SOLAR-C Mission

The next-generation space solar observatory:

The SOLAR-C Mission

K. Watanabe & H. Hara ISAS/JAXA & NAOJ

SOLAR-C WG 2015 Feb 27

ISSI#Coronal#Rain# Basic#Problems## SOLAR-C in#Helio(Physics 1.#Origin#of#large8scale# explosion

Planned##satellite## Solar#observatory# 2.#Hea=ng#of#chromosphere# prepared#by#JAXA## and#corona,# SOLAR8C#W.G. Solar#wind#accelera=on First#determines#3D#magne=c#structures# from#unprecedented#observa=ons#for## elucida=ng#basic#problems#in#Helio8Phys.# # Keywords:# 3.#Magne=c#cycle# #8#Chromospheric#B#measurements# #8#0.1”#–#0.3”#spa=al#resolu=on#(0.1”#=#70#km) #8#1s#high8cadence#observa=ons# #8#high#resolu=on#spectroscopy Science#Objec=ves# Observations of All from photosphere to corona seamlessly as a system

SOLAR8C#will#determine • Physical#origin#of#explosions#that# SOLAR8C#FOV 400#“#× 400” drive#short8=me#geo8space#variability# • Mechanisms#responsible#for## – hea=ng#and#dynamics#of# chromosphere#&#corona# – accelera=on#of#solar#wind# SOLAR8C#FOV280#“#×280” • Fundamental#physical#processes# – Magne=c#reconnec=on,#MHD#waves,# shocks,#etc.# • Fine8scale#magne=sm#and#associated# SOLAR8C#FOV180#“#×140” solar#spectral#irradiance# EPIC: European Participation in Solar-CSOLAR-C 4 MISSION Spacecraft CONFIGURATION AND PROFILE 50cm#dia.#telescope EUVST#(EUV#Spectroscopic#Telescope) +Y EUVST Telemetry Antenna

+X +Z

Startracker

SUVIT/TA

SUVIT/IU SUVIT/UBIS SUVIT/SP Hinode Ultrafne Sun Sensor SUVIT/FG

Telescope Door HCI HCI#(High#Resolu=on# SUVIT#TA# +Z Heat Dump Window1.4#m#diameter# ########Coronal#Imager) Startrackertelescope +X Telemetry Antenna +Y Solar ArrayChromospheric Panel #magne=c#ﬁelds# measurements SUVIT/TA HCI SUVIT:#Solar#UV8Visible8IR#Telescope# Optical Bench Unit

Thrusters Apogee Kick Engine Inertial Reference Unit (Gyros, part of Bus Module) Telemetry Antenna Bus Module

Figure 26: Solar-C Spacecraft; source: NAOJ. The scientific payload also includes the Irradiance Monitor (IM). vide the downlink of science data to ground via X-band Two solar array panels are deployed from the two communication channels (see Section 4.5). The Iner- sides of the spacecraft body and are designed to generate tia Reference Unit (IRU), not visible in Figure 26) will about 5 000 Watt of electrical power. A possible reduc- be established by a fibre-optic gyro system with low- tion of the panel size or of the number of solar cells will est possible drift rates. The startrackers and the IRU be based on the more accurately determined power re- will have considerable heritage from and achieve per- quirements available after the definition phase. The size formance levels as those in Alphasat, Sentinel-2 and of the spacecraft body (telescopes and bus module) is EDRS-C. roughly 3.7 3.2 7.1 m3, excluding the solar arrays. ⇥ ⇥ Instruments and spacecraft structures that are essen- This size fits in the fairing envelope of the H-IIA 4S tial for stability and accuracy, are equipped with heaters rocket. The estimate for the total mass is about 4 met- to provide a stable thermal environment. In addition, in- ric tons, which consists of 2.3 ton dry mass and 1.7 ton struments will have emergency heaters to keep them in a propellant, which requires efforts on reduction for a H- safe state in case of malfunctions of the bus system. The IIA launch, but the mass constraint may be relaxed with heating power requirements are the result of a detailed the new H-III rocket (first flight expected in 2020). thermal analysis which will be carried out as part of the The model specification of the spacecraft system is design phase. summarised in Table 6.

38 1.4m#diameter# telescope SOLAR8C#payload Filtergraph

SUVIT# Solar#UV8Visible8IR#Telescope

Slit#scanning## spectro8polarimter## with#IFU 3#$/, EPIC: European Participation in Solar-C 3 PROPOSED SCIENTIFIC INSTRUMENTS 2$$# Spectro8polarimeter!"#"$%&'"()*+, 2(3*(-,$#% .*&,( 01"2(%,(*('-$.( !"##$#%&''(!)*+

HCI#(High#Resolu=on## 0#&,"/0%&''(!)*+ ,(*('-$.( (*(-,#$/"-' ########Coronal#Imager) EUVST#(EUV#Spectrograph)-'"%,.&/.0'1()*+, 2(,(-,$#%&''(!)*"(' Figure 24: The opto-mechanical layout of HCI. The layout resembles that of the EUV imagers TRACE, SDO/AIA and Hi-C.

10 Hz bandwidth cutoff and will allow smooth operation instruments, HCI will have a guide telescope for Sun- of the image motion compensation system. tracking to feed the image stabiliser. This system will In terms of resources, the instrument occupies a incorporate spacecraft pointing information to achieve volume of 430 70 40 cm3, has a mass of 155 kg the required pointing accuracy and stability. ⇥ ⇥ (including 15 % margin) and requires 68 W power (of Entrance filters will reject visible light. An aper- which 24 W for operational heaters). ture door protects them during launch, as in TRACE and SDO/AIA. A mechanical shutter near the focal plane 3.4 High Resolution Coronal Imager (HCI) controls the exposure time. Typical exposure times (as for the comparable channels of SDO/AIA) will range The HCI is a normal-incidence EUV telescope con- from 0.1 s for flares to 100 s for dark quiet-Sun targets. sisting of primary and secondary mirrors in Ritchey- The analog output from the single CCD will be con- Chretien´ configuration. It will perform high-resolution verted into 14 bits. In standard observing, the readout imaging in the EUV pass-bands described in Sec- area will cover only one quarter of the full FOV (2k 2k ⇥ tion 2.4: 30.4 nm containing the He II resonance line as pixels or 205 205 ) at an exposure cadence of 10 s. 00⇥ 00 diagnostic of the transition region, 17.1 nm containing The planned data rates for normal-cadence observations lines of Fe IX and Fe X showing 1 MK coronal struc- are 5.9 Mbps (raw), 2.9 Mbps (lossless) and 1.3 Mbps tures at high contrast, and 9.4 nm containing Fe XVIII (lossy). In lossless compression each pixel value corre- with emission in very hot outburst features. sponds to 7 bits; in lossy compression only 3 bits. In fast Table 5 summarises key design features of HCI. small-area sampling 1024 1024 pixels (100 100 ) ⇥ 00⇥ 00 The primary and secondary mirrors are both divided readout can reach 1 s cadence with lossy compression. into three sectors, with each sector coated with different HCI will use large heritage from the comparable multi-layer coatings for high reflectance in the pertinent EUV imagers on-board TRACE and SDO/AIA. How- passband. The sectors have different areas to accommo- ever, as the instrument will have 5–6 times better an- date expected count rates (17.1 nm 33%, 30.4 nm 17%, gular resolution, the following issues will be assessed 9.4 nm 50%, respectively). during the definition phase: The primary mirror will have a clear aperture of – mirror micro-roughness, i.e., optimising multi-layer 32 cm diameter. Wavelength selection will be done with reflectance and minimising wide-angle scattering;. a filter wheel as in SDO/AIA. – effect of multi-layer coatings on effective area after The optics will give an effective focal length of masking; 20 m. Combined with a 10 µm pixel back-thinned CCD – stabilisation at twice the resolution of IRIS; (4k 4k format) this gives 0.1 /pixel sampling. ⇥ 00 – vibration from moving elements (as the filter wheel); The secondary mirror will have an active mount that – effect of hits by energetic particles. is actuated to remove instrument pointing errors and fo- cus the system, as in TRACE and SDO/AIA. As in these

36 SOLAR-C High-resolution Observations FOXI#2012# 1.22*k/D 10.0 HXR#focusing#imaging# RHESSI#2002# Yohkoh#1991# Corona8imaging SOHO#1995# Corona8imaging SOHO#1995# Yohkoh#1991# Chrom.8Corona8spectroscopy HXR8imaging Hinode#2006# Hinode#2006## Corona8imaging spectroscopy SDO#2010## SDO#2010## Photospheric#mag. 1.0 Corona8imaging TRACE#1999# IRIS#2013# Chrom.8TR#Spectroscopy HiC##2012# 50 cm 0.5 Corona8imaging Hinode# Fine-scale coronal structures Telescope#diameter #2006# 0.3 inferred from Hinode Fine-scale chromospheric structures 0.2 observed by Hinode & GBO SOLAR(C#HCI& TR8Corona#imaging 140 cm

Spatial Resolution (arcsec) Fine-scale kG photospheric structures SOLAR(C# SOLAR(C# 0.1 inferred from Hinode EUVST& SUVIT& W8b#imaging 0.1”#=##70#km Chrom8corona# N8b#imaging spectroscopy spectro8# 0.01 0.10 1.00 10.00 100.00 1000.00 ###polarimery# Wavelength (nm) ##(mag.#ﬁelds) SOLAR-C High-resolution Observations FOXI#2012# 1.22*k/D 10.0 HXR#focusing#imaging# RHESSI#2002# Yohkoh#1991# Corona8imaging SOHO#1995# Corona8imaging SOHO#1995# Yohkoh#1991# Chrom.8Corona8spectroscopy HXR8imaging Hinode#2006# Hinode#2006## Corona8imaging spectroscopy SDO#2010## SDO#2010## Photospheric#mag. 1.0 Corona8imaging TRACE#1999# IRIS#2013# Chrom.8TR#Spectroscopy HiC##2012# 50 cm 0.5 Corona8imaging Hinode# Fine-scale coronal structures Telescope#diameter #2006# 0.3 inferred from Hinode Fine-scale chromospheric structures 0.2 observed by Hinode & GBO SOLAR(C#HCI& TR8Corona#imaging 140 cm

SUVIT# SUVIT 184”#x#184”# FG SP WB NB EUVST# 280”#x#280” Hi8# # Res. 61”x61” 90”x90” 184”x143”# 184”x184” HCI# Wide# # 410”#x#410” FOV SUVIT#Filtergraph#(FG)

Wide#bands

Narrow#bands#with#a#polarimeter SUVIT#Spectro8polarimeter#(SP)# to#observe#photspheric#&#chromospheric#mag.#ﬁelds

0.07”#slit#width#for#slit#obs.# 0.2”#slit#width#for#IFU EUVST

• Optics: single off-axis mirror (30cmφ, f=360cm) and a grating • Telescope length: 430cm

3#$/, 2$$# !"#"$%&'"()*+, 2(3*(-,$#% .*&,( 01"2(%,(*('-$.( !"##$#%&''(!)*+ With low Slit assembly scattering optics, for exploring low EM regions (MR

0#&,"/0%&''(!)*+ and CH). ,(*('-$.( (*(-,#$/"-' -'"%,.&/.0'1()*+, 2(,(-,$#%&''(!)*"(' Solar-C EUVS FeXIX EUVST FeXXII FeXX FeXXIV

FeX/XI FeXXIII FeXIV FeXXI FeIX FeXII • Optics: single off-axis mirror FeXVIII FeXIII (30cm f=360cm) MgX φ, SiXII CaXIV FeXIX CaXVII and a grating AR (log T/K < 6.2) - 1s e xposure CaXV AR (log T/K > 6.2) - 1s e xposure CaXVI • Telescope length: 430cm FeXIX

4 5 6 7 log (T/[K]) 3#$/, 2$$# !"#"$%&'"()*+, 2(3*(-,$#% .*&,( 01"2(%,(*('-$.( !"##$#%&''(!)*+ With low Slit assembly scattering optics, for exploring low EM regions (MR

0#&,"/0%&''(!)*+ and CH). ,(*('-$.( (*(-,#$/"-' -'"%,.&/.0'1()*+, 2(,(-,$#%&''(!)*"(' EPIC: European Participation in Solar-C 3 PROPOSED SCIENTIFIC INSTRUMENTS High#Resolu=on#Coronal#Imager#(HCI) 8#He#II#304# 8#Fe#IX#171# 8#Fe#XVIII#94

HCI Figure 24: The opto-mechanical layout of HCI. The layout resembles that of the EUV imagers TRACE, SDO/AIA and Hi-C.

36 EPIC: European Participation in Solar-CInternational 4 MISSION Collaboration CONFIGURATION AND PROFILE A planned case of task share that world-wide solar physicists desire EUVST#(EUV#Spectrograph) +Y ESA & EUVST Telemetry Antenna EUVST consortium +X +Z Launch vehicle: JAXA Spacecraft: JAXA Startracker

SUVIT/TA

SUVIT/IU SUVIT/UBIS SUVIT#FGP Hinode SUVIT/SP NASA Ultrafne Sun Sensor SUVIT/FG SUVIT#SPP Telescope Door HCI JAXA+α SUVIT#TA HCI#(Coronal#imager)+Z Heat Dump WindowJAXA+α NASA α:#European#countriesStartracker +X Telemetry Antenna +Y - ProposedSolar Array Panel to US Heliophysics Decadal Survey - EUVST: proposed to ESA Cosmic Vision IISUVIT/TA - Submitted to JAXA-AO HCI

Optical Bench Unit

Thrusters Apogee Kick Engine Inertial Reference Unit (Gyros, part of Bus Module) Telemetry Antenna Bus Module

38 Coordinated Observations

Solar*Orbiter () # #

Credit:#ESA/AOES Credit:#NASA/JHU#APL

Solar*Dynamic*Observatory* or*a*mission*of*full9disk*observa

SOLAR8C Summary • SOLAR-C is a mission to understand the causal linkage between solar magnetic fields and active phenomena on the Sun and in the heliosphere.

• SOLAR-C equips three major payloads to elucidate fundamental problems in Helio-physics by high-resolution (0.1”−0.3”) imaging & spectroscopy with temporally stable chromospheric magnetometry.

• All telescopes of the SOLAR-C have capability to observe coronal rains with enough spatial resolution, enough cadence, and enough coverage of temperature.