The XEUS mission and Instruments

摘要

The X-ray Evolving Universe Spectroscopy mission (XEUS) is an ambitious project under study by the European Space Agency (ESA), which aims to probe the distant hot universe with comparable sensitivity to NGST and ALMA. The effective optical area and angular resolution required to perform this task is 30 m~2 effective area and <5" angular resolution respectively at 1 keV. The single Wolter-I X-ray telescope having these characteristics will be equipped with large area semiconductor detectors and high-resolution cryogenic imaging spectrometers with 2 eV resolution at 1 keV. A novel approach to mission design has been developed, placing the detector instruments on one dedicated spacecraft and the optics on another. The International Space station (ISS) with the best ever-available infrastructure in space will be used to expand the mirror diameter from 4.5 m to 10 m, by using the European Robotic Arm on the ISS. The detector spacecraft (DSC) uses solar-electric propulsion to maintain its position while flying in formation with the mirror spacecraft. The detector instruments are protected from straylight and contamination by sophisticated baffles and filters, and employing the Earth as a shield to make the most sensitive low energy X-ray observations of the heavily red-shifted universe. After completion of an initial observation phase lasting 5 years, the mirror spacecraft will be upgraded (basically expanded to a full 10 m diameter mirror) at the ISS, while the DSC is replaced by a new spacecraft with a new suite of detector instruments optimised to the full area XEUS mirror. An industrial feasibility study was successfully completed and identified no major problem areas. Current activities focus on a full system level study and the necessary technology developments. XEUS is likely to become a truly global mission, involving many of the partners that have teamed up to build the ISS. Japan is already a major partner in the study of XEUS, with ISAS having its main interest in the first DSC.