The Atmospheric Remote-sensing Infrared Exoplanet Large-survey (Ariel) mission will address the fundamental questions on what exoplanets are made of and how planetary systems form and evolve by investigating the atmospheres of many hundreds of diverse planets orbiting different types of stars. This large and unbiased survey will contribute to answering the first of the four ambitious topics listed in the ESAs Cosmic Vision: What are the conditions for planet formation and the emergence of life?. Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. There is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planets surface and atmosphere is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planets birth and evolution. The Ariel survey is aiming to provide a complete picture of the chemical nature of the exoplanets and relate this directly to the planetary parameters and the type and chemical environment of the host star.

The main motivation of the project proposed here is to carry out the necessary developments during the next triennium for the Ariel mission. Our involvement in Ariel is at a very high level, with co-Principal Investigator responsibilities by I. Ribas and E. Pallé, as well as National Project Manager by J. Colomé. Furthermore, E. Pallé is a member of the Ariel Science Team, appointed by ESA. The Spanish
contribution, fully provided by the three proposing teams, has both scientific and technical aspects. Regarding science, we actively participate in various working groups within the Ariel structure of the consortium, with leadership positions in several of them, such as the Stellar Activity WG otr the Ariel-ELT Synergies WG. On the technical side, the contributions are multiple and with mission critical status. Our coordinated effort gathers together the groups that share responsibility for the Spanish participation in the mission and our ultimate goal is to make Ariel a great success.

However, Ariel is part of a well-defined roadmap of space missions and ground-based projects with complementary and synergistic approaches in which our team is heavily involved. These projects include finding and characterizing planets via transit photometry and radial velocity measurements, as well as the atmospheric characterization using low and high spectral dispersion techniques. These will provide the golden sample of planets to be explored by Ariel. With all these projects combined, the final objective is to further our understanding of exoplanets, placing our own planet Earth and Solar System in the context of other planetary systems in the Universe, and, ultimately, exploring temperate planets to search for signs of biological activity.