Yohkoh is a Japan/US/UK mission aiming for the study of high-energy solar physics. Its scientific operations were conducted since early September-1991 until 14-December-2001, while its orbital life was from 31-August-1991 to 12-September-2005. Yohkoh was named after the Japanese word meaning 'sunshine'.
Yohkoh steadily continued its observation more than ten years, and
this made Yohkoh the world's first space mission to provide solar images
over a whole solar cycle. On 14-Dec-2001, however, observing an annular eclipse
Yohkoh lost its attitude control and became unable to resume observations.
For more information about Yohkoh mission, spacecraft, and instruments, we have several versions of documents, including some external links. Hope you find the article that best meets your needs.