PLATO (PLAnetary Transits and Oscillations) mission is a space-based optical multi-camera photometer mission of the European Space Agency to identify and characterize exoplanets and their hosting stars using two main techniques: planetary transit and asteroseismology.
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 imagers/cameras covering a global field of view of > 2232 deg2. The design includes two types of cameras: 24 Normal Cameras (N-CAMs) with measurement cadences of 25s and 2 Fast Cameras (F-CAMs) with a cadence of 2.5s. The PLATO spacecraft data is complemented by ground based observations and processed by a dedicate Science Ground Segment.
We describe the mission and spacecraft architecture and provide a view of the current status of development.
PLATO (PLAnetary Transits and Oscillations of stars) is a European Space Agency medium class mission, whose launch is foreseen for 2026. Its primary goal is to discover and characterise terrestrial exoplanets orbiting the habitable zone of their host stars. This goal will be reached with a set of 26 wide field-of-view cameras mounted on a common optical bench. Here we show some results of the first cryogenic vacuum test campaign made on the Engineering Model (EM) of one PLATO camera, performed at the Netherlands Institute for Space Research (SRON). In particular we present the search for the best focus temperature, which was done first by using a Hartmann mask, and then by maximizing the ensquared energy fractions of the point spread functions (PSFs) on the entire field of view taken at different temperature plateaus. Furthermore we present the PSF properties of the EM at the nominal focus temperature over all the field of view, focusing on the ensquared energy fractions. The Engineering Model camera was successfully integrated and validated under cryo-vacuum tests, allowing the mission to pass ESA’s Critical Milestone, and confirming the mission is on track for launch in 2026.
The ESA M size mission PLATO (PLAnetary Transits and Oscillation of stars) is planned to be launched in the 2026, with the aim of discover exoplanets that will be characterized with unprecedented precision. The optical elements of PLATO are 26 small telescopes, the TOUs (Telescope Optical Units), that using partially overlapping Fields of View will permit instantaneous sky coverage larger than 2100 square degrees. Each TOU has an aperture of 120 mm diameter assured by an internal stop, and it is composed by 6 lenses, the frontal one having an aspherical surface and the last acting as field flattener. The mechanical structure is realized mainly in AlBeMet. We here describe the optical design, summarizing several optical properties (materials, coatings, etc.), and report on nominal performances of the TOU system.
PLATO (PLAnetary Transits and Oscillation of stars) is the ESA Medium size dedicated to exo-planets discovery and cataloguing, adopted in the framework of the Cosmic Vision 2015-2025. The PLATO launch is planned in 2026 and the mission will last at least 4 years in the Lagrangian point L2. The primary scientific goal of PLATO is to discover and characterize a large amount of exo-planets hosted by bright nearby stars. The PLATO strategy is to split the collecting area into 24(+2) identical 120 mm aperture diameter fully refractive cameras with partially overlapped Field of View delivering an overall instantaneous sky covered area of about >2100 square degrees. The opto-mechanical sub-system of each camera, namely Telescope Optical Unit (TOU), is basically composed by a 6 lenses fully refractive optical system, presenting one aspheric surface on the front lens, and by a mechanical structure made in AlBeMet. In this paper we will update on the current working status of the TOUs.
Euclid-VIS is the large format visible imager for the ESA Euclid space mission in their Cosmic Vision program, scheduled for launch in 2021. Together with the near infrared imaging within the NISP instrument, it forms the basis of the weak lensing measurements of Euclid. VIS will image in a single r+i+z band from 550-900 nm over a field of view of ~0.5 deg2 . By combining 4 exposures with a total of 2260 sec, VIS will reach to deeper than mAB=24.5 (10s) for sources with extent ~0.3 arcsec. The image sampling is 0.1 arcsec. VIS will provide deep imaging with a tightly controlled and stable point spread function (PSF) over a wide survey area of 15000 deg2 to measure the cosmic shear from nearly 1.5 billion galaxies to high levels of accuracy, from which the cosmological parameters will be measured. In addition, VIS will also provide a legacy dataset with an unprecedented combination of spatial resolution, depth and area covering most of the extra-Galactic sky. Here we will present the results of the study carried out by the Euclid Consortium during the period up to the beginning of the Flight Model programme
KEYWORDS: Systems engineering, Systems modeling, Space operations, Modeling, Galactic astronomy, Control systems, Systems engineering, Systems modeling, Data modeling, Data processing, Atrial fibrillation, Visualization
In the last years, the system engineering field is coming to terms with a paradigm change in the approach for complexity management. Different strategies have been proposed to cope with highly interrelated systems, system of systems and collaborative system engineering have been proposed and a significant effort is being invested into standardization and ontology definition. In particular, Model Based System Engineering (MBSE) intends to introduce methodologies for a systematic system definition, development, validation, deployment, operation and decommission, based on logical and visual relationship mapping, rather than traditional 'document based' information management.
The practical implementation in real large-scale projects is not uniform across fields. In space science missions, the usage has been limited to subsystems or sample projects with modeling being performed 'a-posteriori' in many instances. The main hurdle for the introduction of MBSE practices in new projects is still the difficulty to demonstrate their added value to a project and whether their benefit is commensurate with the level of effort required to put them in place.
In this paper we present the implemented Euclid system modeling activities, and an analysis of the benefits and limitations identified to support in particular requirement break-down and allocation, and verification planning at mission level.
KEYWORDS: Space operations, Galactic astronomy, Spectroscopy, Systems modeling, Databases, Point spread functions, Seaborgium, Data processing, Calibration, Telescopes
ESA's Dark Energy Mission Euclid will map the 3D matter distribution in our Universe using two Dark Energy probes: Weak Lensing (WL) and Galaxy Clustering (GC). The extreme accuracy required for both probes can only be achieved by observing from space in order to limit all observational biases in the measurements of the tracer galaxies. Weak Lensing requires an extremely high precision measurement of galaxy shapes realised with the Visual Imager (VIS) as well as photometric redshift measurements using near-infrared photometry provided by the Near Infrared Spectrometer Photometer (NISP). Galaxy Clustering requires accurate redshifts (Δz/(z+1)<0.1%) of galaxies to be obtained by the NISP Spectrometer.
Performance requirements on spacecraft, telescope assembly, scientific instruments and the ground data-processing have been carefully budgeted to meet the demanding top level science requirements. As part of the mission development, the verification of scientific performances needs mission-level end-to-end analyses in which the Euclid systems are modeled from as-designed to final as-built flight configurations. We present the plan to carry out end-to-end analysis coordinated by the ESA project team with the collaboration of the Euclid Consortium. The plan includes the definition of key performance parameters and their process of verification, the input and output identification and the management of applicable mission configurations in the parameter database.
The challenging constraints imposed on the Euclid telescope imaging performances have driven the design,
manufacturing and characterisation of the multi-layers coatings of the dichroic. Indeed it was found that the coatings
layers thickness inhomogeneity will introduce a wavelength dependent phase-shift resulting in degradation of the image
quality of the telescope. Such changes must be characterized and/or simulated since they could be non-negligible
contributors to the scientific performance accuracy. Several papers on this topic can be found in literature, however the
results can not be applied directly to Euclid’s dichroic coatings. In particular an applicable model of the phase-shift
variation with the wavelength could not be found and was developed. The results achieved with the mathematical
model are compared to experimental results of tests performed on a development prototype of the Euclid’s dichroic.
KEYWORDS: Data processing, Galactic astronomy, Space operations, Telescopes, Point spread functions, K band, Sensors, Image quality, Data archive systems, Calibration
Euclid is a space-based optical/near-infrared survey mission of the European Space Agency (ESA) to investigate the
nature of dark energy, dark matter and gravity by observing the geometry of the Universe and on the formation of
structures over cosmological timescales. Euclid will use two probes of the signature of dark matter and energy: Weak
gravitational Lensing, which requires the measurement of the shape and photometric redshifts of distant galaxies, and
Galaxy Clustering, based on the measurement of the 3-dimensional distribution of galaxies through their spectroscopic
redshifts. The mission is scheduled for launch in 2020 and is designed for 6 years of nominal survey operations. The
Euclid Spacecraft is composed of a Service Module and a Payload Module. The Service Module comprises all the
conventional spacecraft subsystems, the instruments warm electronics units, the sun shield and the solar arrays. In
particular the Service Module provides the extremely challenging pointing accuracy required by the scientific objectives.
The Payload Module consists of a 1.2 m three-mirror Korsch type telescope and of two instruments, the visible imager
and the near-infrared spectro-photometer, both covering a large common field-of-view enabling to survey more than
35% of the entire sky. All sensor data are downlinked using K-band transmission and processed by a dedicated ground
segment for science data processing. The Euclid data and catalogues will be made available to the public at the ESA
Science Data Centre.
KEYWORDS: Space telescopes, Telescopes, Contamination, Mirrors, Sensors, Scattering, Optical components, Photometry, Contamination control, Picture Archiving and Communication System
In the Euclid mission the straylight has been identified at an early stage as the main driver for the final imaging quality of the telescope. The assessment by simulation of the final straylight in the focal plane of both instruments in Euclid’s payload have required a complex workflow involving all stakeholders in the mission, from industry to the scientific community. The straylight is defined as a Normalized Detector Irradiance (NDI) which is a convenient definition tool to separate the contributions of the telescope and of the instruments. The end-to-end straylight of the payload is then simply the sum of the NDIs of the telescope and of each instrument. The NDIs for both instruments are presented in this paper for photometry and spectrometry.
In June 2012, Euclid, ESA's Cosmology mission was approved for implementation. Afterwards the industrial contracts were signed for the payload module and the spacecraft prime, and the mission requirements consolidated. We present the status of the mission in the light of the design solutions adopted by the contractors. The performances of the spacecraft in its operation, the telescope assembly, the scientific instruments as well as the data-processing have been carefully budgeted to meet the demanding scientific requirements. We give an overview of the system and where necessary the key items for the interfaces between the subsystems.
Euclid-VIS is the large format visible imager for the ESA Euclid space mission in their Cosmic Vision program,
scheduled for launch in 2020. Together with the near infrared imaging within the NISP instrument, it forms the basis of
the weak lensing measurements of Euclid. VIS will image in a single r+i+z band from 550-900 nm over a field of view
of ~0.5 deg2. By combining 4 exposures with a total of 2260 sec, VIS will reach to V=24.5 (10σ) for sources with extent
~0.3 arcsec. The image sampling is 0.1 arcsec. VIS will provide deep imaging with a tightly controlled and stable point
spread function (PSF) over a wide survey area of 15000 deg2 to measure the cosmic shear from nearly 1.5 billion
galaxies to high levels of accuracy, from which the cosmological parameters will be measured. In addition, VIS will also
provide a legacy dataset with an unprecedented combination of spatial resolution, depth and area covering most of the
extra-Galactic sky. Here we will present the results of the study carried out by the Euclid Consortium during the period
up to the Preliminary Design Review.
Euclid is an European Space Agency (ESA) mission to map the geometry of the dark Universe. The mission will investigate the distance-redshift relationship and the evolution of cosmic structures. It will achieve this by measuring shapes and redshifts of galaxies and clusters of galaxies out to redshifts ~2, equivalent to 10 billion years back in time. Euclid will make use of two primary cosmological probes, in a wide survey over the full extragalactic sky : the Weak Gravitational Lensing (WL) and Baryon Acoustic Oscillations (BAO). The main goal of the Euclid payload module (PLM) is to provide high quality imaging of galaxies and accurate measurement (less than 0.1%) of galaxies redshift over a large field of view (FoV). The present paper focuses on the telescope of the PLM excluding the instruments. We present a brief introduction to the Euclid PLM system and will report how the constraints of each instrument have driven the definition of the telescope-to-instrument optical interfaces. Furthermore we introduce the description of the telescope optical characteristics and report its nominal performances. Finally, the technical challenges to be faced by ESA’s industrial partners are underlined.
The focal plane array of the Euclid VIS instrument comprises 36 large area, back-illuminated, red-enhanced CCD detectors (designated CCD 273). These CCDs were specified by the Euclid VIS instrument team in close collaboration with ESA and e2v technologies. Prototypes were fabricated and tested through an ESA pre-development activity and the contract to qualify and manufacture flight CCDs is now underway. This paper describes the CCD requirements, the design (and design drivers) for the CCD and package, the current status of the CCD production programme and a summary of key performance measurements.
MIRI is one of four instruments to be built for the James Webb Space Telescope. It provides imaging, coronography and
integral field spectroscopy over the 5-28.5um wavelength range. MIRI is the only instrument which is cooled to 7K by a
dedicated cooler, much lower than the passively cooled 40K of the rest of JWST, and consists of both an Optical System
and a Cooler System. This paper will describe the key features of the overall instrument design and then concentrate on
the status of the MIRI Optical System development. The flight model design and manufacture is complete, and final
assembly and test of the integrated instrument is now underway. Prior to integration, all of the major subassemblies have
undergone individual environmental qualification and performance tests and end-end testing of a flight representative
model has been carried out. The paper will provide an overview of results from this testing and describe the current
status of the flight model build and the plan for performance verification and ground calibration.
The Mid-Infrared Instrument (MIRI) is one of the three scientific instruments to fly on the James Webb Space
Telescope (JWST), which is due for launch in 2013. MIRI contains two sub-instruments, an imager, which has low
resolution spectroscopy and coronagraphic capabilities in addition to imaging, and a medium resolution IFU
spectrometer. A verification model of MIRI was assembled in 2007 and a cold test campaign was conducted between
November 2007 and February 2008. This model was the first scientifically representative model, allowing a first
assessment to be made of the performance. This paper describes the test facility and testing done. It also reports on the
first results from this test campaign.
The James Webb Space Telescope (JWST) Observatory, the follow-on mission to the Hubble Space
Telescope, will yield astonishing breakthroughs in infrared space science. One of the four
instruments on that mission, the NIRSpec instrument, is being developed by the European Space
Agency with EADS Astrium Germany GmbH as the prime contractor. This multi-object
spectrograph is capable of measuring the near infrared spectrum of at least 100 objects
simultaneously at various spectral resolutions in the 0.6 μm to 5.0 μm wavelength range.
A physical optical model, based on Fourier Optics, was developed in order to simulate some of the
key optical performances of NIRSpec. Realistic WFE maps were established for both the JWST
optical telescope as well as for the various NIRSpec optical stages. The model simulates the optical
performance of NIRSpec at the key optical pupil and image planes. Using this core optical
simulation module, the model was expanded to a full instrument performance simulator that can be
used to simulate the response of NIRSpec to any given optical input. The program will be of great
use during the planning and evaluation of performance testing and calibration measurements.
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