ATHENA (Advanced Telescope for High-ENergy Astrophysics) is an X-ray telescope, selected in June 2014 as the second large (L-class) mission in ESA's Cosmic Vision Programme. It is designed to study the hot and energetic universe, answering questions about the growth of back holes. To achieve the mission's science objectives, ATHENA carries a cryogenic X-ray spectrometer called the X-ray Integral Field Unit (X-IFU) and a Wide Field Imager (WFI), to which IWF will contribute.
ATHENA is planned for launch in 2031. It will operate at L2, the second Lagrange point of the Sun-Earth system, in a large amplitude halo orbit.
Following a detailed study phase, ATHENA will be proposed for "adoption" around 2021, before the start of the construction phase.
Further information on ATHENA is found at ESA.