Athena factsheet

Name: Athena (Advanced Telescope for High-ENergy Astrophysics)

Status: Athena was selected as the second large (‘L-class’) mission in ESA's Cosmic Vision 2015–25 plan on 27 June 2014. The mission is now in the study phase; once the mission design and costing have been completed, it will be proposed for ‘adoption’ in June 2023, after which construction can begin.

Planned launch: 2035

Mission theme: The hot and energetic Universe

Mission objectives: By combining a large X-ray telescope with state-of-the-art scientific instruments, Athena will address key questions in astrophysics, such as: How and why does ordinary matter assemble into the structures (galaxies, galaxy groups and galaxy clusters) that we see today? and How do black holes grow and shape their environment, as well as the cosmological evolution of the galaxies hosting them?

To understand these questions, it is necessary to a) map hot gas in the Universe (gas in clusters and groups of galaxies, and in the space between galaxies) to determine its physical properties and evolution, and b) discover accreting supermassive black holes out into the early Universe and reveal how matter and energy flow in and out of these systems. To achieve these goals, we need to observe gas at millions of degrees in temperature, and energetic phenomena involving particles moving at speeds comparable to the speed of light. This requires space-based observations in the X-ray portion of the electromagnetic spectrum – which Athena will provide.

Athena will be open to the worldwide astronomical community. The observatory’s scientific performance will exceed any existing or planned X-ray mission by more than ten times in several different ways: light collecting area, X-ray survey speed, weak emission line sensitivity and spatially-resolved high-resolution spectroscopy. Athena is therefore expected to have a revolutionary impact on almost every corner of modern astrophysics: planets and exoplanets, compact objects (neutron stars and stellar-mass black holes) in our own galaxy, supernova explosions and remnants, and active stars, to mention just a few examples.

Furthermore, Athena will be able to rapidly respond to unexpected events occurring anywhere in the sky – within four hours for 50% of these events. The spacecraft will be able to follow-up on transient sources, most notably those associated with gravitational wave and neutrino events.

What’s special?: Athena will be the largest X-ray observatory ever built, investigating some of the hottest and most energetic phenomena in the Universe with unprecedented accuracy and depth

Spacecraft and instruments: The Athena scientific payload will have three key elements:

• an X-ray telescope with a focal length of 12 metres, and the largest collecting area ever studied
• two instruments:
  • an X-ray Integral Field Unit (X-IFU) for high-spectral resolution imaging
  • a Wide Field Imager (WFI) for high count rate, moderate resolution spectroscopy over a large field of view

Journey and orbit: Athena will be launched to a halo orbit around the Sun-Earth Lagrange point 1 (L1)

Lifetime: Four years, with possible extensions

Collaboration with LISA: There is the exciting and unique opportunity for Athena to collaborate with ESA’s forthcoming gravitational-wave observatory, LISA (Laser Interferometer Space Antenna), planned for launch in 2037

While Athena and LISA are individually outstanding, the additional science that the two missions will achieve by operating concurrently and gathering coordinated observations (so-called ‘multi-messenger’ astronomy) will provide further breakthroughs and address fundamental questions in modern astrophysics. Together, the duo will unveil new clues about distant and merging black holes, bright quasars in active galaxies, rapid jets believed to be produced around spinning black holes, the cosmic distance scale, and the speed of gravity. These synergies are addressed in this white paper from the Athena-LISA Synergy Working Group.

Partnership: Athena is an ESA-led mission with important contributions from NASA and JAXA. The WFI instrument is provided by an international consortium led by the Max Planck Institute for extraterrestrial Physics in Germany, involving several ESA Member States and the US. The X-IFU instrument is provided by an international consortium led by France (with IRAP as the PI Institute and CNES as the managing authority), the Netherlands (SRON, Co-PI institute) and Italy (INAF-IAPS, Co-PI institute), with further contributions from several ESA Member States, Japan and the US.

Athena mission facts

Athena will perform around 300 observations of strong X-ray sources per year, with a typical duration of 28 hours per pointing. Mapping million-degree gas permeating the space between galaxies will be one of the mission’s primary goals.

Around five times per month, Athena’s routine observing plan will be interrupted by ‘target of opportunity’ observations (for example, gamma-ray bursts and other transient events).

Athena will observe hundreds of thousands of black holes, from relatively near to far away, and map the million-degree-hot matter in their surroundings. This includes black holes that formed in the first few hundred million years of the Universe’s long history.