NASA and Japan Join Together for X-ray Astronomy: ASCA

ASCA Satellite in the clean room
The ASCA satellite in the clean room.

Japan’s Institute of Space and Astronautical Science (ISAS) next X-ray telescope satellite, Astro-D (renamed ASCA when it launched), called for using focusing X-ray optics. The high energy of X-rays (small wavelength), makes focusing them quite a challenge. However, in the mid-1980s, while Astro-D was under development, NASA’s Goddard Space Flight Center had a team working to develop techniques to build mirrors to focus X-rays in a telescope using thin light-weight mirrors.

One member of the Goddard team, Peter Serlemitsos, had previously collaborated closely with members of Nagoya University. This connection and the promising technology Serlemitsos had been developing to focus X-rays led to a collaboration on the X-ray mirrors for Astro-D between NASA and ISAS. This was the first collaboration between NASA and ISAS in X-ray astronomy; however, there was a previous collaboration between them on a satellite mission to study the Sun, called YOHKOH.

In addition to collaborating on the mirrors, ISAS and NASA also coordinated the development of software for satellite operation, data processing and analyses.

ASCA was launched in February 1993 where it observed cosmic X-ray sources until July 2000 when the satellite lost attitude control after a geomagnetic storm. The satellite reentered the Earth’s atmosphere in March 2001.