The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Silvano Fineschi - One of the best experts on this subject based on the ideXlab platform.
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Metis: the Solar Orbiter visible light and ultraviolet coronal imager
Astronomy & Astrophysics, 2020Co-Authors: Ester Antonucci, Vincenzo Andretta, Daniele Spadaro, Gianalfredo Nicolini, Silvano Fineschi, Marco Romoli, John D. Moses, Giampiero Naletto, Petr Heinzel, Luca TeriacaAbstract:Metis is the first solar coronagraph designed for a space mission capable of performing simultaneous imaging of the off-limb solar corona in both visible and UV light. The observations obtained with Metis aboard the Solar Orbiter ESA-NASA observatory will enable us to diagnose, with unprecedented temporal coverage and spatial resolution, the structures and dynamics of the full corona from 1.7 $R_\odot$ to about 9 $R_\odot$. Due to the uniqueness of the Solar Orbiter mission profile, Metis will be able to observe the solar corona from a close vantage point (down to 0.28 AU), achieving out-of-ecliptic views with the increase of the orbit inclination over time. Moreover, observations near perihelion, during the phase of lower rotational velocity of the solar surface relative to the spacecraft, will allow longer-term studies of the coronal features. Thanks to a novel occultation design and a combination of a UV interference coating of the mirrors and a spectral bandpass filter, Metis images the solar corona simultaneously in the visible light band, between 580 and 640 nm, and in the UV H I Lyman-{\alpha} line at 121.6 nm. The coronal images in both the UV Lyman-{\alpha} and polarised visible light are obtained at high spatial resolution with a spatial scale down to about 2000 km and 15000 km at perihelion, in the cases of the visible and UV light, respectively. A temporal resolution down to 1 second can be achieved when observing coronal fluctuations in visible light. The Metis measurements will allow for complete characterisation of the main physical parameters and dynamics of the electron and neutral hydrogen/proton plasma components of the corona in the region where the solar wind undergoes acceleration and where the onset and initial propagation of coronal mass ejections take place, thus significantly improving our understanding of the region connecting the Sun to the heliosphere.
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Metis solar orbiter polarimetric visible light channel calibration
International Conference on Space Optics — ICSO 2018, 2019Co-Authors: M Casti, Gerardo Capobianco, Silvano Fineschi, E Antonucci, G. Naletto, M. Romoli, G. Nicolini, D. Spadaro, P Nicolosi, Vincenzo AndrettaAbstract:Metis is the solar coronagraph of the ESA mission Solar Orbiter. For the first time, Metis will acquire simultaneous images of the solar corona in linearly polarized, broadband visible light (580-640 nm) and in the narrow-band HI Ly-α line (121.6 nm). The visible light path includes a polarimeter, designed to observe and analyse the K-corona linearly polarized by Thomson scattering. The polarimeter comprises a liquid crystal Polarization Modulation Package (PMP) together with a quarter-wave retarder and a linear polarizer. The Metis PMP consists of two Anti-Parallel Nematic Liquid Crystal Variable Retarders (LCVRs) with their fast axis parallel with respect to each other and a pre-tilted angle of the molecules in opposite direction. This configuration results in an instrumental wide field of view (±7°). The LCVRs provide an electro-optical modulation of the input polarized light by applying an electric field to the liquid crystal molecules inside the cells. A given optical retardance can be induced in the LCVRs by selecting a suitable voltage value. This paper reports the polarimetric characterization of the Visible-light channel for the Metis/Solar Orbiter coronagraph. The retardance-to-voltage calibration of the electro-optical polarimeter was characterized over the entire field of view of the coronagraph yielding a complete “polarimetric flat-field” of the Metis Visible-light channel.
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optical performance of the Metis coronagraph on the solar orbiter esa mission
International Conference on Space Optics - ICSO 2018 2018 Chania Greece, 2019Co-Authors: Fabio Frassetto, Silvano Fineschi, E Antonucci, M. Romoli, V. Deppo, G. Nicolini, P Nicolosi, Giampiero Naletto, Paola Zuppella, D. SpadaroAbstract:The Metis coronagraph aboard the Solar Orbiter ESA spacecraft is expected to provide new insights into the solar dynamics. In detail, it is designed to address three main questions: the energy deposition mechanism at the poles (where the fast wind is originated), the source of the slow wind at lower altitude, and how the global corona evolves, in particular in relation to the huge plasma ejections that occasionally are produced. To obtain the required optical performance, not only the Metis optical design has been highly optimized, but the alignment procedure has also been subjected to an accurate evaluation in order to fulfill the integration specifications. The telescope assembling sequence has been constructed considering all the subsystems manufacturing, alignment and integration tolerances. The performance verification activity is an important milestone in the instrument characterization and the obtained results will assure the fulfillment of the science requirements for its operation in space. The entire alignment and verification phase has been performed by the Metis team in collaboration with Thales Alenia Space Torino and took place in ALTEC (Turin) at the Optical Payload System Facility using the Space Optics Calibration Chamber infrastructure, a vacuum chamber especially built and tested for the alignment and calibration of the Metis coronagraph, and suitable for tests of future payloads. The goal of the alignment, integration, verification and calibration processes is to measure the parameters of the telescope, and the characteristics of the two Metis channels: visible and ultraviolet. They work in parallel thanks to the peculiar optical layout. The focusing and alignment performance of the two channels must be well understood, and the results need to be easily compared to the requirements. For this, a dedicated illumination method, with both channels fed by the same source, has been developed; and a procedure to perform a simultaneous through focus analysis has been adopted. In this paper the final optical performance achieved by Metis is reported and commented.
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Alignment procedure for the Gregorian telescope of the Metis coronagraph for the Solar Orbiter ESA mission
International Conference on Space Optics — ICSO 2018, 2019Co-Authors: V. Deppo, Silvano Fineschi, Marco Romoli, Ester Antonucci, Giampiero Naletto, Fabio Frassetto, Paola Zuppella, Sergio Mottini, M. G. Sertsu, Gianalfredo NicoliniAbstract:Metis is a solar coronagraph mounted on-board the Solar Orbiter ESA spacecraft. Solar Orbiter is scheduled for launch in February 2020 and it is dedicated to study the solar and heliospheric physics from a privileged close and inclined orbit around the Sun. Perihelion passages with a minimum distance of 0.28 AU are foreseen. Metis features two channels to image the solar corona in two different spectral bands: in the HI Lyman ∝ at 121.6 nm, and in the polarized visible light band (580 – 640 nm). Metis is a solar coronagraph adopting an “inverted occulted” configuration. The inverted external occulter (IEO) is a circular aperture followed by a spherical mirror which back rejects the disk light. The reflected disk light exits the instrument through the IEO aperture itself, while the passing coronal light is collected by the Metis telescope. Common to both channels, the Gregorian on-axis telescope is centrally occulted and both the primary and the secondary mirror have annular shape. Classic alignment methods adopted for on-axis telescope cannot be used, since the on-axis field is not available. A novel and ad hoc alignment set-up has been developed for the telescope alignment. An auxiliary visible optical ground support equipment source has been conceived for the telescope alignment. It is made up by four collimated beams inclined and dimensioned to illuminate different sections of the annular primary mirror without being vignetted by other optical or mechanical elements of the instrument.
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Metis the multi element telescope for imaging and spectroscopy an instrument proposed for the solar orbiter mission
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 2017Co-Authors: E Antonucci, Silvano Fineschi, D. Moses, V Andretta, S Cesare, A Ciaravella, G A Doschek, S Giordano, P Lamy, Giampiero NalettoAbstract:Metis, the Multi Element Telescope for Imaging and Spectroscopy, is an instrument proposed to the European Space Agency to be part of the payload of the Solar Orbiter mission. The instrument design has been conceived for performing extreme ultraviolet (EUV) spectroscopy both on the solar disk and off-limb, and near-Sun coronagraphy and spectroscopy. The proposed instrument suite consists of three different interconnected elements, COR, EUS and SOCS, sharing the same optical bench, electronics, and S/C heat shield aperture. COR is a visible-EUV multiband coronagraph based on a classical externally occulted design. EUS is the component of the Metis EUV disk spectrometer which includes the telescope and all the related mechanisms. Finally, SOCS is the Metis spectroscopic component including the dispersive system and the detectors. The capability of inserting a small telescope collecting coronal light has been added to perform also EUV coronal spectroscopy. Metis can simultaneously image the visible and ultraviolet emission of the solar corona and diagnose, with unprecedented temporal coverage and space resolution the structure and dynamics of the full corona in the range from 1.2 to 3.0 (1.6 to 4.1) solar radii (R, measured from Sun centre) at minimum (maximum) perihelion during the nominal mission. It can also perform spectroscopic observations of the solar disk and out to 1.4 R
Giampiero Naletto - One of the best experts on this subject based on the ideXlab platform.
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Metis: the Solar Orbiter visible light and ultraviolet coronal imager
Astronomy & Astrophysics, 2020Co-Authors: Ester Antonucci, Vincenzo Andretta, Daniele Spadaro, Gianalfredo Nicolini, Silvano Fineschi, Marco Romoli, John D. Moses, Giampiero Naletto, Petr Heinzel, Luca TeriacaAbstract:Metis is the first solar coronagraph designed for a space mission capable of performing simultaneous imaging of the off-limb solar corona in both visible and UV light. The observations obtained with Metis aboard the Solar Orbiter ESA-NASA observatory will enable us to diagnose, with unprecedented temporal coverage and spatial resolution, the structures and dynamics of the full corona from 1.7 $R_\odot$ to about 9 $R_\odot$. Due to the uniqueness of the Solar Orbiter mission profile, Metis will be able to observe the solar corona from a close vantage point (down to 0.28 AU), achieving out-of-ecliptic views with the increase of the orbit inclination over time. Moreover, observations near perihelion, during the phase of lower rotational velocity of the solar surface relative to the spacecraft, will allow longer-term studies of the coronal features. Thanks to a novel occultation design and a combination of a UV interference coating of the mirrors and a spectral bandpass filter, Metis images the solar corona simultaneously in the visible light band, between 580 and 640 nm, and in the UV H I Lyman-{\alpha} line at 121.6 nm. The coronal images in both the UV Lyman-{\alpha} and polarised visible light are obtained at high spatial resolution with a spatial scale down to about 2000 km and 15000 km at perihelion, in the cases of the visible and UV light, respectively. A temporal resolution down to 1 second can be achieved when observing coronal fluctuations in visible light. The Metis measurements will allow for complete characterisation of the main physical parameters and dynamics of the electron and neutral hydrogen/proton plasma components of the corona in the region where the solar wind undergoes acceleration and where the onset and initial propagation of coronal mass ejections take place, thus significantly improving our understanding of the region connecting the Sun to the heliosphere.
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optical performance of the Metis coronagraph on the solar orbiter esa mission
International Conference on Space Optics - ICSO 2018 2018 Chania Greece, 2019Co-Authors: Fabio Frassetto, Silvano Fineschi, E Antonucci, M. Romoli, V. Deppo, G. Nicolini, P Nicolosi, Giampiero Naletto, Paola Zuppella, D. SpadaroAbstract:The Metis coronagraph aboard the Solar Orbiter ESA spacecraft is expected to provide new insights into the solar dynamics. In detail, it is designed to address three main questions: the energy deposition mechanism at the poles (where the fast wind is originated), the source of the slow wind at lower altitude, and how the global corona evolves, in particular in relation to the huge plasma ejections that occasionally are produced. To obtain the required optical performance, not only the Metis optical design has been highly optimized, but the alignment procedure has also been subjected to an accurate evaluation in order to fulfill the integration specifications. The telescope assembling sequence has been constructed considering all the subsystems manufacturing, alignment and integration tolerances. The performance verification activity is an important milestone in the instrument characterization and the obtained results will assure the fulfillment of the science requirements for its operation in space. The entire alignment and verification phase has been performed by the Metis team in collaboration with Thales Alenia Space Torino and took place in ALTEC (Turin) at the Optical Payload System Facility using the Space Optics Calibration Chamber infrastructure, a vacuum chamber especially built and tested for the alignment and calibration of the Metis coronagraph, and suitable for tests of future payloads. The goal of the alignment, integration, verification and calibration processes is to measure the parameters of the telescope, and the characteristics of the two Metis channels: visible and ultraviolet. They work in parallel thanks to the peculiar optical layout. The focusing and alignment performance of the two channels must be well understood, and the results need to be easily compared to the requirements. For this, a dedicated illumination method, with both channels fed by the same source, has been developed; and a procedure to perform a simultaneous through focus analysis has been adopted. In this paper the final optical performance achieved by Metis is reported and commented.
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Alignment procedure for the Gregorian telescope of the Metis coronagraph for the Solar Orbiter ESA mission
International Conference on Space Optics — ICSO 2018, 2019Co-Authors: V. Deppo, Silvano Fineschi, Marco Romoli, Ester Antonucci, Giampiero Naletto, Fabio Frassetto, Paola Zuppella, Sergio Mottini, M. G. Sertsu, Gianalfredo NicoliniAbstract:Metis is a solar coronagraph mounted on-board the Solar Orbiter ESA spacecraft. Solar Orbiter is scheduled for launch in February 2020 and it is dedicated to study the solar and heliospheric physics from a privileged close and inclined orbit around the Sun. Perihelion passages with a minimum distance of 0.28 AU are foreseen. Metis features two channels to image the solar corona in two different spectral bands: in the HI Lyman ∝ at 121.6 nm, and in the polarized visible light band (580 – 640 nm). Metis is a solar coronagraph adopting an “inverted occulted” configuration. The inverted external occulter (IEO) is a circular aperture followed by a spherical mirror which back rejects the disk light. The reflected disk light exits the instrument through the IEO aperture itself, while the passing coronal light is collected by the Metis telescope. Common to both channels, the Gregorian on-axis telescope is centrally occulted and both the primary and the secondary mirror have annular shape. Classic alignment methods adopted for on-axis telescope cannot be used, since the on-axis field is not available. A novel and ad hoc alignment set-up has been developed for the telescope alignment. An auxiliary visible optical ground support equipment source has been conceived for the telescope alignment. It is made up by four collimated beams inclined and dimensioned to illuminate different sections of the annular primary mirror without being vignetted by other optical or mechanical elements of the instrument.
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Metis the multi element telescope for imaging and spectroscopy an instrument proposed for the solar orbiter mission
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 2017Co-Authors: E Antonucci, Silvano Fineschi, D. Moses, V Andretta, S Cesare, A Ciaravella, G A Doschek, S Giordano, P Lamy, Giampiero NalettoAbstract:Metis, the Multi Element Telescope for Imaging and Spectroscopy, is an instrument proposed to the European Space Agency to be part of the payload of the Solar Orbiter mission. The instrument design has been conceived for performing extreme ultraviolet (EUV) spectroscopy both on the solar disk and off-limb, and near-Sun coronagraphy and spectroscopy. The proposed instrument suite consists of three different interconnected elements, COR, EUS and SOCS, sharing the same optical bench, electronics, and S/C heat shield aperture. COR is a visible-EUV multiband coronagraph based on a classical externally occulted design. EUS is the component of the Metis EUV disk spectrometer which includes the telescope and all the related mechanisms. Finally, SOCS is the Metis spectroscopic component including the dispersive system and the detectors. The capability of inserting a small telescope collecting coronal light has been added to perform also EUV coronal spectroscopy. Metis can simultaneously image the visible and ultraviolet emission of the solar corona and diagnose, with unprecedented temporal coverage and space resolution the structure and dynamics of the full corona in the range from 1.2 to 3.0 (1.6 to 4.1) solar radii (R, measured from Sun centre) at minimum (maximum) perihelion during the nominal mission. It can also perform spectroscopic observations of the solar disk and out to 1.4 R
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Metis: the visible and UV coronagraph for solar orbiter
International Conference on Space Optics — ICSO 2014, 2017Co-Authors: Marco Romoli, Vincenzo Andretta, Federico Landini, Silvano Fineschi, Ester Antonucci, Arkadiusz Berlicki, John D. Moses, Giampiero Naletto, Piergiorgio Nicolosi, Gianalfredo NicoliniAbstract:Metis coronagraph is designed to observe the solar corona with an annular field of view from 1.5 to 2.9 degrees in the visible broadband (580-640 nm) and in the UV HI Lyman-alpha, during the Sun close approaching and high latitude tilting orbit of Solar Orbiter. The big challenge for a coronagraph is the stray light rejection. In this paper after a description of the present Metis optical design, the stray light rejection design is presented in detail together with Metis off-pointing strategies throughout the mission. Data shown in this paper derive from the optimization of the optical design performed with Zemax ray tracing and from laboratory breadboards of the occultation system and of the polarimeter.
Vincenzo Andretta - One of the best experts on this subject based on the ideXlab platform.
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Metis: the Solar Orbiter visible light and ultraviolet coronal imager
Astronomy & Astrophysics, 2020Co-Authors: Ester Antonucci, Vincenzo Andretta, Daniele Spadaro, Gianalfredo Nicolini, Silvano Fineschi, Marco Romoli, John D. Moses, Giampiero Naletto, Petr Heinzel, Luca TeriacaAbstract:Metis is the first solar coronagraph designed for a space mission capable of performing simultaneous imaging of the off-limb solar corona in both visible and UV light. The observations obtained with Metis aboard the Solar Orbiter ESA-NASA observatory will enable us to diagnose, with unprecedented temporal coverage and spatial resolution, the structures and dynamics of the full corona from 1.7 $R_\odot$ to about 9 $R_\odot$. Due to the uniqueness of the Solar Orbiter mission profile, Metis will be able to observe the solar corona from a close vantage point (down to 0.28 AU), achieving out-of-ecliptic views with the increase of the orbit inclination over time. Moreover, observations near perihelion, during the phase of lower rotational velocity of the solar surface relative to the spacecraft, will allow longer-term studies of the coronal features. Thanks to a novel occultation design and a combination of a UV interference coating of the mirrors and a spectral bandpass filter, Metis images the solar corona simultaneously in the visible light band, between 580 and 640 nm, and in the UV H I Lyman-{\alpha} line at 121.6 nm. The coronal images in both the UV Lyman-{\alpha} and polarised visible light are obtained at high spatial resolution with a spatial scale down to about 2000 km and 15000 km at perihelion, in the cases of the visible and UV light, respectively. A temporal resolution down to 1 second can be achieved when observing coronal fluctuations in visible light. The Metis measurements will allow for complete characterisation of the main physical parameters and dynamics of the electron and neutral hydrogen/proton plasma components of the corona in the region where the solar wind undergoes acceleration and where the onset and initial propagation of coronal mass ejections take place, thus significantly improving our understanding of the region connecting the Sun to the heliosphere.
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Metis solar orbiter polarimetric visible light channel calibration
International Conference on Space Optics — ICSO 2018, 2019Co-Authors: M Casti, Gerardo Capobianco, Silvano Fineschi, E Antonucci, G. Naletto, M. Romoli, G. Nicolini, D. Spadaro, P Nicolosi, Vincenzo AndrettaAbstract:Metis is the solar coronagraph of the ESA mission Solar Orbiter. For the first time, Metis will acquire simultaneous images of the solar corona in linearly polarized, broadband visible light (580-640 nm) and in the narrow-band HI Ly-α line (121.6 nm). The visible light path includes a polarimeter, designed to observe and analyse the K-corona linearly polarized by Thomson scattering. The polarimeter comprises a liquid crystal Polarization Modulation Package (PMP) together with a quarter-wave retarder and a linear polarizer. The Metis PMP consists of two Anti-Parallel Nematic Liquid Crystal Variable Retarders (LCVRs) with their fast axis parallel with respect to each other and a pre-tilted angle of the molecules in opposite direction. This configuration results in an instrumental wide field of view (±7°). The LCVRs provide an electro-optical modulation of the input polarized light by applying an electric field to the liquid crystal molecules inside the cells. A given optical retardance can be induced in the LCVRs by selecting a suitable voltage value. This paper reports the polarimetric characterization of the Visible-light channel for the Metis/Solar Orbiter coronagraph. The retardance-to-voltage calibration of the electro-optical polarimeter was characterized over the entire field of view of the coronagraph yielding a complete “polarimetric flat-field” of the Metis Visible-light channel.
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Metis: the visible and UV coronagraph for solar orbiter
International Conference on Space Optics — ICSO 2014, 2017Co-Authors: Marco Romoli, Vincenzo Andretta, Federico Landini, Silvano Fineschi, Ester Antonucci, Arkadiusz Berlicki, John D. Moses, Giampiero Naletto, Piergiorgio Nicolosi, Gianalfredo NicoliniAbstract:Metis coronagraph is designed to observe the solar corona with an annular field of view from 1.5 to 2.9 degrees in the visible broadband (580-640 nm) and in the UV HI Lyman-alpha, during the Sun close approaching and high latitude tilting orbit of Solar Orbiter. The big challenge for a coronagraph is the stray light rejection. In this paper after a description of the present Metis optical design, the stray light rejection design is presented in detail together with Metis off-pointing strategies throughout the mission. Data shown in this paper derive from the optimization of the optical design performed with Zemax ray tracing and from laboratory breadboards of the occultation system and of the polarimeter.
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a virtual appliance as proxy pipeline for the solar orbiter Metis coronagraph
Proceedings of SPIE, 2016Co-Authors: Maurizio Pancrazzi, T. Straus, Vincenzo Andretta, Daniele Spadaro, S. V. H. Haugan, A. De Groof, R. Carr, Mauro Focardi, Gianalfredo Nicolini, Federico LandiniAbstract:Metis is the coronagraph on board Solar Orbiter, the ESA mission devoted to the study of the Sun that will be launched in October 2018. Metis is designed to perform imaging of the solar corona in the UV at 121.6 nm and in the visible range where it will accomplish polarimetry studies thanks to a variable retarder plate. Due to mission constraints, the telemetry downlink on the spacecraft will be limited and data will be downloaded with delays that could reach, in the worst case, several months. In order to have a quick overview on the ongoing operations and to check the safety of the 10 instruments on board, a high-priority downlink channel has been foreseen to download a restricted amount of data. These so-called Low Latency Data will be downloaded daily and, since they could trigger possible actions, they have to be quickly processed on ground as soon as they are delivered. To do so, a proper processing pipeline has to be developed by each instrument. This tool will then be integrated in a single system at the ESA Science Operation Center that will receive the downloaded data by the Mission Operation Center. This paper will provide a brief overview of the on board processing and data produced by Metis and it will describe the proxy-pipeline currently under development to deal with the Metis low-latency data.
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Metis: a novel coronagraph design for the Solar Orbiter mission
Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray, 2012Co-Authors: Silvano Fineschi, Vincenzo Andretta, Daniele Spadaro, Gianalfredo Nicolini, Marco Romoli, Ester Antonucci, Giampiero Naletto, L. Abbo, Alessandro Bemporad, Arkadiusz BerlickiAbstract:Metis (Multi Element Telescope for Imaging and Spectroscopy) Metis, the “Multi Element Telescope for Imaging and Spectroscopy”, is a coronagraph selected by the European Space Agency to be part of the payload of the Solar Orbiter mission to be launched in 2017. The mission profile will bring the Solar Orbiter spacecraft as close to the Sun as 0.3 A.U., and up to 35° out-of-ecliptic providing a unique platform for helio-synchronous observations of the Sun and its polar regions. Metis coronagraph is designed for multi-wavelength imaging and spectroscopy of the solar corona. This presentation gives an overview of the innovative design elements of the Metis coronagraph. These elements include: i) multi-wavelength, reflecting Gregorian-telescope; ii) multilayer coating optimized for the extreme UV (30.4 nm, HeII Lyman-α) with a reflecting cap-layer for the UV (121.6 nm, HI Lyman-α) and visible-light (590-650); iii) inverse external-occulter scheme for reduced thermal load at spacecraft peri-helion; iv) EUV/UV spectrograph using the telescope primary mirror to feed a 1 st and 4 th -order spherical varied line-spaced (SVLS) grating placed on a section of the secondary mirror; v) liquid crystals electro-optic polarimeter for observations of the visible-light K-corona. The expected performances are also presented.
Gianalfredo Nicolini - One of the best experts on this subject based on the ideXlab platform.
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Metis: the Solar Orbiter visible light and ultraviolet coronal imager
Astronomy & Astrophysics, 2020Co-Authors: Ester Antonucci, Vincenzo Andretta, Daniele Spadaro, Gianalfredo Nicolini, Silvano Fineschi, Marco Romoli, John D. Moses, Giampiero Naletto, Petr Heinzel, Luca TeriacaAbstract:Metis is the first solar coronagraph designed for a space mission capable of performing simultaneous imaging of the off-limb solar corona in both visible and UV light. The observations obtained with Metis aboard the Solar Orbiter ESA-NASA observatory will enable us to diagnose, with unprecedented temporal coverage and spatial resolution, the structures and dynamics of the full corona from 1.7 $R_\odot$ to about 9 $R_\odot$. Due to the uniqueness of the Solar Orbiter mission profile, Metis will be able to observe the solar corona from a close vantage point (down to 0.28 AU), achieving out-of-ecliptic views with the increase of the orbit inclination over time. Moreover, observations near perihelion, during the phase of lower rotational velocity of the solar surface relative to the spacecraft, will allow longer-term studies of the coronal features. Thanks to a novel occultation design and a combination of a UV interference coating of the mirrors and a spectral bandpass filter, Metis images the solar corona simultaneously in the visible light band, between 580 and 640 nm, and in the UV H I Lyman-{\alpha} line at 121.6 nm. The coronal images in both the UV Lyman-{\alpha} and polarised visible light are obtained at high spatial resolution with a spatial scale down to about 2000 km and 15000 km at perihelion, in the cases of the visible and UV light, respectively. A temporal resolution down to 1 second can be achieved when observing coronal fluctuations in visible light. The Metis measurements will allow for complete characterisation of the main physical parameters and dynamics of the electron and neutral hydrogen/proton plasma components of the corona in the region where the solar wind undergoes acceleration and where the onset and initial propagation of coronal mass ejections take place, thus significantly improving our understanding of the region connecting the Sun to the heliosphere.
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Alignment procedure for the Gregorian telescope of the Metis coronagraph for the Solar Orbiter ESA mission
International Conference on Space Optics — ICSO 2018, 2019Co-Authors: V. Deppo, Silvano Fineschi, Marco Romoli, Ester Antonucci, Giampiero Naletto, Fabio Frassetto, Paola Zuppella, Sergio Mottini, M. G. Sertsu, Gianalfredo NicoliniAbstract:Metis is a solar coronagraph mounted on-board the Solar Orbiter ESA spacecraft. Solar Orbiter is scheduled for launch in February 2020 and it is dedicated to study the solar and heliospheric physics from a privileged close and inclined orbit around the Sun. Perihelion passages with a minimum distance of 0.28 AU are foreseen. Metis features two channels to image the solar corona in two different spectral bands: in the HI Lyman ∝ at 121.6 nm, and in the polarized visible light band (580 – 640 nm). Metis is a solar coronagraph adopting an “inverted occulted” configuration. The inverted external occulter (IEO) is a circular aperture followed by a spherical mirror which back rejects the disk light. The reflected disk light exits the instrument through the IEO aperture itself, while the passing coronal light is collected by the Metis telescope. Common to both channels, the Gregorian on-axis telescope is centrally occulted and both the primary and the secondary mirror have annular shape. Classic alignment methods adopted for on-axis telescope cannot be used, since the on-axis field is not available. A novel and ad hoc alignment set-up has been developed for the telescope alignment. An auxiliary visible optical ground support equipment source has been conceived for the telescope alignment. It is made up by four collimated beams inclined and dimensioned to illuminate different sections of the annular primary mirror without being vignetted by other optical or mechanical elements of the instrument.
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Metis: the visible and UV coronagraph for solar orbiter
International Conference on Space Optics — ICSO 2014, 2017Co-Authors: Marco Romoli, Vincenzo Andretta, Federico Landini, Silvano Fineschi, Ester Antonucci, Arkadiusz Berlicki, John D. Moses, Giampiero Naletto, Piergiorgio Nicolosi, Gianalfredo NicoliniAbstract:Metis coronagraph is designed to observe the solar corona with an annular field of view from 1.5 to 2.9 degrees in the visible broadband (580-640 nm) and in the UV HI Lyman-alpha, during the Sun close approaching and high latitude tilting orbit of Solar Orbiter. The big challenge for a coronagraph is the stray light rejection. In this paper after a description of the present Metis optical design, the stray light rejection design is presented in detail together with Metis off-pointing strategies throughout the mission. Data shown in this paper derive from the optimization of the optical design performed with Zemax ray tracing and from laboratory breadboards of the occultation system and of the polarimeter.
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a virtual appliance as proxy pipeline for the solar orbiter Metis coronagraph
Proceedings of SPIE, 2016Co-Authors: Maurizio Pancrazzi, T. Straus, Vincenzo Andretta, Daniele Spadaro, S. V. H. Haugan, A. De Groof, R. Carr, Mauro Focardi, Gianalfredo Nicolini, Federico LandiniAbstract:Metis is the coronagraph on board Solar Orbiter, the ESA mission devoted to the study of the Sun that will be launched in October 2018. Metis is designed to perform imaging of the solar corona in the UV at 121.6 nm and in the visible range where it will accomplish polarimetry studies thanks to a variable retarder plate. Due to mission constraints, the telemetry downlink on the spacecraft will be limited and data will be downloaded with delays that could reach, in the worst case, several months. In order to have a quick overview on the ongoing operations and to check the safety of the 10 instruments on board, a high-priority downlink channel has been foreseen to download a restricted amount of data. These so-called Low Latency Data will be downloaded daily and, since they could trigger possible actions, they have to be quickly processed on ground as soon as they are delivered. To do so, a proper processing pipeline has to be developed by each instrument. This tool will then be integrated in a single system at the ESA Science Operation Center that will receive the downloaded data by the Mission Operation Center. This paper will provide a brief overview of the on board processing and data produced by Metis and it will describe the proxy-pipeline currently under development to deal with the Metis low-latency data.
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Metis: a novel coronagraph design for the Solar Orbiter mission
Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray, 2012Co-Authors: Silvano Fineschi, Vincenzo Andretta, Daniele Spadaro, Gianalfredo Nicolini, Marco Romoli, Ester Antonucci, Giampiero Naletto, L. Abbo, Alessandro Bemporad, Arkadiusz BerlickiAbstract:Metis (Multi Element Telescope for Imaging and Spectroscopy) Metis, the “Multi Element Telescope for Imaging and Spectroscopy”, is a coronagraph selected by the European Space Agency to be part of the payload of the Solar Orbiter mission to be launched in 2017. The mission profile will bring the Solar Orbiter spacecraft as close to the Sun as 0.3 A.U., and up to 35° out-of-ecliptic providing a unique platform for helio-synchronous observations of the Sun and its polar regions. Metis coronagraph is designed for multi-wavelength imaging and spectroscopy of the solar corona. This presentation gives an overview of the innovative design elements of the Metis coronagraph. These elements include: i) multi-wavelength, reflecting Gregorian-telescope; ii) multilayer coating optimized for the extreme UV (30.4 nm, HeII Lyman-α) with a reflecting cap-layer for the UV (121.6 nm, HI Lyman-α) and visible-light (590-650); iii) inverse external-occulter scheme for reduced thermal load at spacecraft peri-helion; iv) EUV/UV spectrograph using the telescope primary mirror to feed a 1 st and 4 th -order spherical varied line-spaced (SVLS) grating placed on a section of the secondary mirror; v) liquid crystals electro-optic polarimeter for observations of the visible-light K-corona. The expected performances are also presented.
E Antonucci - One of the best experts on this subject based on the ideXlab platform.
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Optical design of the multi-wavelength imaging coronagraph Metis for the solar orbiter mission
Experimental Astronomy, 2020Co-Authors: S. Fineschi, A M Malvezzi, E Antonucci, G. Naletto, M. Romoli, V. Deppo, D. Moses, G. Nicolini, D. Spadaro, L. TeriacaAbstract:This paper describes the innovative optical design of the Metis coronagraph for the Solar Orbiter ESA-NASA mission. Metis is a multi-wavelength, externally occulted telescope for the imaging of the solar corona in both the visible and ultraviolet wavelength ranges. Metis adopts a novel occultation scheme for the solar disk, that we named “inverse external occulter”, for reducing the extremely high thermal load on the instrument at the spacecraft perihelion. The core of the Metis optical design is an aplanatic Gregorian telescope common to both the visible and ultraviolet channels. A suitable dichroic beam-splitter, optimized for transmitting a narrow-band in the ultraviolet (121.6 nm, HI Lyman-α) and reflecting a broadband in the visible (580–640 nm) spectral range, is used to separate the two optical paths. Along the visible light optical path, a liquid crystal electro-optical modulator, used for the first time in space, allows making polarimetric measurements.
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Metis solar orbiter polarimetric visible light channel calibration
International Conference on Space Optics — ICSO 2018, 2019Co-Authors: M Casti, Gerardo Capobianco, Silvano Fineschi, E Antonucci, G. Naletto, M. Romoli, G. Nicolini, D. Spadaro, P Nicolosi, Vincenzo AndrettaAbstract:Metis is the solar coronagraph of the ESA mission Solar Orbiter. For the first time, Metis will acquire simultaneous images of the solar corona in linearly polarized, broadband visible light (580-640 nm) and in the narrow-band HI Ly-α line (121.6 nm). The visible light path includes a polarimeter, designed to observe and analyse the K-corona linearly polarized by Thomson scattering. The polarimeter comprises a liquid crystal Polarization Modulation Package (PMP) together with a quarter-wave retarder and a linear polarizer. The Metis PMP consists of two Anti-Parallel Nematic Liquid Crystal Variable Retarders (LCVRs) with their fast axis parallel with respect to each other and a pre-tilted angle of the molecules in opposite direction. This configuration results in an instrumental wide field of view (±7°). The LCVRs provide an electro-optical modulation of the input polarized light by applying an electric field to the liquid crystal molecules inside the cells. A given optical retardance can be induced in the LCVRs by selecting a suitable voltage value. This paper reports the polarimetric characterization of the Visible-light channel for the Metis/Solar Orbiter coronagraph. The retardance-to-voltage calibration of the electro-optical polarimeter was characterized over the entire field of view of the coronagraph yielding a complete “polarimetric flat-field” of the Metis Visible-light channel.
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optical performance of the Metis coronagraph on the solar orbiter esa mission
International Conference on Space Optics - ICSO 2018 2018 Chania Greece, 2019Co-Authors: Fabio Frassetto, Silvano Fineschi, E Antonucci, M. Romoli, V. Deppo, G. Nicolini, P Nicolosi, Giampiero Naletto, Paola Zuppella, D. SpadaroAbstract:The Metis coronagraph aboard the Solar Orbiter ESA spacecraft is expected to provide new insights into the solar dynamics. In detail, it is designed to address three main questions: the energy deposition mechanism at the poles (where the fast wind is originated), the source of the slow wind at lower altitude, and how the global corona evolves, in particular in relation to the huge plasma ejections that occasionally are produced. To obtain the required optical performance, not only the Metis optical design has been highly optimized, but the alignment procedure has also been subjected to an accurate evaluation in order to fulfill the integration specifications. The telescope assembling sequence has been constructed considering all the subsystems manufacturing, alignment and integration tolerances. The performance verification activity is an important milestone in the instrument characterization and the obtained results will assure the fulfillment of the science requirements for its operation in space. The entire alignment and verification phase has been performed by the Metis team in collaboration with Thales Alenia Space Torino and took place in ALTEC (Turin) at the Optical Payload System Facility using the Space Optics Calibration Chamber infrastructure, a vacuum chamber especially built and tested for the alignment and calibration of the Metis coronagraph, and suitable for tests of future payloads. The goal of the alignment, integration, verification and calibration processes is to measure the parameters of the telescope, and the characteristics of the two Metis channels: visible and ultraviolet. They work in parallel thanks to the peculiar optical layout. The focusing and alignment performance of the two channels must be well understood, and the results need to be easily compared to the requirements. For this, a dedicated illumination method, with both channels fed by the same source, has been developed; and a procedure to perform a simultaneous through focus analysis has been adopted. In this paper the final optical performance achieved by Metis is reported and commented.
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Metis the multi element telescope for imaging and spectroscopy an instrument proposed for the solar orbiter mission
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 2017Co-Authors: E Antonucci, Silvano Fineschi, D. Moses, V Andretta, S Cesare, A Ciaravella, G A Doschek, S Giordano, P Lamy, Giampiero NalettoAbstract:Metis, the Multi Element Telescope for Imaging and Spectroscopy, is an instrument proposed to the European Space Agency to be part of the payload of the Solar Orbiter mission. The instrument design has been conceived for performing extreme ultraviolet (EUV) spectroscopy both on the solar disk and off-limb, and near-Sun coronagraphy and spectroscopy. The proposed instrument suite consists of three different interconnected elements, COR, EUS and SOCS, sharing the same optical bench, electronics, and S/C heat shield aperture. COR is a visible-EUV multiband coronagraph based on a classical externally occulted design. EUS is the component of the Metis EUV disk spectrometer which includes the telescope and all the related mechanisms. Finally, SOCS is the Metis spectroscopic component including the dispersive system and the detectors. The capability of inserting a small telescope collecting coronal light has been added to perform also EUV coronal spectroscopy. Metis can simultaneously image the visible and ultraviolet emission of the solar corona and diagnose, with unprecedented temporal coverage and space resolution the structure and dynamics of the full corona in the range from 1.2 to 3.0 (1.6 to 4.1) solar radii (R, measured from Sun centre) at minimum (maximum) perihelion during the nominal mission. It can also perform spectroscopic observations of the solar disk and out to 1.4 R
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electro optical polarimeters for ground based and space based observations of the solar k corona
Proceedings of SPIE, 2012Co-Authors: Gerardo Capobianco, Silvano Fineschi, Giuseppe Massone, E Balboni, A M Malvezzi, Giuseppe Crescenzio, L Zangrilli, P Calcidese, E Antonucci, M PatriniAbstract:Polarimeters based on electro-optically tunable liquid crystals (LC) represent a new technology in the field of observational astrophysics. LC-based polarimeters are good candidates for replacing mechanically rotating polarimeters in most ground-based and space-based applications. During the 2006 total solar eclipse, we measured the visible-light polarized brightness (pB) of the solar K-corona with a LC-based polarimeter and imager (E-KPol). In this presentation, we describe the results obtained with the E-KPol, and we evaluate its performances in view of using a similar device for the pB imaging of the K-corona from space-based coronagraphs. Specifically, a broad-band LC polarimeter is planned for the Metis (Multi Element Telescope for Imaging and Spectroscopy) coronagraph for the Solar Orbiter mission to be launched in 2017. The Metis science driver of deriving the coronal electron density from pB images requires an accuracy of better than 1% in the measurement of linear polarization. We present the implications of this requirement on the Metis design to minimize the instrumental polarization of the broad-band visible-light (590-650 nm) polarimeter and of the other optics in the Metis visible-light path. Finally, we report preliminary ellipsometric measurements of the optical components of the Metis visible-light path.