ALEXIS

ALEXIS (for Array of Low Energy X-ray Imaging Sensors) was a space observatory of six soft-X-ray (or extreme ultraviolet) telescopes that monitored the sky for X-ray transients, yielding sources for further study. It was launched in 1993 and operated until 2005. It was an experiment in using very small satellites. The spacecraft had considerable problems when first launched, which required effort to work around.