５
８0
８５13

Plan A: what is required inclination angle?
An exercise
A high-inclination orbit and dual observations•Observe Doppler velocity at high latitudes without undesired projection•Observe waves penetrating deep into the sun with dual stations.
By choosing launch timing,use precious 7 degree tiltof solar axis

Skip angle versus travel-time perturbation
due to flux sheet at tachocline

SOLAR-C

100kG corresponds to25msec travel timedifference.

Courtesy T. Sekii
0deg

50deg

100deg150degRequired inclination : 40～50 minus 7 degree= 33～43 degree: Optimum angle to reach14
bottom of CZ

Key parameters such as payload mass, telemetry,
inclination, flight time have to be clarified beforeha
Case 1:

Ion engine + Earth swing-by

Case 2:Ion engine + Earth swing-by + Venus swing-by

Case 3:Chemical engine + Jupiter swing-by

Case 4:

Chemical engine + Jupiter swing-by + Earth swing-by<Trade-off items>
flight time until starting observation, achievable inclination,observational timing, payload mass, thermal design,tele-communication link, etc.
ex.) One possible solution of Case 1 assumes,Observe both polar and equatorial- JAXA H2A launch
Regions maintaining ～1AU distance- Initial mass = 1200kg.
- Payload mass = 100kg.
Achieves Inclination (to the Solar equator) of30 deg. in 2 years from the launch,
45 deg. in 5 years from the launch.

Chromosphere more dynamic
than expected!

162006 Dec 17 20:00-21:00 UT CaII H broad band filter images taken with Hinode/SOT

SOLAR-C Plan B
From imaging to spectroscopy
From visible to UV-visible-IR

SOT

温度

Hinode imaging
observations reveal
unexpected highly
dynamic chromosphere・Chromosphere needs
x10 heating energy.
(K)・Not static atmosphere・Coronal heating may beclosely related to theinterface region between
the magnetic
photosphere and thedissipative corona.

XRTEISG bandCaII HSpectroscopic observations with SOLAR-Ｃ

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Hinode and SOLAR-C Plan-B•

Hinode/SOLAR-C– Demonstrates power of spectro-polarimetry from space• Significantly enhance spectro-polarimetric capabilities to UV and near-IR– Dynamism of chromosphere is a major Hinode discovery. Chromospheric
dynamics may generate disturbance to corona: new implication to coronalheating (Isobe et al 2008)• High time resolution, high throughput spectrometer– Little diagnostic capability for chromosphere and transition regions• Seamless observations from photosphere to corona•

Scientific Objective– Obtain precise chromospheric and, if possible, coronal vector magnetic
field maps in addition to photospheric magnetic maps with high spatial andtemporal resolution– Obtain coronal 3-D magnetic field map from chromospheric vector field,
predict location and evolution of neutral-sheets, dicontinuities for transientand stationary coronal heating and eruption– Reveal causal relationship of photosphere-chromosphere-transition regioncorona to understand coronal/chromospheric heating and dynamism– Understand the nature of hidden magnetism: Is the observed B tip of theiceberg?
– Deepen Hinode discoveries with quantitative analysis: waves, turbulence,magnetic reconnection
18– Study influence of the Sun to heliospherePlan B model payload•

General– From imaging to spectroscopy• Concentrate best possible lines to represent each layer of atmosphere– High resolution, high S/N, and high time resolution• High throughput multi-object-spectrograph or equivalent needed– From visible to visible+UV+near IR• Seamless coverage of photosphere, chromosphere, TR and corona•

Model payload– Near IR-Visible-UV telescope （TBD-1.1 micron）• ＞50cm diffraction-limited telescope （0.1-0.4arcsec）– Ultra-high resolution EUV/X-ray telescope– High resolution high throughput coronal spectroscopic capability•

Key point1 : Chromospheric, and if possible coronal spectropolarimetry for vector magnetic field observations– Needs He10830 or equivalent with Zeeman+Hanle sensitivity– Evaluate potentiality of UV and EUV lines for Hanle-effect diagnostics ofchromosphere and corona– Closer to force-free layer: provide better BC for coronal field extrapolation:
concern on the adequacy on photospheric BC•

Key point 2: High spatial and temporal resolution chromosphericand transition region spectroscopy for dynamics
19More on Plan B mission• Sun-synchronous orbit• Geo-synchronous orbit– For quasi-continuous access to the spacecraft– Use plan-B spacecraft as ground-based
observatory• Real-time (more dynamic) response to solarsituation

20

SOLAR－C development schedule(provisional)• FY2016• FY2015• FY2011～14• FY2010• FY2009• FY2008• FY2007

LaunchS/C tests
Flight and proto model
Phase-A
Basic development
Concept study
JAXA SOLAR-C WG(FY: Japan fiscal year starting April 1.)21

Prior activities and interactions
among space agencies••

October 16 2007 meeting at NASA HQ
December 15 2007 briefing to NAOJ director in the NAOJ roadmapmeeting••

December 18 NASA-JAXA bilateral-meeting at ISAS
December 27 2007
– ISAS space science steering committee– JAXA SOLAR-C WG approved•

January 30 – February 1 20081– SOLAR-C－Solar orbiter information exchange meeting (MPE)••••

April 1 2008 NAOJ SOLAR-C preparation office open
Presentations on SOLAR-C in various international meetings
August 2008 JAXA president – ESA science director in UK
November 18-21 2008 JAXA/ISAS-JSPEC
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SOLAR-C and other ongoing missions
2010

2020

Solar maximum

CY

Solar maximum

HINODE
Plan B 2016 Aug.

SOLAR-C

Plan A 2016 Aug. Orbit trans

ATST（NSF)
SDO（NASA)

2014
2008 Dec 08.

Solar Orbiter（ESA&NASA)2015 May▲▲
2018 summer 2021 summer
reach obs-deck Helio-lat. 15 degree

Note１：Plan A orbit trans. period not accurate, being studied.
Note２：NASA decadal plan beyond SDO not available.
Note３：ESA SOLAR ORBITER reach 0.22AU on summer of 2018.

▲2022-23
Helio-lat. 35degree23Justification for mid-2010s launch• Plan A satellite has to reach an observing point around2020 to be ready for the solar maximum and polar fieldreversal.
• Joint observations with highly complementary missions– NASA SDO (whole sun field of view)– ESA Solar Orbiter– NASA Solar Probe• Continuity in solar physics research in Japan requires
mission approximately every 10 years– Hinode launched in 2006.
– Hinode provides new data on the solar maximum Sun around2010.

• Avoid vacuum in solar physics.
24

SOLAR-C mission• Solar physics community in Japan has so far
developed 3 solar missions over past 25 years.
• We recognize that success of Hinode andYohkoh is due to strong international support.
• Solar physics community and related-disciplines
in Japan strongly desire and endorse one of theSOLAR-C mission concept to be realized in mid2010s.
• The JAXA SOLAR-C working group invites USand European participation to the SOLAR-C
program, following our remarkable history ofcollaboration.
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Purpose of the Meeting• Develop science cases for plans A and B• Identify discovery space for both plans• Understand Plan-A constraints, and build theplan A mission• Propose model science instruments• Solar physics community should reach common
understanding on issues related to our future• Form international sub working groups for
specific critical issues if necessary• Discuss synergy with approved programs
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Notes• S-C scientific design should be based on Hinode results.
• Presentations and discussions should be done purely
from scientific point of view. Express your preference on
the plan A or B freely.
• Decision-making process and future plan will be
discussed at the end of the meeting i.e. after everyone
has common base on issues.
• SC-WG will prioritize the two plans as a result of themeeting. SC-WG will discuss programmatic aspects withESA and NASA.
• ESA officially supports this meeting.
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