Jean-Philippe Beaulieu

Status report on the Ariel space mission

Ariel is the fouth M class mission from the European Space Agency due to launch late 2029. It is a 1m space telescope at L2 entirely dedicated to the observations of exoplanet atmospheres. Ariel will observe around a thousand transiting planets, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types. Ariel will use transit spectroscopy in the 1.1-7.8 μm spectral range and photometry in multiple narrow bands covering the optical and near-infrared (NIR). We will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials and thus reveal their bulk elemental composition (especially C, O, N, S, Si). Observations of these warm/hot exoplanets will drive understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. Ariel will thus provide a complete picture of the chemical nature of the exoplanets. I will present the status of the development of the Ariel space mission, discuss the evolution of the science case in the context of JWST, and the very important ground based work in preparation of the Ariel input catalogue.