Protected silver coating for Ariel telescope mirrors: study of ageing effects

The Atmospheric Remote-sensing Infrared Exoplanet Large-survey (Ariel), selected as ESA’s fourth mediumclass mission in the Cosmic Vision program, is set to launch in 2029. The objective of the study is to conduct spectroscopic observations of approximately one thousand exoplanetary atmospheres for better understanding the planetary system formation and evolution and identifying a clear link between the characteristics of an exoplanet and those of its parent star. The realization of the Ariel’s telescope is a challenging task that is still ongoing. It is an off-axis Cassegrain telescope (M1 parabola, M2 hyperbola) followed by a re-collimating off-axis parabola (M3) and a plane fold mirror (M4). It is made of Al 6061 and designed to operate at visible and infrared wavelengths. The mirrors of the telescope will be coated with protected silver, qualified to operate at cryogenic temperatures. The qualification of the coating was performed according to the ECSS Q-ST-70-17C standard, on a set of samples that have been stored in ISO 6 cleanroom conditions and are subjected to periodic inspection and reflectance measurements to detect any potential performance degradation. The samples consist of a set of Aluminum alloy Al 6061-T651 disks coated with protected silver. This paper presents the results of the morphological characterization of the samples based on Atomic Force Microscopy (AFM) and the reflectivity measurement in the infrared by Fourier Transform Infrared (FTIR) spectroscopy

Planning the integration and test of a space telescope with a 1 m aluminum primary mirror: the Ariel mission case

Ariel (Atmospheric Remote-Sensing Infrared Exoplanet Large Survey) is ESA’s M4 mission of the “Cosmic Vision” program, with launch scheduled for 2029. Its purpose is to conduct a survey of the atmospheres of known exoplanets through transit spectroscopy. Ariel is based on a 1 m class telescope optimized for spectroscopy in the waveband between 1.95 and 7.8 µm, operating at cryogenic temperatures in the range 40–50 K. The Ariel Telescope is an off-axis, unobscured Cassegrain design, with a parabolic recollimating tertiary mirror and a flat folding mirror directing the output beam parallel to the optical bench. The secondary mirror is mounted on a roto-translating stage for adjustments during the mission. The mirrors and supporting structures are all realized in an aerospace-grade aluminum alloy T6061 for ease of manufacturing and thermalization. The low stiffness of the material, however, poses unique challenges to integration and alignment. Care must be therefore employed when designing and planning the assembly and alignment procedures, necessarily performed at room temperature and with gravity, and the optical performance tests at cryogenic temperatures. This paper provides a high-level description of the Assembly, Integration and Test (AIT) plan for the Ariel telescope and gives an overview of the analyses and reasoning that led to the specific choices and solutions adopted

French guidelines on TIPS: Indications and modalities

Groupe collaboratif AFEF: Delphine Weil-Verhoeven, Agnès Bonadona, Paul Calame, Cyrielle Després, Vincent Di Martino, Patrick Dukan, Manon Allaire, Antoine Monsel, Hélène, Larrue, Sandrine Barge, Dominique Thabut, Jean-Paul Cervoni, Charlotte Bouzbib, Aurélie Plessier, Audrey Payance, Andrea de Gottardi, Lucile Moga, Marie Irles, Anna Sessa, Caroline, Jézéquel, Florent Artru, Arnaud Pauwels, Isabelle Archambeaud, Simon Ville, Clément Deltombe, Laure Elkrief, Louise Barbier, Frédéric Oberti, Carine Chagneau, Adrien Lannes,, Christophe Aube, Antoine Bouvier, Charles Roux, Juan Carlos Garcia Pagan, Wim Laleman, Geert Maleux, Marika Rudler, Nicolas Weiss, Sébastien Dharancy, Audrey Coilly, François, Faitot, Anne Minello, Marie-Astrid Piquet, Marianne Latournerie, Romaric Loffroy, Thomas Mouillot, Eric Assenat, Nathalie Ganne- Carrié, Boris Guiu.International audienceTransjugular intrahepatic portosystemic shunt (TIPS) has become essential in the treatment or prevention of portal hypertension‐related complications. In the early 1990s, the primary indication was refractory bleeding. It is now proposed for the treatment of ascites for the prevention of bleeding and in patients with vascular diseases of the liver. Thus, there are a growing number of patients being treated with TIPS all over the world. The broadening of indications, the involvement of multiple stakeholders, the need for an accurate selection, the positioning in relation to transplantation and the lack of standardization in pre‐therapeutic assessment, in the procedure itself and in the follow‐up have led the board of the French Association for the Study of the Liver to establish recommendations

French guidelines on TIPS: Indications and modalities

Groupe collaboratif AFEF: Delphine Weil-Verhoeven, Agnès Bonadona, Paul Calame, Cyrielle Després, Vincent Di Martino, Patrick Dukan, Manon Allaire, Antoine Monsel, Hélène, Larrue, Sandrine Barge, Dominique Thabut, Jean-Paul Cervoni, Charlotte Bouzbib, Aurélie Plessier, Audrey Payance, Andrea de Gottardi, Lucile Moga, Marie Irles, Anna Sessa, Caroline, Jézéquel, Florent Artru, Arnaud Pauwels, Isabelle Archambeaud, Simon Ville, Clément Deltombe, Laure Elkrief, Louise Barbier, Frédéric Oberti, Carine Chagneau, Adrien Lannes,, Christophe Aube, Antoine Bouvier, Charles Roux, Juan Carlos Garcia Pagan, Wim Laleman, Geert Maleux, Marika Rudler, Nicolas Weiss, Sébastien Dharancy, Audrey Coilly, François, Faitot, Anne Minello, Marie-Astrid Piquet, Marianne Latournerie, Romaric Loffroy, Thomas Mouillot, Eric Assenat, Nathalie Ganne- Carrié, Boris Guiu.International audienceTransjugular intrahepatic portosystemic shunt (TIPS) has become essential in the treatment or prevention of portal hypertension‐related complications. In the early 1990s, the primary indication was refractory bleeding. It is now proposed for the treatment of ascites for the prevention of bleeding and in patients with vascular diseases of the liver. Thus, there are a growing number of patients being treated with TIPS all over the world. The broadening of indications, the involvement of multiple stakeholders, the need for an accurate selection, the positioning in relation to transplantation and the lack of standardization in pre‐therapeutic assessment, in the procedure itself and in the follow‐up have led the board of the French Association for the Study of the Liver to establish recommendations

Ground calibration of the Ariel space telescope: optical ground support equipment design and description

This paper describes the Optical Ground Support Equipment (OGSE) that is being developed for the payload level testing of the Ariel Space Telescope. Ariel has been adopted as ESA’s “M4” mission in its Cosmic Visions Programme and will launch in 2029 to the second Earth-Sun Lagrange point. During four years of operation the Ariel payload (PL – the cryogenic payload module plus warm units) will perform precise transit spectroscopy of approximately 1000 known exoplanetary atmospheres using a 1.1 m × 0.7 m telescope coupled to two instruments: the Fine Guidance Sensor (FGS) and the Ariel Infrared Spectrometer (AIRS). These instruments provide three spectrometric channels that cover 1.0 to 7.8 μm wavelength range and three photometric channels between 0.5 and 1.1 μm. The Ariel OGSE will verify the optical and radiometric performance of the integrated Ariel PL under vacuum and cryogenic (<40 K) test conditions within the limitations of operation under Earth’s gravity and vibration environments. To achieve these verification requirements the OGSE is integrated with the main Ariel ground test 5 m thermal vacuum chamber. The test chamber contains a cryogenic enclosure (the Cryogenic Test Rig) that surrounds the PL and the OGSE itself comprises of four subsystems. (1) A cryogenic vacuum chamber and integrating sphere illumination module that is fed by visible, near infrared and thermal infrared sources. The illumination module is mounted external to the Ariel test chamber and coupled via a vacuum feedthrough that relays a 22 mm diameter test beam into the Cryogenic Test Rig. The test beam is then relayed using (2) an injection module that steers the beam to maintain alignment during cool-down and scan the Ariel telescope field of view. The beam is then expanded to partially illuminate the Ariel telescope primary mirror using an (3) ~0.3 m diameter target projector collimating mirror. The final optical component of the OGSE is a (4) beam expander placed on the Ariel common optical bench to compensate for the sub-aperture illumination of the primary and to ensure that the spectrometer modules provide illumination with correct cone angles during ground testing. It is planned to use the OGSE in 2026 for a full range of calibration and verification tests of the end-to-end telescope and instrument performance, including detectors, field of view and alignment. These tests will then ensure that Ariel meets it challenging photometric and spectral performance requirements