SOLAR‐C meeting summary
Saku Tsuneta(JAXA SOLAR‐C WG chair)2008 November 21

Two SOLAR‐C mission concepts understudy• 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, high cadence
spectroscopic (polarimetric) and X‐ray observations
seamlessly from photosphere to corona to investigate
magnetism of the Sun and its role in heating and dynamism ofsolar 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)
22

Purpose of the Meeting
Extremely successful meeting!
• Develop science cases for plans A and B in progress• Identify discovery space for both plans in progress• Understand Plan‐A constraints, and build the plan A
mission in progress• Propose model science instruments in progress• Solar physics community should reach common
understanding on issues related to our future very welldone• Form international sub working groups for specificcritical issues if necessary open
• Discuss synergy with other programs open
33

Current understanding•••••

We are in the golden age for solar physics due to Hinode and othermissions.
The meeting was very successful, and will provide basis for SOLAR‐C.
We are in the era to build one and only one mission by combining all theresources in the world (see particle physics LHC, ILC).
It is good to have two completely different plans rather than to rely on
single plan at this point. This situation should not be taken negatively.
Both plans have sufficient science motivation to be developed further,and the choice is a matter of priority.
– Serial approach (plan 1 followed by plan 2 in time)– Parallel approach (plan 1 pursued by agency 1, plan 2 by agencies 2+3)
– Who can do plan A best? Who can do plan B best?

Plan ANo one has every done this.
Address fundamental physics associated with the sun as a star
Need to develop helio‐seismic approach to dynamo problem
Fully convective late‐type stars have active dynamo
Required development effort including cost and risk associatedwith interplanetary flight not yet fully visible• However, expect strong support from JAXA/JSPEC re systemdevelopment

•
••
•
•

– New idea appears from Prof. Kawaguchi• Smaller community involved in plan A especially in Japan• Japan can have one solar mission. It is not clear whether we cantolerate the duration of several years before the start of theobservations.
• Relationship with ESA&NASA solar orbiter is an issue

Plan B
• Address important scientific issues for chromosphericand coronal heating and dynamics• Everyone now discusses magnetic reconnection thanksto Yohkoh• Need to clearly state scientific gain (discovery space)with respect to Hinode result– No one blames us even if we can not solve coronal heatingproblem.

• Development effort (cost) and risk predictable• Excellent continuity from Hinode• Larger community involved in plan A

Plan A vs plan B
Factors to be considered• Scientific value• Can attract many students (wrt ALMA, ASTRO‐G/H, TMT)?
– Produce 20 PhD thesis or one Nobel prize– Can contribute to significant enhancement of solar physics andastronomy in Japan• Enthusiasm of young Hinode (=SOLAR‐C) core team inJapan– An issue related to social system and sociology in Japan••••

Technical visibility
NASA and/or ESA participation absolutely needed
Relationship with other agency’s program
Support from other disciplines in Japan

Other note
• Two approaches– To solve single declared problem (e.g. elementaryparticle physics) Conventional wisdom may bewrong.
– Increase in instrumental power always brings
serendipitous discoveries (astronomy in general)• Instrument driven or science driven– Proposal on new X‐ray telescope– Proposal on innovative instruments may affectthe decisionOur relationship to space agencies• We continue to invite NASA and ESA to participate in SOLAR‐Cprogram.
• Bottom‐up process critically important in US and in Europe• More communication and coordination among space agencies insolar physics needed– SOLAR‐C, Solar Orbiter, Solar probe– Bilateral relationship should expanded to tri‐lateral (NASA‐ESA‐JAXA).
– Lessons learned from X‐ray astronomy (XEUS, CO‐X)– We discussed A vs B, how about A vs solar orbiter?

• NASA+ESA+JAXA has >1 billion$ worth of money for solar physics inthe coming 10 years. The issue is how to use this money
intelligently.
• We may ask NASA and ESA for formation of NASA/ESA SOLAR‐C
WG or equivalent to work with us.

Attitude of space agencies• ISAS– Decision should be made purely from scientificpoint of view with concurrence with international
colleagues• NASA– Scientific case should be consistent with NASAroadmap. (We believe that this is the case.)• ESA– Expect collaboration with Japan re SOLAR‐C

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

LaunchS/C tests
Flight and proto model (PM‐FM)
Phase‐A
Mission proposal to ISAS SSC
Basic development
Concept study
JAXA SOLAR‐C WG (pre‐phase‐A)(FY: Japan fiscal year starting April 1.)1111

Mission Selection Criteria
1. Scientific values* Creation of a new science field and/or a big jump in the existing
discipline anticipated?
* Japan’s unique contribution to the world in the discipline expected?
* Why urgently needed?
2. Conformity between scientific objectives and payload instruments
3. Technological feasibility* Spacecraft system* Bus subsystems* Each payload instruments
4. Maturity of the scientists / engineers team to be in charge of the mission(Review Criteria adopted in the Steering Committee for Space Science)Approval Layes• 3 approval layers for project authorization.
• Bottom – Approval by ISAS/JAXA– Evaluation from scientific/engineering viewpoint– Mission Definition Review (MDR)– System Requirements Review (SRR)– SSC plays role of evaluation on behalf of ISAS

• Middle – Approval by JAXA HQ– Evaluation from JAXA management/administration/budgetary viewpoint• Top – Approval by Government, MEXT
– Evaluation by SAC

SOLAR－C Near term
development schedule• By March 2010 Mission proposal to JAXA
• FY2009
Start development of key
technology (especially for Plan A)• January 2009 Report to JAXA re plan A andplan B (Can we do this?)• April 2008
JAXA SOLAR‐C WG started• (FY: Japan fiscal year starting April 1.)
1515

Final Remarks• This meeting provides basis for SOLAR‐C.
• We will discuss and refine the both mission concepts interms of the issues raised in this meeting. The answer canemerge from further study including continued efforts on
Hinode data analysis. Please continue to think about this.
• We have excellent people here, and desire that this groupevolves to international working group under
JAXA/ESA/NASA.
• We will discuss programmatic aspects with ESA and NASA
as well as JAXA/ISAS/JSPEC.
• Ground‐based solar observations continue to very
important.