the next-generation space solar observatory: the solar-c ... · solar-c high-resolution...

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##in#Helio(Physics1.#Origin#of#large8scale#

explosion

2.#Hea=ng#of#chromosphere#and#corona,#

Solar#wind#accelera=on

3.#Magne=c#cycle#

Planned##satellite##Solar#observatory#prepared#by#JAXA##SOLAR8C#W.G.

First#determines#3D#magne=c#structures#from#unprecedented#observa=ons#for##elucida=ng#basic#problems#in#Helio8Phys.##

Keywords:##8#Chromospheric#B#measurements##8#0.1”#–#0.3”#spa=al#resolu=on##8# 1s#high8cadence#observa=ons##8#high#resolu=on#spectroscopy

SOLAR-C

(0.1”#=#70#km)

Science#Objec=ves#Observations of All from photosphere to corona seamlessly

as a system

SOLAR8C#FOV 180#“#× 140”

SOLAR8C#FOV 280#“#× 280”

SOLAR8C#FOV 400#“#× 400”•  Physical#origin#of#explosions#that#

drive#short8=me#geo8space#variability#

•  Mechanisms#responsible#for##–  hea=ng#and#dynamics#of#chromosphere#corona#

–  accelera=on#of#solar#wind#•  Fundamental#physical#processes#

–  Magne=c#reconnec=on,#MHD#waves,#shocks,#etc.#

•  Fine8scale#magne=sm#and#associated#solar#spectral#irradiance#

SOLAR8C#will#determine

EPIC: European Participation in Solar-C 4 MISSION CONFIGURATION AND PROFILE

SUVIT/IUSUVIT/UBIS

SUVIT/SPSUVIT/FG

HCI

Startracker

UltrafineSun Sensor

+Z

+Y

+X

Telemetry Antenna

SUVIT/TA

EUVST

Telescope Door

+Z

+Y

+X

Heat Dump WindowStartracker

Telemetry AntennaSolar Array Panel

Apogee Kick EngineThrusters

SUVIT/TAHCI

Optical Bench Unit

Telemetry AntennaBus Module

Inertial Reference Unit(Gyros, part of 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-bandcommunication channels (see Section 4.5). The Iner-tia Reference Unit (IRU), not visible in Figure 26) willbe established by a fibre-optic gyro system with low-est possible drift rates. The startrackers and the IRUwill have considerable heritage from and achieve per-formance levels as those in Alphasat, Sentinel-2 andEDRS-C.

Instruments and spacecraft structures that are essen-tial for stability and accuracy, are equipped with heatersto provide a stable thermal environment. In addition, in-struments will have emergency heaters to keep them in asafe state in case of malfunctions of the bus system. Theheating power requirements are the result of a detailedthermal analysis which will be carried out as part of thedesign phase.

Two solar array panels are deployed from the twosides of the spacecraft body and are designed to generateabout 5 000 Watt of electrical power. A possible reduc-tion of the panel size or of the number of solar cells willbe based on the more accurately determined power re-quirements available after the definition phase. The sizeof the spacecraft body (telescopes and bus module) isroughly 3.7 ⇥ 3.2 ⇥ 7.1m3, excluding the solar arrays.This size fits in the fairing envelope of the H-IIA 4Srocket. The estimate for the total mass is about 4 met-ric tons, which consists of 2.3 ton dry mass and 1.7 tonpropellant, which requires efforts on reduction for a H-IIA launch, but the mass constraint may be relaxed withthe new H-III rocket (first flight expected in 2020).

The model specification of the spacecraft system issummarised in Table 6.

38

SOLAR-C Spacecraft

Hinode

SUVIT#TA#1.4#m#diameter#telescope

EUVST#(EUV#Spectroscopic#Telescope)

HCI#(High#Resolu=on#########Coronal#Imager)

SUVIT:#Solar#UV8Visible8IR#Telescope#

50cm#dia.#telescope

Chromospheric#magne=c#fields#measurements

EPIC: European Participation in Solar-C 3 PROPOSED SCIENTIFIC INSTRUMENTS

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 operationof the image motion compensation system.

In terms of resources, the instrument occupies avolume of 430 ⇥ 70 ⇥ 40 cm3, has a mass of 155 kg(including 15 % margin) and requires 68 W power (ofwhich 24 W for operational heaters).

3.4 High Resolution Coronal Imager (HCI)

The HCI is a normal-incidence EUV telescope con-sisting of primary and secondary mirrors in Ritchey-Chrétien configuration. It will perform high-resolutionimaging in the EUV pass-bands described in Sec-tion 2.4: 30.4 nm containing the He II resonance line asdiagnostic of the transition region, 17.1 nm containinglines of Fe IX and Fe X showing 1 MK coronal struc-tures at high contrast, and 9.4 nm containing Fe XVIIIwith emission in very hot outburst features.

Table 5 summarises key design features of HCI.The primary and secondary mirrors are both dividedinto three sectors, with each sector coated with differentmulti-layer coatings for high reflectance in the pertinentpassband. The sectors have different areas to accommo-date expected count rates (17.1 nm 33%, 30.4 nm 17%,9.4 nm 50%, respectively).

The primary mirror will have a clear aperture of32 cm diameter. Wavelength selection will be done witha filter wheel as in SDO/AIA.

The optics will give an effective focal length of20 m. Combined with a 10µm pixel back-thinned CCD(4k⇥4k format) this gives 0.100/pixel sampling.

The secondary mirror will have an active mount thatis actuated to remove instrument pointing errors and fo-cus the system, as in TRACE and SDO/AIA. As in these

instruments, HCI will have a guide telescope for Sun-tracking to feed the image stabiliser. This system willincorporate spacecraft pointing information to achievethe required pointing accuracy and stability.

Entrance filters will reject visible light. An aper-ture door protects them during launch, as in TRACE andSDO/AIA. A mechanical shutter near the focal planecontrols the exposure time. Typical exposure times (asfor the comparable channels of SDO/AIA) will rangefrom 0.1 s for flares to 100 s for dark quiet-Sun targets.

The analog output from the single CCD will be con-verted into 14 bits. In standard observing, the readoutarea will cover only one quarter of the full FOV (2k⇥2kpixels or 20500⇥20500) at an exposure cadence of 10 s.The planned data rates for normal-cadence observationsare 5.9 Mbps (raw), 2.9 Mbps (lossless) and 1.3 Mbps(lossy). In lossless compression each pixel value corre-sponds to 7 bits; in lossy compression only 3 bits. In fastsmall-area sampling 1024 ⇥ 1024 pixels (10000⇥10000)readout can reach 1 s cadence with lossy compression.

HCI will use large heritage from the comparableEUV imagers on-board TRACE and SDO/AIA. How-ever, as the instrument will have 5–6 times better an-gular resolution, the following issues will be assessedduring the definition phase:– mirror micro-roughness, i.e., optimising multi-layer

reflectance and minimising wide-angle scattering;.– effect of multi-layer coatings on effective area after

masking;– stabilisation at twice the resolution of IRIS;– vibration from moving elements (as the filter wheel);– effect of hits by energetic particles.

36

!"##$#%&''(!)*+

,(*('-$.((*(-,#$/"-'

01"2(%,(*('-$.(

2(3*(-,$#%.*&,(

3#$/,2$$#!"#"$%&'"()*+,

-'"%,.&/.0'1()*+,

0#&,"/0%&''(!)*+

2(,(-,$#%&''(!)*"('

SOLAR8C#payload1.4m#diameter#telescope

SUVIT#Solar#UV8Visible8IR#Telescope

Spectro8polarimeter

Filtergraph

EUVST#(EUV#Spectrograph)HCI#(High#Resolu=on##########Coronal#Imager)

Slit#scanning##spectro8polarimter##with#IFU

1.22*k/D

0.01 0.10 1.00 10.00 100.00 1000.00Wavelength (nm)

0.1

1.0

10.0Sp

atia

l Res

olut

ion

(arc

sec)

140 cm

50 cm

SOLAR-C High-resolution Observations

SDO#2010##Corona8imaging

Yohkoh#1991#Corona8imaging

Hinode#2006#Corona8imaging

IRIS#2013#Chrom.8TR#Spectroscopy

Yohkoh#1991#HXR8imaging

TRACE#1999#

HiC##2012#Corona8imaging

Hinode#2006##spectroscopy

Hinode##2006#

SOLAR(C#SUVIT&

SOHO#1995#Corona8imaging SOHO#1995#

Chrom.8Corona8spectroscopy

SOLAR(C#EUVST&Chrom8corona#spectroscopy

SOLAR(C#HCI&TR8Corona#imaging

0.2

0.3

0.5

RHESSI#2002#

FOXI#2012#HXR#focusing#imaging#

Telescope#diameter

0.1”#=##70#kmspectro8#

###polarimery###(mag.#fields)

W8b#imaging

N8b#imaging

SDO#2010##Photospheric#mag.

Fine-scale coronal structures inferred from HinodeFine-scale chromospheric structures observed by Hinode & GBO Fine-scale kG photospheric structures inferred from Hinode

EUVST#280”#x#280”

HCI#410”#x#410”

SUVIT#184”#x#184”#

SOLAR8C:#Field#of#View#(FOV)

SUVIT

FG SP

WB NB

Hi8#Res.

###Wide#

FOV

184”x184”184”x143”

61”x61” 90”x90”

Narrow#bands#with#a#polarimeter

Wide#bands

SUVIT#Filtergraph#(FG)

SUVIT#Spectro8polarimeter#(SP)#to#observe#photspheric#chromospheric#mag.#fields

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

Solar-C EUVS

!"##$#%&''(!)*+

,(*('-$.((*(-,#$/"-'

01"2(%,(*('-$.(

2(3*(-,$#%.*&,(

3#$/,2$$#!"#"$%&'"()*+,

-'"%,.&/.0'1()*+,

0#&,"/0%&''(!)*+

2(,(-,$#%&''(!)*"('

EUVST

Slit assembly

•  Optics: single off-axis mirror (30cmφ, f=360cm)

and a grating •  Telescope length: 430cm

With low scattering optics, for exploring low EM regions (MR and CH).

!"##$#%&''(!)*+

,(*('-$.((*(-,#$/"-'

01"2(%,(*('-$.(

2(3*(-,$#%.*&,(

3#$/,2$$#!"#"$%&'"()*+,

-'"%,.&/.0'1()*+,

0#&,"/0%&''(!)*+

2(,(-,$#%&''(!)*"('

EUVST•  Optics: single off-axis mirror

(30cmφ, f=360cm) and a grating •  Telescope length: 430cm

AR (log T/K < 6.2) - 1s exposureAR (log T/K > 6.2) - 1s exposure

log (T/[K])4 5 6 7

FeIX

FeX/XI

MgX

FeXII

FeXIII

FeXIV

SiXII CaXIV

CaXV

CaXVI

CaXVII

FeXVIII

FeXIX

FeXIX

FeXIX

FeXX

FeXXIII

FeXXIIFeXXIV

FeXXI

Slit assembly

With low scattering optics, for exploring low EM regions (MR and CH).

EPIC: European Participation in Solar-C 3 PROPOSED SCIENTIFIC INSTRUMENTS

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 operationof the image motion compensation system.

In terms of resources, the instrument occupies avolume of 430 ⇥ 70 ⇥ 40 cm3, has a mass of 155 kg(including 15 % margin) and requires 68 W power (ofwhich 24 W for operational heaters).

3.4 High Resolution Coronal Imager (HCI)

The HCI is a normal-incidence EUV telescope con-sisting of primary and secondary mirrors in Ritchey-Chrétien configuration. It will perform high-resolutionimaging in the EUV pass-bands described in Sec-tion 2.4: 30.4 nm containing the He II resonance line asdiagnostic of the transition region, 17.1 nm containinglines of Fe IX and Fe X showing 1 MK coronal struc-tures at high contrast, and 9.4 nm containing Fe XVIIIwith emission in very hot outburst features.

Table 5 summarises key design features of HCI.The primary and secondary mirrors are both dividedinto three sectors, with each sector coated with differentmulti-layer coatings for high reflectance in the pertinentpassband. The sectors have different areas to accommo-date expected count rates (17.1 nm 33%, 30.4 nm 17%,9.4 nm 50%, respectively).

The primary mirror will have a clear aperture of32 cm diameter. Wavelength selection will be done witha filter wheel as in SDO/AIA.

The optics will give an effective focal length of20 m. Combined with a 10µm pixel back-thinned CCD(4k⇥4k format) this gives 0.100/pixel sampling.

The secondary mirror will have an active mount thatis actuated to remove instrument pointing errors and fo-cus the system, as in TRACE and SDO/AIA. As in these

instruments, HCI will have a guide telescope for Sun-tracking to feed the image stabiliser. This system willincorporate spacecraft pointing information to achievethe required pointing accuracy and stability.

Entrance filters will reject visible light. An aper-ture door protects them during launch, as in TRACE andSDO/AIA. A mechanical shutter near the focal planecontrols the exposure time. Typical exposure times (asfor the comparable channels of SDO/AIA) will rangefrom 0.1 s for flares to 100 s for dark quiet-Sun targets.

The analog output from the single CCD will be con-verted into 14 bits. In standard observing, the readoutarea will cover only one quarter of the full FOV (2k⇥2kpixels or 20500⇥20500) at an exposure cadence of 10 s.The planned data rates for normal-cadence observationsare 5.9 Mbps (raw), 2.9 Mbps (lossless) and 1.3 Mbps(lossy). In lossless compression each pixel value corre-sponds to 7 bits; in lossy compression only 3 bits. In fastsmall-area sampling 1024 ⇥ 1024 pixels (10000⇥10000)readout can reach 1 s cadence with lossy compression.

HCI will use large heritage from the comparableEUV imagers on-board TRACE and SDO/AIA. How-ever, as the instrument will have 5–6 times better an-gular resolution, the following issues will be assessedduring the definition phase:– mirror micro-roughness, i.e., optimising multi-layer

reflectance and minimising wide-angle scattering;.– effect of multi-layer coatings on effective area after

masking;– stabilisation at twice the resolution of IRIS;– vibration from moving elements (as the filter wheel);– effect of hits by energetic particles.

36

High#Resolu=on#Coronal#Imager#(HCI)8#He#II#304#8#Fe#IX#171#8#Fe#XVIII#94

HCI

EPIC: European Participation in Solar-C 4 MISSION CONFIGURATION AND PROFILE

SUVIT/IUSUVIT/UBIS

SUVIT/SPSUVIT/FG

HCI

Startracker

UltrafineSun Sensor

+Z

+Y

+X

Telemetry Antenna

SUVIT/TA

EUVST

Telescope Door

+Z

+Y

+X

Heat Dump WindowStartracker

Telemetry AntennaSolar Array Panel

Apogee Kick EngineThrusters

SUVIT/TAHCI

Optical Bench Unit

Telemetry AntennaBus Module

Inertial Reference Unit(Gyros, part of 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-bandcommunication channels (see Section 4.5). The Iner-tia Reference Unit (IRU), not visible in Figure 26) willbe established by a fibre-optic gyro system with low-est possible drift rates. The startrackers and the IRUwill have considerable heritage from and achieve per-formance levels as those in Alphasat, Sentinel-2 andEDRS-C.

Instruments and spacecraft structures that are essen-tial for stability and accuracy, are equipped with heatersto provide a stable thermal environment. In addition, in-struments will have emergency heaters to keep them in asafe state in case of malfunctions of the bus system. Theheating power requirements are the result of a detailedthermal analysis which will be carried out as part of thedesign phase.

Two solar array panels are deployed from the twosides of the spacecraft body and are designed to generateabout 5 000 Watt of electrical power. A possible reduc-tion of the panel size or of the number of solar cells willbe based on the more accurately determined power re-quirements available after the definition phase. The sizeof the spacecraft body (telescopes and bus module) isroughly 3.7 ⇥ 3.2 ⇥ 7.1m3, excluding the solar arrays.This size fits in the fairing envelope of the H-IIA 4Srocket. The estimate for the total mass is about 4 met-ric tons, which consists of 2.3 ton dry mass and 1.7 tonpropellant, which requires efforts on reduction for a H-IIA launch, but the mass constraint may be relaxed withthe new H-III rocket (first flight expected in 2020).

The model specification of the spacecraft system issummarised in Table 6.

38

Hinode

SUVIT#TA

EUVST#(EUV#Spectrograph)

SUVIT#SPP

HCI#(Coronal#imager)

International CollaborationESA & EUVST consortium

NASA

NASA

JAXA+α

JAXA+α

Launch vehicle: JAXA Spacecraft: JAXA

A planned case of task share that world-wide solar physicists desire

-  Proposed to US Heliophysics Decadal Survey -  EUVST: proposed to ESA Cosmic Vision II -  Submitted to JAXA-AO

α:#European#countries

SUVIT#FGP

Coordinated Observations

Credit:#ESA/AOES

Solar*Orbiter

Credit:#NASA/JHU#APL

( )

##

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

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.

the next-generation space solar observatory: the solar-c ... · solar-c high-resolution...

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