An innovative telescope concept for XEUS and its performance

The XEUS mission is conceived as Europe's next generation X-ray space observatory aiming at the detection and spectroscopy of faint astronomical sources located at high red-shift. With unprecedented sensitivity to the million-degree hot universe, XEUS is supposed to explore key areas of contemporary astrophysics. Due to the considerable telescope focal length of 35 m, the mission profile foresees two separate spacecraft, one carrying the mirrors, the other one carrying the detectors, flying in precise formation as if connected by a rigid telescope tube. The paper presents an innovative light-weight X-ray telescope design and its predicted performance as resulting from a recent study on XEUS Telescope Accommodation funded by the European Space Agency ESA. The main challenge of this work was to find a telescope concept compatible with the Ariane V launcher constraints while meeting highly demanding optical performance requirements.