  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 a status of the ESA's Advanced Telescope for High
Energy Astrophysics (Athena) mission, particularly focusing on the science
performance of its two focal plane instruments for the studies of extended
X-ray sources: the Wide Field Imager (WFI) and the X-ray Integral Field Unit
(X-IFU). 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 12th, 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.
