ESA has opened the Athena web site
Athena is an X-ray observatory to be proposed as a large mission for the ESA science program.
Athena will be conceived to answer some of the most pressing questions in Astrophysics for the late 2020s that can uniquely be addressed with X-ray observations.
Athena will transform our understanding of two major components of the Cosmos:
The Hot Universe : the bulk of visible matter in the Universe comprises hot gas which can only be accessed via space-based facilities operating in the X-ray band. Revealing this gas and relating its physical properties and evolution to the cosmological large-scale structure, and the cool components in galaxies and stars, is essential if we are to have a complete picture of our Universe.
The Energetic Universe : accretion onto black holes is one of the major astrophysical energy generation processes, and its influence via cosmic feedback is profound and widespread. X-ray observations provide unique information about the physics of black hole growth and the causes and effects of the subsequent energy output, as well as revealing where in the Universe black hole accretion is occurring and how it evolves to the highest redshifts.
Read more about the Athena science and the mission itself, by looking at Publications.