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.


Read more about the Athena science and the mission itself, by looking at the official site
http://www.the-athena-x-ray-observatory.eu/