Skip to Main Content


IXO mission graphic

International X-ray Observatory

Phase: Under Study

Mission Project Home Page -

Program(s):Physics of the Cosmos

Pin it

The International X-ray Observatory (IXO) is a new X-ray telescope with joint participation from NASA, the European Space Agency (ESA), and Japan's Aerospace Exploration Agency (JAXA). This project supersedes both NASA's Constellation-X and ESA's XEUS mission concepts.

In mid-2008, a officials from ESA, NASA, and JAXA headquarters agreed to conduct a joint study of IXO with a single merged set of top-level science goals. This agreement established key science measurement requirements. The spacecraft configuration for the IXO study is a mission featuring a single large X-ray mirror and an extendible optical bench, with a focal length of ~20 m, and a suite of five focal plane instruments.

The X-ray instruments under study for the IXO concept include: a wide field imaging detector, a high-spectral-resolution imaging spectrometer (calorimeter), a hard X-ray imaging detector, a grating spectrometer, a high timing resolution spectrometer, and a polarimeter. The IXO mission concept is being submitted to the U.S. Decadal Survey committee and to ESA's Cosmic Vision process.

Related Links
  • ESA IXO Website -