2. International Collaboration

A close relationship between ISAS and NASA has existed from early 1989. The YOHKOH mission (Solar-A) launched in 1991, for example, provides an excellent example for a modest yet scientifically highly rewarding collaboration in astrophysics. The collaboration on ASTRO-D was the second example. We quickly reached an agreement that NASA would collaborate in the development of the X-ray telescopes, the X-ray CCD cameras, and computer software.

Like the YOHKOH collaboration, this ISAS/NASA collaboration emphasized the importance of developing instruments jointly. Accordingly, it was decided that the X-ray telescopes would be developed by GSFC/Nagoya/ISAS groups and the CCD cameras by MIT/Pennsylvania State College/Osaka/ISAS groups. The gas scintillation imager was to be built by Tokyo University/ISAS groups. Software for satellite operation, data processing and analyses was to be prepared as a joint effort by several Japanese and US groups under close coordination. In addition, NASA offered tracking support through its Deep Space Networks.

The scientific aspects of the mission (such as the optimization of the scientific capabilities and the planning of observations) were discussed in the International ASTRO-D Science Working Group consisting of participating scientists from Japan and the US. Several senior scientists from the US and one from the UK were also included as experiment advisors. This Working Group met frequently as shown in the table. The table also shows the number of overseas visitors each year during the five-year development of ASCA.