The International X-ray Observatory (IXO) is an L class mission candidate within the science programme Cosmic Vision
2015-2025 of the European Space Agency, with a planned launch by 2020. IXO is an international cooperative project,
pursued by ESA, JAXA and NASA. By allowing astrophysical observations between 100 eV and 40 keV using a very
large effective collecting area mirror and state-of-the art instruments, IXO would represent the new generation X-ray
observatory, following the XMM-Newton, Astro-H and Chandra heritage.
The IXO mission concept is based on a single aperture telescope with an external diameter of about 3.5 m and a focal
length of 20 m. The focal plane consists of a fixed and a moveable instrument platform (FIP and MIP respectively). The
model payload consists of a suite of five instruments which can each be located at the telescope's focus by the MIP,
1. a wide field imager (WFI) based on a silicon DEPFET array;
2. a Hard-X-ray Imager (HXI), which will be integrated together with the WFI;
3. an X-ray microcalorimeter spectrometer (XMS);
4. an X-ray Polarimeter camera (X-POL) based on a gas cell with integrated anode array;
5. a High-Time Resolution Spectrometer (HTRS) based on a silicon drift detector array.
In addition, the FIP will carry a grating spectrometer (XGS) mounted in a fixed position and which will allow
simultaneous observations with the on-axis instrument.
This paper provides a summary of the preliminary results achieved during the assessment activities presently ongoing at
ESA. Whereas we will provide a brief overview on the overall spacecraft design, we will focus on the payload
description, characteristics, the technology used and the accommodation on the instrument platform.