ATHENA: phase A study status and optics/instrument accommodation (Conference Presentation)

ATHENA is the 2nd ‘Large’ mission in the ESA Cosmic Vision programme, and currently in Phase A with a view to adoption in 2021. This paper presents an overview of the ATHENA mission architecture, instruments and spacecraft design, highlighting the main spacecraft-level challenges involved in realizing the mission. Firstly a consideration of the accommodation of the Silicon Pore Optics (SPO) Mirror Modules (MM) is presented, taking into account: The procedure for MM integration into the Mirror Assembly (MA) to achieve the required alignment; stiffness requirements and handling scheme required to constrain deformation under gravity during x-ray testing; temperature control to constrain thermo-elastic deformation during flight; the capability to focus using the Instrument Switching Mechanism (ISM), and strategies to minimize mechanical loading of the MMs during launch. Then the accommodation of the X-IFU and WFI instruments onto the Science Instrument Module (SIM) is presented, considering in particular: The very large thermal dissipation (~4 kW at a variety of interfaces and temperatures) necessitating a challenging thermal design for the SIM; the location of the SIM at the top of the launch stack, necessitating combination of a stiff SIM design with maximized instrument support, and mechanical-damping measures to maintain the loads seen by the instruments to feasible levels. The paper concludes with a programmatic outlook to the adoption.