KEYWORDS: Cameras, Space operations, Stars, Design, Data processing, Control systems, Planets, Scanning tunneling microscopy, Satellites, X band, Exoplanets, Astronomical telescopes, Space telescopes
PLATO (PLAnetary Transits and Oscillations) mission is a space-based optical multi-camera photometer mission of the European Space Agency (ESA) to identify and characterize exoplanets and their hosting stars using two main techniques: planetary transit and asteroseismology. Selected as the M3 (third Medium class mission) of the ESA 2015-2025 Cosmic Vision program, PLATO is scheduled to launch end of 2026 and designed for 4 years of nominal observation. The PLATO spacecraft is composed of a Service Module and a Payload Module. The Service Module comprises all the conventional spacecraft subsystems and the sun shield with attached solar arrays. The Payload Module consists of a highly stable optical bench, equipped with 26 optical cameras covering a global field of view of > 2232deg2. The PLATO spacecraft data is complemented by ground-based observations and processed by a dedicated Science Ground Segment. We describe the mission and spacecraft architecture and provide a view of the current status of development.
PLATO is an exoplanet hunting mission of the European Space Agency. It is a medium-class mission, with a launch foreseen in 2026. Its prime objective is to uncover Earth-sized planets residing in their habitable zone. The payload consists in 26 cameras with a very wide field of view. These cameras consist in a Telescope Optical Unit, aligned at ambient and characterised at the operational temperature, and a Focal Plane Array bearing the detectors, and delivered after coupling with the Front End Electronics. In this contribution, we report on the alignment of the Engineering Model camera of Plato, i.e., the input metrology, the mechanical alignment of the optical unit with the focal plane array, the test environment and the optical characterisation throughout the process until the integrity check after delivery to the cryo-vacuum testing facility where the camera underwent a thorough performance demonstration. We also give a detailed description of the bolting process and the associated error budget.
The PLAnetary Transits and Oscillations of stars mission (PLATO) is an ESA M3 mission planned to detecting and characterizing extrasolar planetary systems as Earth-like exoplanets orbiting around the habitable zone of bright solartype stars. PLATO consists of 26 cameras (CAM) mounted on the same instrument platform in order to cover a large field of view (FoV) with the highest possible photon detection statistics. Each PLATO CAM consists of a telescope Optical Unit (TOU), the FPA, and the detector read-out Front End Electronics (FEE). The FPA is the structure located at the focal plane position of the CAM that supports four identical CCDs and the mechanical interface parts to match with the TOU and FEE. Due to the critical repeatability aspect of the mission, each FPAs must be identical with very stringent specifications which includes strict opto-mechanical positioning tolerances. Also the number of FPAs that have to be manufactured, integrated and tested at the same time requires a special space industrialization process and an optimized metrology verification due to the very restrictive design and schedule constraints. In order to solve this challenge a flight-representative QM has been developed in order to validate a manufacturing, assembly, integration and verification (AIV) on-ground processes. As well, an innovative metrology system has being developed for improving the alignment and verification under the tightly AIV requirements before, during and after a proper qualified campaign in a very demanding environment. INTA has adapted into an ISO6 cleanroom facility a high accuracy and vast performance non-contact CNC vision dimensional measuring system, and has developed a Ground Support Equipment (GSE) for a real-time alignment step in order to reach that requirements.
PLATO is an exoplanet hunting mission from the European Space Agency. It is a medium-class mission, with a launch foreseen in 2026. Its prime objective is to uncover Earth-sized planets residing in the habitable zone of their host star. The payload consists of 26 cameras with a very wide field-of-view. While the operational temperature of the cameras will be -80°C, the focal plane of each camera will be integrated with its telescope assembly (bearing the optics) at room temperature. The degradation of the optical quality at ambient, combined with the detector dark current and with the very high accuracy required from the alignment process bring a number of interesting challenges. In the present article, we review the alignment concept, present optical simulations of the measurements at ambient along with their analysis, and present an error budget for the optical measurements. The derivation of this error budget is easily applicable to all optical measurements to be performed during the alignment, i.e. the definition of the best image plane at the operational temperature and the optical alignment itself, at room temperature.
PLATO, PLAnetary Transits and Oscillation of stars, is an ESA mission mainly devoted to survey the Galaxy searching for and characterizing Earth-like exoplanets, and their host stars. This will be achieved using continuous and extremely accurate photometry for both exoplanetary transits and asteroseismology analysis. Current design plans to mount 26 cameras in the same instrument bench in order to cover a large field of view with the highest possible photon statistics. Each PLATO camera consists of the telescope (TOU, Telescope Optical Unit), the focal plane assembly (FPA), and the detector and camera read out electronics (FEE). Four CCDs (Charge Coupled Devices) will be included in each FPA, which implies a really delicate assembly and integration verification (AIV) process due to the stringent scientific requirements breakdown into hard engineering ones (among others, CCDs co-alignment in terms of tip and tilt and roll with respect to the optical axis). In the following lines, the FPA current opto-mechanical design is briefly presented and an integration process conceptual proposal is reported on, discussing the error budgets associated to the main requirements to be verified during FPAs AIV, and the main results obtained during the prototype first AIV round.
J. Moreno, E. Vielba, A. Manjón, A. Motos, E. Vázquez, E. Rodríguez, D. Saez, M. Sengl, J. Fernández, G. Campos, D. Muñoz, M. Mas, A. Balado, G. Ramos, C. Cerruti, M. Pajas, I. Catalán, M. Alcacera, A. Valverde, P. Pflueger, I. Vera
This paper describes the thermo-mechanical design of the Focal Plane Assembly (FPA) of the PLAnetary Transits and Oscillations of stars (PLATO) Instrument, developed by INTA and LIDAX. This is an ESA program with OHB as industry prime. In terms of assembly, alignment, and operational stability very demanding needs are required by a huge focal plane composed of four CCDs to assure the proper performance. This is translated into a complex thermomechanical design which shall be also focused on the correct production approach of the main parts involved, including several processes, and taking into account the number of cameras, and therefore Focal Plane Assemblies, to be produced (26). Part of these challenges, and their associated risks, are mitigated by means of the development of a totally representative prototype, which is currently finishing the integration phase and facing the test campaign.
EChO (Exoplanet atmospheres Characterization Observatory), a proposal for exoplanets exploration space mission, is considered the next step for planetary atmospheres characterization. It would be a dedicated observatory to uncover a large selected sample of planets spanning a wide range of masses (from gas giants to super-Earths) and orbital temperatures (from hot to habitable). All targets move around stars of spectral types F, G, K, and M. EChO would provide an unprecedented view of the atmospheres of planets in the solar neighbourhood. The consortium formed by various institutions of different countries proposed as ESA M3 an integrated spectrometer payload for EChO covering the wavelength interval 0.4 to 16 µm. This instrument is subdivided into 4 channels: a visible channel, which includes a fine guidance system (FGS) and a VIS spectrometer, a near infrared channel (SWiR), a middle infrared channel (MWiR), and a long wave infrared module (LWiR). In addition, it contains a common set of optics spectrally dividing the wavelength coverage and injecting the combined light of parent stars and their exoplanets into the different channels. The proposed payload meets all of the key performance requirements detailed in the ESA call for proposals as well as all scientific goals. EChO payload is based on different spectrometers covering the spectral range mentioned above. Among them, SWiR spectrometer would work from 2.45 microns to 5.45 microns. In this paper, the optical and mechanical designs of the SWiR channel instrument are reported on.
Gonzalo Ramos Zapata, Tomás Belenguer, Ana Balado, Javier Barandiarán, Iñaki Armendáriz, Manuel Reina, César Arza, Santiago Rodríguez, Maria Ángeles Alcacera, José Fernández, Elisa Muñoz, Giovanna Tinetti, Paul Eccleston, Bruce Swinyard, Marc Ferlet, Ian Bryson, María Rosa Zapatero
EChO, a space mission for exoplanets exploration, is considered the next step for planetary atmospheres
characterization. It will be a dedicated observatory to uncover a large selected sample of planets spanning a
wide range of masses (from gas giants to super-Earths) and orbital temperatures (from hot to habitable). All
targets move around stars of spectral types F, G, K, and M. EChO will provide an unprecedented view of the
atmospheres of planets in the solar neighbourhood.
The consortium formed by various institutions of different countries is proposing an integrated
spectrometer payload for EChO covering the wavelength interval 0.4 to 16 µm. This instrument is subdivided
into 4 channels: a visible channel, which includes a fine guidance system (FGS) and a VIS spectrometer, a
near infrared channel (SWiR), a middle infrared channel (MWiR), and a long wave infrared module (LWiR).
In addition, it contains a common set of optics spectrally dividing the wavelength coverage and injecting the
combined light of parent stars and their exoplanets into the different channels. The proposed payload meets all
of the key performance requirements detailed in the ESA call for proposals as well as all scientific goals.
EChO payload will be based on different spectrometers covering the spectral range mentioned above.
Among them, SWiR spectrometer will work from 2.45 microns to 5.45 microns. In this paper, the optical and
mechanical designs of the SWiR channel instrument, including the evolution of the different trades followed
and the current identification of critical points, are reported on.
T. Belenguer, M. A. Alcacera, A. Aricha, A. Balado, J. Barandiarán, A. Bernardo, M. R. Canchal, M. Colombo, E. Diaz, V. Eiriz, I. Figueroa, G. García, A. Giménez, L. González, F. Herrada, A. Jiménez, R. López, M. Menéndez, M. Reina, J. A. Rodríguez, A. Sánchez
KEYWORDS: Space telescopes, James Webb Space Telescope, Mirrors, Telescopes, Device simulation, Integrating spheres, Control systems, Molybdenum, Imaging systems, Interfaces
The MTS, MIRI Telescope Simulator, is developed by INTA as the Spanish contribution of
MIRI (Mid InfraRed Instrument) on board JWST (James Web Space Telescope).
The MTS is considered as optical equipment which is part of Optical Ground Support
Equipment for the AIV/Calibration phase of the instrument at Rutherford Appleton
Laboratory, UK.
It is an optical simulator of the JWST Telescope, which will provide a diffractionlimited test
beam, including the obscuration and mask pattern, in all the MIRI FOV and in all defocusing
range. The MTS will have to stand an environment similar to the flight conditions (35K) but
using a smaller set-up, typically at lab scales.
The MTS will be used to verify MIRI instrument-level tests, based on checking the
implementation/realisation of the interfaces and performances, as well as the instrument
properties not subject to interface control such as overall transmission of various modes of
operation.
This paper includes a functional description and a summary of the development status.
F. Herrada, V. Eiriz, M. Alcacera, A. Aricha, A. Balado, J. Barandiaran, T. Berenguer, E. Diaz, I. Figueroa, L. Gonzalez, R. Lopez, M. Menendez, A. Bernardo, M. Reina, A. Sanchez, G. Garcia, A. Jimenez, M. Colombo, M. Canchal, J. Rodriguez
MTS (MIRI telescope simulator) is the Spanish contribution to the JWST Project. MTS is a part of the
Optical Ground Support Equipment (OGSE) for the Assembly Integration and Verification (AIV) and
Calibration phase of the MIRI instrument at the RAL (Rutherford Appleton Laboratory) facilities. Briefly,
MTS main objetive consists on delivering a diffraction-limited test beam, including the obscuration and
mask pattern, to the MIRI instrument that reproduces the output beam of the JWST in environmental
conditions similar to those corresponding to the flight.
In this work, the current status of the project is reported on. Mainly, after a description of the whole
instrument and the optomechanical performances required, the paper will be focused on the current status
of the purchase and characterization of certain critical elements belonging to the different subsystems.
The first step has been the verification of the thermoelastic behaviour of its structure, employing a
mass prototype. Both extensometer measurements and optical measurements with alignment mirror cubes
have been carried out during a thermal vacuum test of this MTS prototype. The correlation of the
measurements, optically and mechanically, will provide a better knowledge of the structure behavior and
will be used to define the integration process.
Luis Colina, Eva Diaz, A. Aricha, M. Alcacera, A. Balado, Javier Barandiaran, D. Barrado y Navascues, Tomas Belenguer, J. Blanco, I. Figueroa, G. Garcia, L. Gonzalez, R.L. Heredero, F. Herrada, Carlos Laviada Hernandez, M. March, M. Menendez, C. Pastor, Manuel Reina, A. Sanchez
The MIRI Telescope Simulator (MTS) is part of the Optical Ground Support System (OGSE) for the verification and calibration phase of the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI). The MTS will simulate the optical characteristics of the JWST output beam in an environment similar to the flight conditions. The different functionalities of the MTS are briefly described and its current design, including the illumination and imaging subsystems, is presented.
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