De-risk assessment: Fully carbon-based filters for X-ray astronomy

•Filters were designed and built for meeting the mechanical, environmental and performance requirements defined in the ongoing ATHENA mission planning.•X-ray Integral Field Unit (X-IFU) utilizes several THFs with area and performance requirements beyond any existing or accepted mission.

Achievements and status:•Designed filters were successfully produced and they were extensively characterized and compared with the achieved results from the baseline polyimide (PI) based X-IFU THFs filter candidate structures.•Demonstration the feasibility and reliability of CNT meshes with small blocking factors (<4% at 250 eV, <2% at E > 400 eV) was reached with full success. Also, the mechanical integration of the mesh and membrane was significantly improved when compared to previously studied structures with CNT filters or with baseline PI filters. Benefits:•A main innovation of this project is a large area CNT mesh structure that can be integrated successfully with the large area CNT membrane. Other innovations were related to methods to decrease pin hole density on the membranes by utilizing multilayer membranes and to improve the mesh strength by using oriented CNT structures.•This technology is foreseen to bring a notable performance gain to X-IFU thermal filters (THFs).