The properties (temperature, density, chemical composition, velocity) of hot astrophysical plasma and the physical processes affecting them (heating/cooling, turbulence, shocks, acceleration) can be probed by high−resolution X−ray spectroscopy, to be complemented by high−spatial−resolution imaging. The paper presents the status of the European Space Agency’s Advanced Telescope for High Energy Astrophysics (Athena) mission, particularly focusing on the science performance of its two focal−plane instruments for studies of extended X−ray sources: the wide−field imager and the X−ray integral field unit. This paper then provides a brief summary of the breakthroughs expected with Athena on the astrophysics of hot plasma, building on the vast heritage of the discoveries and revolutionary results obtained by Chandra and XMM−Newton in this field. As of November 12, 2019, Athena successfully concluded its feasibility study, and has since then moved into the definition phase, with a launch date scheduled in the early 2030s.
