In March 2011 ESA announced its decision to reformulate its large mission candidates (IXO, EJSM-Laplace and LISA) in the light of changing boundary conditions for international participation, particularly from NASA. As part of this reformulation exercise, a new study team was appointed by ESA to look into a new, large X-ray observatory called ATHENA (Advanced Telescope for High ENergy Astrophysics). Upon completion of this study a report will be submitted to ESA for programmatic and technical review before the end of 2011, and for scientific review by the ESA advisory bodies thereafter, in order to support an eventual decision by the SPC in February 2012.
The science objectives of ATHENA are to:
- Explore the extreme physical conditions around supermassive black holes, and determine the contribution of accretion power to the energy budget of the Universe.
- Map the large scale structure of the Universe, and reveal the physical state and cosmic evolution of the hot gas which forms the major baryonic component of the cosmos.
- Determine the importance of and establish the physical mechanism behind cosmic feedback, the process that connects black holes and cosmic structures over 10 orders of magnitude in physical size.
ATHENA is also a powerful, general-purpose observatory, able to address a wide range of current astrophysical topics
The ATHENA mission concept is currently under study by ESA, and the mission architecture is, at this stage, in a preliminary state. The baseline concept is, however, as follows:
- The heart of the Athena mission is a pair of high-throughput X-ray telescopes, based on ultra-lightweight Silicon Pore Optics (SPO) technology developed by ESA. The focal length of each telescope is approximately 11.5m.
- At one focal plane is an imaging calorimeter spectrometer, based on transition edge sensor technology, which provides an unprecedented combination of spectral resolution and effective area in the X-ray band.
- The other telescope feeds a wide field imager, based on Silicon active pixel sensor technology, which provides a large field of view for broad-band X-ray surveys and imaging, with near Fano-limited energy resolution and high count-rate capability.
- ATHENA will be launched into a halo orbit at the Sun-Earth L2 (2nd Lagrangian) point, which provides for high observing efficiency, uninterrupted observations, and a benign thermal environment.