The Euclid mission design

Abstract

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. * Euclid Project Manager, giuseppe.racca@esa.int; phone +31 71 565 4618; fax: F +31 71 565 5244; http://sci.esa.int/euclid Starting from the overall mission requirements, we describe the spacecraft architectural design and expected performance and provide a view on the current project status.

Chemical Mapping of the Milky Way with The Canada–France Imaging Survey: A Non-parametric Metallicity–Distance Decomposition of the Galaxy

“…They set their absolute magnitude calibration M r to depend on Here we use u-band data from the new Canada-France Imaging Survey (CFIS, which we present in detail in Ibata et al 2017; hereafter Paper I) to greatly improve on the SDSS u-band photometry and thereby probe the MS populations of the Milky Way out to much larger distances than was possible with the SDSS. CFIS is a large community program at the CanadaFrance-Hawaii Telescope that was organized to obtain u-and r-band photometry needed to measure photometric redshifts for the Euclid mission (Laureijs et al 2011;Racca et al 2016). As we show in PaperI, at a limiting uncertainty of 0.03mag for point sources, CFIS-u reaches approximately three magnitudes deeper than the SDSS u-band data.…”

The read-out shutter unit of the Euclid VIS instrument

“…The other requirements concern the life-time of the unit and its operations in a strictly controlled environment. As the Euclid mission has to be operated for more than 6 years in order to achieve its science goals ( [1]), it is expected that the RSU will perform during this period more than 350'000 opening and closing cycles at 110-160 K. The RSU operations at these cold temperatures are required due to the proximity of the shutter to the FPA that is equipped with CCDs reaching the highest performances only at cold temperatures ( [2]). The presence of this critical optical surface poses also strict requirements to the RSU on the cleanliness and stray-light level, which should be kept low during the entire motion of the relatively large RSU leaf.…”

Mission-level performance verification approach for the Euclid space mission

“…The performance verification has to demonstrate (i) that single redshifts are unbiased and measured with sufficient precision in order to reach the needed flux limit of 2×10 -16 erg/s/cm 2 (3.5σ) and (ii) that the completeness and purity are sufficient to get galaxy number densities per redshift bins that meet the scientific goal of at least 1700 galaxies/deg 2 . In order to optimize the survey and the unit observing block, it is crucial the relative importance of contributing factors to purity and completeness are well characterized (in particular for signal-to-noise, stellar densities, and number of dispersion orientations parameters).…”

“…The overall scientific aims of Euclid have been recently summarized in [5], an overview of the mission design and performances are also available in this proceedings [2] and in the Euclid Red Book [1].…”