Ground calibrations of PHEBUS spectrometer onboard of BepiColombo mission

Probing of Hermean Exosphere by Ultraviolet Spectroscopy (PHEBUS) is a two channels spectrometer working in the Extreme Ultraviolet (EUV) and Far Ultraviolet (FUV) range. It will be onboard of ESA Bepicolombo mission and it is devoted to study the composition, the formation mechanisms and the dynamics of the Mercury exosphere. The instrument has French leadership but Russian, Japanese and Italian teams are involved in the project. In particular, the Italian team is responsible of the radiometric ground calibrations of the instrument. In this work an innovative approach to model the radiometric behavior of an optical instrument is described and applied to PHEBUS. The model obtained takes into account also the eects induced by the polarized light. We have found that, under specic conditions, the radiometric response can be divided into two main components: the eciency term which takes into account the eciency of each optical element and the geometrical parameter which takes into account the geometry of the instrument (eld of view, entrance pupil diameter, etc...). In additional to the theoretical model, the PHEBUS calibration activates carried out at the CNR-IFN UOS Padova laboratory are also presented. All activities are focused to determine and experimentally validate the PHEBUS radiometric model by using both an optical sub-system level and an instrument level measurements. In the sub-system level measurements, each optical component has been characterized in order to retrieve the instrument eciency. Instead, with instrument level measurements, the geometric parameters which aect the radiometric response as well as the instrument linear range and its spectral behavior can be experimentally determined: all these points will be fully described and the early experimental results presented

The afocal telescope of the ESA ARIEL mission: analysis of the layout

ARIEL (Atmospheric Remote-sensing Infrared Exoplanet Large-survey) is one of the three present candidates as an M4 ESA mission to be launched in 2026. During its foreseen 3.5 years operation, it will observe spectroscopically in the infrared a large population of known transiting planets in the neighborhood of the Solar System. The aim is to enable a deep understanding of the physics and chemistry of these exoplanets. ARIEL is based on a 1-m class telescope ahead of a suite of instruments: two spectrometer channels covering the band 1.95 to 7.8 μm and four photometric channels (two wide and two narrow band) in the range 0.5 to 1.9 μm. The ARIEL optical design is conceived as a fore-module common afocal telescope that will feed the spectrometer and photometric channels. The telescope optical design is based on an eccentric pupil two-mirror classic Cassegrain configuration coupled to a tertiary paraboloidal mirror. The temperature of the primary mirror (M1) will be monitored and finely tuned by means of an active thermal control system based on thermistors and heaters. They will be switched on and off to maintain the M1 temperature within ±1 K thanks to a proportional-integral-derivative (PID) controller implemented within the Telescope Control Unit (TCU), a Payload electronics subsystem mainly in charge of the active thermal control of the two detectors owning to the spectrometer. TCU will collect the housekeeping data of the controlled subsystems and will forward them to the spacecraft (S/C) by means of the Instrument Control Unit (ICU), the main Payload's electronic Unit linked to the S/C On Board Computer (OBC)

Spectral Imager of the Solar Atmosphere: The First Extreme-Ultraviolet Solar Integral Field Spectrograph Using Slicers

Particle acceleration, and the thermalisation of energetic particles, are fundamental processes across the universe. Whilst the Sun is an excellent object to study this phenomenon, since it is the most energetic particle accelerator in the Solar System, this phenomenon arises in many other astrophysical objects, such as active galactic nuclei, black holes, neutron stars, gamma ray bursts, solar and stellar coronae, accretion disks and planetary magnetospheres. Observations in the Extreme Ultraviolet (EUV) are essential for these studies but can only be made from space. Current spectrographs operating in the EUV use an entrance slit and cover the required field of view using a scanning mechanism. This results in a relatively slow image cadence in the order of minutes to capture inherently rapid and transient processes, and/or in the spectrograph slit ‘missing the action’. The application of image slicers for EUV integral field spectrographs is therefore revolutionary. The development of this technology will enable the observations of EUV spectra from an entire 2D field of view in seconds, over two orders of magnitude faster than what is currently possible. The Spectral Imaging of the Solar Atmosphere (SISA) instrument is the first integral field spectrograph proposed for observations at ∼180 Å combining the image slicer technology and curved diffraction gratings in a highly efficient and compact layout, while providing important spectroscopic diagnostics for the characterisation of solar coronal and flare plasmas. SISA’s characteristics, main challenges, and the on-going activities to enable the image slicer technology for EUV applications are presented in this paper

The Solar Particle Acceleration Radiation and Kinetics (SPARK) Mission Concept

© 2023by the authors. Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Particle acceleration is a fundamental process arising in many astrophysical objects, including active galactic nuclei, black holes, neutron stars, gamma-ray bursts, accretion disks, solar and stellar coronae, and planetary magnetospheres. Its ubiquity means energetic particles permeate the Universe and influence the conditions for the emergence and continuation of life. In our solar system, the Sun is the most energetic particle accelerator, and its proximity makes it a unique laboratory in which to explore astrophysical particle acceleration. However, despite its importance, the physics underlying solar particle acceleration remain poorly understood. The SPARK mission will reveal new discoveries about particle acceleration through a uniquely powerful and complete combination of γ-ray, X-ray, and EUV imaging and spectroscopy at high spectral, spatial, and temporal resolutions. SPARK’s instruments will provide a step change in observational capability, enabling fundamental breakthroughs in our understanding of solar particle acceleration and the phenomena associated with it, such as the evolution of solar eruptive events. By providing essential diagnostics of the processes that drive the onset and evolution of solar flares and coronal mass ejections, SPARK will elucidate the underlying physics of space weather events that can damage satellites and power grids, disrupt telecommunications and GPS navigation, and endanger astronauts in space. The prediction of such events and the mitigation of their potential impacts are crucial in protecting our terrestrial and space-based infrastructure.Peer reviewe

The Solar Particle Acceleration Radiation and Kinetics (SPARK) mission concept

Particle acceleration is a fundamental process arising in many astrophysical objects, including active galactic nuclei, black holes, neutron stars, gamma-ray bursts, accretion disks, solar and stellar coronae, and planetary magnetospheres. Its ubiquity means energetic particles permeate the Universe and influence the conditions for the emergence and continuation of life. In our solar system, the Sun is the most energetic particle accelerator, and its proximity makes it a unique laboratory in which to explore astrophysical particle acceleration. However, despite its importance, the physics underlying solar particle acceleration remain poorly understood. The SPARK mission will reveal new discoveries about particle acceleration through a uniquely powerful and complete combination of γ-ray, X-ray, and EUV imaging and spectroscopy at high spectral, spatial, and temporal resolutions. SPARK’s instruments will provide a step change in observational capability, enabling fundamental breakthroughs in our understanding of solar particle acceleration and the phenomena associated with it, such as the evolution of solar eruptive events. By providing essential diagnostics of the processes that drive the onset and evolution of solar flares and coronal mass ejections, SPARK will elucidate the underlying physics of space weather events that can damage satellites and power grids, disrupt telecommunications and GPS navigation, and endanger astronauts in space. The prediction of such events and the mitigation of their potential impacts are crucial in protecting our terrestrial and space-based infrastructure

The Solar Particle Acceleration Radiation and Kinetics (SPARK) Mission Concept

Particle acceleration is a fundamental process arising in many astrophysical objects, including active galactic nuclei, black holes, neutron stars, gamma-ray bursts, accretion disks, solar and stellar coronae, and planetary magnetospheres. Its ubiquity means energetic particles permeate the Universe and influence the conditions for the emergence and continuation of life. In our solar system, the Sun is the most energetic particle accelerator, and its proximity makes it a unique laboratory in which to explore astrophysical particle acceleration. However, despite its importance, the physics underlying solar particle acceleration remain poorly understood. The SPARK mission will reveal new discoveries about particle acceleration through a uniquely powerful and complete combination of γ-ray, X-ray, and EUV imaging and spectroscopy at high spectral, spatial, and temporal resolutions. SPARK’s instruments will provide a step change in observational capability, enabling fundamental breakthroughs in our understanding of solar particle acceleration and the phenomena associated with it, such as the evolution of solar eruptive events. By providing essential diagnostics of the processes that drive the onset and evolution of solar flares and coronal mass ejections, SPARK will elucidate the underlying physics of space weather events that can damage satellites and power grids, disrupt telecommunications and GPS navigation, and endanger astronauts in space. The prediction of such events and the mitigation of their potential impacts are crucial in protecting our terrestrial and space-based infrastructure

Nanostructured optical coatings for solar physics observations from space

METIS is a coronagraph onboard of Solar Orbiter. It will perform simultaneous observation at HeII Lyman-α line, HI Lyman-α line and in visible. To achieve such capability, instrument mirrors need to be coated by multilayer structures with high efficiency at all three spectral ranges. Coatings with higher performances respect than standard coating based on Mo/Si couple are desirable. SCORE, an instrument prototype of METIS, has just flown on board of a NASA sounding rocket: in this case, optics were coated with Mg/SiC couple. Better performances have been obtained in term of reflectivity, but long term stability of this coating is an open problem. Moreover the harsh conditions of the environment met during the Solar Orbiter mission given by plasma particles and high temperature could affect the lifetime of the optical components on the long term. We present the design and reflectivity tests of new multilayer structure in which performances improvement is obtained by the use of novel capping layers. All multilayers are tuned at 30.4nm line but the design also maximize the performances at 121.6nm and 500 - 650 nm visible range. Analysis of Solar Orbiter environment have been carried on in order to point out the main damaging sources for the nanostructures. Experimental tests for investigating the effects of the thermal heating and particles bombardments in the reflectivity performances have been planne

Ground calibrations of PHEBUS spectrometer onboard of BepiColombo mission

Probing of Hermean Exosphere by Ultraviolet Spectroscopy (PHEBUS) is a two channels spectrometer working in the Extreme Ultraviolet (EUV) and Far Ultraviolet (FUV) range. It will be onboard of ESA Bepicolombo mission and it is devoted to study the composition, the formation mechanisms and the dynamics of the Mercury exosphere. The instrument has French leadership but Russian, Japanese and Italian teams are involved in the project. In particular, the Italian team is responsible of the radiometric ground calibrations of the instrument. In this work an innovative approach to model the radiometric behavior of an optical instrument is described and applied to PHEBUS. The model obtained takes into account also the eects induced by the polarized light. We have found that, under specic conditions, the radiometric response can be divided into two main components: the eciency term which takes into account the eciency of each optical element and the geometrical parameter which takes into account the geometry of the instrument (eld of view, entrance pupil diameter, etc...). In additional to the theoretical model, the PHEBUS calibration activates carried out at the CNR-IFN UOS Padova laboratory are also presented. All activities are focused to determine and experimentally validate the PHEBUS radiometric model by using both an optical sub-system level and an instrument level measurements. In the sub-system level measurements, each optical component has been characterized in order to retrieve the instrument eciency. Instead, with instrument level measurements, the geometric parameters which aect the radiometric response as well as the instrument linear range and its spectral behavior can be experimentally determined: all these points will be fully described and the early experimental results presented.Probing of Hermean Exosphere by Ultraviolet Spectroscopy (PHEBUS) è uno spettrometro a due canali che lavora nell'estremo ultravioletto (EUV) e nel lontano ultravioletto (FUV). Questo spettrometro sarà a bordo della missione ESA BepiColombo e si dedicherà allo studio della composizione, dei meccanismi di formazione e della dinamica dell'esosfera di Mercurio. Lo strumento è realizzato dalla Francia ma ad esso collaborano Russia, Giappone e Italia. In particolare, il team italiano è responsabile delle calibrazioni radiometriche a terra dello strumento. In questo lavoro, è descritto un innovativo approccio per modellizzare il comportamento radiometrico di uno strumento ed esso è applicato a PHEBUS. Questo nuovo modello consente di considerare anche gli e etti della luce polarizzata sulla risposta radiometrica dello strumento. E' stato trovato che, sotto determinate condizioni, la risposta radiometrica può essere divisa in due parti principali: il termine di efficienza che tiene conto dell'efficienza di ogni componente ottico e il parametro geometrico che tiene conto della geometria sica dello strumento (campo di vista, diametro della pupilla d'ingresso, ecc...). In aggiunta al modello teorico dello strumento, sono anche presentate le attività di calibrazione di PHEBUS che sono state svolte presso il laboratorio del CNR-IFN UOS Padova. Tutte le attività hanno lo scopo di determinare e validare sperimentalmente il modello radiometrico di PHEBUS utilizzando misure a livello dei sotto componenti ottici e dell'intero strumento. Con le misure a livello di sotto componenti, ogni componente ottico è stato caratterizzato allo scopo di determinare l'efficienza dello strumento. Invece, con le misure a livello di strumento, i parametri geometrici che condizionano la risposta radiometrica, il range di linearità dello strumento e il suo comportamento spettrale possono essere caratterizzati sperimentalmente: tutti questi aspetti verranno ampliamente descritti e i primi risultati sperimentali presentati