In May 2008, ESA and NASA established a coordination group involving
ESA,
NASA and
JAXA, with the intent of exploring a joint mission merging the ongoing
XEUS and Constellation-X efforts. The coordination group met twice, first in May 2008 at
European Space Research and Technology Centre (ESTEC), then in June 2008 at the Center for Astrophysics. As a result of these meetings a joint understanding was reached by the coordination group on a proposal to proceed towards the goal of developing an
International X-ray Observatory (IXO). The coordination group proposed the start of a joint study of IXO. A single merged set of top level science goals and derived key science measurement requirements were established. == References ==