Status of the optics for the X-ray Evolving Universe Spectroscopy Mission (XEUS)

The X-ray optics for the X-ray Evolving Universe Spectroscopy Mission (XEUS) have to satisfy the demanding requirements of this ambitious mission. XEUS is under study at the European Space Agency in the frame of the Horizon 2000+ program, utilizing the International Space Station (ISS) to take X-ray astrophysics into a new era. In a single launch XEUS1 is brought into orbit and deployed, providing a 4.5 m diameter X-ray optics with an angular resolution of 5 arcseconds. After a pre-cursor phase of astrophysical observation the XEUS mirror spacecraft docks to the ISS and is there significantly expanded, whereby the effective area of the optics is increased by a factor of 5, reaching 30 m(2). This servicing at the ISS is based on the currently foreseen capabilities of the ISS and strongly relies on robotics and the presence of astronauts. The progress in developing the X-ray optics for XEUS is reported. Based on electro-formed mirror plates, which are mounted into mirror petals, the optics is modular and elegantly breaks the size limitation dictated try current designs. The necessary high level of control of the Nickel electroforming process is based on the legacy of the XMM project, launched by ESA in December 1999, but substantially improves the angular resolution and the collecting area. New materials are being explored for the fabrication of the high precision Welter I shaped mandrels, scaled model petals are being made to study the X-ray imaging properties, and full-scale structural models are built to confirm the numerical evaluation of the optics and engineering designs. Appreciable progress has been achieved on the X-ray optics, supporting the system level and feasibility studies of the mission, which are aimed at proving the feasibility of the novel concept of XEUS.