Solar-C

SpaceSolar-C

Solar-C

Science Overview

Solar-C is the next Japanese solar physics mission to be developed with significant contributions from the US, Europe and Japan. The mission carries an Extreme UV (EUV) imaging spectrometer with a slit-jaw imaging system called EUV High-Throughput Spectroscopic Telescope (EUVST) as the mission principal payload.

EUVST is designed to take a fundamental step towards answering how the plasma universe is created and evolves, and how the Sun influences the Earth. In 2020, SOLAR-C_EUVST was down-selected as the fourth in the series of the competitively chosen M-class mission to be launched with an Epsilon launch vehicle in 2028. The mission underwent the Mission Design Review in 2021.

The second instrument onboard SOLAR-C is the Solar Spectral Irradiance Monitor (SoSpIM) and is led by PMOD/WRC. It will provide “Sun-as-a-star” spectral irradiance measurements over two bands that overlap with EUVST, the Short EUV and Lyman-Alpha bands. This provides both scientific and cross-characterisation capabilities.

SoSpIM and EUVST will work hand-in-hand. While EUVST will deliver spectral observations from the chromosphere to the corona, tracking the energy flow on small spatial scales, SoSpIM will measure the integrated irradiance over the bands of interest, not just those within the EUVST field-of-view. The SoSpIM instrument provides the connectivity between the flare processes captured in detail on the Sun by EUVST and the impact of those irradiance changes in different layers of the Earth’s atmosphere.

PMOD/WRC Instrument: SoSpIM

PMOD/WRC Instrument: The Solar Spectral Irradiance Monitor (SoSpIM)

SoSpIM will provide ‘Sun-as-a-star’ measures in two wavelength bands also covered by EUVST. This provides measurements of all solar flares visible from Earth, not only those within the EUVST field-of-view. SoSpIM provides the connectivity between the flare processes captured in detail on the Sun by EUVST and the impact of that irradiance changes in different layers of Earth’s atmosphere. SoSPIM is funded by the Swiss Space Office through ESA Prodex.

SoSpIM aims to specifically address two aspects:

  • Understand how the solar atmosphere becomes unstable, releasing the energy that drives solar flare which will be achieved through probing fast time cadence solar flare variations.
  • Measuring solar irradiance that impacts the Earth’s thermosphere and the mesosphere, linking to spatially resolved measurements of the solar atmosphere with EUVST.

In order to achieve these goals, the SoSpIM instrument will monitor the spectrally resolved solar irradiance with sub-second time cadence. There will be two channels with redundancy in the following bands:

  • Channel 1: covering 170-215 Å (Al/Zr/Al filter combination)
  • Channel 2: covering 1115-1275 Å (MgF2 filter)

A key advantage of having a ‘Sun-as-astar’ instrument onboard the mission is that all solar flares visible from Earth can be observed. SoSpIM will allow the direct connection to the impact on the Earth. The two channels on SoSpIM will probe the effects on the ionosphere/ thermosphere (mainly with Channel 1)  and the mesosphere and stratosphere (with Channel 2).

Achievements and Status

The Preliminary Design Review (PDR) of SoSPIM was successfully completed in November 2023. Since then, extensive work has been carried out on the Engineering Model (EM; see Figure 1) with thermal and electromagnetic compatibility tests completed. An extensive electrical testing campaign over the year yielded valuable results for the development of the Qualification Model (QM).

The EM is set to join the Communication & Interface Test Campaign in Japan with the EUVST Telescope Electronics Box (TEB) in May 2025. The Structural Thermal Model was manufactured and fully assembled in-house at PMOD/WRC. Its structural integrity was confirmed through a vibration test (Figure 2), and its optical path stability was tested under thermo-elastic loads.

The SoSpIM instrument development is a collaborative effort involving three Swiss industrial partners and the Royal Observatory of Belgium (ROB; Belgium). Dlab GmbH (Switzerland) is tasked with developing the controller board and necessary firmware and electrical ground support equipment (EGSE) nanoTRONIC AG (Switzerland) is advancing the power supply, and MICOS Engineering GmbH (Switzerland) is designing and manufacturing the protective cover and shutter mechanism. ROB is integral in the scientific collaboration, selecting EUV and Lyman-alpha filters and detectors, which were characterised at the Physikalisch-Technische Bundesanstalt (PTB; Germany).

Figure 1. The SoSpIM engineering model (EM) with the electronic boards integrated into the housing.

Figure 2. Test setup of the SoSpIM Structural Thermal Model on the vibration shaker.

Source and credits: ESA, NASA, JAXA, PMOD/WRC

News & Info

News

Wie sagt man das Wetter im All voraus, Frau Harra?

Am Physikalisch-Meteorologischen Observatorium Davos (PMOD) baut ein Forschungsteam rund um ETH-Professorin Louise Harra (54) ein Instrument, das ins All fliegen wird . . .
Blick, 12 Sep. 2023

Information

Links

Solar-C, JAXA
Solar-C, Institute of Space and Astronautical Science, JAXA

Main Collaboration Partners

Royal Observatory of Belgium (ROB), Brussels, Belgium
Japanese Aerospace Exploration Agency (JAXA), Japan
National Astronomical Observatory of Japan (NAOJ), Japan
Physikalisch-Meteorologisches Observatorium Davos (PMOD/WRC), Davos, Switzerland

Swiss Scientific Contact

Louise Harra

SoSpIM Science Meeting 2024

SoSpIM Science Meeting 2024

Download PDFs of talks (password protected) →
Please contact Krzysztof Barczynski for access

Mission Facts

Mission Facts

Launch 2028
Spacecraft Solar-C
Orbit/Location Polar orbit, inclination 89°
Nominal mission duration tbd
PMOD/WRC instruments/involvement Spectral Solar Irradiance Monitor (SoSpIM)
Mass 3500 g
Dimensions tbd
Power consumption 4.6 Watt (average)
Funding Swiss Space Office SSO / ESA PRODEX Programme

 

Source and credits: ESA, NASA, JAXA, PMOD/WRC