Disentangling the properties of matter and dark energy is one of the key problems of current astrophysics. This is the main objective of theEuclid mission, considered the most ambitious challenge for European astrophysics in the coming years. Euclid will carry out bot photometric and spectroscopic surveys that will generate the largest and deepest maps ever obtained of the Universe. These will make it possible to trace the distribution of light from galaxies and the components of matter and dark energy in the different epochs of the Universe. In addition, the expected sensitivity and angular coverage of such surveys will allow enormous progress in many areas of astrophysics ranging from the local Universe to the most distant. The researchers from the UPCT and the IAC signing this proposal maintain common scientific and technological interests that allow an adequate synergy as shown by their achievements during these years in the various working groups of the consortium, and that is reflected in a remarkable scientific production. This collaboration has also been the seed that has enabled the birth of other joint projects. The collaboration between both groups within the framework of the Euclid project was established about ten years ago, and has been maintained uninterruptedly, strengthening Spanish participation in the mission and providing throughout this preparation period a significant number of both technical and scientific results. That has made possible to complete the technological development of the mission, and on the other hand, to acquire the knowledge, tools and complementary data necessary for optimal exploitation of the Euclid data.

The purpose of this proposal is to continue supporting the participation of the IAC and the UPCT in the mission, which up to now has implied important contributions to the Infrared Spectrograph Instrument Control Unit (ICU) (NISP), and to the processing and exploitation Euclid data scientist. Now that the mission is nearing its launch, scheduled for 2023, we are entering a phase in which the knowledge and techniques acquired during these ten years will be applied to the data collected by that mission. After the commissioning period, the first scientific data will arrive in 2024 and therefore an explosion of scientific articles can be expected in the coming years. The UPCT and IAC groups, due to their experience, capabilities and, in addition, their access to important astronomical facilities (GTC, ESO) are in a perfect position to lead key aspects of Euclid science and to make relevant contributions in numerous fields. These areas have in common the study of the physical laws that govern the evolution of the Universe and how the complexity of structures that we observe today has been generated from the initial singularity. Two targets of the present proposal are, on the one hand, the study of the large structures of the Universe, clusters and protoclusters of galaxies, and on the other, the physical conditions that make possible the formation of complex organic molecules as precursors of the rich diversity of biological organisms that we observe. today. These are key problems in current science and their study will guide important lines of basic science in the coming decades.