ASTENA: an innovative mission concept for broadband high-energy astrophysics

Hard-x/soft gamma-rays are probes of the most powerful phenomena in the universe. Unlike soft x-ray astrophysics, this band has benefited less from the technological advancement due to the difficulty to absorb this radiation and to the lack of focusing instrumentation. For these reasons the quest for innovative soft gamma-ray instrumentation is pressing and their effective recognition and realization are urgent. In this context, and in the framework of the AHEAD project, funded by the European Commission, the ASTENA experiment was proposed as an innovative mission concept to face some of the most debated questions in hard x-/gamma-ray astronomy. This effort will be done through the use of instruments based on groundbreaking technologies, capable of providing unprecedented broad energy passband in a wide field of view, high sensitivity observations and, at the same time, sub-arcminute localization of gamma-ray sources and polarimetric measurement. In this paper we describe the instruments on board ASTENA, the technologies involved, the performances achievable with their exploitation and their level of readiness.