300 mK and 50 mK cooling systems for long-life space applications

The X-ray Evolving Universe Spectroscopy mission is a candidate for the ESA Cosmic Vision 2015–2025 plan, with two possible instruments at 300 mK and 50 mK. Astrium, under ESA contract, has worked with MSSL, RAL, and CEA-SBT, to propose a suitable payload accommodation scheme meeting ESA’s requirements. Exhaustive trade-offs were performed, according to a described methodology, leading to two designs incorporating closed-cycle active coolers maximizing well proven heritage concepts. These concepts are described, and although they have been prepared for XEUS, there are other future mission concepts which could also benefit from 50 mK cooling with a lifetime greater than 10 years.