2015 was a crucial year for the Euclid programme, the European Space Agency's new cosmology mission after Planck, whose main objective is to study the origin and expansion of the Universe. In fact, the satellite’s design review and that of the mission’s other elements were completed successfully in July and October respectively and fully confirmed the feasibility and scientific objectives of the programme.
During the year, Thales Alenia Space as Prime Contractor, also completed the selection of the industrial team in charge of building the various parts of the satellite. It will be assisted by more than 100 companies from 18 European countries.
The objectives of Euclid
One of the issues of greatest interest in astrophysics today is in gaining insight on Dark Matter and Dark Energy. EUCLID will contribute to this research with a survey of the extragalactic sky using a 1.2 m diameter space telescope that feeds two instruments, a Visible Imaging Spectrometer (VIS) and a Near Infrared Spectrometer/Photometer (NISP).
The survey will consist of elementary half degree square tiles of sky, each of which will be observed by the telescope in different ways for about an hour and a half, before moving to an adjacent tile. Through six years of observation conducted from the second Lagrange point in the Sun-Earth system, about 150 million kilometres from Earth, Euclid will produce images and photometric data for more than two billion galaxies and spectra of tens of millions of sources.
In addition to the cosmological result, which can be represented by a three-dimensional map of the galaxies and their evolution over the last ten billion years, these data will nurture all areas of astrophysics for many years after the mission has ended.
The role of Thales Alenia Space
In July 2013, ESA and Thales Alenia Space signed the contract that gave Thales Alenia Space Italy the role of Prime Contractor of the satellite. Airbus Defence & Space from Toulouse, France is among the main subcontractors and in charge of the Payload Module that holds the telescope.
The optical system’s quality and stability, great precision and agility of the pointing system and reliability of the data transmission system are the satellite’s fundamental features. Designed by Thales Alenia Space Italy, it was influenced by the Herschel/Planck platform that demonstrated excellent performance in orbit, integrated with an innovative pointing system and next generation telecommunications.
In addition to operating as Prime Contractor of the entire satellite at its Turin premises, Thales Alenia Space Italy contributes to this mission with the supply of on-board X-Band Transponder (XBT), the High-Gain Antenna (HGA) and Coarse Rate Sensors (CRS) from its premises in Milan and Rome. Affiliates TAS Spain and TAS Belgium are also in charge of the TT&C subsystem and RF amplifiers (TWTAs).
The satellite, to be launched in 2020, is dedicated to the study of Dark Matter and Dark Energy, unknown but basic ingredients of today's "Standard Model" of physical cosmology. In this model, only 4% of the mass-energy of the Universe is made of ordinary matter (protons and neutrons). The rest is invisible (Dark Matter), and the Universe itself is expanding at an accelerating rate under the action of a hitherto unknown source of energy (Dark Energy).
The role of Finmeccanica's Airborne & Space Systems Division
Thanks to the cold-gas thruster system realised by Finmeccanica, ESA will be able to control the probe’s orientation in space with clusters of micro-thrusters able to make infinitesimal corrections to the direction of observation; pointing information also comes from a Finmeccanica sensor: the Fine Guidance Sensor (FGS) is a star sensor developed specifically for the Euclid mission, which when mounted directly in the telescope’s focus, ensures absolute alignment between the axis of the telescope itself and the reference stars.
Added to this equipment is the photovoltaic panel, which, with its 900 W power and 28% efficiency, provides power to the probe’s systems.