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.
LEONARDO SpA is leading an Italian Space Industry Team, funded by ASI, collaborating to the ESA mission PLATO (PLAnetary Transits and Oscillation of stars). Its aim is the study of extrasolar planetary systems, with a focus on the discovery of exo-planets hosted by bright, nearby stars. PLATO is composed by 26 fully dioptric designed cameras, each composed of a telescope optical unit (TOU) and a focal plane array (FPA). The FPA is integrated with the TOU at ambient temperature by other Partners of the PLATO CAM-Team, although we determine the best image plane (BIP) of each TOU during test at cryo-vacuum operative conditions. This poses a metrology challenge at TOU manufacturing and testing facilities, with relatively high production rate of the flight units. At cold temperature (-80°C), the orientation and location of the FPA is found out as the BIP, meanwhile at ambient temperature, them are co-registered by using Hartmann masks. The results of this approach show a correspondence between the two analysis methods and give an input for subsequent FPA integration at PLATO CAM level.
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.
The Atmospheric Remote-sensing InfraRed Large-survey (ARIEL) is a medium-class mission of the European Space Agency whose launch is planned by late 2029 whose aim is to study the composition of exoplanet atmospheres, their formation and evolution. The ARIEL’s target will be a sample of about 1000 planets observed with one or more of the following methods: transit, eclipse and phase-curve spectroscopy, at both visible and infrared wavelengths simultaneously. The scientific payload is composed by a reflective telescope having a 1m-class primary mirror, built in solid aluminum, and two focal-plane instruments: 1. FGS (Fine Guidance System), performing photometry in visible light and low resolution spectrometry over three bands (from 0.8 to 1.95 µm) 2. AIRS (ARIEL InfraRed Spectrometer) that will perform infrared spectrometry in two wavelength ranges between 1.95 and 7.8 µm. This paper depicts the status of the TA (Telescope Assembly) electric section whose purpose is to deploy sensors, managed by the Telescope Control Unit, for the precise monitoring of the Telescope’s temperatures and the decontamination system, used to avoid the contamination of the optical surfaces (mirrors in primis).
Leonardo SpA is leading an Italian Space Industry Team, funded by ASI, collaborating to the ESA mission PLATO program for the realization of the 26 telescopes, which will fly on a single platform, aimed to discover, observe and analyze the exoplanets. The mission is based on a challenging telescope design with peculiar optical performance to be assured at very low operative temperature (-80°C). The “large” number of telescopes, produced in high rate (up to 3 telescopes every 2 months), is quite unusual for the production of scientific payloads. It has imposed a change with respect the prototypical manufacturing and test approach, generally a few flight units for space equipment, addressing the implementation of smart and fast methodologies for aligning and focusing each telescope, based on simulation of the peculiar “as-built” data. The opto-mechanical design of the telescope has been optimized to implement an industrial approach for all the manufacturing, assembly, integration and test (MAIT) phases. The number, production rate and the performance results of the flight units so far delivered by Leonardo to the PLATO Consortium, are validating the selected design solutions and all the selected MAIT processes. All the units already delivered present very similar performance, full specs and very close to the theoretical design.
EnVisS (Entire Visible Sky) is a space camera aboard the Comet Interceptor ESA mission. This is the first F-class space mission, a new generation of fast ESA missions, and it is scheduled for launch in 2029. Comet Interceptor aims to study, by means of in situ observations, a dynamically new comet, or interstellar object, that enters the Solar System for the first time. Approaching the comet, three modules will detach: spacecraft A will provide remote sensing and communications, while spacecraft B1 and B2 will cross the coma and fly-by the nucleus. EnVisS is a fish-eye camera with a field of view (FOV) of 180° × 45°. It is mounted on B2, which is spin stabilized; the spin provides the scanning motion for the camera allowing imaging the whole sky (180° × 360°) including the comet. The EnVisS optical head is composed of ten lenses; the collected visible light passes through a three-strip filter assembly before reaching the detector. The central filter strip is a broadband filter, while the sides filter strips are linear polarizers, with the aim of studying the polarization state of the light reflected by both the comet coma and its core. The optical performance of EnVisS has been evaluated through ray tracing analyses. In this paper, the ghost study will be described and ghost images will be shown. This analysis, performed in the ZEMAX OpticStudio®, highlights which optical element causes the most intense ghost images and shows their distribution over the detector.
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