Hinode-13/IPELS 2019, 2 - 6 September 2019
@The University of Tokyo

The Solar-C_EUVST mission

Toshifumi SHIMIZU(ISAS/JAXA, Japan)
2019/9/6

Hinode-13/IPELS 2019: Solar-C_EUVST

1New observations,better understanding
YohkohHinode(1991-2000)(2006-present)

Magnetic behaviors at the surface
Dynamic chromosphere (image)

Pieces of evidence for MR
SoHO(1995-present)

Convection zone probedwith helioseismology
CME evolution
with coronagraph2019/9/6

SDO(2010-present)

Full Sun monitoring forspace weather
Hinode-13/IPELS 2019: Solar-C_EUVSTIRIS (2013-present)(NASA)

Quantified dynamicchromosphere2

Better understanding of MHD processes,advanced with Hinode observations
waves

magnetic reconnection
Acceleration, turbulence（source of solar wind）

localdynamo

MHD instability
Magneto-convection
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New observations,better understanding
YohkohHinode(1991-2000)(2006-present)

Magnetic behaviors at the surface
Dynamic chromosphere (image)

Pieces of evidence for MRSoHO(1995-present)

Convection zone probedwith helioseismology
CME evolution
with coronagraph2019/9/6

SDO(2010-present)

Full Sun monitoring forspace weatherHinode-13/IPELS 2019: Solar-C_EUVSTIRIS (2013-present)(NASA)

Quantified dynamicchromosphere4

Solar-C_EUVST mission= Solar-C EUV High-throughput Spectroscopic Telescope
CCD/IAPS radiator panels
EUVST-Bus I/F

Guide telescope

CFRP
structure

Aperture door
Mirror assembly

Heat dump

Spacecraft bus
Optical bench
CCD

IAPS

Slit
GratingE-box

Slit-jaw imager• Down-selected as a candidate for JAXA competitive M-class missions in July
2018, to be launched by a JAXA Epsilon vehicle in 2025.
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Hinode-13/IPELS 2019: Solar-C_EUVST5Science goals of the mission

The importance of observing the solar atmosphere• How the plasma universe is created and evolves?
• How the Sun influences the Earth and other planets in our solar system?

EarthSun

The interplay of magnetic fields and plasma creates behaviors
Quasi-steady: corona, solar winds
Energy and mass transfer and energy dissipation
Transient: Flares, CMEs
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Solar-C_EUVST: Scientific objectives
I.

Understand how fundamental
processes lead to the formationof the solar atmosphere and thesolar windII.

Low-b Corona (>1 MK)

Understand how the solar
atmosphere becomes unstable,
releasing the energy that drives
solar flares and eruptions

Magnetically coupled2000 km

10000 kmWith too different spatial resolution for the corona,
impossible for the existing instruments to trace theenergy and mass transport toward the corona.
T ~ 106 - 107 K

Hinode/SOT ~0.3”
CoronaTransition region
Upper chromosphere

km00

080

Lower chromospherePhotospheric mag

netic field

160000 km

High-b Photosphere (6000 K)

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The energy injected from underneath is finally released, leading
to the hot corona, the solar wind, and coronal mass ejections.

T ~ 105 K
The Alfvén and sound speeds both increase rapidly with height,
playing critical role in the energy transfer.

T ~ 104 K

Hinode/EIS

Regulates the mass and energy loading into the corona by
Resolution ~ 3”fine-scale dynamics, such as jets and waves.

T ~ 6000 K
Turbulent convection and its interaction with magnetic fields are
the source of energy injection into the outer atmosphere.

Hinode-13/IPELS 2019: Solar-C_EUVST

Hinode/SOT Resolution ~ 0.3”
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which could lead to the ability to predict flares in the near future.

Solar-C_EUVST: Scientific objectives
I.

Understand how fundamental
processes lead to the formationof the solar atmosphere and thesolar windII.

Understand how the solar
atmosphere becomes unstable,
releasing the energy that drives
solar flares and eruptions

Ideal MHD instability

Reconnection

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Flare trigger

Hinode-13/IPELS 2019: Solar-C_EUVST

Tsuneta 19978

To achieve the scientific objectives,
The EUVST is designed tomake three significant advances

A: Seamlessly observe all the temperature regimes of theatmosphere from the chromosphere to the corona
simultaneously at the same spatial resolution(10^4-10^7 K)
B: Resolve elemental structures of the solar atmosphereand track their changes with sufficient cadence(0.4”, 1 sec exposure)
C: Obtain spectroscopic information on dynamics ofelementary processes taking place in the solar atmosphere(Velocity, density, temperature, composition, ionization etc)
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Science and instrument
design requirements
Driving requirements from science goals
à design requirements for the instrument• table2019/9/6

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Baseline architecture• Minimum number of optical components for a spectrographto achieve high throughput performance

Off-axis parabola (28 cm diameter, focal length 280 cm) makes an image on the slit.
The slit selects a one-dimensional portion of the image, which is incident onto
a concave diffraction grating (two gratings).
The radiation dispersed in the spectral direction is imaged at detectors.
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EUVSTEUV High-throughput Spectroscopic Telescope
CCD/IAPS radiator panels
EUVST-Bus I/FGuide telescope

CFRP
structureAperture door
Mirror assembly

Heat dump

Spacecraft bus
Optical bench
CCDIAPSSlit
GratingE-box

Slit-jaw imager• The instrument: length 3.8 m, weight ~200 kg

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Spacecraft system

JAXA Epsilon vehicle

Spacecraft installedin the fairing envelope

Weight 520-550 kg

Sun synchronous polar orbit (>600 km)
High pointing stability, based on Hinode knowledge
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Performance (1/2)• 7 times higher spatial resolution (3” à 0.4”)
The power to resolve about 50 times smaller features in the area size

Distinguishmagnetic loops

Active-region
overall structure
The image quality of the design expected: Initial budget table2019/9/6

Hinode-13/IPELS 2019: Solar-C_EUVST14

assumption that the diameter of the primary mirror is twice as large as Hinode/EIS and the visible-IRfilter in the optical path is removed. The EAs of LW bands are calculated under the assumption thatthe number of reflections is reduced from 3 to 1 and the diameter of the primary mirror increases
from 12~cm to 28~cm. The calculation includes the mirror, grating and detector efficiencies, as wellas the •relevant
factors
mirrorofarea
the splitting of thePeak geometricalefficiencies
is a(i.e.,factor10andimprovement
ingrating into the SW andLW channels). The plot includes, for comparison, the published effective areas of Hinode/EIS,
Hinode/EIS
and 40 overSoHO/SUMERSoHO/SUMER
and SoHO/CDS.
The peakefficiencies give a factor of ≈ 10 improvement withrespect to Hinode/EIS in the EUV and an improvement of a factor of ≈ 40 over SoHO/SUMER in theFUV. Figure 6.2(b) shows the expected signal (inàcount/arcsec2) obtained by multiplying the EA by
the radiances for different solar regions and by considering typical exposure times for those regions
Count rate of spectral lines
and a resolution element of 1~arcsec2.

Performance (1/2)

Effective area vs. wavelengthx10
Hinode/EIS

x40
SoHO/SUMERCounts in exposure

Effective area (cm2)(a)

vs. temperature(b)

Δv < 2km/sec

Log (T/K)

Wavelength (nm)Figure 6.2: (a) Assumed Solar-C_EUVST effective area based on the baseline architectures described in section 15.
The effective areas of Hinode/EIS, SoHO/SUMER, and SoHO/CDS are also shown for comparison. (b) Expected countrates (count/arcsec2) for the indicated exposure times for different solar observational targets (5~s for the quiet Sun, 1~sfor active regions, and 0.5~s for a small flare). The horizontal dashed line marks the 200~counts (in the spectral line)
level necessary to determine line positions with a ≤ 2~km/s accuracy as shown in section 6.2.4.

10 1

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1 2 1

1 ,,. 2 2, 22

Hinode-13/IPELS 2019: Solar-C_EUVST220, 215

Mission status• Selected as a candidate for JAXA competitive M-classmissions in July 2018
• After an international science review in December 2018 andthe pre-project candidate selection review in March 2019,the mission is currently in the Mission Definition phase(JAXA Pre-Phase A2).
• ISAS/JAXA has scheduled the final down-selection inDecember 2019 for competitive M-class mission #4,
expected launch around 2025.
• JAXA-led mission with substantial participations from US
and European countries.
• A Partner Mission of Opportunity proposal to NASA selected!
• Coordinating with European countries (Germany, UK, France, Italy,…) for developing components to EUVST.
• ESA has officially started the mission definition toward the ESAparticipation. Involvement of ESA for securing involvement from
European national agencies and for science-data downlink
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Notional instrument set recommended in NGSPMSOT final report and current view in Japan• The NGSPM-SOT report (2017/7) recommended a minimum set of instrumentswith which NGSPM can address the greatest number of sub-objectives andmaximize the science return of the mission.
Higher priority of notional instruments
in order from the top
in NGSPM-SOT report0.3” coronal/TR spectrograph (T-9)
seamless plasma diagnostics
through the atmosphere

Solar-C_EUVST
as JAXA competitive M-class mission

Expect a NASA MiDEX mission0.2”-0.6” coronal imager (T-7)
0.1” – 0.3” chromospheric imager
and magnetograph (T-4)
0.1” photospheric magnetograph (T-1)
0.1” chromospheric spectrograph (T-5)
Magnetic and velocity fields
at chromosphere2019/9/6

Constellation of small/med-classmissions around 2025.

Spectro-polarimetry:CLASP (UV), Sunrise-3 balloon(1m)à Closely coordinatedobservations withground-based 4m (DKIST)

Hinode-13/IPELS 2019: Solar-C_EUVST

à 1m-class telescopefor a launch in 2030’s

17Connecting the Sun to the BepiColombo/Mio (MMO)
Inner heliosphere
Parker Solar Probe?

65Rs – 100 Rs @Mercury(2025~)“in situ” measurements

Credit: NASA/JHU

PUNCH (2022~)
Outer corona from
5Rs outward

IPS

8.9Rs (closest @ Credit:2025~)
NASA/JHU APL“in situ” measurements

Solar Orbiter

Credit: ESA/AOES

Solar-C_EUVST(2025~)

60Rs (closest), 25 deg. solar latitude(2026~)
Coronal image/spectra,
photospheric magnetogram(low resolution/telemetry)

EUVST fills a critical gap in solar observations for the next solar cycle. New observations for both thephotosphere and chromosphere are planned (e.g., DKIST) and the heliosphere (PSP, PUNCH, Solar
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Orbiter,etc), but nothing new is planned to study the source of space weather events and solar18wind.

Summary

Solar-C_EUVST mission= Solar-C EUV High-throughput Spectroscopic Telescope• Much advanced capabilitiesü Temp coverage: 10^4-10^7 K
ü Spatial resolution: 0.4”
ü High throughput: x10 ~ x40 higher(Temporal resolution: 1-sec cad.)• Science objectives
ü Atmospheric heating and solar wind
ü Fast reconnection, flare/CME eruption• Target launch dateü 2025 (JFY 2024 – 2026)
ü In the next solar maximum

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